Term
| DNA is stored in what formed in the nucleus? |
|
Definition
|
|
Term
| What forms nucleosome "beads" in chromatin? |
|
Definition
| DNA looped around postiviely charged histones |
|
|
Term
| What histone ties nucleosome beads together? |
|
Definition
|
|
Term
| What is unique about the histone H1? |
|
Definition
Only histone not in the nucleosome core
larger and more basic |
|
|
Term
| phosphate groups give DNA a..... charge? |
|
Definition
|
|
Term
| lysine and arginine give histones a....charge? |
|
Definition
|
|
Term
| in mitosis, DNA condenses to form what? |
|
Definition
|
|
Term
| DNA and histone synthesis occurs during which phase? |
|
Definition
| S phase: DNA replication phase |
|
|
Term
| What is the name for condensed, transcriptionally inactive, sterically inaccessible DNA? |
|
Definition
|
|
Term
|
Definition
condensed
appears darker on EM
sterically inaccessible
transcription inactive
increased methylation
decreased acetylation
Highly Condensed |
|
|
Term
| What is the name for less condensed, transcriptionally active, sterically accessible DNA? |
|
Definition
|
|
Term
|
Definition
Euchromatin is Expressed
less condensed
appears lighter on EM
sterically accessible
transcription active |
|
|
Term
|
Definition
methyl group added to cytosine(CG islands) and to both cytosine and adenine in bacteria.
70% of human DNA is methylated.
it changes the expression of a DNA segment without changing the sequence. involved with: aging, carcinogenesis, genomic imprinting, transposable element repression, inactivation of the X chromosome-barr bodies-
methylation within gene promoter-initiates transcription- CpG islands: silences gene transcription.
Methylation makes DNA Mute. |
|
|
Term
|
Definition
usually causes reversible transcriptional suppression, but can also cause activation depending on location of methyl groups.
Histone Methylation Mostly Makes Dna MUTE. |
|
|
Term
|
Definition
adding acetyl group to LYSINE-removal of histone's + charge.
relaxes chromatin for transcription.
Acetylation....Active |
|
|
Term
|
Definition
| removal of acetyl groups will tightened DNA coiling..... lower transcription. |
|
|
Term
| How many histones make up a nucleosome? |
|
Definition
|
|
Term
| What histones make up the nucleosome core? |
|
Definition
| 2 sets of H2A, H2B, H3, H4 |
|
|
Term
| Which nucleotides are purines? |
|
Definition
Adenine, Guanine (mnemonic: PURe As Gold)
+ hypoxanthine |
|
|
Term
| What nucleotides are pyrimidines? |
|
Definition
| Cytosine, Uracil, Thymine (mnemonic: CUT the PY) |
|
|
Term
| the origin of nitrogen found in nucleotides? |
|
Definition
| all nitrogen comes from amino acids |
|
|
Term
| Deamination of cytosine makes what nucleotide? |
|
Definition
|
|
Term
| Deamination of adenine makes what nucleotide? |
|
Definition
|
|
Term
| Deamination of guanine makes what nucleotide? |
|
Definition
|
|
Term
| Deamination of 5-methyl cytosine makes what nucleotide? |
|
Definition
|
|
Term
| methylation of uracil makes? |
|
Definition
|
|
Term
| What amino acids are necessary for purine synthesis? |
|
Definition
| Glycine, Aspartate, Glutamine |
|
|
Term
| What amino acids are necessary for pyrimidine synthesis? |
|
Definition
|
|
Term
| What is the purine precursor in de novo synthesis? |
|
Definition
|
|
Term
| What is the pyrimidine precursor in de novo synthesis? |
|
Definition
| orotate with PRPP added later |
|
|
Term
| What pathways involve carbamoyl phosphate? |
|
Definition
| De novo pyrimidine synthesis and the urea cycle |
|
|
Term
| Ornithine transcarbamoylase deficiency in the urea cycle leads to an accumulation of what? |
|
Definition
|
|
Term
| Excess carbamoyl phosphate is converted to what? |
|
Definition
|
|
Term
| Methotrexate inhibits what? |
|
Definition
|
|
Term
| Orotic aciduria causes what conditions? |
|
Definition
| Megaloblastic anemia, increased orotic acid in urine, no B12/folate response and growth retardation. |
|
|
Term
| Orotic aciduria results from a defect in what step of de novo pyrimidine synthesis? |
|
Definition
| Conversion of orotic acid to UMP |
