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Genetics
Final exam cram
261
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Undergraduate 2
04/07/2009

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Term
Coding Strand
Definition
the strand opposite to the template strand
Term
Codons
Definition
– 3-nucleotide sequences within the mRNA that specify particular amino acids. Sequence within mRNA determines sequence within polypeptide (mRNA). Where the genetic information is coded within mRNA
Term
Core Promotor
Definition
determines transcriptional start site, and produces a basal level of transcription. Composed of TATA box and Transcriptional start site.
Term
Chromosomal DNA
Definition
stores information in genes
Term
Eukaryotic transcription
Definition
– similar to bacterial, but more complex. 3 RNA polymerase subunits, and 3 RNA polymerases – RNA pol I, RNA pol II, and RNA pol III.
Term
Messenger RNA (mRNA)
Definition
Temporary copy of a gene that contains information to make a polypeptide. Identical to DNA sequence except for substitution of Uracil for Thymine.
Term
Open Complex
Definition
17 bases long, is where the RNA polymerase attaches to – opened at the TATA box. Behind, DNA rewinds into double helix. RNA synthesis rate is 43 nucleotides per second.
Term
Polypeptide
Definition
– part of a functional protein that contributes to an organism’s traits
Term
Preinitiation complex
Definition
of RNA polymerase II, and 5 general transcription factors (TFIID, TFIIB, TFIIF, TFIIE, TFIIH[acts as helicase]), and a mediator
Term
Pribnow Box
Definition
TATA box that is the -10 sequence of the promoter region
Term
Promotor
Definition
Site for RNA polymerase to bind to (DNA). Recognised by Transcription Factors. Eukaryotes – 3 features in common for structural genes – regulatory elements, TATA box, Transcriptional start site.
Term
Regulatory elements
Definition
affect binding of RNA polymerase to the promoter: Enhancers and Silencers
Term
Regulatory sequences
Definition
sites for binding of regulatory proteins which influence transcription rates (DNA) Recognized by Transcription Factors.
Term
Replication
Definition
making of DNA copies that are transmitted from cell to cell and from parent to offispring
Term
ρ independent termination
Definition
termination of translation facilitated by 2 RNA sequences - stem loop, and U rich sequence behind stem loop. As the RNA polymerase is paused at the stem loop, the U can’t hold on,
Term
Ribosomal Binding Site
Definition
site for binding of ribosome. Signals region where transcription will start. _Eukaryotes – looks for start codon in mRNA (mRNA)
Term
RNA polymerase - what direction does it travel in? synthesize in?
Definition
travels 3’-5’, synthesizing RNA 5’-3’
Term
RNA pol I
Definition
Transcribes rRNA genes (except for 5S rRNA) (eukaryotic)
Term
RNA pol II
Definition
Transcribes structural genes (thus mRNA), transcribes some snRNA (eukaryotic). Form preinitiation complex with the General transcription factors.
Term
RNA pol III
Definition
all tRNA genes and 5S rRNA gene (eukaryotic)
Term
RNA polymerase holoenzyme
Definition
binds loosely to DNA and scans until it recognizes -10 and -35 squences of the promoter region.
Term
RNA Transcripts
Definition
have different functions
Term
Sense strand
Definition
see coding strand
Term
Start Codon
Definition
specifies the first amino acid in a sequence formylmehionine in bacteria, or methionine in eukaryotes. (mRNA)
Term
Structural genes
Definition
encode polypeptides – must encode in the proper cell at the proper time and in the right amounts
Term
Stop Codon
Definition
– specifies the end of polypeptide synthesis (mRNA)
Term
Termination
Definition
end of RNA synthesis when RNA-DNA hybrid of open complex is forced to separate. In bacteria, is either ρ dependant or ρ independent.
Term
Terminator
Definition
Signal for end of transcription (DNA)
Term
Template Strand
Definition
the strand that is physically transcribed
Term
Transcription
Definition
Produces an RNA copy of a gene. Does not alter the structure of DNA. Has 3 stages: Initiation, Elongation, Termination, which are protein-DNA interactions, like RNA polymerase
Term
Transcription factors
Definition
– protein that binds to DNA to regulate action of RNA polymerase
Term
Translation
Definition
Production of a polypeptide using information in mRNA
Term
Steps to make a protein
Definition
cDNA provides info for transcription of mRNA, which provides the template to make a polypeptide.
Term
5’ capping / 3’ polyA tailing
Definition
RNA modification of mRNA transcripts.
Term
ATP dependent chromatin remodelling
Definition
– energy of ATP is used to alter structure of nucleosomes and make DNA more accessible. Can significantly alter gene expression.
Term
Base Editing
Definition
RNA modification in tRNA
Term
Capping
Definition
the covalent addition of 7-methyl guanosine to the 5’ end of an mRNA. Happens when pre-mRNA is being synthesized by RNA pol II. 3 step process: de-phosphorylation, hyldrolyzation, methylation. Cap structure then recognized by cap-binding proteins.
