Genetics Exam 4 Chapter 15 - UCF Bayer Flashcards Quizlet PDF

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11/3/21, 7:30 PM

Genetics Exam 4 Chapter 15 - UCF Bayer Flashcards | Quizlet

Genetics Exam 4 Chapter 15 - UCF Bayer Terms in this set (27) - polypeptide = chain of amino acid monomers - all 20 amino acids amino acid structure

carboxyl group (COO-) amino group (NH3+) radical (R) group side chain

R groups

polypeptide

nonpolar/polar +/-

peptide bonds: join amino acids in a dehydration synthesis

polypeptide - primary

- seq of amino acids (monomers)

structure

- determined by DNA code

- Hydrogen bonding between peptide bond atoms polypeptide - secondary structure

of polypeptide - backbone twists & folds polypeptide into secondary structures: ALPHA HELIXES & BPLEATED SHEETS

polypeptide - tertiary structure

bonds between R groups: fold polypeptide into 3D shape

polypeptide - quarternary

multiple polypeptides associate to form: functional

structure

protein

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Genetics Exam 4 Chapter 15 - UCF Bayer Flashcards | Quizlet

set of 3 nucleotides (triplet code) that codes for an AMINO ACID codon [AUG] [GUG] [UUG] [AGC]

anticodon (tRNA) = base-pairs with complementary codon of the mRNA @ ribosome translating genetic code anticodon (top) codon (bottom)

codon = 3 nucleotides (64 possible combinations of 4 bases) genetic code

61 = sense codons = code for amino acids 3 = termination codons = stop/anti-sense....signal end of translation

genetic code = degenerate (redundant) = amino acids are specified by more than 1 codon degeneracy (redundancy) of genetic code

- organisms encode 30-50 different tRNA's to carry 30 amino acids = some amino acids are carried by more that 1 tRNA

isoaccepting tRNA's

attach to same amino acid but have different anticodons

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Genetics Exam 4 Chapter 15 - UCF Bayer Flashcards | Quizlet

61 sense codon more than available tRNA's = some nonstandard base pairing occurs at 3' end (ACG UGU) Wobble (at 3' end)

- flexibility in hydrogen bonding at 3' end makes some codons SYNONYMOUS = UCC & UCU code for SERINE

occurs in 4 stages: 1. charging translation

2. initiation 3. elongation 4. termination

Charging (tRNA)

linking a tRNA to its appropriate amino acid requires energy = coupled to ATP hydrolysis

- enzyme catalyzes binding of amino acid to its tRNA Aminoacyl-tRNA synthetase

- each synthetase enzyme recognizes a specific: tRNA by its nucleotides Amino Acid by its size, shape, R group

(Bacterial - prokary) IF-3 = prevents small & large subunit from joining Initiation - bacterial (prokary)

initially Shine-Dalgarno = seq pairs with 16s rRNA of small sunbit

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Genetics Exam 4 Chapter 15 - UCF Bayer Flashcards | Quizlet

1. allowing small subunit to attach to mRNA 2. tRNA charge with N-formylmethionine forms complex with IF-2 & GTP 3. binds to the initiation codon while IF-1 joins the initiation steps

small subunit 6. all initiation factors dissociate from the complex: GTP is hydrolyzed to GDP 7. large subunit joins to create a 70s initiation complex

end of initiation

ribosome is assembled on the mRNA and the FIRST tRNA is attached to the initiation codon

5' cap of mRNA is bound by initiation complex - initiation complex = small subunit + 7 initiation factors + initiator tRNA (tRNAi - Met) Initiation - eukary

- initiation complex scan mRNA until finds AUG within consensus Kozak seq - porteins binding poly(A) tail interact with proteins binding 5' cap = forms a CLOSED LOOP

Kozak seq

5' - ACCAUGG - 3'

3 tRNA binding sites on ribosome elongation

1. aminoacyl (A) 2. Peptidyl (P) 3. Exit (E)

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1. Complex at A (aminoacyl) site - tRNA + elongation factor Tu (EF-Tu) + GTP - GTP hydrolyzed to GDP - elongation factor Ts (EF-Ts) regenerates EF-Tu + GTP elongation (3 steps) 2. Peptide bond formation within large subunit 3. translocation - movement of ribosome down mRNA - requires elongation factor G (EF-G) & GTP

translocation

movement of ribosome down mRNA

1. EF-Tu, GTP, and charged tRNA form complex 2. enters the A (aminoacyl) site of the ribosome 3. after charge tRNA placed into A site....GTP is cleaved/hydrolyzed & EF-Tu-GDP complex is elongation steps

released 4. EF-Ts regenerates the EF-Tu-GTP complex...then ready to combine with another charged tRNA 5. peptide bond forms between the amino acids in the P and A sites & tRNA in the P site releases its amino acid

amino acid that was in the A site is added to the end of elongation

polypeptide chain and the A site is free to accept another tRNA

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Genetics Exam 4 Chapter 15 - UCF Bayer Flashcards | Quizlet

1. Stop Codon = signals the termination of translation = NO tRNA to bind with stop codon 2. Protein release factors = bind to the A site of the Termination

ribosome instead 3. translation apparatus breaks apart and polypeptide release

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