Chapter 15,16,17 Lecture 17

Question 1

What disease are the Hutterites effected by>

Answer 1

Bowen-Conradi Syndrome

• results from defective ribosome biosynthesis affecting the process of translation
• Emg1 is essential for 40S ribosome subunit biogenesis

Question 2

one gene, one enzyme hypothesis

Answer 2

-Beadle and Tatum 1941

0 genes function by encoding enzymes, andeach gene encodes a separate enzyme

Question 3

auxotrophic mutation 103 grows on minimal medium supplemented with A, B, or C. Mutation 106 grows on medium supplemented with A and C, but not B; and mutation 102 grows only on medium supplemented with C. what is the order of A, B, C, in a biochemical pathway?

Answer 3

B –> A –> C

Question 4

structure and function of proteins

Answer 4

• proteins are polymers consisting of amino acids linked by peptide bonds
  amino acid sequence is its primary structure
• this structure folds to create secondary and tertiary structures
• 2 or more polypeptide shians associate to form quaternary structure

Question 5

What primarily determines the secondary and tertiary structure?

Answer 5

the primary structure

Question 6

a codon is

a. one of three nucleotides that encode an amino acid
b. three nucleotides that encode an amino acid
c. three amino acids that encode a nucleotide
d. one of four bases in DNA

Answer 6

b. three nucleotides that encode an amino acid

Question 7

degenerate code

Answer 7

amino acid may be specified by more than one codon

Question 8

synonymous codons

Answer 8

codons that specify the same amino acid

Question 9

isoaccepting tRNAs

Answer 9

different tRNAs that accept the same amino acid but have different anticodons

Question 10

sense codons

Answer 10

encoding amino acids

Question 11

initiation codon

Answer 11

AUG methionine

Question 12

termination codon

Answer 12

UAA, UAG, UGA

- stop codons

Question 13

through wobble, a single ___ can pair with more than one ___

a. codon; anticodon
b. group of three nucleotides in DNA: codon in mRNA
c. tRNA; amino acid
d. anticodon; codon

Answer 13

d. anticodon; codon

Question 14

reading frame

Answer 14

3 ways in which the sequence can be read in groups of three;

-each different way of reading encodes a different amino acid sequence

Question 15

nonoverlapping

Answer 15

a single nucleotide may not be included in more than one codon

Question 16

universality of the codon

Answer 16

near universal, with some exceptions

Question 17

Do the initiation and termination codons specify an amino acid? if so which one?

Answer 17

initiation does
- bacteria = n-formylmethionine
eukaroytes = methionine

Question 18

amino acids bind to which part of the tRNA?

a. anticodon
b. DHU arm
c. 3’ end
d. 5’ end

Answer 18

c. 3’ end

Question 19

during the initiation of translation, the small ribosome binds to which consensus sequence in bacteria?

Answer 19

the Shine-Dalgarno sequence

Question 20

What sequence facilitates the identification of the start codon?

Answer 20

the Kozak sequence

Question 21

The initiation of translation requires what?

Answer 21

initiation factors

• IF-3
• initiator tRNA with N-formylmethionine attached to form fmet-tRNA
• GTP (energy molecule)

Question 22

in elongation, the creation of peptide bonds between amino acids is catalyzed by

a. rRNA
b. protein in the small subunit
c. protein in the large subunit
d. tRNA

Answer 22

a. rRNA

Question 23

polyribosomes

Answer 23

an mRNA with several ribosomes attached

Question 24

in a polyribosome, the polypeptides associated with which ribosomes will be the longest?

a. those at the 5’ end of mRNA
b. those at the 3’ end of mRNA
c. those in the middle of mRNA
d. all polypeptides will be the same length

Answer 24

b. those at the 3’ end of mRNA

Question 25

What are some of different processes that affect gene regulation by altering chromatin structure?

Answer 25

modification of histone processes (methylation and acetylation) and DNA methylation

Question 26

most transcriptional activator proteins affect transcription by interacting with a. introns b. basal transcription apparatus c. DNA polymerase d. the terminator

Answer 26

b. basal transcription apparatus

Question 27

How does the binding of regulatory proteins to enhancers affect transcription at genes that are thousands of base pairs away?

Answer 27

the DNA between the enhancer and the promotor loops out, so regulatory proteins bound to the enhancer are able to interact directly with the transcription apparatus

Question 28

How does the poly(A) tail affect stability?

Answer 28

the poly(A) tail stabilizes the 5' cap which must be removed before the mRNA molecule can be degraded from the 5' end

Question 29

in RNA silencing, siRNAs and miRNAs usually bind to which part of the mRNA molecules that they control? a. 5' UTR b. segment that encodes amino acids c. 3' poly (A) tail d. 3' UTR

Answer 29

d. 3'UTR

Question 30

What is a constitutive gene?

Answer 30

a constitutive gene is not regulated and is expressed continually

Question 31

why is transcription a particularly important level of gene regulation in both bacteria and eukaryotes?

Answer 31

because it is the first step in the process of information transfer from DNA to protein . for cellular efficiency, gene expression is often regulated early in the process of protein rpoduction

Question 32

how do amino acids in DNA-binding proteins interact with DNA? a. by forming covalent bonds with DNA bases b. by forming hydrogen bonds with DNA bases c. by forming covalent bonds with DNA sugars

Answer 32

b. by forming hydrogen bonds with DNA bases

Question 33

What is the difference between a structural gene and a regulator gene? a. structural genes are transcribed into mRNA, but regulator genes aren't b. structural genes have complex structures; regulator genes have simple structures c. structural genes encode proteins that function in the structure of the cell; regulator genes carry out metabolic reactions d. structural genes encode proteins; regulator genes control the transcription of structural genes

Answer 33

d. structural genes encode proteins; regulator genes control the transcription of structural genes

Question 34

``` in a negative repressible operon, the regulator protein is synthesized as a. an active activator b. an inactive activator c. an active repressor d, an inactive repressor ```

Answer 34

d, an inactive repressor

Question 35

``` in the presence of allolactose, the lac repressor a, binds to the operator b. binds to the promoter c, cannot bind to the operator d. binds to the regulator gene ```

Answer 35

c, cannot bind to the operator

Question 36

in the trp operon, what happens to the trp repressor in the absences of tryptophan? a, it binds to the operator and presses transcription b. it cannot bind to the operator and transcription takes place c. it binds to the regulator gene and represses transcription d. it cannot bind to the regulator gene and transcription takes place

Answer 36

b. it cannot bind to the operator and transcription takes place

Question 37

``` attenuation results when which regions of the 5' UTR pair? A. 1 and 3 b. 2 and 3 c, 2 and 4 d. 3 and 4 ```

Answer 37

d. 3 and 4

Question 38

What is the effect of high levels of glucose on the lac operon? a. transcription is stimulated b. little transcription take place c transcription is not affected d. transcription may be stimulated or inhibited, depending on the levels of lactose

Answer 38

b. little transcription take place