Term
Covalent Modification of Histones
Definition
– amino terminals of the histones are modified (acetylation, phosphorylation, methylation)
Term
Exon
Definition
coding sequences
Term
Introns
Definition
– non-coding, intervening sequences. Can be visualized by denaturing dsDNA and mixed with complementary mRNA. The 2 hybridize. If present, forms r-loops where introns are. Bound by specific sequences recognized by the spliceosome. Gives benefit of alternative splicing.
Term
Nucleosome
Definition
a structure made of DNA wound around histone octamers – tight wrapping inhibits function of RNA pol I – fixed by loosening of chromatin structure through Covalent modification of histones or ATOP dependent chromatin remodeling
Term
RNA modification
Definition
gene expression should be collinear (DNA=RNA=polypeptide), but euk. Structural genes are not always. Exons are interrupted by introns – entire gene product froduced during transcription, but introns are later excised, and exons are spliced.
Term
RNA splicing
Definition
the excision of introns from transcribed product. Can be done by group-1 inttron splicing, group 2 intron splicing, or by a spliceosome, Groud 1 and 2 self-splice, and does not req. aid of enzymes. RNA is its orn Ribozyme.
Term
snRNPs
Definition
small nuclear RNA and a set of proteins.
Term
Spliceosome
Definition
complex that splices pre-mRNA, composed of snRNPs
Term
Tailing / poly-A tail
Definition
addition of adenine nucleotides to 3’ ends. PolyA tail not encoded in gene sequence. Added after transcription of the gene.
Term
Trimming
Definition
cutting precursor rRNA and tRNA into individual parts. A form of modification
Term
Amino Acids
Definition
if nonpolar and charged – hydrophilic = surface dwellers
Term
Degenerate
Definition
when there are several codons that encode the same amino acid
Term
Enzymes
Definition
Accellerate chemical reactions within a cell.
Term
Anabolic enzymes
Definition
synthesize molecules and macromolecules
Term
Catabolic enzymes
Definition
Break down large molecules into small ones (energy!)
Term
Genetic code
Definition
the dictionary used for translation of mRNA into peptides. Deciphered by the production of synthetic mRNA with polynucleotide phosphorylase in a cell free system, to which mRNA ribosomes and tRNA – AA are addedin in specific ratios (other methods too)
• UUU – phenylalanine
• AAA – Lysine
• GGG – glycine
• CCC - Proline
Term
mRNA translation
Definition
lead to synthesis of proteins
Term
One gene-one polypeptide theory
Definition
not all proteins are enzymes like in beadle and tatum’s experiments
Term
Polypeptide Chain directionality?
Definition
has directionality (5’  3’): stuck together by peptide bonds. First exposed amino acid group = N-terminal, Last amino acid has exposed carboxy terminal = Cterminal – C& N condense
Term
Protein function
Definition
defines cell characteristics. Perform variety of functions. Key proteins are enzymes
Term
Reading Frame
Definition
Set by the start codon, is the 3 codons that are being interpereted as a word.
Term
Special Codons
Definition
nearly universal in all species
Term
Start codons
Definition
AUG (sometimes GUG or UUG in translation initiation)
Term
Stop codons
Definition
UAA, UAG, UGA
Term
tRNA
Definition
caries amino acid and recognizes triplet RNA sequences
Term
Wobble Base
Definition
the 3rd position in a codon
Term
Adaptor hypothesis
Definition
that tRNA just look for complementary codon
Term
Aminoacyl-tRNA synthetases
Definition
enzymes that attach amino acids to tRNA (Charging). 1 per amino acid. Catalyze 2 step rxn btwn Amino acid, tRNA and ATP. Very accurate as anti-codon and tRNA are used for recog.
Term
Coupling
Definition
translation and transcription happen at the same time. = Polysome
Term
Polysome
Definition
mRNA that is undergoing both transcription and translation
Term
Recognition between tRNA and mRNA
Definition
anticodon in tRNA recognizes complementary codon in mRNA
Term
Release Factors
Definition
recognize stop codons, 3d structure similar to tRNAs – BACTERIAL: RF1 (UAA, UAG), RF2 (UAA, UGA) RF3 (binds to GTP and helps facilitate termination) EUKARYOTIC: eRF (recognizes all 3 stop codons)
Term
Ribosomal Functional Sites
Definition
APE, 5’ – 3’ direction
Peptidyl sit
Aminoacyl site
Exit Site
Term
Ribosome
Definition
– macromolecular complex across whose surface translation occurs. Bacteria have 1 type ([30s: 16s] [50s; 23s + 5s]), Eukaryotes have 2 (cytoplasm & mitochondria/chloroplasts) ([40s; 18s][60s; 5s, 28s, 5.8s]). Composed of a Large and small subunit formed of proteins and rRNA
Term
Shine-Dalgarno sequence
Definition
– ribosomal binding site 9 nucleotides long – complementary to sequence in 16sRNA. Binding occurs through hydrogen bonds
Term
Translation Elongation stage
Definition
addition of amino acids to polypeptide chain. Very fast (faster in bact). Ribosome catalyzes itself via peptidyltransferase in the 50s subunit
Term
Translation Initiation Stage
Definition
Bacteria: initiation complex formed by mRNA, initiation tRNA – tRNAfmet (IF3, IF2) and ribosomal subunits. Initiator tRNA recognizes start codon in mRNA – shine dalgarno sequence Eukaryotes: similar, except that eukaryotic Initiation Factors are required (eIFs). tRNAmet looks for 1st AUG after 5’ cap.
