Chapter 12 - DNA Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Why are hydrogen bonds effective at joining nitrogenous bases?

A

Hydrogen bonds are strong enough to hold the bases together but weak enough to allow the bases to separate if needed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are nucleotides and what are they made of?

A

Nucleotides join together to form strands of DNA. They are made up of a sugar, a phosphate group, and nitrogenous bases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does DNA polymerase do?

A

DNA polymerase is an enzyme that joins nucleotides to produce a new strand of DNA. It also corrects base pair errors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a bacteriophage?

A

A bacteriophage (“bacteria eater”) is a kind of virus that infects bacteria. When it enters a bacterium, it attaches to the bacterial cell and injects its genetic information into it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the role of DNA in heredity?

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe Griffith’s experiment.

A

In 1928, he isolated 2 strains (rough and smooth strain) of the same bacterial species. Only the disease-carrying S strain carried pneumonia. When he took the S strain, used heat to kill the cells, and injected a mouse with it, the mouse survived. He later mixed the killed S strain with the harmless R strain. When the mouse was injected with the mix, it developed pneumonia and died. It died due to a transformation in genes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe Avery’s experiment.

A

Avery wanted to determine which molecule in the heat-killed bacteria was most important for transformation. When molecules of the heat-killed S-strain were mixed with an enzyme that destroys proteins, lipids, carbohydrates, and RNA, transformation still occurred. When it was mixed with an enzyme that killed DNA, transformation did not happen. This shows that DNA is the transforming factor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe Hershey and Chase’s Experiment.

A

They wanted to determine which part of the virus (protein or DNA) entered the bacterial cell. The two men grew viruses containing two radioactive isotopes: phosphorus-32 and sulfur-35. Because proteins contain no phosphorus and DNA contains no sulfur, the scientists could now determine which molecules actually entered the bacteria. If they found radioactivity from the sulfur in the bacteria, then protein entered. If they found radioactivity from the phosphorus in the bacteria, then the DNA entered. In conclusion, the genetic material of the bacteriophage was DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the four nitrogenous bases? What is Chargaff’s rule about them?

A

They are Adenine, Guanine, Thymine, and Cytosine. Chargaff’s rule states that the percent of adenine and thymine is equal in any sample of DNA. The same concept applies to cytosine and guanine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How did Rosalind Franklin find out that there are 2 strands of nitrogenous bases?

A

She used X-ray diffraction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Who took the definitive picture of DNA using x-rays?

A

Rosalind Franklin took the picture.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the function of DNA?

A

The main role of DNA in the cell is the storage, transmission, and copy information. It also contains the code to make proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is DNA in prokaryotic bacteria different from DNA in eukaryotes?

A

Prokaryotic organisms have only one chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the concept of DNA being made of two strands and running in opposite directions called?

A

The strands of DNA are known as “antiparallel”.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What scientists devised a 3D model of the DNA’s double helix?

A

Watson and Crick built the double helix model.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is telomerase?

A

Telomerase is an enzyme that adds DNA sequences to telomeres, tips of chromosomes, in attempt to compensate for DNA loss. DNA is lost because the ends of DNA molecules are hard to replicate. Thus, some DNA is lost each time a chromosome is replicated.

17
Q

How does replication differ between eukaryotes and prokaryotes?

A

In most prokaryotic cells, replication starts from a single point and proceeds in 2 directions until the entire chromosome is copied. In eukaryotic cells, replication may begin at dozens or even hundreds of places on the DNA molecule, proceeding in both directions until each chromosome is copied.