Week 7

Question 1

What is the central dogma?

Answer 1

The process of going from DNA to RNA to proteins using transcription and translation

Question 2

What differentiates DNA and RNA in structures?

Answer 2

RNA has a 2’ OH group, RNA is single stranded vs DNA which is double stranded

Question 3

Primary structure

Answer 3

The amino acid sequence

Question 4

Secondary structure

Answer 4

The local folding of alpha helices/beta pleated sheets

Question 5

Tertiary structure

Answer 5

Overall folded shape of the amino acid chain

Question 6

Quaternary structure

Answer 6

The shape of multiple tertiary structures together

Question 7

Stop Codons

Answer 7

UGA, UAA, UAG

Question 8

What is the start codon?

Answer 8

AUG

Question 9

Reading frame

Answer 9

AUG to stop codon

Question 10

Intragenic suppression

Answer 10

How a gene can still function if one mutation cancels another in the same gene (frame restoration)

Question 11

Frameshift mutations

Answer 11

A single-base deletion/insertion that shifts the reading frame of the amino acid sequence

Question 12

tRNA

Answer 12

74 to 95 nucleotides long, carries a specific amino acid, have anticodons

Question 13

How was the amino acid code decoded?

Answer 13

Used radioactively labelled amino acids. As translation occurred, the mixture was poured through a filter, allowing only tRNAs that had the correct amino acid stick to the filter

Question 14

Transcription

Answer 14

Going from DNA to RNA, uses Uracil instead of Thymine, still complementary base pairing

Question 15

Synthesis occurs in what direction?

Answer 15

5’ to 3’

Question 16

RNA polymerase

Answer 16

Enzyme used to catalyze transcription

Question 17

Promoter

Answer 17

DNA sequence near the beginning of genes that tell RNA polymerase where to start transcription

Question 18

Terminators

Answer 18

Sequence in RNA product that tells RNA polymerase where to stop transcription

Question 19

Transcription Initiation

Answer 19

Sigma factor recognizes the promoter on DNA, and RNA polymerase binds (which releases the sigma factor)

Question 20

Transcription Elongation

Answer 20

RNA polymerase makes its way along the chain, complementary base pairing rNTPs

Question 21

Rho-dependent Transcription Termination

Answer 21

Rho protein binds to RNA sequence that is C-rich pulls mRNA away from polymerase

Question 22

Rho-independent Transcription Termination

Answer 22

G/C rich section in RNA, creates hairpin loop, RNA polymerase is released

Question 23

Differences between prokearyotic genes and eukaryotic genes

Answer 23

Prokaryotes cannot rearrange genes like eukaryotes rearrange exons, different post-translational modifications

Question 24

G’ cap

Answer 24

Adding a methylated G at 5’ end of eukaryotic mRNA to prevent degradation

Question 25

Poly A Tail

Answer 25

3’ end of eukaryotic mRNA, also prevents degradation, helps with translation

Question 26

RNA splicing

Answer 26

Rearranging of exons by removing introns (alternative splicing) - Cuts at 5’ site, which folds over, cut at 3’ site EX: Dystrophin gene has MANY introns

Question 27

Translation

Answer 27

Converting RNA to protein

Question 28

Prokaryotic Translation Initiation

Answer 28

Shine-Dalgarno sequence is recognized by complementary sequences in rRNA (upstream of initiation codon). Initiation codon signals addition of tRNA with Methionine, which binds the two subunits of the ribosome together (previously just small subunit, Met is in P site

Question 29

Eukaryotic Translation Initiation

Answer 29

Small subunit binds to G’ cap instead

Question 30

Translation Elongation

Answer 30

- Elongation factors bring next tRNA over into A site, peptidyl transferase creates the peptide bond between the two amino acids - Ribosome moves along mRNA, Met moves to E site, more tRNA appears, etc

Question 31

Translation Termination

Answer 31

Stop codon is reached, release factor binds to A site, polypeptide is released

Question 32

Wobble

Answer 32

Where some tRNAs are able to recognize more than one codon (has specific rules)

Question 33

Structure of the ribosome

Answer 33

- Three sites, Aminoacyl site (A), Peptidyl site (P), Exit site (E) - Made of large and small subunit - Protein and rRNA

Question 34

Polyribosome

Answer 34

Several ribosomes translating the same mRNA

Question 35

Post-translational processing

Answer 35

Cleavage: cutting protein into smaller polypeptides Adding a phosphate group, etc