Chapter 3: From Genes to Proteins

Question 1

What are the base of nucleic acids?

Answer 1

purines and pyrimidines

Question 2

What is the difference between RNA and DNA in their bases?

Answer 2

RNA contains uracil rather than thymine

Question 3

Difference between nucleoside and nucleotide

Answer 3

nucleoside is made of sugar and base, and nucleotide is a nucleoside with one or more phosphate groups attached

Question 4

How do nucleotides link?

Answer 4

connected via phosphodiester bonds

Question 5

Describe which of the nucleotide bases held together

Answer 5

adenine and thymine form 2 H-bonds

guanine and cytosine form 3 H-bonds

Question 6

Chargaff’s rule

Answer 6

the amount of A + G = C+ T

Question 7

two methods for deducing high-resolution protein structures

Answer 7

1. X-ray crystallography (dominant method)

2. Cyro-electron microscopy

Question 8

X-ray cyrstallography

Answer 8

• x-rays scatter as they pass through crystallized protein

- resulting waves interfere with each other, creating a diffraction pattern from which the position of atoms is deduced

Question 9

Cryo-electron microscopy

Answer 9

• beam of electrons is fired at a frozen protein solution
• the emerging scattered electrons pass through a lens to create a magnified image on the detector, and the structure can then be deduced

Question 10

Can DNA be denatured and/or renatured?

Answer 10

it can be both denatured and renatured

Question 11

List the three predominant forces stabilizing DNA

Answer 11

hydrophobicity, base stacking and entropy

Question 12

Other forces that stabilizing DNA (excluding predominant forces)

Answer 12

hydrogen bonding and ionic interactions

Question 13

Describe the renaturation process of DNA

Answer 13

DNA is heated at high heat and melts, and the strands separate. Then either option can occur (a) cooling to 20-25C below Tm can cause renaturation (i.e. DNA strands will reassemble), (b) rapid cooling to temperature much lower than Tm will result in improper base pairing, however next the rewarming to 20-25C below Tm can lead to renaturation (i.e. DNA strands will reassemble)

Question 14

What are genes?

Answer 14

sequences of DNA

Question 15

What does replication?

Answer 15

copying DNA

Question 16

What does transcription?

Answer 16

converting DNA into RNA

Question 17

What does reverse transcription?

Answer 17

converting RNA into DNA

Question 18

What does translation?

Answer 18

making proteins from an RNA template

Question 19

Is DNA replication natural in vivo?

Answer 19

• yes, DNA must be copied in order to sustain life but excessive DNA replication can be indicative of cancer

Question 20

What technology replicates DNA in vitro?

Answer 20

technology such as the Polymerase chain reaction (PCR)

Question 21

Is the RNA transcript complementary to the coding template strand or the noncoding template strand?

Answer 21

noncoding template strand

Question 22

three types of RNA

Answer 22

mRNA, tRNA, and rRNA

Question 23

mRNA

Answer 23

encodes for polypeptide sequences

Question 24

tRNA

Answer 24

carries amino acids to ribosome

Question 25

rRNA

Answer 25

aids in polypeptide synthesis

Question 26

Two ways in which genes are identified

Answer 26

1. Scan for open reading frame (start and stop)

2. Comparison with known genes

Question 27

Gene number is often correlated with ___________.

Answer 27

organismal complexity

Question 28

What parts of a DNA do restriction enzymes normally cut?

Answer 28

palindromic, double stranded DNA, sticky ends, blunt ends, restriction digest, and restriction fragments

Question 29

What is the role of restriction enzymes?

Answer 29

aid in defense for bacteria

Question 30

Which restriction enzyme is used to selectively cut DNA?

Answer 30

type II

Question 31

characteristics of type II restriction enzymes

Answer 31

• cleave 4-8 bp segment of dsDNA
• palindromic recognition sequences
• they form blunt or sticky ends