Ch 14 Gene Expression: From Gene to Protein

Question 1

where does transcription occur in cell

Answer 1

nucleus

Question 2

how does transcription start

Answer 2

binding of RNA polymerase to promoter in DNA

Question 3

what is required for transcription to occur

Answer 3

• tata box (promoter)
• RNA polymerase 2
• Transcription factors

Question 4

how many H-bonds between A-U

Answer 4

two

Question 5

features of mature mRNA

Answer 5

• 5’ prime cap
• 3’ end get poly A tail
• exons spliced together and introns cut out

Question 6

where does translation occur in cell

Answer 6

cytoplasm

Question 7

how does translation start

Answer 7

binding of ribosome, starts at AUG codon

Question 8

how does translation terminate

Answer 8

when stop codon in mRNA reaches A site of ribosome, site accepts prone release factor–> causes add-on of H2O instead of a.a. reaction then real seas polypeptide and translation assembly comes apart

Question 9

what are the components of translation machinery

Answer 9

need tRNA
amino acyl tRNA synthase
ribosome (large+small subunit)

Question 10

structural features of tRNA

Answer 10

transfers amino acid to polypeptide in ribosome

Question 11

what are the steps of elongation cycle of translation

Answer 11

1. codon recognition
2. peptide bond formation
3. translocation

Question 12

Codon recognition of elongation

Answer 12

amino acid added one by one to previous amino acid at c-terminu of growing chain

Question 13

translocation of elongation

Answer 13

happens along mRNA in 5’–>3’ direction

Question 14

what are the features of genetic code

Answer 14

• red in triplets “codons”
• composed of 4 nucleotides on mRNA
• 64 possible combos

Question 15

what is a codon

Answer 15

sequence of three nucleotides that together form unit of genetic code in DNA/RNA molecule

Question 16

Types of mutations

Answer 16

Frameshift: insertion and deletion
Point mutation
Substitution: silent, missense, non-sense

Question 17

Silent mutation

Answer 17

have no effect on amino acids produced by codon b/c redundancy in genetic code

Question 18

Missense mutation

Answer 18

code for amino acid but not correct amnio acid

Question 19

Non-sense mutation

Answer 19

change a.a codon into stop codon almost always using non-functional protein

Question 20

Frameshift mutations

Answer 20

caused by deletion/insetion in DNA sequence that shifts the way a sequence is read

Question 21

mutagens

Answer 21

agent that causes genetic mutation (radiation)