Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

General Biology 1 and 2 > chapter 15 > Flashcards

chapter 15 Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What two components make up chromosomes?

A

DNA and proteins.

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

What experiment showed that DNA is the genetic material?

A

hersey chase experiment

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

Why did scientists initially think genes were made of protein?

A

Proteins are more complex and variable compared to DNA, which has only four nucleotides.

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

What did the Hershey-Chase experiment demonstrate?

A

It proved that DNA, not protein, is the hereditary material.

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

What are the three models of DNA replication?

A

Semiconservative replication,Conservative replication,Dispersive replication

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

three models of DNA replication

Semiconservative replication:

A

Each new molecule has one old strand and one new strand.

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

Conservative replication

A

The original molecule remains intact, and a completely new molecule is formed.

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

Dispersive replication

A

DNA is fragmented and recombined, mixing old and new DNA in each strand.

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

What experiment confirmed the semiconservative replication model?

A

The Meselson-Stahl experiment using heavy and light nitrogen isotopes.

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

In what direction does DNA synthesis occur?

A

DNA synthesis proceeds in the 5’ to 3’ direction.

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

What enzyme catalyzes DNA synthesis?

A

DNA polymerase.

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

What is a primer, and how is it synthesized?

A

A primer is a short RNA strand that provides a starting point for DNA polymerase. It is synthesized by the enzyme primase.

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

What is the leading strand, and how is it synthesized?

A

The leading strand is synthesized continuously toward the replication fork.

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

What is the lagging strand, and how is it synthesized?

A

The lagging strand is synthesized discontinuously in short fragments called Okazaki fragments, moving away from the replication fork.

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

How are Okazaki fragments joined?

A

DNA ligase forms phosphodiester bonds (covalent) to link fragments into a continuous strand.

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

What is the end-replication problem?

A

The lagging strand cannot complete synthesis at the very end of a chromosome, leaving a single-stranded overhang that shortens with each replication cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What enzyme prevents chromosome shortening?

A

Telomerase extends the telomeres, the repetitive sequences at chromosome ends.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why do telomeres shorten in somatic cells?

A

Somatic cells lack active telomerase, leading to progressive shortening with age.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How accurate is DNA replication?

A

DNA replication has an error rate of one mistake per billion nucleotides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is proofreading in DNA replication?

A

DNA polymerase detects and removes mismatched bases during synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is mismatch repair?

A

It is a system that corrects mismatched bases left after DNA replication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does UV light damage DNA?

A

UV light induces thymine dimers, which create kinks in the DNA strand and block replication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is nucleotide excision repair?

A

A repair system that removes damaged DNA, fills the gap with new DNA, and seals it with DNA ligase.

e.g., UV-induced thymine dimers) by removing the damaged strand and replacing it using the intact strand as a template.

24
Q

What is xeroderma pigmentosum (XP)?

A

A genetic disorder caused by defects in nucleotide excision repair, leading to UV sensitivity and increased cancer risk.

25
Q

What is the role of topoisomerase in DNA replication?

A

It relieves tension caused by unwinding the DNA helix.

26
Q

What is the replisome?

A

A dynamic molecular machine that coordinates the enzymes and proteins involved in DNA synthesis.

27
Q

What makes DNA polymerization energetically favorable?

A

The high potential energy of dNTPs (deoxyribonucleoside triphosphates) drives the reaction.

28
Q

What did the Hersey and chase experiment study

A

t2 virus infects and replicates becterium in ECOLI

29
Q

when does the T2 infection of Ecoli begin

A

when the virus injects into cell, genes direct production of new virus particles

30
Q

hersey chase experiment

what is left behind on viruses exterior protien coat

A

capsid is left behind on outside of cell

31
Q

where did hersey and chase grow their virus in the presence of what?

A

two radiotic isotopes of 32^Phosphate and 35^sulfar

32
Q

hersey and chase experiment

where was phosphate isotope incorporated into

A

The DNA

33
Q

Where was S incorporated into

A

protiens

34
Q

hersey and chase

what were used to infect ecoli cells

A

labeled viruses

35
Q

What do t2 viruses contain and don’t contain

A

t2 protiens contain sulfur but not phosphorous

36
Q

what does DNA contain

A

phosphorous but not sufur

37
Q

what did hersey and chase find inside cell

A

radioactive dna

Proved that genes were composed of DNA

38
Q

What is DNA’s structure?

A
  1. DNA is a double helix with antiparallel strands.
  2. It has a sugar-phosphate backbone and complementary base pairs (A-T and G-C).
39
Q

Which hypothesis for DNA replication was correct?

A

The semiconservative model was proven correct by the Meselson-Stahl experiment.

40
Q

What is the role of DNA polymerase?

A

DNA polymerase synthesizes new DNA by adding nucleotides to the 3’ end of a growing strand.

41
Q

What is the difference between the leading and lagging strands during replication?

A

Leading strand: Synthesized continuously toward the replication fork.
Lagging strand: Synthesized in short fragments (Okazaki fragments) away from the fork.

42
Q

What is the role of telomerase?

A

Telomerase extends the ends of linear chromosomes (telomeres) to prevent shortening during replication.

43
Q

What happens if DNA is not repaired?

A

Mutations accumulate, increasing the risk of diseases like cancer.

44
Q

Why is DNA considered a polymer?

A

DNA is a polymer because its nucleotides are linked by phosphodiester bonds between the sugar of one nucleotide and the phosphate group of another.

45
Q

What was the key technique used in the Meselson-Stahl experiment?

A

Density gradient centrifugation was used to separate DNA based on its density after replication in heavy (15N) and light (14N) nitrogen media.

46
Q

What is the function of DNA helicase?

A

DNA helicase unwinds the DNA double helix by breaking hydrogen bonds between the strands.

47
Q

What is the role of single-strand DNA-binding proteins (SSBPs)?

A

SSBPs bind to separated DNA strands to prevent them from reannealing.

48
Q

How does topoisomerase alleviate tension during replication?

A

Topoisomerase cuts and rejoins the DNA to relieve supercoiling caused by unwinding.

49
Q

What repetitive sequences are found in telomeres?

A

Telomeres consist of short, repeated sequences of bases (e.g., TTAGGG in humans).

50
Q

What are the two key types of errors during DNA synthesis?

A

Mismatched bases
DNA damage

51
Q

Mismatched bases

A

Incorrect base pairing.

52
Q

DNA damage

A

From external factors like UV light or chemicals.

53
Q

What happens if the DNA repair systems fail?

A

Accumulated mutations can lead to diseases like cancer, where cells grow uncontrollably.

54
Q

What stabilizes the DNA double helix?

A

Hydrogen bonding between complementary bases (A-T and G-C).
Base stacking interactions within the helix.

55
Q

Why is DNA synthesis considered bidirectional in eukaryotic cells?

A

Replication begins at multiple origins of replication, forming replication bubbles that grow in both directions.

General Biology 1 and 2 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions