Molecular genetics - DNA

Question 1

What are the three components of nucleotides

Answer 1

Deoxyribose sugar, Phosphate group, nitrogenous base

Question 2

What are purines?

Answer 2

Double ringed structures. Guanine and Adenine

Question 3

What are purines?

Answer 3

Single ringed structures. Thymine, Uracil and Cytosine

Question 4

What are the three bonds on DNA’s backbone?

Answer 4

Glycosyl, phosphodiester, hydrogen bonds

Question 5

The 2 DNA strands are ______ but are ______

Answer 5

not identical, complementary

Question 6

How do complementary bases bond?

Answer 6

Purine to pyrimidine

Question 7

What are the complementary bases?

Answer 7

Adenine to Thymine (or Uracil in RNA), Cytosine to Guanine

Question 8

What is Chargaff’s rule?

Answer 8

% composition of Adenine is the same as that of Thymine and % composition of Cytosine is the same as that of Guanine

Question 9

What does it mean that DNA strands are antiparallel?

Answer 9

The two strands run in opposite directions, one runs 3’ to 5’ and the other 5’ to 3’

Question 10

How big is one turn of the helix?

Answer 10

3.4nm

Question 11

What is the distance between nucleotides?

Answer 11

0.34

Question 12

How many nucleotides in one turn of the helix?

Answer 12

10

Question 13

What is the diameter of the helix?

Answer 13

2nm

Question 14

Genome

Answer 14

Complete genetic make-up of an organism

Question 15

Gene

Answer 15

Basic unit of heredity. Functional units of DNA. The coding sequences for proteins.

Question 16

Nucleoid

Answer 16

Structure in prokaryotes that contains the chromosomal DNA

Question 17

Regulatory sequence

Answer 17

A sequence of DNA that regulates the activity of a gene

Question 18

Where is DNA found in prokaryotes?

Answer 18

In one circular chromosome, the nucleoid

Question 19

The nucleoid is made of supercoiled DNA. What controls that supercoiling?

Answer 19

Topoisomerase I and Topoisomerase II

Question 20

What is the point of antibiotics

Answer 20

To inhibit topoisomerase

Question 21

Where is eukaryotic DNA found

Answer 21

Nucleus

Question 22

Histone

Answer 22

A protein that helps to compact DNA

Question 23

Nucleosome

Answer 23

The condensed structure formed when double stranded DNA wraps around an octamer of histone

Question 24

Chromatin

Answer 24

Non-condensed form of genetic material made of DNA and proteins. This is how DNA fits in a cell

Question 25

What must DNA be able to do efficiently

Answer 25

Replicate with a high degree of accuracy and code for production of proteins by the cell

Question 26

What happens during Mitosis?

Answer 26

Cells divide into 2 daughter cells with identical DNA

Question 27

What method of replication does DNA use? Explain it

Answer 27

Semi-conservative replication. One strand of the DNA is used to create the second one

Question 28

Explain the initiation phase of DNA replication

Answer 28

A portion of the double helix is unwound and the bases are exposed for base pairing

Question 29

Explain the elongation phase

Answer 29

2 new strands of DNA are assembled using the parent DNA as a template. New strand and old strand for helices

Question 30

Termination phase

Answer 30

Replication process completed & the two strands separate from each other. Replication machine disassembled.

Question 31

Helicase

Answer 31

Unwinds parent DNA

Question 32

DNA primase

Answer 32

Synthesizes DNA primer to generate Okazaki fragments

Question 33

Single Stranded Binding Proteins (SSBPs)

Answer 33

Helps to stabilize single-stranded regions of DNA when it unwinds. Prevents annealing

Question 34

Topoisomerase II

Answer 34

Relieves strain on parent chain generated by the unwinding of the two strands

Question 35

DNA polymerases

Answer 35

Synthesizes new Daughter strands, removes RNA primers and fills the gaps from Okazaki fragments. Proofread new DNA

Question 36

Ligase

Answer 36

Joins the ends of Okazaki fragments in lagging strand fragments

Question 37

Primer

Answer 37

Short segment of RNA that is complementary to a part of the 3' to 5' DNA template strand and serves as a starting point for additional nucleotides.

Question 38

Replication bubbles

Answer 38

There are many origins to DNA replication, which forms many replication forks. They end up looking like bubbles

Question 39

In what direction is DNA synthesized? Why?

Answer 39

5' to 3' because the enzyme binds to the parent strand at the 3' end

Question 40

What is the role of DNA polymerase in the elongation phase?

Answer 40

To proofread

Question 41

What is the role of ligase in the elongation phase?

Answer 41

To stitch together okazaki fragments

Question 42

Okazaki fragments

Answer 42

Short DNA fragments generated during synthesis of the lagging strand in DNA replication

Question 43

Mismatch repair

Answer 43

mechanism for repairing errors made during DNA replication. A group of proteins recognize an error and therefore replace the the nucleotide

Question 44

Do prokaryotes or eukaryotes have a faster replication rate?

Answer 44

Prokaryotes, 1000 nucleotides per second added as opposed to eukaryotes' 40 nucleotides per second

Question 45

How many polymerase enzymes in prokaryotes?

Answer 45

5

Question 46

How many polymerase enzymes in eukaryotes?

Answer 46

13

Question 47

Telomere

Answer 47

Repetitive section of DNA near the end of each chromosome. This helps to prevent the loss of important genetic information during the replication of linear eukaryotic DNA