The Process Whereby A Gene Makes Its Protein

Question 1

transcription

Answer 1

gene (DNA) makes pre-mRNA

Question 2

post transcriptional RNA processing

Answer 2

introns excised out of pre-mRNA; 5’ end capped w methyl-guanine; 3’ end gets poly-A tail

Question 3

translation

Answer 3

ribosome reads mRNA, string amino acids together

Question 4

post-translational processing

Answer 4

folding, adornment w chemical side groups, localization, possibly enzymatic cleavage, possibly joining w other proteins to form multimers

Question 5

transcription factors

Answer 5

bind gene’s promoter to initiate transcription

Question 6

acetyl groups

Answer 6

have neg charge that neutralizes positive lysines that grip neg charged DNA tightly so that DNA is loosen and transcription factors can bind

Question 7

histone deacetylase

Answer 7

removes acetyl groups from histone = chromatin recondenses and transcription stops

Question 8

elongation

Answer 8

RNA polymerase makes pre-mRNA

Question 9

pre mRNA

Answer 9

same as coding strand but has uracils instead of thymines

Question 10

coding strand

Answer 10

sense strand

Question 11

noncoding template strand

Answer 11

antisense strand

Question 12

RNA polymerase

Answer 12

transcribes the gene to make mRNA

Question 13

termination of transcirption

Answer 13

specific sequences signals signal the end

Question 14

rho protein

Answer 14

used by some bacterial and viral genes to terminate transcription; binds to RNA and moves toward RNA polymerase/DNA template complex; RNA polymerase slows down when it encounters specific termination sequence in gene’s DNA; rho protein catches up to RNA polymerase/DNA complex and knocks off RNA polymerase allowing RNA to separate from DNA template strand

Question 15

intrinsic termination

Answer 15

rho-independent method; sequence ends w short segment of inverted GC-rich repeats followed by string of adenines (A); CG rich repeat gets transcribed then RNA forms hairpin due to complementarity to inverted repeats which causes RNA to fall of template

Question 16

RNA polymerase II

Answer 16

in eukaryotes transcribes protein-coding genes and many noncoding RNAs including small nuclear RNAs (snRNAs), small nucleolar RNAs (snoRNAs)and microRNA (miRNA) precursors

Question 17

polyadenylated

Answer 17

when pre-mRNA is cleaved; marked by highly conserved consensus sequence (AAUAAA)

Question 18

5’ cap

Answer 18

5’ end is capped w methylated guanine that has extra phosphate group on its 5’ carbon using 5’ to 5’ linkage

Question 19

poly-a-tail

Answer 19

after transcription approx. 250 adenosine monophosphates are added to 3’ end of mRNA by polynucleotide adenylyltransferase

Question 20

RNA splicing

Answer 20

introns are excised out and exons spliced together

Question 21

spliceosome

Answer 21

complex of proteins and RNAs excises the introns out of the pre-mRNA and splices exons together

Question 22

small nuclear RNAs

Answer 22

combine w proteins to make small nuclear ribonucleoproteins (aka SNRPs)

Question 23

self-splicing introns

Answer 23

fold into loops and lariats on their own

Question 24

post transcriptional RNA processing

Answer 24

5’ cap + poly a tail put on then then introns are excised out and exons are spliced together in archaea and eukaryotes

Question 25

splice site mutations

Answer 25

cause multiple RNAs to be produced

Question 26

alternative splicing

Answer 26

allows one gene to make several different isoforms of its protein; allows one gene to make different proteins in different tissues

Question 27

mature mRNA

Answer 27

has untranslated regions at 5' and 3' ends

Question 28

RNA editing after transcirption

Answer 28

cleaved/edited by guide RNAs; nucleotides can be added/deleted/substituted; resultant mRNA might no match predicted sequence from gene's coding sequence

Question 29

ribosome

Answer 29

reads mRNA 3 bases at a time (called a codon) to ad one amino acid to growing polypeptide

Question 30

STOP codon

Answer 30

terminates translation and releases polypeptide which is folded, adorned w chemical side groups + sent to where it needs to be = some join w other to form multimers; some get cleaved into multiple independently active peptides; some made inactive form and activated by cleavage

Question 31

initiation of translation

Answer 31

proteins that bind to 5' cap and poly-A-tail help ribosome bind mRNA

Question 32

elongation factors

Answer 32

help ribosome chain amino acids together

Question 33

tRNA

Answer 33

carries amino acids in for translation; mRNA codon tells which anticodon tRNA must have; specific tRNA for each amino acid

Question 34

tRNA charging

Answer 34

ATP provides energy to tRNA to bring in amino acids

Question 35

Shine-Dalgarno sequence

Answer 35

in bacterial mRNA orients ribosome

Question 36

AUG codon

Answer 36

translation begins here

Question 37

Kozak sequence

Answer 37

consensus sequence around START codon

Question 38

initiation factors

Answer 38

help ribosome assemble; in eukaryotes 5' cap and poly-a-tail both bind to initiation factors

Question 39

missense mutation

Answer 39

one amino acid gets replaced by another: no effect to no protein activity; translation continues after mutation as downstream sequences get translated

Question 40

nonsense mutation

Answer 40

creates STOP codon at site of the mutation; protein is truncated = abolishes protein's activity; translation stops at that point downstream sequences do not get translated

Question 41

ribosome reading frame

Answer 41

begins at START codon ends at STOP codon; deletion/insertion w multiple of 3 nucleotide does not shift reading frame (not multiple of 3 will shift reading frame and protein cannot function/new function)

Question 42

ribosome reading

Answer 42

assembled polypeptide at P site next amino acid carried to A site = bond between new AA amino group and previous AA carboxyl group

Question 43

STOP codons

Answer 43

UGA, UAA, and UAG

Question 44

releasing factors

Answer 44

terminate translation

Question 45

proteins left on mRNA

Answer 45

signals enzymes to degrade the mRNA

Question 46

tmRNA

Answer 46

part tRNA part mRNA used by bacteria to rescue translation where there is no STOP codon; carries alanine and binds to A site to deliver it; adds 10 more AAs then uses its STOP codon to release the stalled ribosome

Question 47

nonstop mRNA decay in eukaryotes

Answer 47

no STOP codon: ribosomes A site is hanging off which signals protein to attach to mRNA and degrade it from its 3' end forward

Question 48

post translation processing

Answer 48

folding, adornment, placement, and cleavage; ribosome makes polypeptide which must be processed into protein