|
|
Term
| What enzymes are deficient in orotic aciduria? |
|
Definition
| UMP synthase: a bifunctional enzyme: orotic acid phosphoribosyltransferase or orotidine 5'-phosphate decarboxylase |
|
|
Term
| What is the mode of inheritence for orotic aciduria? |
|
Definition
|
|
Term
| Adenosine deaminase deficiency causes what disease? |
|
Definition
| SCID: Severe Combined Immunodeficiency Disease -autosomal recessive scid- |
|
|
Term
| Adenosine deaminase deficiency causes excess ATP and dATP, preventing what? |
|
Definition
| DNA synthesis:increased dATP, results in decreased lymphocyte count: lymphotoxicity |
|
|
Term
| Defective purine salvage due to the absence of HGPRT is characteristic of what disease? |
|
Definition
|
|
Term
| What is the mode of inheritence for Lesch-Nyhan syndrome? |
|
Definition
|
|
Term
| What is the function of HGPRT? |
|
Definition
| Converts hypoxanthine to IMP and guanine to GMP in the purine salvage pathway |
|
|
Term
| Lesch nyhan syndrome causes? |
|
Definition
| excess uric acid production and de novo purine synthesis |
|
|
Term
| Lesch nyhan syndrome presentation? |
|
Definition
Hyperuricemia: orange sand: sodium urate crystals in diaper.
Gout
Pissed off: aggression and self mutilation
Retardation: intellectual disability
dyTonia
chorea
macrocytosis |
|
|
Term
| treatement of Lesch nyhan syndrome |
|
Definition
Allopurinol: inhibit xanthine oxidase
febuxostat -2nd line- |
|
|
Term
|
Definition
| inhibits dihydroorotate dehydrogenase |
|
|
Term
|
Definition
forms 5 f-dUMP which inhibits thymidylate synthase- decrease dTMP.
mimics uracil
chemotherapy agent
binds N5,N10 THF and thymidylate synthase.
prodrug: capecitabine |
|
|
Term
| 6 mercaptopurine and its prodrug azathioprine |
|
Definition
inhibit de novo purine synthesis.
mimic hypoxanthine/guanine.
decrease: IMP/GMP/AMP
6 MP+ PRPP....... thioinosinic acid(inactive) catalysed by xanthine oxidase |
|
|
Term
|
Definition
- DHF reductase so decrease dTMP in humans for MTX
trimethoprim: inhibit DHF reductase of bacteria
pyrimenthamine: protozoa |
|
|
Term
|
Definition
| carbamoyl phosphate synthetase in mitochondria: urea cycle |
|
|
Term
|
Definition
carbamoyl phosphate synthetase II in cytosol
converts: glutamine + co2 into carbamoyl phosphate (ATP to ADP) |
|
|
Term
| What are the "features" of the genetic code? |
|
Definition
| Unambiguous (1 codon = 1 amino acid), redundant (more than 1 codon may code for same amino acid), comaless (read from fixed starting point as a continuous sequence of bases), universal (genetic code is conserved throughout evolution) |
|
|
Term
| What are exceptions to the universal feature of the genetic code? |
|
Definition
| mitochondria, archaebacteria, mycoplasma, some yeasts |
|
|
Term
| A particular sequence in the genome where DNA replication begins is known as what? |
|
Definition
| Origin of replication (single in prokaryotes, multiple in eukaryotes) |
|
|
Term
| Leading and lagging strands are synthesized at what location along the DNA template? |
|
Definition
|
|
Term
| What unwinds DNA at the replication fork? |
|
Definition
|
|
Term
| DNA supercoils are relieved by what? |
|
Definition
|
|
Term
| What enzyme creates a RNA primer on which DNA polymerase III can initiate replication? |
|
Definition
|
|
Term
| What DNA polymerase is found only in prokaryotes? |
|
Definition
DNA polymerase I and III
I to IV |
|
|
Term
| Which proofreads synthesized DNA in prokaryotes? |
|
Definition
|
|
Term
| What degrades RNA primers and fills in gaps with DNA in prokaryotes? |
|
Definition
|
|
Term
| What seals DNA fragments during DNA synthesis? |
|
Definition
|
|
Term
| Okazaki fragments are found in which strand? |
|
Definition
|
|
Term
| DNA is synthesized in what direction? |
|
Definition
|
|
Term
| Leading strand replication is? |
|
Definition
|
|
Term
| lagging strand replication is? |
|
Definition
| discontinuous: okazaki fragments |
|
|
Term
|
Definition
particular sequence in genome where DNA replication begins. may be single: prokaryotes... or multiple: eukaryotes.
