Brainscape's Knowledge GenomeTM

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


See full index

BCHM111 > Chapter 16 - Nucleic acids and Inheritance > Flashcards

Chapter 16 - Nucleic acids and Inheritance Flashcards

1
Q

What is your genetic endowment?

A

The DNA you inherited from your parents. DNA, the substance of inheritance, is the most celebrated molecule of our time

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

Before DNA was determined the hereditary material in organisms what was thought to be?

A

Proteins.

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

What is a polymer?

A

A polymer is a large molecule, or macromolecule, composed of many repeated subunits

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

What are the four bases of DNA?

A

(A) Adenine, (T) Thymine, (G) Guanine, or (C) Cytosine

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

What did Chargaff’s analysis find in regards to patterns of the four bases of DNA?

A

That the percentages of Adenine and Thymine were approximately the same and that the percentages of Guanine and Cytosine were also approximately the same.

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

What is a easier way to imagine the structure of DNA?

A

That the structure of DNA is similar to a rope ladder in that the rope are the phosphate groups and deoxyribose sugars (Sugar-Phosphate backbones) and the steps are the pairs nitrogenous bases. (A-T & C-G)

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

What part of the Sugar-Phosphate backbone of DNA is attached to the nitrogenous bases?

A

The sugar therefore the phosphate group always sits on the outside of DNAs structure.

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

What does antiparallel mean when discussing the structure of DNA?

A

A term applied to two molecules that are side by side but run in opposite directions. The two strands of DNA are antiparallel. The head of one strand is always laid against the tail of the other strand of DNA.

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

How often does the DNA helix make a full turn?

A

Every 3.4nm along its length

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

How closes are the bases packed in the DNA helix?

A

They are stacked 0.34nm apart therefore there are 10 layers (or steps on a ladder) each full turn of the helix

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

Why does Adenine pair with Thymine but cant pair with Cytosine and Guanine in DNA?

A

Adenine and guanine are purines, nitrogenous bases with two organic rings, while cytosine and thymine are nitrogenous bases called pyrimidines, which have a single ring. Pairing a purine with a pyrimidine is the only combination that results in a uniform diameter for the double helix. Therefore Adenine can only pair with Thymine and Cytosine can only pair with Guanine.

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

How do the nitrogenous bases pair with each other in the DNA helix?

A

By forming hydrogen bonds

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

How many hydrogen bonds are formed between Adenine and Thymine?

A

Two Hydrogen bonds

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

How many hydrogen bonds are formed between Cytosine and Guanine?

A

Three Hydrogen bonds

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

When drawing DNA how do you know which is the 5’ side?

A

The 5’ side has the phosphate group at the end.

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

When drawing DNA how do you know which is the 3’ side?

A

The 3’ side has the sugar group at the end

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

What is the the semiconservative model of DNA replication?

A

Semiconservative replication describes the mechanism of DNA replication in all known cells. It derives its name from the production of two copies of the original DNA molecule, each of which contains one original strand, and one newly-synthesized strand

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

How many DNA molecules does each of your somatic cells have in its nucleus?

A

46 DNA molecules

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

How is DNA replicated?

A

The double helix is untwisted and the hydrogen bonds between the nucleotide bases and disconnected allowing one of the strands to be copied and then replicated outside the cell DNA lives in.

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

During the copying of 20 billion nucleotide on average how many errors are made by the cells?

A

2

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

What are the origins of replication in DNA?

A

short stretches of DNA that have a specific sequence of nucleotides

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

What is a replication fork in DNA?

A

The replication fork is the area where the replication of DNA will actually take place. There are two strands of DNA that are exposed once the double helix is opened

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

What proteins participate in the unwinding of the DNA helix to prepare the replication fork?

A

Topoisomerase breaks, swivels, and rejoins the parental DNA ahead of the replication fork, relieving the strain caused by unwinding.
Primase synthesizes RNA primers, using the parental DNA as a template.
Helicase unwinds and separates the parental DNA strands.
Single-strand binding proteins stabilize the unwound parental strands keeping them from re-pairing.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What does the protein primase do?

A

It makes an RNA chain (Primer) based of the DNA template strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How long usually is a completed primer? (DNA strand)

A

5-10 nucleotides long

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Which enzymes catalyze the formation of new DNA and what do they do?

A

DNA polymerases and they catalyze the formation by adding nucleotides to the 3’ end of the preexisting chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the two DNA polymerases that play major roles in DNA replication in E coli?

A

DNA polymerase III and DNA polymerase I.

28
Q

True or False? the two strands of DNA in a double helix are antiparallel

A

True

29
Q

True or False? DNA polymerase catalyzes the addition of each monomer via a dehydration reaction

A

True

30
Q

When DNA polymerase catalyzes the addition of another nucleotide, other than the nucleotide what is added?

A

Each nucleotide to be added to a growing DNA strand consists of a sugar attached to a base and to three phosphate groups

31
Q

Where can DNA polymerases can add nucleotides on the primer strand?

A

To the free 3’ strand but never to the 5’ strand

32
Q

What is the difference between the leading strand and the lagging in DNA?

A

The strand formed from Okazaki fragments (disruption) is termed the lagging strand, whereas the one synthesized without interruption is the leading strand. Both the Okazaki fragments and the leading strand are synthesized in the 5′ → 3′ direction. Because they will ALWAYS be built in the 5’ to 3’ direction.

33
Q

What is the function of the Helicase protein?

A

It unwinds the parental double helix at the replication forks

34
Q

What is the function of the Single-Strand binding protein?

A

It binds to and stabilises single-stranded DNA until it has been used as a template.

