dna

Question 1

what is RNA

Answer 1

the intermediate for genes + the proteins that encode them

Question 2

what is transcription

Answer 2

synthesis of an RNA under the direction of DNA - produces a messenger RNA (mRNA)
- DNA -> RNA

Question 3

what is translation

Answer 3

synthesis of a polypeptide / protein under the direction of mRNA
- RNA -> PROTEIN

Question 4

prokaryotes rna characteristics

Answer 4

• No mRNA processing
• All happens in cytosol

Question 5

eukaryotes rna characteristics

Answer 5

• mRNA is processed
• nucleus separates transcription from translation

Question 6

what are ribosomes

Answer 6

site of translation

Question 7

what strand is used as a template to make RNA during transcription

Answer 7

template strand - complementary to the non-template strand

Question 8

important to remember about the non-template strand

Answer 8

its the same sequence as the newly formed RNA (except for the substitution of uracil for thymine)

Question 9

what exists instead of Thyamine in RNA

Answer 9

U

Question 10

whats a codon

Answer 10

the 3 bases that are read from the mRNA to make an amino acid
- smallest uniform length that can code for all amino acids

Question 11

what is the problem with genetic code

Answer 11

20 amino acids but only 4 RNA bases

Question 12

how many possible codons are there

Answer 12

64 - all of these were solved in 1960s
- 61 code for amino acids
- 3 code for stop codons

Question 13

whats the start codon

Answer 13

AUG (Met)

Question 14

3 things important to know about the genetic code

Answer 14

• redundant - can have multiple codon over the same thing
• unambiguous
• universal

Question 15

what enzyme catalyses transcription

Answer 15

RNA polymerase - has same base pairing rules as DNA except U substitutes T

Question 16

where does RNA polymerase attach

Answer 16

PROMOTER

Question 17

where does the end of transcription happen in prokaryotes

Answer 17

TERMINATOR

Question 18

3 stages of transcription

Answer 18

1. initiation
2. elongation
3. termination

Question 19

what is initiation in transcription

Answer 19

• promoters signal the initiation of RNA synthesis
• TRANSCRIPTION FACTORS bring RNA polymerase to the promoter (transcription factors + RNA polymerase = TRANSCRIPTION INITIATION COMPLEX)
• a promotor element (TATA element) = crucial in newly eukaryotic genes for formation TIC

Question 20

what is elongation in transcription

Answer 20

• RNA polymerase zips along the double helix 10-20
• transcription progresses at 40 bases/second
• a gene can be transcribed by multiple RNA polymerases at once

Question 21

what is termination in transcription

Answer 21

• prokaryotes: transcription stops at terminator
• eukaryotes: polymerase continues beyond end of gene + the pre mRNA is cleaved off and polymerase falls off