Week 9-11

Question 1

Topoisomerase

Answer 1

sits at the front of DNA replication fork and alleviates tension by cutting, swivelling, and rejoining DNA strands

Question 2

Helicase

Answer 2

unzips the DNA

Question 3

Single-stranded binding proteins

Answer 3

stabilizes single strand DNA, stops strands from going back together

Question 4

Primase

Answer 4

makes RNA primer

Question 5

RNA primer

Answer 5

DNA polymerase can bind to it

Question 6

DNA polymerase 3

Answer 6

adds complementary nucleotides to the 3’ end, can proofread

Question 7

DNA polymerase 1

Answer 7

replaces the primers with nucleotides

Question 8

DNA ligase

Answer 8

acts as glue

Question 9

Nucleotide excision repair

Answer 9

process to repair mistake in the DNA sequence

Question 10

Nuclease

Answer 10

acts as scissors, cuts out the bad DNA

Question 11

Initiation (transcription)

Answer 11

RNA polymerase binds to the promoter with the help of transcription factors. All of these bound on the DNA creates initiation complex

Question 12

Elongation (transcription)

Answer 12

RNA polymerase moves along and untwists double helix. Nucleotides get added to the 3’ end

Question 13

Termination (transcription)

Answer 13

RNA polymerase hits stop codon, dissociates and helix zips back up

Question 14

RNA processing

Answer 14

Introns (non-coding regions) get sliced out, creating an mRNA strand of continuous code (exons). A modified guanine 5’ cap is added to the front while a poly A tail of 50-250 adenines are added to the end.

Question 15

tRNA

Answer 15

Charged with an amino acid on one end and has an anticodon on the other. Helps with translation

Question 16

aminoacyl-tRNA

Answer 16

Enzyme that helps tRNA covalently bond to amino acid.

Question 17

P site

Answer 17

Where the charged tRNA and polypeptide chain is held

Question 18

A site

Answer 18

Acts a queue, holds the next amino acid to be added

Question 19

E site

Answer 19

Exit, tRNA leaves

Question 20

Initiation (translation)

Answer 20

Ribosome association, bottom attaches to mRNA and top is brought in by initiation factors.

Question 21

Elongation (translation)

Answer 21

Ribosome slides down mRNA, nucleotides get added in the 5’ to 3’ direction

Question 22

Termination (translation)

Answer 22

Ribosome hits stop codon, release factors come in and promote hydrolysis, water gets added instead of an amino acid. Ribosomal subunits dissociates.

Question 23

Wobble

Answer 23

Flexibility in 3rd base pairing in tRNA, several codons code for one amino acids so there are 32 tRNAs that recognize 61 different amino acids. It is okay if the pair is not complementary as long as the amino acid is the same.

Question 24

Polysome

Answer 24

Multiple ribosome translating a single mRNA strand. This can happen in prokaryotes and eukaryotes

Question 25

Coupling

Answer 25

Transcription couples translation and translation can take place before transcription finishes. Only possible in prokaryotes.

Question 26

Frameshift mutation

Answer 26

Mutations that shift the reading frame. Can be insertion or deletion.

Question 27

Silent mutation

Answer 27

Substitution mutation where there is not effect on the amino acid produced.

Question 28

Missense mutation

Answer 28

Substitution mutation where there is code for an amino acid, but it’s the wrong amino acid.

Question 29

Nonsense mutation

Answer 29

Substitution mutation where an amino acid is changed into a stop codon.

Question 30

Operon

Answer 30

proteins that are similar in structure and function coded for by the same transcript

Question 31

Parts of an operon

Answer 31

Regulatory genes, operator (where regulator binds), structural genes (genes that are regulated by the operon)

Question 32

Inducible

Answer 32

An operon that is usually off but can be turned on

Question 33

Repressible

Answer 33

An operon that is usually on but can be turned off

Question 34

Lac operon

Answer 34

Operon responsible for transporting and metabolizing lactose. It is inducible

Question 35

Trp operon

Answer 35

Operon responsible for production of tryptophan. It is repressible

Question 36

Catabolic

Answer 36

Breaks down

Question 37

Anabolic

Answer 37

Builds up

Question 38

Low glucose

Answer 38

cAMP is made, CAP binds to DNA and helps RNA polymerase bind to promoter. High transcription

Question 39

High glucose

Answer 39

no cAMP is made, no CAP binding, low transcription.