AT rich sequences like TATA box regions are found in the origin of replication and in promoters -easy to unwind bcz of the fewer bonds- |
|
|
Term
|
Definition
| Y shaped region along DNA template where leading and lagging strands are sythesized. |
|
|
Term
|
Definition
unwinds DNA template at replication fork.
hydrolizes ATP.
Helicase Halves DNA.
deficient in BLooM syndrome: BLM gene mutation. |
|
|
Term
| Single stranded binding proteins? |
|
Definition
prevent strands from reannealing
assist helicase
stabilize and straighten single strands of DNA. |
|
|
Term
|
Definition
create a single or double stranded break in the helix to add or remove supercoils.
Relieve tension/twists
prevent DNA tangling |
|
|
Term
|
Definition
| break single stranded of DNA then reseal them. |
|
|
Term
|
Definition
DNA gyrase
break double stranded DNA then reseal. |
|
|
Term
| drugs that can inhibit TOP I in eukaryotes? |
|
Definition
|
|
Term
| drugs that can inhibit TOP II in eukaryotes? |
|
Definition
|
|
Term
| drugs that can inhibit TOP II an IV in prokaryotes? |
|
Definition
|
|
Term
|
Definition
| makes an RNA primer on which DNA polymerase III can initiate replication. |
|
|
Term
| DNA polymerase can't initiate replication without? |
|
Definition
|
|
Term
|
Definition
short nucleotide sequences that are formed at the initiation of new chain, required by DNA polymerase to function.
made by DNA primase
contain RNA, eventually removed and replaced by DNA. |
|
|
Term
|
Definition
major polymerase
only in prokaryotes
elongates leading strand by adding deoxynucleotides to the 3* end.
elongates lagging strand until it reaches primer of preceding fragment.
5'-3' synthesis
proofreads 3'-5' exonuclease to correct errors. |
|
|
Term
|
Definition
prokaryotes only
degrades RNA primer and replaces it with DNA
also excises RNA primer with 5'-3' exonuclease. |
|
|
Term
| primer removal in eukarotes? |
|
Definition
|
|
Term
|
Definition
catalyzes the formation of a phosphodiester bond within a strand of double stranded DNA.
joins okazaki fragments.
Ligase Links DNA |
|
|
Term
|
Definition
eukarotes only.
a reverse transcriptase: RNA dependent DNA polymerase.
adds DNA -TTAGGG- to 3' ends of chromosomes to avoid loss of genetic material with every duplication.
often dysregulated in cancer cells, immortality. |
|
|
Term
| What kind of mutation does not result in the translation of a different amino acid? |
|
Definition
|
|
Term
| What kind of mutation leads to the translation of a different amino acid? |
|
Definition
|
|
Term
| What kind of mutation creates an early stop codon? |
|
Definition
|
|
Term
|
Definition
UGA U Go Away
UAA U Are Away
UAG U Are Gone |
|
|
Term
| What kind of mutation results in a misreading of all nucleotides downstream from the change? |
|
Definition
|
|
Term
| severity of mutation's damage by ascending order? |
|
Definition
silent
missense
nonsense
frame shift |
|
|
Term
| types of single nucleotide -point- mutations? |
|
Definition
transition: most common, purine to purine or pyrimidine to pyr.
transversion: purine to pyr ot the inverse. |
|
|
Term
|
Definition
| nucleotide substitution codes for the same amino acid, often base change in 3rd position of codon: tRNA wobble |
|
|
Term
|
Definition
nucleotide substitution results in changed AA -called conservative if new AA has similar chemical structure-
exp: sickle cell disease |
|
|
Term
| sickle cell disease contains which type of mutation? |
|
Definition
missense mutation beta globin gene.
substitution 6th codon of b gene.
adenine changed with thymine.
