chapter seventeen part two

Question 1

where does translation occur

Answer 1

ribosomes in the cytoplasm

Question 2

how is mRNA read during translation?

Answer 2

5’ to 3’

Question 3

how are amino acids synthesized during translation? (direction)

Answer 3

N to C
(amino to carboxyl group)

Question 4

where is the amino acid attached on tRNA

Answer 4

3’ end

Question 5

how many total codons are there?

Answer 5

64
- 61 code for 20 amino acids

Question 6

codon

Answer 6

sequence of 3 nucleotides
- complementary to template strand

Question 7

universal (almost) codes

Answer 7

start - AUG
stop - UAA, UGA, UAG

Question 8

aminoacyl-tRNA synthetases

Answer 8

match tRNA and amino acid
- charge tRNA

Question 9

4 steps of translation

Answer 9

1. charging
2. initiation
3. elongation
4. termination

Question 10

1. charging

Answer 10

• tRNA joined to respective amino acid
• tRNA has anticodon that matches the codon on mRNA

Question 11

2. initiation

Answer 11

• ribose assembles and reads mRNA 5’ to 3’
• ribosome reads AUG (start)
• tRNA w/ met into P site
• anticodon on tRNA matches mRNA codon

Question 12

3. elongation

Answer 12

• next codon read
• tRNA w/ AA into A site
• met cut from its tRNA and attached to AA in A site (peptide bond forms)
• uncharged tRNA released from ribosome to get recharged w/ met
• next codon read

Question 13

4. termination

Answer 13

• ribosome reads stop codon
• releasing factor causes addition of water molecule instead of AA to chain, breaks bond between completed polyps and tRNA in P site

Question 14

co-transcriptional translation

Answer 14

transcription and translation occur at same time
- prokaryotes: lack of compartmental organization

Question 15

polyribosomes

Answer 15

strings of ribosomes working on 1 strand of mRNA
- prok or euk

Question 16

mutations

Answer 16

change in genetic material of cell
- ultimate source of new genes

Question 17

base pair substitutions

Answer 17

1. silent
2. missense
3. nonsense

Question 18

silent base pair substitution

Answer 18

no phenotypic change, partly due to 2 different codons translating into same amino acid

Question 19

missense base pair substitution

Answer 19

change 1 AA in sequence
- little effect on protein but dramatic phenotypic effect
- sickle cell

Question 20

nonsense base pair substitution

Answer 20

change 1 AA to stop codon
- translation terminated prematurely, shorter polypeptide

Question 21

insertion or deletion

Answer 21

addition or losses of nucleotides
- results in frameshift

Question 22

frameshift

Answer 22

alters reading frame and triplet grouping of nucleotides on mRNA strand
- when insertion/deletion not a multiple of 3

Question 23

missense downstream

Answer 23

wrong AA

Question 24

early nonsense

Answer 24

stop at wrong spot

Question 25

base insertion/deletion in multiple of 3

Answer 25

no frameshift, but AA added or missing

Question 26

causes of mutations

Answer 26

1. unknown/spontaneous 2. mutagen

Question 27

mutagen

Answer 27

physical/chemical agents that cause mutations - radiation (ultraviolet) - chemical (incorrectly paired nucleotides) - virus

Question 28

gene editing with CRIPSR

Answer 28

- altering genes in specific, predictable way - Cas9

Question 29

Cas9

Answer 29

nuclease that cuts double-stranded DNA molecules - helps defend bacteria against viruses - works with guide RNA made from CRIPSR region of bacterial genome - cuts both strands of DNA complementary to guide RNA to trigger DNA repair system

Question 30

what does guide RNA do?

Answer 30

guides Cas9 protein to target gene

Question 31

positive potential of CRIPSR

Answer 31

repair gene that has harmful mutation, possible cure for genetic diseases

Question 32

negative potential of CRIPSR

Answer 32

misapplication and ethics

Question 33

peptide transferase

Answer 33

cuts covalent bond of AA and tRNA in P site - attaches carboxyl end to amino end of AA attached to tRNA in A site

Question 34

ribozyme

Answer 34

peptides transferase + RNA

Question 35

DNA poly in prokaryotes

Answer 35

I - R&R II - repair processes III - most replication

Question 36

DNA poly in eukaryotes

Answer 36

alpha and delta

Question 37

RNA poly in prokaryotes

Answer 37

core enzyme holo enzyme (core + sigma factor) - sigma factor has dif types that aid in promoter selection

Question 38

RNA poly in eukaryotes

Answer 38

I - rRNA II - protein genes (hnRNA to mRNA) III - tRNA, some other small RNAs

Question 39

polyadenylation signal in transcription

Answer 39

first recognized by endonuclease - cuts 12 nuts downstream - poly-A polymerase adds 150-200 As