Chapter 13 Review Questions/ Community Exam Questions

Question 1

What is DNA composed of/what is a DNA nucleotide made of

Answer 1

Base, nucleotide, and phosphate

Question 2

The function of DNA in cells is to enable

Answer 2

Transfer of information, respond to feedback in the cell, and replicate easily

Question 3

————, RNA

Answer 3

RNA has a shorter pitch than DNA
RNA has uracil where DNA has thymine
RNA is less stable than DNA
RNA is more acidic than DNA

Question 4

Each DNA base is attached to the sugar by —— bonds

Answer 4

Covalent Phosphodiester

Question 5

DNA bases on opposite strands are attached to each other by —— bonds

Answer 5

2 hydrogen bonds

Question 6

DNA is a directional polymer which means what

Answer 6

• the strands run in opposite directions to permit the base paring between them

Question 7

The polarity of the strands in a double-stranded DNA is what?

Answer 7

5’ to 3’

Question 8

A sample of DNA contains 21% adenine bases. The percent of T, G, and C bases respectively is?

Answer 8

T = 21%
G = 29%
C = 29%

Question 9

—— synthesized DNA with the help of other enzymes, including a(n)?

Answer 9

DNA polymerase
Helicase

Question 10

DNA replication is semi-conservative because?

Answer 10

The two new ds DNA are created with one strand from the old and one from the new so that less energy is used

Question 11

—— is used to synthesize large amounts of ——

Answer 11

PCR is used to synthesize large amounts of A specific DNA fragment

Question 12

A PCR reaction is programmed to run —— cycles and amplify —— copies of an input DNA fragment. The maximum number of copies of this fragment at the end of the reaction is?

Answer 12

N = number of cycles

A = number of copies initially

The equation to solve this is a2^n

Question 13

—— organisms have been essential for the development of PCR technology because

Answer 13

Thermal bacteria or thermus aquaticus
- a thermophile (can live in. Wide range of temps) and can withstand the desaturation process without getting messed up
Is used as a starting point for DNA synthesis

Question 14

Restriction enzymes are produced naturally by some bacteria in order to

Answer 14

• chop up potentially harmful foreign DNA to protect against invading phage
• can even cut up its own DNA that is similar to a phage

Question 15

A palindromic DNA sequence is shown in

Answer 15

A DNA when the 5’ to 3’ and the 3’ to 5’ show the exact same sequence

Question 16

Double-stranded DNA is likely to be hydrolyzed by a restriction enzyme at the ovations indicated by arrows in the sequence

Answer 16

G(arrow pointing down here)AATTC
CTTAA(arrow pointing down here)G

Question 17

Altering an organisms DNA (generating GMOs) is possible because

Answer 17

They are all made of DNA so you can change the genes
- this is because DNA is all the same chemically

Question 18

3

What is the difference between a genome and a gene

Answer 18

A genome is made up of all genetic information in a cell
A gene is a small subsection of the genome that codes for a single protein

Question 19

5

A) what three units must be present in a nucleotide
B) what type of bonding holds these three units together

Answer 19

A) a nucleotide links a nitrogen-containing base, a sugar, and a phosphate group
B) covalent bonds hold the unites together

Question 20

8

Circle and name the functional groups in this nucleotide. Also label the sugar, the base, and the phosphate group

Answer 20

Shown in a drawing

Question 21

9

Compare the DNA segment in Figure 13.4 with the nucleotide shown in question 8.
A) circle the two functional groups that react to form a polymer similar to DNA
B) the sugar in this nucleotide is ribose rather than deoxyribose

Answer 21

A) nucleotides polymerize to form DNA when the phosphate group from one nucleotide reacts with the hydroxyl group on another nucleotide. The nucleotide shown has two hydroxyl groups. The one closer to phosphate group is the correct site for polymerization, similar to DNA. the second hydroxyl group results in significant chemical instability seen in this DNA-related polymer
B) in the name DNA, the D stands for deoxyribose in deoxyribose nucleic acid. The name for the polymer built with ribose instead is RNA for ribonucleic acid

Question 22

12

Explain why the base sequence ATG is different from the base sequence GTA

Answer 22

Sequences are always read in one direction. On paper, we read each sequence from left to right to determine which amino acid it codes for. Chemically, the directionality comes form the specific order of bonds connecting the alternating sugars and phosphates in the backbone. Although the economy sequence in this question is simply the reverse of the first base sequence, it would code for a different amino acid. (ATG codes for methionine; GTA codes for valine)

Question 23

13

Given a short sequence of DNA: TATCTAG
A) write and align a DNA code that complements the sequence given
B) draw connecting lines between the sequences to represent the number of hydrogen bonds between each base pair

Answer 23

A) the complementary base sequence is ATAGATC
B) your answer should have two lines between each A and T, and three lines between each C and G in the sequence

Question 24

23

Use figure 13.7 to explain why adenine-thymine base pairs are less stable than cytosine-guanine base pairs

Answer 24

Adenine-thymine base pairs are less stable than cytosine-guanine base pairs because thy have fewer hydrogen bonds holding them together

Question 25

26

Ionizing radiation can break covalent bonds to disrupt one or more strands of DNA. A cell can more easily repair damage to a single strand in a DNA double helix than repair a double-strand break. Why/

Answer 25

The two DNA strands are complementary, meaning that the sequence on one strand can be reconstructed from the other. If a single strand breaks, the other strand can be used by repair enzymes to correctly replace any lost nucleotides and reassemble the backbone. If both strands break, the information on how to repair the break is lost and the correct sequence of DNA will be permanently altered

Question 26

28 errors in DNA replication can alter the base sequence of a strand permanently. But not all of these errors result in incorporation of an incorrect amino acid in a protein for which the DNA codes. Explain why a single base change may not change the amino acid

Answer 26

Many amino acids are represented by more than one DNA codon. For example, GTT, GTC, GTA, or GTG all translate to valine. If an error in the base sequence of DNA did not change the meaning of the codon, the protein would contain correct amino acids. This redundancy makes the genome more resilient to change.

Question 27

In a PCR reaction, DNA primers are needed to?

Answer 27

Start polymerization and define a piece of DNA

Question 28

In the experiment listed how can you find a certain amino acid from the terminus

Answer 28

• if its from the left find the amino acid terminus of H3N- then count to the right
• if its from the right find the carboxylic acid which is COO- and count to the left