substitution of glutamic acid with valine. |
|
|
Term
|
Definition
| nucleotide substitution results in early stop codon. usually results in nonfunctional protein.. |
|
|
Term
|
Definition
deletion or insertion of a number of nucleotides not divisible by 3.
misreading of all nucleotides downstream.
protein may be shorter or longer, and its function may be disrupted or altered.
exp: Duchenne muscular dystrophy and tay sachs disease.
alters the reading frame |
|
|
Term
|
Definition
lysosomal storage disease due to frame shift mutations.
gene for hexosaminidase A
leading to: accumulation of fats in the brain and other organs. |
|
|
Term
| Duchenne muscular dystrophy |
|
Definition
dystrophin gene
frameshift deletion: absence of functional dystrophin. |
|
|
Term
|
Definition
retained intron in mRNA: protein with impaired or altered function.
exp: rare causes of cancers, dementia, epilepsy, some types of B thalassemia, gaucher disease, Marfan syndrome. |
|
|
Term
| slipped strand mispairing: DNA slippage? |
|
Definition
occurs in areas of repeated nucleotide sequences.
occurs with inadequate mismatch repair.
can cause insertions or deletions leading to frameshift mutations. |
|
|
Term
| slippage in template strand? |
|
Definition
| deletion: DNA not replicated, shorter |
|
|
Term
| slippage in replicated strand? |
|
Definition
| insertion: replicated strand longer |
|
|
Term
| trinucleotide repeat disorders |
|
Definition
occurs in genes with repeat trinucleotides unites.
extra repeats in gene leading to diseases.
mechanism: probably from DNA slippage.
exp: fragile X synd, Friedreich's ataxia, Huntington's disease, myotonic dystrophy. |
|
|
Term
| Microsatellite instability? |
|
Definition
short segments of DNA
repeated sequences
mismatch repair enz failure leading to instability in size of segments among celles.
found in COLON cancer. |
|
|
Term
| A specific endonucleases being used to release damaged bases in order to allow DNA polymerase and ligase to fill and reseal the gap describes what kind of repair? |
|
Definition
| Nucleotide excision repair |
|
|
Term
| A specific glycosylase being used to recognize and remove a single damaged base to be replaced describes what kind of repair? |
|
Definition
|
|
Term
| single strand repair mechanisms? |
|
Definition
base excision
nucleotide excision
mismatch repair |
|
|
Term
| double strand repair mechanisms? |
|
Definition
Homologous end joining
NHEJ |
|
|
Term
|
Definition
recognizes specific base errors: deaminated bases, oxidized bases and open rings, spontaneous/toxic deamination.
functions throught the cell cycle.
base specific GLYCOSYLASE removes altered base and creates AP site: apurinic/apyrimidinic.
one or more nucleotides are removed by AP-Endonuclease which cleaves 5' end.
AP-Lyase cleaves 3' end.
DNA Polymerase B fills the gap and DNA ligase seals it.
GEL PLease |
|
|
Term
| nucleotide excision repair? |
|
Definition
removes bulky DNA damage.
G1 phase -prior to DNA synthesis-
specific endonucleases release the oligonucleotides containing damaged bases.
DNA polym and ligase fill and reseal the gap. |
|
|
Term
| in which disease the nucleotide excision repair is deficient? |
|
Definition
|
|
Term
|
Definition
inhability to repair DNA pyrimidine dimers caused by UV exposure.
dry skin, extreme light sensitivity, skin cancer, freckling of skin, very easy sunburning, changes in skin's pigmentation. |
|
|
Term
|
Definition
| mismatched nucleotides in newly synthesized -unmethylated- strands are removed and gap is filled and resealed. phase S/G2 after DNA synthesis |
|
|
Term
| mismatch repair is defective in? |
|
Definition
|
|
Term
|
Definition
germline mutation MLH1/MSH2
leads to colon cancer via microsatellites instability |
|
|
Term
| homologous recombination HEJ |
|
Definition
uses sister chromosomes template.
requires 2 homologous DNA duplexes
restores duplexes accurately without loss of nucleotides. |
|
|
Term
|
Definition
| breast/ ovarian cancers with BRCA1 mutation and in fanconi anemia. |
|
|
Term
|
Definition
inherited aplastic anemia
more than 13 genetic abnormalities
hypersensitivity to DNA damage
cells vulnerable to DNA strand crosslinks
impaired homologous recombination |
|
|
Term
|
Definition
no template used
highly error prone
brings together 2 ends of DNA fragments to repair double stranded breaks.
no requirement for homology
some DNA may be lost |
|
|
Term
|
Definition
|
|
Term
|
Definition
DNA region not transcribed, where RNA polymerase II and othe transcription factors TF bind to DNA upstream from gene locus.
