genetic code (1B)

Question 1

order of the central dogma

Answer 1

DNA –> transCRIPtion –> RNA –> tranSLAtion –> protein

Question 2

where is DNA found?

Answer 2

nucleus

Question 3

where does transcription happen

Answer 3

nucleus

Question 4

where does translation happen

Answer 4

cytoplasm

Question 5

what organelle makes proteins

Answer 5

ribosomes

Question 6

mRNA is a sequence of

Answer 6

nucleotides

Question 7

3 nucleotides (aka a codon) code for an

Answer 7

Amino acid (AA)

Question 8

where is the anticodon located

Answer 8

on the tip of the tRNA

Question 9

why are genetic codes considered degenerate

Answer 9

bc more than one codon codes for a given Amino Acid

Question 10

what is the wobble position

Answer 10

the third base in the codon

Question 11

what happens when there’s a mutation in the wobble position

Answer 11

there’s no effect on the expression of the AA –> so no adverse effect on the polypeptide sequence

wobble = designed to protect against mutations

Question 12

missense codon

Answer 12

mutated codon that results ina DIFFERENT AMINO ACID

Question 13

nonsense codon

Answer 13

mutated codon that results in a STOP codon

Question 14

what is the initiation codon and what does it signal ?

Answer 14

AUG

the start of translation

Question 15

what are the termination codons and what do they signal ?

Answer 15

UGA, UAG, UAA

the end of translation

Question 16

what is unique to termination codons and not others

Answer 16

tRNA is not involved

Question 17

what terminates translation

Answer 17

a protein called release factor

Question 18

what protects the 5’ end of mRNA from exonuclease degradation

Answer 18

5’ cap (a modified nucleotide) that’s linked in a special way to mRNA

Question 19

what protects the 3’ end of mRNA from exonuclease degradation

Answer 19

poly-A tail

Question 20

difference between eukaryotic and prokaryotic mRNA

Answer 20

eukaryotic have 5’ cap - nucleotides - 3’ poly A tail while prokaryotic mRNA don’t have the cap nor the tail

Question 21

what type of RNA are products of transcription: transfer RNA (tRNA), ribosomal RNA (rRNA) and/or messenger RNA (mRNA)?

Answer 21

all 3: tRNA, mRNA, rRNA

Question 22

what type of RNA are templates for translation: transfer RNA (tRNA), ribosomal RNA (rRNA) and/or messenger RNA (mRNA)?

Answer 22

mRNA

Question 23

role of tRNA?

Answer 23

responsible for bringing in the right AA for translation

Question 24

role of rRNA?

Answer 24

make up ribosomes which are responsible for translation (ribosomes turn mRNA into protein)

Question 25

what is the tRNA structure? i.e. what's at the tip and the tail

Answer 25

at the tip is an anticodon and at the tail is an amino acid

Question 26

at the 3' end of the tRNA, the amino acid is attached to what? via what?

Answer 26

attached to 3'OH (tertiary alcohol? look into) via ester linkage

Question 27

rRNA has an active site for

Answer 27

catalysis

Question 28

the rRNA of large ribosomal subunit is responsible for

Answer 28

catalyzing peptide bond formation & can do this even without ribosomal proteins

Question 29

first step of transcription is: chain INITIATION which involves...

Answer 29

RNA polymerase binds to promoter (TATA box) of (closed) double stranded DNA --> causing double stranded DNA complex to open

Question 30

second step of transcription is: chain ELONGATION which involves...

Answer 30

nucleoside triphosphates (A,U,G,C) adds the corresponding to the DNA template

Question 31

are primers required for transcription

Answer 31

no

Question 32

RNA is made in what direction

Answer 32

5' to 3'

Question 33

third step of transcription is: chain TERMINATION which can happen in 2 ways - describe them

Answer 33

(1) intrinsic termination - specific sequences (termination sites) create a stem loop structure on RNA that causes RNA to slip off the template (2) rho dependent termination - the rho factor (a protein) bumps off the polymerase

Question 34

RNA molc capable of catalyzing specific chemical reactions

Answer 34

ribozyme

Question 35

small nuclear RNAs (snRNA)

Answer 35

complex with proteins to form small nuclear ribonuclearproteins (snRNPs) to splice primary RNA transcripts

Question 36

small nuclear ribonuclearproteins (snRNPs) combined with unmodified pre-mRNA to form a

Answer 36

spliceosome = large complex where splicing of pre-mRNA occurs

Question 37

what would happen if there were less introns or alternative splicing

Answer 37

less protein variability

Question 38

what are used to splice introns

Answer 38

snRNAs / snRNP

Question 39

what are the post-transcriptional modifications (3)

Answer 39

adding of the 5'cap, poly A tail and splicing

Question 40

t/f: adding of the cap and polyA tail is considered post-transcriptional

Answer 40

true

Question 41

what enzyme catalyzes protein synthesis

Answer 41

ribosome

Question 42

which ribosome subunit is responsible for recognizing mRNA and binds to Shine-dalgarno sequence on mRNA in prokaryotes (kozak seq in eukaruotes)

Answer 42

small

Question 43

first step of translation is: chain INITIATION which involves...

Answer 43

combining mRNA, initiator tRNA, and ribosome | this complex forms around initiation codon (AUG)

Question 44

second step of translationg is: chain ELONGATION which involves...

Answer 44

(1) binding (2) peptidyl transfer (3) translocation

Question 45

protein is made from what terminus to what

Answer 45

N terminus to C

Question 46

mRNA reads in what direction

Answer 46

5' to 3' end

Question 47

during the binding portion of chain elongation, new tRNA and its amino acid (aminoacyl-tRNA) enters the A site. what is required for this to happen

Answer 47

GTP and elongation factor

Question 48

during the peptidyl transfer portion of chain elongation, attachment of the new AA to existing chain in the P site. This chain in the P site migrates and attaches to...

Answer 48

the aminoacyl-tRNA in the A site

Question 49

the codon that was in the A site goes where after translocation (part 3 of translation elongation)

Answer 49

its now in the P site | **watch video on this...v confusing

Question 50

second step of translation is: chain termintion which involves...

Answer 50

stop codon encountered --> release factor proteins bound to GTP block the A site --> peptide chain gets cleaved from tRNA --> peptide chain falls off and whole translation complex falls apart

Question 51

inactivation by tagging protein for proteasome degradation

Answer 51

ubiquitination

Question 52

list 3 examples of post-translational modifications to proteins

Answer 52

phosphorylation glycosylation ubiquitination