Biochemistry Chapter 7: RNA and the Genetic Code

Question 1

What is the central dogma of biochem?

Answer 1

DNA - RNA - protein

Question 2

What is the start codon?

Answer 2

AUG

Question 3

What are the stop codons?

Answer 3

UGA, UAA, UAG

Question 4

What allows mutations to occur without effects in the protein?

Answer 4

redundancy and wobble

Question 5

Silent mutations

Answer 5

no effect on protein synthesis

Question 6

Nonsense mutations

Answer 6

produce a premature stop codon

Question 7

Missense mutation

Answer 7

produce a codon that codes for a different amino acid

Question 8

Frameshift mutations

Answer 8

result from nucleotide addition or deletion & change the reading frame of subsequent codons

Question 9

Differences in RNA from DNA

Answer 9

• ribose sugar
• uracil instead of thymine
• single-stranded

Question 10

mRNA

Answer 10

carries the message from DNA in the nucleus via transcription of the gene; travels into the cytoplasm to be translated

Question 11

tRNA

Answer 11

brings in amino acids, recognizes the codon on the mRNA using its anticodon

Question 12

rRNA

Answer 12

makes up the ribosome

Question 13

Helicase and topoisomerase

Answer 13

Unwind the DNA double helix

Question 14

RNA polymerase II

Answer 14

Binds to the TATA box within the promoter region of the gene

Question 15

hnRNA

Answer 15

synthesized from the DNA template antisense strand

Question 16

What are some posttranscriptional modifications?

Answer 16

• 7-methylguanylate triphosphate cap is added to the 5’ end
• Poly A tail is added to the 3’ end
• splicing

Question 17

How can prok and euk increase variability?

Answer 17

Prok - polycistronic genes

Euk - alternative splicing

Question 18

What are the three steps of translation?

Answer 18

Initiation
Elongation
Termination

Question 19

What starts initiation in prok?

Answer 19

30S ribosome attaches to the Shine-Dalgarno sequence

Question 20

What starts initiation in euk?

Answer 20

When the 40S ribosome attaches to the 5’ Cap and scans for a start codon

Question 21

What are some posttranscriptional modifications

Answer 21

• folding by chaperones
• formation of quarternary structure
• cleavage of proteins or signal sequences
• covalent addition of other biomolecules