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Biology Final
Lectures 8-14
76
Biology
Undergraduate 1
12/11/2007

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Term
asexual reproduction
Definition
one parent produces genetically identical offspring by mitosis
Term
sexual reproduction
Definition
two parents give rise to offspring that have unique combinations of genes inherited from the two parents
Term
sporophyte
Definition
diploid organism that makes haploid spores by meiosis
Term
gametophyte
Definition
spores that grow by mitosis into a haploid organism
Term
meiosis I
Definition
homologous chromosomes separate, resulting in two haploid daughter cells with replicated chromosomes
Term
meiosis II
Definition
sister chromatids separate, resulting in four haploid daughter cells with unreplicated chromosomes
Term
prophase I
Definition
chromosomes condense, tetrads form
Term
chiasmata
Definition
x-shaped regions where crossing over occured
Term
metaphase I
Definition
tetrads line up at metaphase plate, microtubules reach from poles to kinetochores
Term
anaphase I
Definition
pairs of chromosomes separate and move to opposite poles guided by spindle apparatus
Term
telophase I/cytokinesis
Definition
forms two haploid daughter cells with a haploid set of chromosomes each
Term
prophase II
Definition
chromosomes moved toward metaphase plate
Term
metaphase II
Definition
non-identical sister chromatids on metaphase plate
Term
anaphase II
Definition
sister chromatids separate and move toward opposite poles
Term
telophase II/cytokinesis
Definition
chromosomes decondense
Term
mitosis
Definition
conserves # of chromosome sets, producing cells that are identical to parent cell
Term
meiosis
Definition
reduces # of chromosome sets from two to one and produces cells that are genetically different from each other and the parent cell
Term
independent assortment of chromosomes
Definition
segregation of alleles at one gene occurs independently of the segregation of alleles at another
Term
crossing over
Definition
contributes to genetic variation by combining DNA from two parents into a single chromosome
Term
random fertilization
Definition
adds to genetic variation because any sperm can fuse with any ovum
Term
blending hypothesis
Definition
idea that genetic material from two parents blends together
Term
particulate hypothesis
Definition
idea that parents pass on discrete heritable units
Term
Mendel
Definition
documented particulate mechanism through experiments with garden peas
Term
traits
Definition
character variations
Term
characters
Definition
distinct heritable features
Term
hybridization
Definition
the mating of two contrasting, true breeding varieties
Term
law of segregation
Definition
states that two alleles for a heritable character separate during gamete formation and end up in different gametes
Term
testcross
Definition
breeding known phenotype with homozygous recessive to find genotype
Term
law of independent assortment
Definition
states that each pair of alleles segregates independently of other pairs of alleles during gamete formation
Term
complete dominance
Definition
occurs when phenotypes of heterozygote and dominant homozygote are identical
Term
codominance
Definition
two dominant alleles affect the phenotype in separate, distinguishable ways
Term
incomplete dominance
Definition
phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
Term
multiple alleles
Definition
most genes exist in populations in more than two allelic forms (ex. blood types)
Term
pleiotropy
Definition
multiple phenotypic effects, and can be responsile for certain hereditary diseases
Term
epistasis
Definition
gene at one locus alters the phenotypic expression of a gene at a second locus
Term
polygenic inheritance
Definition
additive effect of two ore more genes on a single phenotype
Term
multifactoral
Definition
genetic and environmental factors influence phenotype
Term
chromosome theory of inhertance
Definition
states that mendalian genes have specific loci on chromosomes that undergo segregation and independent assortment
Term
Thomas Hunt Morgan
Definition
studied Drosphilia and noted wild phenotypes that were common and noted that the mutant allele must e located on the X chromosome
Term
Alfred Sturtevant
Definition
predicted that the farther apart two genes are, the higher the probaility that a crossover will occur between them, causing a higher recomination frequency
Term
transcription
Definition
synthesis of mRNA under direction of DNA
Term
translation
Definition
synthesis of polypeptide that occurs under direction of mRNA; done at ribosomes
Term
snRNP's
Definition
recognize splice sites
Term
tRNA
Definition
helps to translate an mRNA message into protein
Term
P-site
Definition
biding site for tRNA that carries the growing polypeptide chain
Term
A-site
Definition
binding site for tRNA that carries the next amino acid to be added to the chain
Term
E-site
Definition
binding site for tRNA that is the exit site where tRNA's leave the ribosome
Term
point mutations
Definition
changes in just one base pair of a gene
Term
missense mutations
Definition
code for the wrong amino acid
Term
nonsense mutations
Definition
change an amino acid codon into a stop codon, resulting in a nonfunctional protein
Term
bacterial operon
Definition
composed of an operator, a propmoter, and genes for metabolic enzymes
Term
corepressor
Definition
small molecule that cooperates with a repressor to switch an operon off
Term
epigenetic inheritance
Definition
inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence
Term
control elements
Definition
interact with specific transcription factors to code genes
Term
activator
Definition
protein that binds to an enhancer to stimulate transcription of a gene
Term
proteasomes
Definition
giant protein complexes that ind protein molecules and degrade them
Term
natural selection
Definition
differential success in reproduction from interaction between individuals that vary in heritable traits and their environments; produces an increase in adaptation of organisms to their environment
Term
homology
Definition
similarity due to common ancestry
Term
dna replication in prokaryotes
Definition
-have a single origin of replication
-replication proceeds in both directions until entire molecule is copied
Term
dna replication in eukaryotes
Definition
- replication beings at many sites in DNA molecule
-shotre DNA molecules as the replication cannot complete the 5'ends
-telomeres are located at the ends of nucleotides
Term
origins of replication
Definition
where dna strands are separated
Term
dna polymerase
Definition
catalyze the elongation of new DNA at a replication fork; can only add nucleotides to 3' end, dna elongates in 5'->3' direction
Term
leading strands
Definition
synthesized in the direction towards replication fork
Term
lagging strand
Definition
synthesize in the direction away from the replication fork
Term
okazaki fragments
Definition
segments on the lagging strand that are joined together by DNA ligase
Term
primase
Definition
can start an RNA chain from scratch; synthesizes RNA primer at 5' ends of leading strand and the Okazaki fragments
Term
DNA poly III
Definition
synthesizes leading strand and elongates okazaki fragments
Term
DNA pol I
Definition
replaces primer with DNA
Term
helicase
Definition
untwists double helix and separates template DNA strands at replication fork
Term
single-strand binding proteins
Definition
bind to and stabilize template DNA strands
Term
topoisomerase
Definition
corrects "overwinding" ahead of replication forks
Term
mismatch repair
Definition
repair enzymes correct errors in base pairing
Term
nucleotide excision repair
Definition
enzymes cut out and replace damaged stretches of DNA
Term
telomeres
Definition
postpone erosion of genes near ends of DNA molecules
Term
telomerase
Definition
catalyzes the lengthening of telomeres in germ cells
Term
beadle/tatum
Definition
developed one gene-one enzyme hypothesis, stating that each gene dictates production of a specific enzyme
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