Term
Translation Termination Stage
Definition
when stop codon is reached- codons recognized by release factors
Term
tRNA structure
Definition
– 2ndry structure = cloverleaf = 3 stem-loops, acceptor stem, and 3’ single strand region (ACC). 3rdry = more folding. Often contain modified nucleotides on top of AUGC
Term
Wobble hypothesis
Definition
occurs in 3rd position, is tolerance for certain mismatches.
Term
Activators
Definition
bind to DNA and increase transcription
Term
Antisense RNA
Definition
RNA strand complimentary to mRNA.
Term
Bacteriophage
Definition
viruses that infect bacteria. Termed λ phage. Has 2 life cycles – Lytic and lysogenic. Which is chosen depends on cellylar proteases  cll easily degraded by proteases, and whether or not they’re produced depends on environmental conditions
Term
Bacteriophage operon
Definition
48,503 nucleotides long, circular - see notes...........
Term
• Q
Definition
antiterminator needed for lytic cycle. Also permits transcription through PR.
Term
• P
Definition
same as above
Term
• Cll protein
Definition
activator protein
Term
• PRE
Definition
promoter for λ repressor during establishment of lysogenic cycle
Term
• Cro
Definition
binds OR and OL
Term
• OR
Definition
– if Cro binds here, inhibits transcription from PRM in leftward direction. Prevents expression of cl gene and λ repressor, low level of transcription in rightward direction enabling transcription of O, P, and Q genes needed for the replication of λ DNA
Term
• OL
Definition
inhibits transcription from PL
Term
• Cl
Definition
λ cl repressor binds to operators and inhibits expression of genes req. for lytic cycle. Also activates Prm
Term
• PRM
Definition
enough λ repressor to maintain lysogenic cycle
Term
• PR
Definition
– controls large operon encoding proteins necessary fpr assembly of Phage coat, packaging of DNA, and lysis of bacterial cell.
Term
• N protein
Definition
antiterminator. Binds to RNA polymerase and prevents transcriptional termination
Term
• Clll protein
Definition
protein helps stabilize cll activator protein
Term
• Bet, exo
Definition
Recombinant proteins
Term
• xis
Definition
Excisionase = Pl
Term
• int
Definition
= integrase. Integrates λ DNA into bacterial chromosome
Term
• Regulator of late genes
Definition
late promoters for the lytic cycle.
Term
Bacteriophacge RNA transcripts
Definition
encode 2 proteins – N and cro.
Term
cAMP
Definition
regulates catabolite repression of lac operon – produced by ATP by adenylyl cyclase, which is inhibited by glucose. Binds to CAP
Term
CAP
Definition
Catabolite Activator Protein – activarot protein to which cAMP binds
Term
Catabolite repression in lac operon
Definition
- if exposed to lactose and glucose, glc used first, with catabolite repression preventing lac operon from functioning. Regulated by cAMP. Glc = cAMP inhibition = lac inhibition
Term
Covalent Modification of proteins
Definition
some modifications are irreversible, while acetylations, phosphorylation, and methylation are transient
Term
Diauxic growth
Definition
sequential use of 2 sugars by a bacterium
Term
Feedback inhibition
Definition
regulates the activity of metabolic enzymes where the final product of a polypeptide pathway inhibits an enzyme that acts early in the pathway.
Term
Inducer Allolactose
Definition
binds to lac repressor and inactivates it
Term
lac Operon
Definition
can be regulated by repressor protein mechanism (lac repressor protein and allolactase as inducer) or activator protein mechanism
• Lac I – inducer
• Lac P –
• Lac O –
• Lac Z – β-galactosidase
• Lac Y – Lactose permease
• Lac A – Galactoside transacetylase
Term
Lactose present no glc in lac operon
Definition
– lacI induced, lac repressor inactivated
Term
No lacto, no glc lac operon
Definition
lac repressor active, cAMP active
Term
Lac and glc
Definition
lac induced, repressor inactivated, no cAMP inhibition
Term
Glc no lac
Definition
lac repressor active, no cAMP inhibition
Term
Lysogenic cycle
Definition
λ DNA integrates into host chromosome (prophage)  copied by DNA  sometimes can be excised (induction), but rare. TEMPERATE stage when the going is thoughll and clll complex accumulates to high levels, lysogenic cycle prevails.
