Chapter 12 DNA Review Part 2

What is the role of DNA?

Its role is to store, copy, and transmit genetic information into a cell.

What is DNA?

Deoxyribonucleic acid; it holds all of our cell's information and is located in the cell's nucleus.

The nucleic acid of DNA is a?

The nucleic acid is a macromolecule.

What are the monomers of DNA (nucleic acids)?

The monomers are nucleotides.

The basic components of nucleotides are?

The basic components of nucleotides are: 5-carbon sugar called deoxyribose, phosphate group, and nitrogenous base.

What are the nitrogenous bases of DNA?

The nitrogenous bases are adenine (A), guanine (G), cytosine (C), and thymine (T).

DNA looks like?

It looks like a ladder. The sugars and the phosphates are the sides (backbone) of this ladder and the nitrogenous bases are the rungs (steps).

Chargaff's rule states?

It states that the amount of A is equal to T and the amount of G is equal to C.

What did Rosalind Franklin do?

She used X-ray diffraction to help determine the shape of DNA, which was a double helix.

What did Watson and Crick do?

They constructed a 3D model of DNA.

What does it mean when we say that the strands of DNA are antiparallel?

It means that the two strands of DNA run in opposite directions. Nitrogenous bases connect at the center and that is significant in DNA replication.

Hydrogen bonds are just strong enough to \___ and weak enough that \___?

They are just strong enough to hold two strands together and weak enough that the two strands can be separated during DNA replication.

What did Watson and Crick observe about base pairing?

They observed that adenine joins with thymine and that guanine pairs with cytosine. This explained Chargaff's early discovery that the amount of A\=T and the amount of C\=G.

What is a complementary strand?

It is a strand of DNA that matches up with another strand.

During DNA replication, what is "unwinding"?

Unwinding is when a parental DNA molecule is "unzipped" (the weak H bonds are broken between paired bases).

During DNA replication, what is "complementary base pairing"?

Complementary base pairing is when new complementary nucleotides are positioned by the rules of base pairing (A\=T, C\=G).

During DNA replication, what is "joining"?

Joining is when complementary (matching) nucleotides join to form new strands. Each daughter DNA molecule contains an old strand and a new strand (semi-conservative model).

What is used for strand separation during DNA replication?

Helicase is used. It is an enzyme that catalyzes the unwinding and separation (breaking H-bonds) of the parental double helix.

What is used for creating new strands of DNA during DNA replication?

Polymerase and telomerase are used. Polymerase is an enzyme that joins new individual nucleotides together, creating a new strand of DNA, and telomerase prevents genes from being damaged or lost.

What is the difference between DNA replication in prokaryotic cells and DNA replication in eukaryotic cells?

The difference is that prokaryotic chromosomes have a single point of origin while eukaryotic chromosomes have multiple points of origin.

What are replication forks (in eukaryotic cells)?

They are hundreds of Y-shaped regions of replicating DNA molecules where new strands are growing. Replication proceeds in both directions until DNA is copied.

What is a gene?

It is a segment of DNA with a particular sequence of bases (AGC).

What is a genetic mutation?

It is a change in a gene's sequence of bases.

True or false: Some genetic mutations are due to errors in DNA replication, but proofreading enzymes prevent this.

True.

What are the environmental causes of DNA damage (mutations)?

The environmental causes are UV radiation in sunlight, chemicals in tobacco smoke, nuclear radiation, pesticides, and pollutants.

True or false: DNA repair enzymes reverse most of the damage done to DNA, but some mutations escape notice.

True.

True or false: Genetic mutations can be harmful (cancer), beneficial (evolution), and/or cause no change (most mutations).

True.

Environmental factors can damage DNA and cause mutations by?

They can damage DNA and cause mutations by altering nucleotide bases so that they look like other nucleotide bases.