Chapter 3 Review

Question 1

DNA is a polymer of

Answer 1

dNMPs

Question 2

Pyrimidines include

Answer 2

cytosine, thymine and uracil

Question 3

Purines include

Answer 3

adenine and guanine

Question 4

Base + ribose =

Answer 4

nucleoside

Question 5

Base + ribosome phosphate =

Answer 5

nucleotide

Question 6

Of deoxyribose, phosphates will react with the ______ on the _____ carbon or the ____ carbon.

Answer 6

Alcohols ; 3’ or 5’

Question 7

Spontaneous deamination leads to _______. Water spontaneously reacts with _________ to form _____.

Answer 7

Uracil; cytosine, uracil ; A PROTEIN LOOKING FOR URACIL CAN’T DISTINGUISH IF IT WAS SUPPOSED TO BE THERE OR IF IT’S A PRODUCT OF DEAMINATION.

Question 8

Why are nucleotide sequences synthesized 5’ to 3’?

Answer 8

3’ always attacks the phosphate of the 5’ of the growing DNA chain.

Question 9

Edwin Chargaff (1950s)

Answer 9

Equal # of A to T, and Equal # of G to C

Question 10

Rosalind Franklin (1950s)

Answer 10

• X-Ray diffraction of DNA

- The strong diffraction base on the reciprocal space was 1/d = 3.14 angstroms.

Question 11

Jerry Donohue (1950s)

Answer 11

• Bases can be in keto or enol state; HOWEVER, almost always in keto state.

Question 12

Endonuclease

Answer 12

Cleaves a nucleic acid within the polypeptide strand; CUT DNA at certain sequences.

Question 13

Exonuclease

Answer 13

Cleaves a nucleic acid by removing one of its terminal residues.

Question 14

Restriction Endonuclease

Answer 14

A bacterial enzyme that recognizes a specific DNA sequence and cleaves the DNA as part of a restriction-modification system.

Question 15

Modification Methylase

Answer 15

A bacterial enzyme that methylates a specific sequence of DNA as part of a restriction-modification system.

Question 16

The bases primarily exist in their ____ form.

Answer 16

keto

Question 17

Why do G-C bonds have a higher melting temp. than A-T?

Answer 17

They have more hydrogen bonds than A-T

Question 18

What is necessary for replication?

Answer 18

Complimentary bases

Question 19

Transcription and Translation

Answer 19

DNA goes to transcription –> mRNA (codes for tRNAs) –> tRNA (translational RNA ; amino acids are attached to them) –> translation –> Bonds together to make a protein

Question 20

mRNA is short-lived because

Answer 20

it is “chewed up” and translated to become a protein.

Question 21

mRNA start codon

Answer 21

AUG

Question 22

mRNA stop codon

Answer 22

UAG

Question 23

Eukaryotes package DNA in

Answer 23

nucleosomes

Question 24

DNA is wrapped around _____ ; These then stack on top of each other to make ______

Answer 24

Histones; chromatin

Question 25

tRNA

Answer 25

• reads three bases at a time

- hydrogen bonds (good because it is reversible)

Question 26

DNA Ligase

Answer 26

Adds phosphodiester bonds

Question 27

Template strand of DNA is being sequenced from

Answer 27

3’ to 5’

Question 28

Always read DNA strands from

Answer 28

5’ to 3’

Question 29

The two strands of DNA are ______ but each forms a right-handed helix

Answer 29

antiparallel

Question 30

The _________ occupy the core of the double helix .

Answer 30

aromatic bases

Question 31

The ____________ run along the periphery, thereby minimizing the repulsions between charged phosphate groups

Answer 31

sugar-phosphate chains

Question 32

The surface of the double helix contains two grooves of unequal width: the ______ and ______ grooves.

Answer 32

major and minor

Question 33

Each base is _________ to a base in the opposite strand to form a ______ base pair

Answer 33

Hydrogen bonded ; Planar

Question 34

Incoming dNTP is attacked at the _____ phosphate by the ____ hydroxyl of the growing DNA chain.

Answer 34

α ; 3’

Question 35

The direction of ribosome movement on the mRNA is

Answer 35

5’ to 3’

Question 36

Nucleotides participate in

Answer 36

• oxidation-reduction reactions
• Energy transfer
• Intracellular signaling
• biosynthetic reactions

Question 37

Stem-loop structure is the result of

Answer 37

RNA bases pairing with themselves.

Question 38

Molecular Cloning with Restriction Enzymes

Answer 38

The cloning vector and the foreign DNA are cut by the same restriction endonuclease –> The sticky ends of the vector and the foreign DNA fragments anneal and are covalently joined by DNA ligase –> Result: chimeric DNA containing a portion of the foreign DNA inserted into the vector

Question 39

Polymerase Chain Reaction (PCR)

Answer 39

• An in vitro method for amplifying the amount of a particular DNA sequence.
  1. Separate strands by heating, cooling, and annealing primers
  2. Extend primers by DNA polymerase
  3. Repeat steps 1 & 2