Term
Lytic cycle
Definition
phage binds to cell, injects its DNA, uses cell toolkit to produce many new phages  host DNA degraded  cell lyses and releases new phages to attack new cells. VIRULENT stage – when things are great
Term
Negative Control
Definition
regulation by repressor proteins
Term
Operon
Definition
group of structural genes under the control of 1 promotor which encodes polucistronic mRNA for 2 + structural genes. – allows for coordinated regulation of proteins with common functions. Has different regions: promoter, terminator, structural genes, operator.
Term
Operator
Definition
. of bases that provides a binding site for a regulatory
Term
Positive Control
Definition
– regulation by activator proteins
Term
Posttranslational regulation
Definition
– after translation usually via feedback inhibition, or by control of protein function by covalent modification of their structure.
Term
Promotor
Definition
– signals the beginning of transcription
Term
Repressors
Definition
Bind to DNA and inhibit transcription – Negative control
Term
Repressors
Definition
Bind to DNA and inhibit transcription – Negative control
Term
Structural Genes
Definition
encode proteins.
Term
Terminator
Definition
specifies end of transcription.
Term
Trancscriptional regulation
Definition
usually happens at transcription initiation. Increases or decreases rate of RNA synthesis uses repressors for negative control, and activators for positive control
Term
Translational regulation
Definition
can be through transcription, or through antisense RNA. Antisense RNA binds to mRNA so it cant be translated.
Term
CpG islands
Definition
1000-2000 nucleotides long, with high number of CpG sites. Unmethylated in housekeeping genes. Maybe be methylated in tissue specific genes to silence, change binding of TFs, or recruit factors leading to compaction of chromatin.
Term
CREB protein
Definition
cAMP Response Element-Binding. RTF. Gets activated in response to cell-signalling molecules that cause an increase in cAMP. Recognizes response element with concensus seq. 5’-TGACGTCA-3’. Binds to DNA and stimulates transcription. If unphosphorylated it can still bind to DNA, but not activate the RNA pol.
Term
DeNovo methylation
Definition
– infreq. And highly regulated event.
Term
DNA methylase
Definition
– converts hemi-methylated to fully methylated DNA. Efficient and routine event.
Term
DNA methylation
Definition
change in chromatin structure. Carried out by DNA methhyltransferase. Silences gene. Eg. abnormal methylation of tumor suppressor gene= bad. Heritable.
Term
Gene regulation
Definition
– necessary to ensure (1) expression of genes in an accurate pattern during development (2) differences between distinct cell types. Influences = regulatory transcription factors, compaction level of chromatin during transcription, DNA methylation (inhibits), Durign RNA processing: Alternative splicing, RNA editing. During Translation: Small RNAs (miRNA) silence translation of mRNA. Phosporylation of TFs, Protein binding to 5’ end Posttranslational: feedback inhibition, covalent modifications
Term
General transcription factors:
Definition
req for binding of RNA pol. To core promoter and for its progression to elongation stage. Necessary for basal transcription.
Term
Glucocorticoids
Definition
. influence nutrient metabolism in most cells. Promote glc use, fat metabol, protein breakdown.
Term
Gonadocorticoids
Definition
inc. estrogen and testosterone. Infl. Growth and fn of the gonads
Term
Helix-turn-helix
Definition
assists in recognition of base sequence between DNA and RTF
Term
Heterodimers
Definition
– formed by 2 different transcription factors
Term
Homodimers
Definition
formed by two identical TFs
Term
Leucine zipper
Definition
causes zipping up by protein dimerization - DNA binding protein
Term
Mediator
Definition
– activator protein interacts with it, enables RNA polymerase to form preinitiation complex
Term
Regulatory transcription factors
Definition
regulate the rate of transcription of nearby genes. Influence ability of RNA pol to begin transcription of a particular gene. Recognize regulatory elements (respose/control/regulatory elements)located near core promoter. Binding of RTFs affects transcription of associated gene. Is either an Activator binding to an enhancer, or a repressor binding to a silencer. Are usually orientation independent/bidirectional. Have domains that have specific functions eg DNA binding or molecule binding.. eg. helix-turn-helixm leucine zipper, zinc finger. Usually do not bind directly to RNA pol. But through TFIID or Mediator. Modulated by binding of small effector molecule, protein protein interactions, or covalent modification.
Term
Steroid receptors
Definition
– RTFs that respond to steroids. Hormone binds to TFs. EG glucocorticoids and Gonadocorticoids
Term
TFIID
Definition
when bound activates transcription
Term
Zinc Finger
Definition
charge interactions allow binding - DNA binding protein
Term
Alternative Splicing
Definition
biological advantage, when pre-mRNA can be spliced in more than one way. In most cases, large sections of coding regions are the same resulting in 2 alt. versions. Degree of splicing varies greatly among different species. Eg how smooth vs striated muscle cells are produced. Not random – involves splicing factors which choose splice sites.