AT rich with TATA and CAAT boxes. |
|
|
Term
| What are the promoters found in eukaryotes? |
|
Definition
TATA (TATA AA)and CCAAT boxes
+ GC box |
|
|
Term
| promoter mutation results in? |
|
Definition
| dramatic decreased levels of gene transcription. |
|
|
Term
| The site where RNA polymerase and multiple other transcription factors bind to DNA upstream from the gene locus is called what? |
|
Definition
|
|
Term
| The stretch of DNA that alters gene expression by binding transcription factors is known as what? |
|
Definition
|
|
Term
| Sites where negative regulators (repressors) bind on genes is know as what? |
|
Definition
|
|
Term
|
Definition
DNA locus where regulatory proteins TF: activators bind, increasing expression of a gene on the same chromosome.
stabilize TF/RNA POLY |
|
|
Term
|
Definition
| DNA locus where regulatory proteins called repressors bind, decreasing the rate of transcription. |
|
|
Term
| location of enhancers and silencers? |
|
Definition
the may be located close to or far from or even withinh -in an intron- the gene whose expression they regulate.
bcz of DNA coiling, many geometrically close but many nucleotides away from gene can regulate it. |
|
|
Term
| What is the function of RNA polymerase I? |
|
Definition
rRNA synthesis in eukaryotes: 5.8S, 18 and 28S
present only in the nucleolus |
|
|
Term
| What is the function of RNA polymerase II? |
|
Definition
mRNA synthesis in eukaryotes
+ miRNA + snRNA
snRNA: splicing of pre mRNA
opens DNA at promoter site |
|
|
Term
| What is the function of RNA polymerase III? |
|
Definition
| tRNA synthesis in eukaryotes and 5s r RNA |
|
|
Term
| What other function does RNA polymerase have other than mRNA synthesis? |
|
Definition
| Opens DNA at promoter site |
|
|
Term
| What is the function of RNA polymerase in prokaryotes? |
|
Definition
| Only 1 RNA polymerase complex in prokaryotes, produces all 3 kinds of RNA |
|
|
Term
| does the RNA polymerase need a primer? |
|
Definition
|
|
Term
| proofreading function of RNA polymerase? |
|
Definition
| no proofreading function but can initiate chains |
|
|
Term
| What is alpha-amanitin and its effects? |
|
Definition
| Found in death cap mushrooms, inhibits RNA polymerase II, lethal: liver failure |
|
|
Term
|
Definition
| also called Dactinomycin, ihibits RNA polymerase in both prok and eukaryotes. |
|
|
Term
|
Definition
| inhibits DNA dependant RNA polymerase in prokaryotes. |
|
|
Term
| What are the steps of RNA processing in eukaryotes? |
|
Definition
1. 5' cap
2. 3' Poly-A tail
3. Splicing out of introns |
|
|
Term
|
Definition
addition of 7-methylguanosine to 5'end
added soon after transcription begins
distinguishes mRNA from other RNA |
|
|
Term
|
Definition
occurs at the termination of mRNA transcription
triggered by specific DNA/RNA sequences |
|
|
Term
|
Definition
AAUAAA followed by 10-30 nucleotides then CA
signal for the gene to stop transcription and to add a series of adenosine= poly A tail |
|
|
Term
|
Definition
adds nearly 200 adenosine nuc to 3'end of mRNA.
no template |
|
|
Term
| what does the 3' polyadenylation require? |
|
Definition
several RNA binding proteins:
CSF: cleavage and polyadeny specificity factor which binds the AAUAAA.
