Prokaryotic Transcription and Translation

Question 1

Seymour Benzer’s experiments (1953) helped find the link btwn classical concept of the gene and _____ concept of the gene

Answer 1

molecular (structure? change? fxt?)

Question 2

T/F: rII mutant phenotype:

difference in plaque morphology; produces large plaques on strain B E. coli

Answer 2

true

Question 3

T/F: transcription is asymmetric

Answer 3

True

Question 4

RNA polymerase fxts (3)?

Answer 4

initiation: 1) promoter binding and trascriptional control
2) elongation: transcription of polycistronic mRNAs (mRNA encoding several proteins)
3) termination: release of RNA pmrs and mRNA

Question 5

binding site on DNA for RNA pmrs

Answer 5

promoter

Question 6

T/F: in bacteria, often genes that are part of a common biochemical pathway are transcribed from the same promoter

Answer 6

true

Question 7

all genes in the unit is referred to as…

Answer 7

operon

Question 8

What is at the end of the hairpin loop of an intrinsic termination site (Rho-independent)?

Answer 8

string of U’s

Question 9

T/F: Rho factor mediates termination

Answer 9

T

Question 10

In an ATP-mediated rxt, a ______ binds to the mRNA and unwinds RNA from the DNA template

Answer 10

rho protein complex

Question 11

may not have hairpins or U tracts, tend to be C-rich

Answer 11

recognition sites

Question 12

T/F: transcription and translation are coupled in bacteria?

Answer 12

True; bacteria grow super fast

Question 13

still in the process of being sythesized

Answer 13

nascent

Question 14

Even prior to the conclusion of transcription, _____ will assemble on nascent (i.e. developing) mRNA…
and begin to synthesize protein

Answer 14

ribosomes

Question 15

Whose experiments supported that intragenic suppresssor mutations in T4 rll locus indicated a triplet code?

Answer 15

crick and brenner

Question 16

molecules have the dimensions of a purine-pyrimidine base pair

Answer 16

proflavin dyes

Question 17

distortion in helix will cause errors during DNA replication; leads to ?

Answer 17

addition or loss of base pair…frameshift mutations

Question 18

Who?
the code is non-overlapping, and there is colinearity of mutations in genetic map with amino acid changes in mutant proteins…

Answer 18

C. Yanofsky

Question 19

3 major components necessary to translate info in mRNA molecule

Answer 19

mRNA, ribosome, charged tRNAs

Question 20

adaptor molecule for protein synthesis

Answer 20

tRNA

Question 21

structure of what?
small; approximately 75 nucleotides
extensive intrastrand hydrogen bonding
“cloverleaf” structure contains 3 characteristic loops; anticodon loop is responsible for pairing with mRNA
3’ end of molecule associates with specific amino acid

Answer 21

tRNA molecules

Question 22

charge tRNAs in a two-step reaction…

Answer 22

Aminoacyl tRNA synthetases

Question 23

T/F: specific…different tRNA synthetase enzymes charge the appropriate tRNA with the appropriate amino acid…

Answer 23

true

Question 24

In prokaryotic translation, what associates with the small subunit?

Answer 24

specialized charged tRNA

Question 25

large subunit is recruited to finish the complex, first tRNA is present where?

Answer 25

“P” site of the ribosome

Question 26

how is correct initiation sequence determined for prokaryotic mRNAs?

Answer 26

Shine-Dalgarno sequence

Question 27

where is the S-D sequence in the mRNA located?

Answer 27

5’ non-coding region of mRNA upstream of start codon

Question 28

in elongation, charged tRNA enters ______ via pairing to codon. _______activity on large subunit forms peptide bond, transferring growing peptide to A site

Answer 28

A site, peptidyl transferase

Question 29

stop codons

Answer 29

UAG, UGA, UAA (they terminate by entering A site, pptd chain is released and ribosome dissociates)

Question 30

_______ made to “crack the code”, which produces a protein synthesizeing rxt in vitro (test tube)

Answer 30

synthetic mRNA

Question 31

which has higher frequency of 8 codons? UUU or UUG?

Answer 31

UUU. Decreased freq. as G is added

Question 32

Developed a way to chemically synthesize short stretches of ribonucleotides in an ordered array,,,cys-val-cys-val

Answer 32

Khorana

Question 33

Ribosome binding assay: under in vitro conditions, the two subunits of a ribosome and the appropriate tRNA can assemble on a short RNA consisting of just a single codon triplet.
Synthesized all triplet combinations.
Tested to see which charged tRNA (out of the twenty possible) could lead to the assembly of a ribosome complex. Who?

Answer 33

Nirenberg

Question 34

T/F: Binding of correct charged tRNA promotes ribosome assembly and traps radioactivity on filter…

Answer 34

true; if incorrect anticodon, no radioactivity would be trapped

Question 35

Leu codons (6)

Answer 35

UUA, UUG, CUU, CUC, CUA, CUG

Question 36

Gly codons (6)

Answer 36

GGU, GGC, GGA, GGG

Question 37

T/F: acidic residues are GAN (N = G, C, U or A)

all codons with a U in the second position are hydrophobic

Answer 37

true

Question 38

T/F: Because of relaxed base pairing interactions occurring at the third position of the codon and the 1st position in tRNA anticodon, some tRNAs can recognize more than one codon…

Answer 38

true

Question 39

I is wobble base, codes for ____

Answer 39

U, C, or A

Question 40

T/F: mitochondria and golgi bodies contain their own genomes?

Answer 40

False, mit and chloroplasts (usually closed and circular DNA molecules) these genomes encode their own rRNA and tRNAs and have their own translation apparatus

Question 41

T/F: human mDNA>yeast mDNA

Answer 41

false, human 17 kb, yeast: 78 kb

Question 42

What is the endosymbiont theory?

Answer 42

organelles represent remnants of free-living organism that established symbiotic relationship with proto-eukaryotes (Lynn Margulus)
inheritance of organelle genetic information is often uniparental, usually maternal
Mechanism of inheritance will therefore be non-Mendelian, often only through egg cytoplasm (e.g. MERRF)