Term
dsRNA
Definition
can silence exp. of certain genes. - RNAi
Term
Guide RNA
Definition
directs addition or deletion of Uracils in trypanosomes. Eg also, human ApoB mRNA = CAA  UAA. Amyotrophic lateral sclerosis (ALS)
Term
Iron Response Element (IRE)
Definition
found in 5’ UTR in ferritin mRNA and in 3’ UTR in transferring receptor mRNA
Term
Iron regulatory protein (IRP)
Definition
regulates iron assimilation by influencing ferritin mRNA and transferring receptor mRNA. Binds to IRE. When high iron on Ferritin receptor, binds to iron and releases. Ferritin protein synthesized. Low iron on Transferring: stays bound, stabilizing mRNA, and Transferrin is synthesized high, binds to iron and mRNA is degraded.
Term
mRNA stability
Definition
varies considerably – can be regulated so its half life is lengthened or shortened, influencing mRNA concentration. Length of polyAtail affects this. Recognized by polyA-binding protein. Over cell life, poly-A tail shortened. When too short, cannot be recognized anymore, and is degraded. Also affected by destabilizing elements: found esp. in mRNAs that have short half lives. Can be found anywhere on the mRNA, but are most common at 3’ end btwn codon and polyAtailEg. AU rich element (ARE)
Term
microRNAs (miRNA)
Definition
cause RNAi
Term
RNA editing
Definition
change in nucleotide seq. of RNA molecule. Involves additions/deletions/conversions of bases. Can generate start or stop codons, or change coding seq of polypeptide.
Term
RNAi
Definition
form of gene regulation that can offer defence against viruses and plays roles in silencing transposable elements.
Term
RNA induced silencing complex
Definition
RISC. Formed by dicer forming a siRNA (ds) – recognized by protein that forms RISC, forming to (SS). siRNA then binds to mRNA and is degraded or just prevents translation
Term
Spliceosome
Definition
- recognizes 5’ and 3’ splice sites and removes the intron.
Term
Splicing factors
Definition
choose splicing sites eg. sr proteins modulate ability of spliceosomes to recog. or choose splice sites. Happens by inhibition of spliceosome recognition, or enhancement of spliceosome recognition.
Term
SR proteins
Definition
at their C-terminal end have domain rich in serine (S) and arginine (R). At N terminal end, have RNA binding domain.
Term
UTR
Definition
Untranslated region
Term
ampR
Definition
antibiotic resistance to host cell
Term
Competent cells
Definition
– have a plasmid inside
Term
cDNA
Definition
complementary DNA, made from RNA by reverse transcriptase. Used because no introns, therefore useful for protein expression
Term
DNA ligase
Definition
splices 2 DNA fragments together with a covalent bond –type of restriction enzyme.
Term
Gene cloning
Definition
isolating and making many copies of a gene usually involve chromosomal DNA (source of segment of interest) and Vector DNA (Carrier of segment to be cloned- can replicate independently of host chromosomal DNA). Common vectors are Plasmids and Viruses. Plasmids can have selectable markers.
Steps - confer resistance to antibiotics via ampR, and make sure that they can encode β-galactosidase for identification
- mix with e-coli permeable to plasmid
- plate on media w/ x-gal (blue if cleaved by βgalatosidase), ampicillin and IPTG (induces lacZ). WHITE = competent, blue – non-competent
Produces an enormous amount of copies of a gene
Term
Host cell
Definition
cell that harbours a vector
Term
Recombinant DNA molecules
Definition
– chimera of 2 DNA fragments from different sources
Term
Restriction endonucleases / restriction enzymes
Definition
– bind and cleave at specific locations. Natural role involves protection from invasion by foreign DNA. Typically palindromic. Sometimes ends are sticky, sometimes blunt.
Term
Restriction Mapping
Definition
– way of examining locations of restriction sites. – cut with various restriction enzymes, then run out on gel.  compare sizes. Or by sequencing.
Term
Subcloning
Definition
process of obtaining smaller clones from a larger chromosomal DNA insert
Term
Automated sequencing
Definition
– single tube sequencing, and each dideoxyribonucleotide has a diff. colour fluorescent label attached. Loaded into single lane of gel. Identified by spec.
Term
Denaturing-annealing-synthesis
Definition
cycle used in PCR to synthesis DNA # cycles = 2x X increase.
Term
Chain termination
Definition
– see dideoxy sequencing
Term
Colony hybridization
Definition
DNA probe technique to clone a specific gene – identified by transferring some of a colony to an x-ray film, treating it and identifying
Term
cDNA library
Definition
when starting material is RNA. Represents expressed genes.
Term
DNA library
Definition
collection of thousands of different cloned fragments of DNA from cutting up genome of an organism.
