Exam 4

Question 1

You have a piece of double stranded DNA with 13% cytosine (C). What % thymine (T) would you expect to see?
A. 26%
B. 13%
C. 74%
D. 37%

Answer 1

D. 37%

Question 2

What daughter strand will be made from the following parental strand during DNA replication?
5’-CTAGATTC-3’

Answer 2

3’-GATCTAAG-5’

Question 3

What are TWO features of the Watson-Crick model of DNA you had to know to answer the above question correctly?

Answer 3

1) anti-parallel strands
2) strict base pairings

Question 4

DNA is a double-helix with two strands - what holds the two strands of the double helix together?
A. Hydrophobic interactions
B. Phosphodiester bonds
C. Hydrogen bonds
D. Ionic bonds

Answer 4

C. Hydrogen bonds

Question 5

Where does DNA replication start?
A. The origin
B. +1
C. First 5’ AUG
D. The promoter

Answer 5

A. The origin

Question 6

What feature do all polymerases (RNA or DNA) have in common?
A. They correct errors
B. They add to the 3’-end
C. They need primers
D. They unwind DNA

Answer 6

B. They add to the 3’-end

Question 7

We indicate the polarity of a polynucleotide strand by labeling the 3’-end, which has a ____ for a functional group, and the 5’-end, which has a _____ for a functional group

Answer 7

hydroxyl and phosphate

Question 7

Define the Central Dogma of Molecular Biology

Answer 7

DNA –> RNA –> proteins (polypeptides)

Question 7

Which daughter strand represents leading strand DNA 1 or 3? How do you know?

Answer 7

1 because it is moving towards the fork

Question 7

Label the 3’ ends of the parental strands A and B and the daughter strands 1 and 4

Answer 7

End of the direction where it is being transcribed

Question 8

What would we call polynucleotide 2? What enzyme made this polynucleotide?

Answer 8

RNA primers made by primase

Question 9

Draw a star at ONE place where you should find DNA pol III.

Answer 9

the 2nd part below the fork (smaller)

Question 10

Draw a triangle where you would find DNA pol I at work. What are two things DNA polymerase i does during DNA replication?

Answer 10

3rd part near the 4th part
1) removes RNA primers
2) replaces with DNA nucleotides

Question 11

What enzyme will connect DNA fragments together during DNA synthesis?
A. Primase
B. DNA polymerase I
C. Topoisomerase
D. Ligase

Answer 11

D. Ligase

Question 12

Label upstream on this gene. What information from the figure did you use to determine this

Answer 12

Upstream is on the right because the TATA box is on the right.

Question 13

Draw a box where you would expect to find the promoter (transcribed to the left).

Answer 13

Right side of the +1

Question 14

Draw an arrow representing the RNA that will be made (transcribed to the left). Label the ends.

Answer 14

<————
Left (3’-5’)

Question 15

Which strand (top or bottom) is the template strand? How did you determine this?

Answer 15

It is the top strand because the bottom strand is the one being transcribed since it is moving towards the 3’.

Question 16

What is the function of the promoter in a gene?
A. Recruit RNA polymerase
B. Provide a translation start site
C. Code for an RNA transcript
D. Determine upstream

Answer 16

B. Provide a translation start site

Question 17

Where does RNA transcription start?
A. The origin
B. +1
C. First 5’ AUG
D. The Shine Delgarno sequence

Answer 17

B. +1

Question 18

The human body contains many different kinds of cells that look different and do different things. What what makes different cells different?
A. They have different DNA
B. Different genes have been deleted
C. They use different transcription factors
D. They are not related to one another

Answer 18

C. They use different transcription factors

Question 19

Write out the RNA being translated and label the ends.

Answer 19

5’-Transcribed-3’
Left or right of +1 depending on the direction of transcription

Question 20

Name ONE feature that was added to the pre-mRNA after transcription, and give ONE function that feature serves on the mRNA.

Answer 20

5’ cap and 3’ polyAtail i which protects the mRNA on the end from hydrolysis

Question 21

This mRNA has been spliced. Draw a box around the intron on the DNA above.

Answer 21

AAATTATA (TATA Box)

Question 22

Translate the mRNA

Answer 22

___ 3 letters into polypeptide until you reach stop

Question 23

Which of the following happens during assembly of the translation initation complex?
A. A Met-tRNA enters the ribosomal P-site
B. A Met-tRNA enters the ribosomal A-site
C. A polypeptide inserts into the ribosomal P-site
D. The large ribosomal subunit scans for the first 5’ AUG

Answer 23

A. A Met-tRNA enters the ribosomal P-site

Question 24

What will be the anti-codon at location G?

Answer 24

GCU

Question 25

Which amino acid is on the tRNA at location J (CGA)?

Answer 25

Arg

Question 26

Which amino acid is at the beginning of the polypeptide chain, at location H? How do you know?

Answer 26

Met because it starts at AUG

Question 27

Briefly, explain what happens to terminate translation.

Answer 27

There is a stop codon of UGA which terminates translation and RF in A site.

Question 28

A lot of prokaryotic gene expression is controlled by negative regulation, which means a _____ binds to the DNA and prevents transcription
A. Repressor
B.Activator
C. Co-repressor
D. Inducer

Answer 28

A. Repressor

Question 29

All eukaryotic genes require positive regulation because RNA polymerase cannot bind to the promoter directly. What needs to bind to the promoter first for eukaryotic RNA polymerase to function properly?

Answer 29

basal transcription factors because it is an on/off switch