MCAT BIO: Chapter 4 / Molecular Biology

Question 1

What does DNA stand for?

Answer 1

Deoxyribose nucleic acid

Question 2

What does RNA stand for?

Answer 2

Ribonucleic acid

Question 3

Where is DNA found?

Answer 3

In the nucleus

Question 4

What is the building block of DNA?

Answer 4

Deoxyribonucleoside 5’ triphosphate (dNTP)

Question 5

What does N represent?

Answer 5

“N” refers to one of the nitrogenous bases

Question 6

What are all nitrogenous bases?

Answer 6

Thymine, Adenine, Guanine, Cytosine, Uracil

Question 7

What are the purines?

Answer 7

Adenine and Guanine

Question 8

What are the pyrimidines?

Answer 8

Cytosine, Thymine, Uracil

Question 9

What is the mnemonic for pyrimidines?

Answer 9

Pi-Cut

Question 10

What is the mnemonic for purines?

Answer 10

Pure As Gold

Question 11

What is a nucleoside?

Answer 11

A ribose or deoxyribose w/ a purine or pyrimidine linked to a 1’ carbon

Question 12

What is a nucleotide?

Answer 12

Phosphate esters of nucleosides w/ 1-3 phosphates joined to the ribose ring by the 5’ hydroxy group

Question 13

What is the term for nucleotides that contain 3 phosphate residues?

Answer 13

Nucleoside triphosphate (NTP)

Question 14

What does the sugar and phosphate portion of nucleotides refer to as?

Answer 14

Backbone of the DNA

Question 15

How does phosphodiester bonds covalently link one nucleotide to another?

Answer 15

This occurs between the 3’ hydroxyl group of one deoxyribose and the 5’ phosphate of another deoxyribose

Question 16

What are several nucleotides linked together called?

Answer 16

Oligonucleotides

Question 17

What are many nucleotides linked together called?

Answer 17

Polynucleotides

Question 18

What does the Watson-Crick Model of DNA structure state?

Answer 18

DNA is cellular, a right-handed double helix held together by hydrogen bonds between bases

Question 19

When DNA is found in the nucleus, is it double-stranded or single stranded?

Answer 19

Double-stranded (ds)

Question 20

What does dsDNA mean?

Answer 20

Refers to two polynucleotides in antiparallel configuration hydrogen bonded

Question 21

What does antiparallel mean in terms of DNA?

Answer 21

There is a 5’ chain end that pairs to a 3’ end of the complementary strand

Question 22

How many hydrogen bonds hold Adenine and Thymine together? Adenine and Uracil?

Answer 22

2 hydrogen bonds

Question 23

How many hydrogen bonds hold Guanine and Cytosine?

Answer 23

3 hydrogen bonds

Question 24

What is the term for the nitrogenous base pairing?

Answer 24

Complementary-base pairs

Question 25

What is annealing or hybridization in DNA?

Answer 25

The binding of two complementary strands of DNA into double-stranded structure

Question 26

What can cause the separation of dsDNA?

Answer 26

Melting or Denaturation

Question 27

Why is DNA coiled?

Answer 27

The 2 hydrogen-bonded antiparallel dsDNA forming a right-handed double helix

Question 28

What does the DNA structure look like in a corkscrew, clockwise motion?

Answer 28

The bases face the interior and the sugar/phosphate backbone face the exterior

Question 29

How is the double helix stabilized?

Answer 29

Van der Waals interaction between the bases; due to pi-bond stacking bases upon each other

Question 30

What is term for the sum total of an organism's genetic information called?

Answer 30

Genome

Question 31

Each piece of dsDNA is called?

Answer 31

Chromosome

Question 32

How many chromosomes do humans have?

Answer 32

46 chromosomes; 23 chromosomes from each parent

Question 33

What genome is composed of several large pieces of dsDNA?

Answer 33

Eukaryotic

Question 34

What genome is composed of a single circular chromosome?

Answer 34

Prokaryotic

Question 35

Viral genome may be in linear or circular DNA or RNA (T/F)

Answer 35

True

Question 36

How does prokaryotes make their singular chromosome more compact and sturdy?

Answer 36

The use of DNA gyrase

Question 37

What is DNA gyrase?

Answer 37

An enzyme that uses ATP to twist DNA

Question 38

In what conformation does DNA gyrase twist the dsDNA structure?

Answer 38

Supercoiled

Question 39

What does the eukaryotic genome require to fit in the cell?

Answer 39

Denser packaging

Question 40

How is denser packaging achieved?

Answer 40

DNA wraps itself around histones

Question 41

What is a histone?

Answer 41

A globular protein that DNA wraps itself around?

Question 42

What wraps themselves around an octamer of histones before DNA is completely packed away?

Answer 42

Nucleosomes

Question 43

What is a nucleosome?

Answer 43

Beads on a string that wrap themselves around histones

Question 44

What is a linker DNA?

Answer 44

The length of double-helical DNA composed of the string between the beads

Question 45

What is linker DNA bound by?

Answer 45

A single histone linker

Question 46

What is a fully packed DNA referred to as?

Answer 46

Chromatin