Term
DNAase I footprinting
Definition
to study binding of proteins to sites on DNA
Term
Dideoxy sequencing method
Definition
PCR DNA, clone target DNA into vector nd isolate ssDNA (if dsDNA used, must be denatured at beginning of exp.). dideoxy added so that growing DNA strand can no longer grow aka chain termination – known to be ATG or C. Then run out on acrylamide gel.
Term
Gel retardation assay
Definition
used to study binding of proteins to sites on DNA. Binding of protein to a frag of DNA retards its rate of movement through a gel aka band shift assay
Term
Genomic library
Definition
– a DNA library when starting material is chromosomal DNA. Contains genes, introns, junk DNA, and regulatory stuff
Term
PCR
Definition
technique for copying DNA w/o host cell and vectors Starting material =
• Template DNA
• Oligonucleotide primers (complementary to seq flanking DNA frag.)
• dNTPs –deoxynucleoside triphosphates
• Taq polymerase – Thermus aquaticus
Term
Northern Blotting
Definition
identifies specific RNA within a mix of many RNA molecules
Term
RT-PCR
Definition
reverse transcriptase PCR – used to quantify amount of RNA in cells. RNA isolated from sample, mixed with reverse transcriptase and a 3’ primer to gen. sscDNA which is used as a template for conventional PCR
Term
Southern Blotting
Definition
detects presence of a particular gene seq within many. Can determine copy number of a gene, can detect small gene deletions, gene families and homologous genes among diff species.
Term
Western blotting
Definition
identifies specific proteins within mixtures of many protein molecules via antibodies
Term
Allele freq. calc
Definition
# copies of an allele in pop / tot. # all alleles for that gene in a pop.
Term
Deme
Definition
see local population
Term
Gene pool
Definition
all alleles of every gene in a population
Term
Genotype freq calc
Definition
# individuals w/ genotype in pop / tot # individuals in pop
Term
Hardy-Weinberg equation / equilibrium theory
Definition
calc. that relates allele and genotype freq. in a pop. In uilibrium = allele and genotype freq. do not change over course of many generations
p2+2pq+q2 where p = dom allele freq, q = recessive allele freq
does not apply if:
• new mutations
• genetic drift
• migration
• nat. selection
• not random mating
can be applied to 3+ alleles by (p+q+r…)2 = 1. tested by χ2 test
Term
Local population
Definition
– a subpopulation more likely to breed with each other. Usually separated by geographic barriers
Term
Monomorphic
Definition
exists predominantly as a single allele. 99%
Term
Polymorphic
Definition
traits display variation within a population. Eg Happyface spider. At DNA level: due to 2+ alleles that influence phenotype (gen var….) also used to desc. a gene that exists as 2+ alleles in a population.
Term
Population
Definition
– a group of individuals of the same species that occupy the same region and can interbreed
Term
Population genetics
Definition
central issue = genetic variation- extent, why, and how it changes
Term
Single-nucleotide polymorphism
Definition
SNP – account for 90% of var btwn people.
Term
χ2 – formula
Definition
χ2 = (Oi –Ei)2 / Ei
Term
Assortative mating
Definition
– individuals do not mate randomly
Term
Balancing
Definition
– nat selection that favours the maintenance of 2+ alleles. Pop not evolving toward allele fixation. Can occur b/c of heterozygote advantage, or because a species occupies a region that contains heterogeneous environments.
Selection coefficient = s = 1-W
eg sicklecell/malaria, cystic fibrosis, tay-sach disease.
Term
Bottleneck effect
Definition
when a population is reduced dramatically by nat. disaster randomly eliminating individuals.
Term
Conglomerate
Definition
recipient pop of migration. Can calc new allelic freq. if we know original allelic freq of donor and recip pops, and the proportion of conglomerate pop that is due to migrants. ΔpC = m(pD – pR). ΔPC = change in allele freq in conglomerate pop. PD is allele freq. in donor pop. PR in orig. recipient pop. M = proportion of migrants that make up conglomerate pop……m=# donor individuals in cong / total # individuals in conglomerate.
Term
Darwinian Fitness
Definition
relative likelihood that a phenotype will survive and contribute to the gene pool of the next generation. Gene with highest reproductive ability = 1.0. other genes set relative to that. Can be due to fittest phenotype being more likely to survive, mate, or is more fertile.
Term
DNA transposons
Definition
jumping genes about 1 500 bp. Can move about in the genome. 11 in atlantic salmon. Simlar seq. in other fish. Burst of transposon seq. coincides with speciation time, possibly from reorginizing the genome or parasites spreading transposons?
Term
Directional selection
Definition
nat. selection that favours survival or one extreme phenotype that is better adapted to survive an environmental condition. Affects hardy-weinberg eq. and allele freq. by favouring the extreme phenotype. In next gen, HW eq. will be p2WAA, 2pqWAa, q2Waa.. do not add up to 1, but the mean fitness value = Wbar. Solve by dividing both sides by Wbar.. Eg = DDT resistance in insects.
