Bacteria

Question 1

what does bacteria need

Answer 1

tryptophan (Trp)

Question 2

where does Trp come from

Answer 2

from food, but can be made if food is poor- to make it 5 enzymes are needed- this costs energy, so bacteria shouldn’t waste energy if it is present in food

Question 3

what does the Trp operon make

Answer 3

it only makes enzymes when the Trp levels are low

Question 4

what are operons

Answer 4

a bacterial gene cluster controlled by a single promoter e.g Trp operon

Question 5

what controls operons

Answer 5

this is controlled by a repressor- it binds to the promotor and blocks transcription

Question 6

how does gene regulation in eucaryotes differ from procaryotes

Answer 6

1. 3 RNA polymerase instead of 1
2. regulation at distance
3. Effects due to DNA packing
4. need for general transcription factors

Question 7

how many RNA polymerases are in eucrayotic cells

Answer 7

3

Question 8

what is the 1st RNA polymerase

Answer 8

most rRNA genes

Question 9

what is the 2nd RNA polymerase

Answer 9

all protein coding genes

Question 10

what is the 3rd RNA polymerase

Answer 10

tRNA genes, 5S rRNA gene and genes for some small structural RNAs

Question 11

what are most genes transcribed by

Answer 11

RNA 2

Question 12

What is pituitary dwarfism

Answer 12

a lack of a growth hormone and mutations in growth hormone gene. If they lack several hormones they have a mutation in transcription factor- Pit-1

Question 13

where is DNA found

Answer 13

the nucleus

Question 14

where are proteins found

Answer 14

the cytoplasm

Question 15

why are messengers needed for DNA and proteins

Answer 15

to carry it from the nucleus to the cytoplasm

Question 16

why is RNA a messenger

Answer 16

as it is structurally similar to DNA and abundant in the cytoplasm and can be found in the nucleus

Question 17

what sugar does RNA and DNA have

Answer 17

RNA - ribose sugar
DNA- deoxyribose sugar

Question 18

why is RNA less favoured for storing permanent info

Answer 18

1. ribose sugar less capable of forming long chains
2. double strand DNA favours repair and increases stability

Question 19

what Is converted in transcription

Answer 19

DNA ->RNA using mRNA from template DNA strand

Question 20

what is the template strand

Answer 20

the coding strand as its sequence is equivalent to the RNA product (but the 3’ to 5’ strand used as a template for base pairing)

Question 21

is transcription quick

Answer 21

it is quicker than DNA replication as it has no proof-reading and the helix rewind behind RNA transcription, displacing it

Question 22

how is DNA transcribed into RNA

Answer 22

by RNA polymerase- it adds nucleotides on by one to the RNA using an exposed DNA strand (3’ 5’) as a template

Question 23

what is the resulting RNA after it is transcribed

Answer 23

it is singe-stranded with complementary copy of one of 2 DNA strands. The incoming nucleotides are triphosphate and the energy in their phosphate bonds is the driving force to polymerisation