chapter 22: gene expression - transcription + translation

Question 1

eukaryotic transcription

Answer 1

initiation
elongation
termination

Question 2

initiation (eukaryotes)

Answer 2

chromatin (open)
Tfs: activators bind / repressors unbind
GTFs: bind and flash bat signal
RNA pol: binds

Question 3

elongation (eukaryotes)

Answer 3

• DNA unwinds, RNA pol moves along using template strand of gene as a template for mRNA
• RNA pol reads template strand 3’ -> 5’ and makes antiparallel, complementary mRNA transcript 5’ -> 3’

Question 4

termination (eukaryotes)

Answer 4

DNA termination sequence reached, RNA pol falls off DNA, mRNA dissociates from enzyme

Question 5

what must happen before mRNA is ready to leave the nucleus

Answer 5

• alternative splicing
• add 5’ cap
• add polyA tails

Question 6

splicing

Answer 6

• introns removed (stay in nucleus)
• exons join together on mRNA strand (exit nucleus)

Question 7

why do eukaryotes splice?

Answer 7

protein variation

Question 8

capping and tailing

Answer 8

• 5’ end of strand gets a cap
• 3’ end gets string of adenine nucleotides

Question 9

why do eukaryotes cap and tail?

Answer 9

stabilizes mRNA transcript; helpful for translation machinery

Question 10

properties of genetic code

Answer 10

• triplet
• non - overlapping
• redundant
• unambiguous
• punctuated
• universal

Question 11

triplet

Answer 11

• all words of genetic language are 3 RNA nucleotides long
• indicates chemical properties of amino acids

Question 12

punctuated

Answer 12

• 1 start codon
• 3 stop codons

Question 13

redundant

Answer 13

most amino acids are represented by more than 1 codon

Question 14

unambiguous

Answer 14

each codon specifies only one amino acid

Question 15

3 RNAs that mediate translation

Answer 15

tRNA, rRNA, mRNA

Question 16

where is mRNA translated

Answer 16

cytoplasm or rough ER

Question 17

tRNA

Answer 17

• links genetic code with amino acid based on hydrogen bonding
• ribosomes google translate
• transfers amino acids
• “charged” with amino acids
• tRNA synthases attach amino acid to tRNA with corresponding anticodon

Question 18

rRNA

Answer 18

• ribosomal
• 3-d printer of biological life
• mediates tRNA binding to mRNA strand
• catalyzes bond between amino acids
• large and small subunits
• A, E, P sites

Question 19

P site

Answer 19

holds tRNA with growing polypeptide attached

Question 20

E site

Answer 20

hold a tRNA that will exit

Question 21

A site

Answer 21

holds an aminoacyl tRNA- where anticodon binds with complementary codon

Question 22

prokaryotes transcription + translation

Answer 22

occur together