Term
Disruptive selection
Definition
nat. selection that favours survival of 2+ different phenotypes. Caused by fitness values that vary in different environments. Eg. snail that lives in woods and open fields. Migration maintains balance of polymorphisms.
Term
Exon shuffling
Definition
when an exon and flanking introns are inserted into a gene. May involve duplication and rearrangement. Results in novel genes with additional fnctnl domains. May be promoted by transposable elements, can be caused by nonhomologous double crossovers.
Term
Finch example
Definition
– beak length depends on expression of calmodulin gene – high levels = long pointy beaks. Low levels = more robust beaks. Depth depends on Bmp4 (bone morphogenic protein 4, transcription factor) high exp = deep and broad.
Term
Founder effect
Definition
small group of individuals separates from a larger pop and establishes a colony in a new loc. Founding pop is expected to have less gen var than original pop. Will also have allelic freq. that may differ markedly from the original pop.
Term
Genetic drift
Definition
random changes in allele freq due to chance fluctuations. Favours loss or fixation of an allele. Smaller pops, allele freq. fluctuates a lot from gen to gen. Isolated populations are more susceptible to drift. Eg. Bottleneck effect and founder effect.
Term
Horizontal gene transfer
Definition
xchng of gen material among different species. Common phenomenon – prokaryotic cell may be taken up by eukaryotic cell, bacterial conjugation, viral transfer. Eg salmonidae
Term
Inbreeding
Definition
mating btwn genetically related individuals. Small gene pool.
Term
Inbreeding coefficient (F)
Definition
quantification of degrwee of relatedness. Measures change that homozygosity is due to common ancestor.
Term
microevolution
Definition
– changes in a population’s gene pool from generation to generation. Affects allelic frequencies. Driven by mutation, genetic drift, migration, natural selection, non-random mating
Term
Migrations
Definition
– btwn 2 different established populations. New pop is a conglomerate
Term
Mutation rate
Definition
probability that a gene will be altered by a new mutation = # of new mutations in a given gene per generation. Usually around 10-5 – 10-6. Increased by mutagens.
Term
Mutations
Definition
the source of genetic variation. Changes in DNA sequence. Random and low rates. Can be beneficial, neutral, or deleterious. Last two far more likely than beneficial. U = rate of Aa. After 1 generation, increase in a = Δq = u∙p. Many generations = (1-u)t = Pt / P0 where t = # generations and p are allelic freq.
Term
Natural selection
Definition
Darwin and Russel – most adapted individuals survive and pass on gene. Related to mating efficiency and fertility, as well as differential survival.
• Withing a pop there is allelic var. arising from var. factors such as mutations causing differences in DNA seq. Distinct alleles encode proteins of differing fns.
• Some alleles may encode proteins that enhance an individual’s survival or reproductive capacity
• Individuals with beneficial alleles are more likely to survive and reproduce.
• Over many generations, allele freq. of many different genes may change through nat. selection.
Occurs on phenotypes. Operates by directional selection, stabilizing selection, disruptive selection, or balancing
Term
Negative assortative mating
Definition
individuals with dissimilar phenotypes mate preferentially
Term
Nonrandom mating
Definition
happens! Violated freq. in human pops. Wrt phenotypes: Assortative matin, Positive assortative mating, negative assortative mating. Wrt genotypes – inbreeding and outbreeding
Term
Outbreeding
Definition
mating between genetically unrelated individuals
Term
Positive assortative mating
Definition
– occurs when individuals with dissimilar phenotypes mate preferentially.
Term
Sources of gen. var.
Definition
sex. Reproduction, prokaryotic gene transfer, DNA mutations, chromosome structure changes.
Term
Stabilizing selection
Definition
nat. selection that favours the survival or individuals with intermediate phenotypes. Tends to decrease genetic diversity. Eg laying eggs. Too many eggs drains resources to care for young. Too few does not contribute to next gen.
Term
Allopatric speciation
Definition
– when species have become geographically separated from each other – geological or founder effect
Term
Anagenesis
Definition
– single species transformed into different sp. over many generations
Term
Biological species concept
Definition
species is a group of individuals whose members can interbreed to produce viable fertile offspring.
Term
Cladogenesis
Definition
single species divided into 2+ species….most common form of speciation c an be allopatric, parapatric, or sympatric
Term
Ecological species concept
Definition
each species occupies an ecological niche. Unique set of habitat resources .Nice overlap results in competition. Competing individuals likely to be of same species.
Term
Evolutionary developmental biology
Definition
(EVO-DEVO) role of developmental genes in the evolution of new species – embryonic development
Term
Evolutionary species concept
Definition
– derived from single distinct lineage. Based on pathway that led to species. Want to look at the relationships between species.
Term
Gene family
Definition
+ copies of homologous genes within the genome of a single organism.
