Lecture 8 Protein Synthesis Flashcards Preview

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Flashcards in Lecture 8 Protein Synthesis Deck (18):
1

Information molecules
(nucleic acids)

hold and transfer genetic information

2

Structure
(nucleic acids)

chain of nucleotides
pentose sugar + phosphate + nitrogenous base (A,G,C,T or U)

3

DNA

double stranded
double helical structure
base pairing; A-T (2 bonds), G-C (3 bonds)

4

RNA

mostly single stranded
higher level structures in tRNA and rRNA
base pairing: A-U, G-C
major classes: mRNA, rRNA, tRNA

5

Transcription
what is it? where does it happen?

happens in the nucleus
highly regulated
transfer of genetic information from DNA to mRNA

6

Transcription steps 1-3
(RNA synthesis)

1. transcription is activated by binding of regulatory proteins to regulatory regions in DNA (promoter and enhancers) located upstream of the gene
2. DNA "unzips" in region to be transcribed
3.RNA polymerase enzyme binds to DNA

7

Transcription steps (4-6)

4. RNA nucleotides form complementary base pairs with DNA, then RNA polymerase joins RNA nucleotides and elongates strand to form pre-mRNA
5. pre-mRNA is spliced (introns removed) and processed to form mature mRNA
6.mRNA leaves the nucleus and enters the cytoplasm

8

activation of transcription requires?

interaction of several regulatory proteins

9

transcription factors

proteins that bind to DNA to activate transcription of specific genes
regulates transcription
ex: liver had liver transcription factors, muscle has muscle transcription factors.

10

what is a promoter composed of

A's and T's

11

Translation
what is it?

transfer of information from mRNA to amino acid sequence of protein
genetic code contained in 3 nucleotides
-64 possible codons

12

mRNA

contains the codons - base triplets
each codon codes for a specific amino acid (also start and stop codons)

13

tRNA

contains the anticodon complementary to a specific codon of mRNA
each specific tRNA carries a particular amino acid
Key link between the genetic code in mRNA and the amino acid sequence of the protein

14

aminoacyl-tRNA

tRNA linked to amino acid

15

ribosome

key organelle for translation, binds to mRNA and tRNA
catalyzes peptide bond formation

16

Translation steps 1-4

1. ribosome binds to mRNA
2. first aminoacyl-tRNA comes in, matches anticodon to first mRNA codon (AUG)
3. second aminoacyl-tRNA comes in, matches anticodon to next mRNA codon
4. peptide bond forms between first two amino acids

17

translation steps 5-7

5. first tRNA releases; ribosome moves to next codon on mRNA
6. next aminoacyl-tRNA comes in, process repeats steps 3-5; growing polypeptide chain
7. last amino acids is added to chain

18

rRNA

ribosome catalyzes peptide bond
moves three spaces down