CstF: cleavage stimulation factor: binds CA. |
|
|
Term
|
Definition
| part of process by which precursor mRNA*pre mrna* is transformed into mature m RNA |
|
|
Term
| capped,tailed and spliced transcript is called? |
|
Definition
|
|
Term
| What must occur before RNA is transported out of nucleus? |
|
Definition
|
|
Term
| The coding segments of DNA are known as what? |
|
Definition
|
|
Term
| The non-coding segments of DNA are known as what? |
|
Definition
introns
*important in regulation of gene expression |
|
|
Term
| name of the initial transcript of RNA? |
|
Definition
| hn RNA: heterogenous nuclear RNA or pre mRNA. |
|
|
Term
|
Definition
occurs at cytoplasmic processing bodies P bodies, which contain: exonucleases and decapping enzymes and microRNAs.
mRNA may be degraded or stored in p bodies for future translation. |
|
|
Term
|
Definition
regulate gene expression
target mRNA
binds via base pairing
extensive binding car remove poly A tail and exposes mRNA to degradation.
modofies gene expression at mRNA level |
|
|
Term
|
Definition
| some mRNA moved to pb in cytoplasm: seen with less extensive miRNA binding. |
|
|
Term
|
Definition
small nuclear ribonucleproteins
short RNA polymers complexed with proteins
RNA has a high content of uridine: U-RNA: u1/2/4/5/6 |
|
|
Term
| What is tthe function of snRNPs? |
|
Definition
| Forms spliceosomes in order to join exons |
|
|
Term
| Alterations in snRNP assembly cause which disease? |
|
Definition
|
|
Term
|
Definition
| snRNP assembly is affected due to decreased SMN protein *survival motor neuron*: congenital degeneration of anterior horns of spinal cord leading to symmetric weakness: hypotonia or floppy baby syndrome. |
|
|
Term
|
Definition
| primary transcript combined with small nuclear ribonucleoproteins. |
|
|
Term
|
Definition
| can produce a variety of protein products from a single hnRNA sequence |
|
|
Term
| alternative splicing examples? |
|
Definition
transmembrane vs secreted ig
tropomyosin variants in muscle
dopamine receptors in the brain |
|
|
Term
| Antibodies to spliceosomal snRNPs are found in what disease? |
|
Definition
|
|
Term
| anti bodies anti smith? anti Sm |
|
Definition
| against protein in snRNP found in SLE lupus |
|
|
Term
|
Definition
against pr associated with U1 RNA
strongly associated with mixed connective tissue disease
also in: scleroderma and sle. |
|
|
Term
|
Definition
| portions of m RNA at 5' and 3' ends that are not transcribed into proteins. |
|
|
Term
| 5' UTR? untranslated region |
|
Definition
upstream from coding sequence
recognized by ribosomes to initiate translation |
|
|
Term
| 3' UTR?untranslated region |
|
Definition
found following a stop codon
important for post transcriptional gene expression |
|
|
Term
| What is the most abundant type of RNA? |
|
Definition
|
|
Term
| What is the mRNA start codon? |
|
Definition
|
|
Term
The start codone AUG codes for what in eukaryotes?
in prokaryotes? |
|
Definition
Methionine, which may be removed before translation is completed by protease enz.
N-formyl methionine in prokaryotes: stimulates neutrophil chemotaxis. |
|
|
Term
| What is bound to the 3' end of tRNA? |
|
Definition
|
|
Term
| What enzyme is responsible for the accuracy of amino acid selection during protein synthesis? |
|
Definition
| Aminoacyl-tRNA synthetase |
|
|
Term
| Accuracy of base pairing is dependent on which nucleotides in an mRNA codon? |
|
Definition
|
|
Term
| GTP hydrolysis and initiation factors perform what function in protein synthesis? |
|
Definition
| Assembling of 40S ribosomal subunit with initiator tRNA |
|
|
Term
| tRNA binds to what site on ribosomes? |
|
Definition
|
|
Term
| Translated codons are translocated to what part of the ribosome? |
|
Definition
|
|
Term
| What is the energy requirement for translation? |
|
Definition
2 ATP and 2 GTP
ATP for tRNA Activation *charging*
GTP for tRNA Gripping and Going places *translocation* |
|
|
Term
|
Definition
75-90 nucleotides *tiny*
secondary structure
cloverleaf form
base pairing within the molecule
all tRNA in both euk and prok have CCa at 3' end along with a high percentage of chemically modified bases. |
|
|
Term
|
Definition
anticodon
D loop part
T loop part
3'end |
|
|
Term
|
Definition
3 nucleotides on tRNA
pairs with complementary mRNA
anticodon end is opposite 3' aminoacyl end. |
|
|
Term
|
Definition
contains DIHYDROURIDINE residues necessary for tRNA recognition by the correct aminoacyl-t RNA synthetase.