Term
Gradualism
Definition
– each new sp. evolves continuously over long spans of time
Term
Hybrid zones
Definition
where 2 pops can interbreed. Geneflow here must be limited for speciation to occur.
Term
Homologous genes
Definition
derived from the same ancestor orthologous or paralogous eg humans vs horses – α globin and β globin genes are othologues between humans and horses. But human α globin and β globin genes are paralogs. Orthologues more similar than paralogues.
Term
Macroevolution
Definition
relatively large changes in form and function that are sufficient to produce new species and higher taxa.
Term
Microevolution
Definition
changes in gene pool wrt. Particular alleles over measurable periods of time
Term
Molecular evolution
Definition
molecular changes in gen material that underlie the phenotypic changes assoc. with evolution.
Term
Orthologous genes
Definition
homolgous genes found in diff sp.
Term
Paralogous genes
Definition
homologous genes found within a single sp. from gene duplication.
Term
Parapatric speciation
Definition
sp. not completely geographically separated eg mountain range, or a species is sedentary.
Term
Postzygotic isolation
Definition
prevents development of viable individual after fertilization.
Term
Prezygotic isolation
Definition
prevents formation of a zygote
Term
Phylogenetic tree
Definition
diagram that desc. phylogeny of a species. Based on morph, phys, biochem, behaviour, DNA
Term
Phylogenic species concept
Definition
members of a single species are identified by having a unique combination of char. Traits.
Term
Phylogeny
Definition
seq. of events involved in evodevo of sp, or group of sp.
Term
Punctuate equilibrium (punk-eek)
Definition
species exist unchanged for many generations, with short periods of rapid evolution.
Term
Speciation
Definition
formation of new species via evolution Anagenesis or cladogenesis. Can be fast or slow. Not constant Gradualism or punctuated equilibrium (punk-eek)
Term
Species
Definition
group of organisms w/ distinct set of attributes – may exist in 2+ distinct pops that are evolving slowly into diff. species. Can be defined by morphological traits, ability to interbreed, evolutionary lineages, ecological factors. Depends on species in question.
Term
Sympatric speciation
Definition
– occurs when members of a species initially occupy same habitat within same range. Eg polyploidy in plants leads to reproductive isolation
Term
Cladistic approach to phylogenetic tree
Definition
groups consist of single common ancestor and all its descendants. Shared traits are ancestral (primitive)
Term
Evo-Devo
Definition
– compares development of species to understand ancestral relationships and developmental mechanisms that bring about evo change. Esp. master control genes eg. webbed feet of ducks vs claws of chickens – BMP4 causes cell death, while gremlin prevents is. Gremlin expressed in ducks. Eg eyes and pax6
Term
Molecular clocks
Definition
– a measure of evo time. Constant rate of neutral mutations = number of mutations propotional to separation time. Assumes nucleotide differences assumed to be mostly due to neutral mutations, and assumes linear relationship.
Term
Neutral mutations
Definition
do not affect phenotype of organism, therefore not acted on by nat. selection. ..survival of the luckiest, non-darwinian evo.
• For each protein, rate of evo in terms of amino acid subs. Is approx. constant wrt neutral substituations.
• During evo, proteins that are fn less important will accumulate amino acid substitutions more rapidly that important proteins
• Amino acid substitutions that do not disrupt existing structure and function occur more freq. in evolution than disruptive aminon changes.
• Gene duplication must always precede the emergence of a gene having a new fn.
• Selective elimination of definitely deleterious mutations and random fixation of selectively neutral or very slightly deleterious alleles occur far more freq. in evo than Darwinian selection of advantageous mutants
Term
Neutral theory of evolution
Definition
kimura –most gen. var obtained in nat pops is due to accumulation of neutral mutations.
Term
Parsimony
Definition
principal of least astonishment
Term
Shared derived character
Definition
– trait shared by group of organisms, but not distant common ancestor.
Term
2D gel electrophoresis
Definition
delineate proteins on gel with spots – then correlated with protein. Cut out from gel, purify, protease treat it, then do tandem mass spec. MALDI-TOF
Term
Bioinformatics
Definition
– extract info within gen. seq. using a mathematical approach
Term
Cluster analysis
Definition
– identifying genes whose pattern of expression strongly correlates with each other.
Term
Functional genomics
Definition
elucidate roles of genetic sequences in a given seq.
Term
Microarray
Definition
dotted with many small DNA seq. frags, corresponding to known genes. Allows study of whole genome under different enviro conditions.
Term
Proteome
Definition
entire collection of proteins an organism can make. Much larger than genome. Largersize related to alternative splicing, RNA editing, and posttans. Covalent mod. Proteins produced depends on cell type, stage of development, and enviro. Conditions.
Term
Proteomics
Definition
understand fn roles of proteins
Term
BLAST
Definition
basic local alignment search tool. When 2+ geneti c sequences are multiple seq. alignment
Term
Open reading frame
Definition
nucleotide sequence w/o stop codons.
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