DNA

Question 1

Four different nucleotides are found in DNA. In what ways do they differ?

Answer 1

They differ in their nitrogenous base content

Question 2

What are the four different nucleotide bases in DNA?

Answer 2

Adenine, guanine, thymine, and cytosine

Question 3

DNA is a polymer, and its monomers are…

Answer 3

nucleotides

Question 4

What are the components of a single nucleotide?

Answer 4

A sugar (in DNA its deoxyribose), a phosphate group, and a nitrogenous base

Question 5

The molecules making up the sides of the ladder are __________________.

Answer 5

sugars and phosphates

Question 6

Which shape indicates sugar?

Answer 6

pentagon

Question 7

Which shape indicates a phosphate group?

Answer 7

circle

Question 8

What is meant by the phrase “complementary base pairing”?

Answer 8

A always “pairs” (bonds) with T; G always “pairs” (bonds) with C. The base on one strand determines the base on the opposite/complementary strand.

Question 9

Explain what is meant by antiparallel strands.

Answer 9

The two opposite/complementary strands run parallel to each other but in opposite directions. One strand runs 5’ to 3’ while the other runs 3’ to 5’. Like two-lane traffic on a road.

Question 10

What is the specific information that is stored in the DNA of organisms?

Answer 10

The coding information for building proteins in a cell

Question 11

DNA is found in all living organisms.

Answer 11

True

Question 12

DNA codes the same way in all organisms.

Answer 12

True

Question 13

DNA sequences are exactly the same in all organisms.

Answer 13

False
(They are different in each organisms)

Question 14

In DNA, A pairs with G, and T pairs with C.

Answer 14

FALSE
(A goes with T/C goes with G)

Question 15

In a double-stranded DNA molecule, a purine always pairs with a pyrimidine.

Answer 15

True

Question 16

What are the purines of DNA and RNA

Answer 16

DNA & RNA - adenine and guanine

Question 17

What are the pyrimidines of DNA and RNA

Answer 17

DNA - Cytosine and Thymine
RNA - Cytosine and Uracil

Question 18

The sugar-phosphate backbone is held together by hydrogen bonds.

Answer 18

False
(covalent bonds)

Question 19

Complementary base pairs are held together by hydrogen bonds.

Answer 19

True

Question 20

DNA is never subject to errors or mutations.

Answer 20

False
(There are errors that can cause genetic mutations)

Question 21

What about DNA’s structure accounts for the diversity of life on Earth?

Answer 21

The variety in the sequence of DNA bases gives variety in the types of proteins that are built, which gives a variety of traits. The specific sequence of bases in a DNA molecule is what makes every organism different.

Question 22

Chromosomes are made up of many _______ that code for different ________. The genes are composed of ______.

Answer 22

Genes
Proteins
DNA

Question 23

The bases in parental DNA are held together by what type of bond (not shown)?

Answer 23

Hydrogen bonds

Question 24

What happens to these bonds for replication to take place?

Answer 24

They break to “unzip” the two strands from each other

Question 25

Which enzyme is responsible for building the new DNA strands?

Answer 25

DNA Polymerase

Question 26

When replication is finished, there will be _____ DNA molecules.

Answer 26

2

Question 27

Each new double helix consists of an __________ strand and a ____ strand. Therefore, the process is called _____________.

Answer 27

Original
New
Semiconservative

Question 28

Unzips the two original/parental strands of DNA to create a replication fork

Answer 28

Helicase

Question 29

Builds the new strands of DNA by adding the complementary nucleotides using “free” nucleotides and base pairing rules; Proofreads the new DNA strands to check for errors

Answer 29

DNA Polymerase

Question 30

Links/”glues” together the Okazaki fragments of the lagging strand

Answer 30

Ligase

Question 31

Explain the difference between how the leading strand and the lagging strand are replicated.

Answer 31

Leading strand = built continuously in the 5’ to 3’ direction
Lagging strand = built in small pieces (Okazaki fragments) because it is the 3’ to 5’ strand but can only be built in the 5’ to 3’ direction

Question 32

Considering the bonds that hold together the backbones of a single DNA strand and the bonds that connect the two DNA strands of a double helix, how does this influence the way that DNA is replicated?

Answer 32

The sugar-phosphate backbones are held together by strong covalent bonds but the bases of the two strands are held together by weak hydrogen bonds. So in replication, it is easier to keep the strong backbones intact and just break the weak hydrogen bonds to separate the two strands in replication.

Question 33

DNA replication is (faster / slower) in prokaryotes than in eukaryotes.

Answer 33

Faster because their DNA is very simple

Question 34

In eukaryotic cells, DNA replication happens along (one / several) point(s) of the chromosomes.

Answer 34

several

Question 35

In a DNA molecule, the sugar (3)

Answer 35

Bonds covalently to a phosphate group and a nitrogenous base
It is a deoxyribose

Question 36

What is NOT true about the amount of complementary base pairing?

Answer 36

The amount of A + T is always equal to the amount of G + C.

Question 37

During DNA replication the daughter molecules

Answer 37

Are just like the parental molecule so that genetic constancy is maintained.

Question 38

In the DNA double helix, if 20% of the bases are adenine, then ____ of the bases is guanine.

Answer 38

30%