D arm allows Detection by aminoacyl synthetase. |
|
|
Term
|
Definition
contains the TΨC sequence:
T: ribothmidine
Ψ: pseudouridine
C: cytidine
necessary for tRNA ribosome binding.
T arm Tethers*bonds* tRNA to ribosome. |
|
|
Term
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Definition
always ends in CCA
hydroxyl OH of adenosine attaches to aminoacid.
the AA is covalently bound to the 3' end. |
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Term
| what do we mean by charging? tRNA |
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Definition
process of linking AA to tRNA
each tRNA linked to 1 AA
catalyzed by Aminoacyl tRNA synthetase
requires ATP
= aminoacylation |
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Term
| the accuracy of AA selection is due to? |
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Definition
| Aminoacyl tRNA synthetase and binding of charged tRNA to the codon |
|
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Term
| what happens if an incorrect AA is attached to tRNA? |
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Definition
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Term
| what do we mean by hydrolic editing? |
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Definition
Amino acyl tRNA synthetase matches an AA to the tRNA by scrutinizing the AA before and after it binds to tRNA.
if an incorrect AA is attached: the bond is hydrolized -hydrolyze the AA from AMP or tRNA- |
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Term
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Definition
1/ initiation
2/ elongation
3/ termination
synthesis occurs from N terminus to C terminus
addition to C terminal |
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Term
| ribosome in eukaryotes and prokaryotes? |
|
Definition
different size:
E: 40S + 60S *80S
P: 30S+ 50S *70S
S*Svedberg units: rate of sedimentation |
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Term
| initiation in protein synthesis? |
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Definition
1. Eukaryotic initiation factors eIFs identify the 5' cap.
2. eIFs help assemble the 40S ribosomal subunit with the initiator tRNA.
3. the eIFs released when the mRNA and the ribosomal 60S subunit assemble with the complex.
requires GTP |
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Term
| elongation in protein synthesis? |
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Definition
1. Aminoacyl tRNA binds to A site -except for initiator methionine which binds the P site- requires an elongation factor and GTP.
2.rRNA* ribozyme* catalyzed peptide bond formation, transfers growing polypeptide to AA in A site.
3.ribosome advances 3 nucleotides towards 3' end of mRNA, moving peptidyl tRNA to P site -translocation- |
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Term
| termination in protein synthesis? |
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Definition
Eukaryotic release factors eRFs recognize the stop codon and halt translation: completed polypeptide is released from ribosome.
requires GTP |
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Term
| Inactive enzyme precursors are known as what? |
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Definition
|
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Term
| What is used to tag defective proteins for breakdown by proteasome? |
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Definition
|
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Term
| Covalent alterations of proteins include what? |
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Definition
Phosphorylation, glycosylation, hydroxylation
methylation, acetylation and ubiquitination |
|
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Term
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Definition
intracellular protein involved in facilitating and maintaining protein folding.
in yeast, heat shock pr are expressed at high temperatures to prevent pr denaturing or misfolding.
help cells survive environmental stress. |
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Term
| trimming? post transcriptional modification |
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Definition
removal of N or C terminal propeptides from zymogen to generate mature protein.
exp: trypsinogen to trypsin. |
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Term
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Definition
|
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Term
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Definition
| accomodates growing peptide |
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Term
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Definition
| holds empty tRNA as it exits |
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Term
| which intermediate is involved in both pyrimidine synthesis and the urea cycle? |
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Definition
|
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Term
| what type of aa are histones made of? are they acidic or basic? |
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Definition
| lysine and arginine; basic |
|
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Term
| if a cell has a hyperchromatic or condensed nucleus is it undergoing transcription etc? |
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Definition
|
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Term
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Definition
| DNA is wrapped around core histones, forming a nucleosome fiber (10-nm fiber) |
|
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Term
| 3 levels of chromatin organization? |
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Definition
1.DNA wraps around histone proteins, forming nucleosomes and the so-called beads on a string structure (euchromatin).
2.Multiple histones wrap into a 30-nanometer fibre consisting of nucleosome arrays in their most compact form (heterochromatin).
3.Higher-level DNA supercoiling of the 30-nm fiber produces the metaphase chromosome (during mitosis and meiosis). |
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