35
Q

What is the function of the Topoisomerase protein?

A

Relieves overwinding strain ahead of replication forks by breaking, swiverling and rejoining DNA strands

36
Q

What is the function of the primase protein?

A

Synthesises (forms) an RNA primer at the 5’ end of the leading strand and at the 5’ end of each Okazaki fragment of lagging strand.

37
Q

What is the function of the DNA Pol 3 protein?

A

Using parental DNA as a template, it synthesises new DNA strands by adding nucleotides to an RNA primer or pre-existing DNA strand

38
Q

What is the function of the DNA Pol 1 protein?

A

Removes RNA nucleotides of primers from the 5’ end and replaces them with DNA nucleotides added to the 3’ end of the adjacent fragment

39
Q

How long are the Okazaki fragments in E coli?

A

1,000 to 2,000 nucleotides long

40
Q

How long are the Okazaki fragments in Eukaryotes?

A

100-200 nucleotides long.

41
Q

What is a difference between the leading and lagging strand in terms of rate?

A

Both strands are synthesised at relatively similar rated although the lagging strand has a slight delay.

42
Q

What does dna pol 3 do?

A

DNA polymerase III will then synthesize a continuous or discontinuous strand of DNA, depending if this is occurring on the leading or lagging strand (Okazaki fragment) of the DNA. DNA polymerase III has a high processivity and therefore, synthesizes DNA very quickly.

43
Q

What does dna pol 1 do?

A

DNA polymerase 1 is essential for removing of the RNA primers from the fragments and replacing it with the required nucleotides

44
Q

True or False, RNA polymerases proofread each nucleotide against its template as soon as it is covalently bonded to the growing strand.

A

False, DNA polymerases proofread each nucleotide against its template as soon as it is covalently bonded to the growing strand. This reduces the error rate in gene expression.

45
Q

What would happen if DNA polymerase found an incorrectly paired nucleotide?

A

The polymerase removes the nucleotide and then resumes synthesis. (This action is similar to fixing a texting error by deleting the wrong letter and then entering the correct one.)

46
Q

What happens in an incorrectly paired nucleotide avoids being detected by DNA polymerase?

A

Other enzymes remove and replace incorrectly paired nucleotides that have resulted from replication errors.

47
Q

Are defects in repair enzymes bad and why (use an example).

A

Yes it is bad. Researchers highlighted found that a hereditary defect in one of them is associated with a form of colon cancer. Apparently, this defect allows cancer-causing errors to accumulate in the DNA faster than normal.

48
Q

What is the trombone model of DNA replication?

A

The “trombone” model of DNA replication says that the lagging strand forms a loop which means the leading- and lagging-strands replication proteins contact one another

49
Q

True or False? DNA bases may undergo spontaneous chemical changes under normal cellular conditions

A

True, although these changes in DNA are usually corrected before they become permanent changes (mutations) perpetuated through successive replications

50
Q

How is it ensured that changes are rid of in DNA at all times?

A

Each cell continuously monitors and repairs its genetic material.

51
Q

What is nuclease?

A

An enzyme that splits the chains of nucleotides in nucleic acids into smaller units.

52
Q

How do cellular systems usually repair incorrectly paired nucleotides?

A

By cutting out the damaged segment and the resulting gap is then filled in with nucleotides, using the undamaged strand as a template.

53
Q

What are the enzymes involved in filling the gap after the cell has removed a DNA segment?

A

DNA polymerase and DNA ligase

54
Q

What is the nucleotide excision repair?

A

Nucleotide excision repair is a DNA repair mechanism where damaged bases are cut out within a string of nucleotides, and replaced with DNA as directed by the undamaged template strand. DNA damage occurs constantly because of chemicals, radiation and other mutagens.

55
Q

What is xeroderma pigmentosum (XP)?

A

Xeroderma pigmentosum (XP) is a genetic disorder in which there is a decreased ability to repair DNA damage such as that caused by ultraviolet (UV) light

56
Q

What is a permanent change in the DNA sequence called?

A

A mutation

57
Q

True or False? Mutations can be passed on from generation to generation.

A

True

58
Q

True or False? For linear DNA, such as the DNA of eukaryotic chromosomes, the usual replication machinery cannot complete the 5′ ends of daughter DNA strands.

A

True, This is another consequence of the fact that a DNA polymerase can add nucleotides only to the 3′ end of a preexisting polynucleotide.

59
Q

What are telomeres?

A

A telomere is a region of repetitive nucleotide sequences at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neigh boring chromosomes. It opposes the consequence in linear DNA where their machinery cannot complete the 5’ ends of daughter DNA strands.

60
Q

What is the shortening of telomeres?

A

Telomere length shortens with age. Rate of telomere shortening may indicate the pace of aging. Lifestyle factors such as smoking, lack of physical activity, obesity, stress, exposure to pollution, etc. can potentially increase the rate of telomere shortening, cancer risk, and pace of aging

61
Q

What does the the telomerase enzyme do?

A

The enzyme telomerase adds TTAGGG repeats onto mammalian telomeres, which prevents their shortening. Telomerase is ordinarily inactive in most somatic cells but can be detected in tumor cells.

62
Q

Watson and crick deduced what?

A

That DNA is a double helix with two antiparallel sugar-phosphate chains wind around the outside of the molecules with the nitrogenous bases inside connected by hydrogen bonds in specific pairs.

63
Q

What model fits DNA replication?

A

The semi-conservative model

64
Q

Primase does what?

A

Synthesizes a short RNA primer

65
Q

DNA pol 1 does what?

A

Replaces the RNA primer with DNA nucleotides

BCHM111 (21 decks)

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