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PRIS (CLB) > DNA Structure > Flashcards

DNA Structure Flashcards

1
Q

What are the building blocks of nucleic acids?

A

Nucleotides

Nucleotides are formed of phosphates, ribose/deoxyribose, and nitrogenous bases.

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2
Q

What is a polymer of nucleotides called?

A

Nucleic acids

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3
Q

What is the structure of Deoxyribonucleic Acid (DNA)?

A

Usually a double helix made up of two chains of deoxyribonucleotides

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4
Q

What is Ribonucleic Acid (RNA) typically composed of?

A

Usually a single-stranded chain of ribonucleotides

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5
Q

List the core bases found in DNA.

A
  • Guanine (G)
  • Cytosine (C)
  • Adenine (A)
  • Thymine (T)
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6
Q

List the core bases found in RNA.

A
  • Guanine (G)
  • Cytosine (C)
  • Adenine (A)
  • Uracil (U)
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7
Q

What type of bond connects each nucleotide in nucleic acids?

A

Phosphodiester bonds

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8
Q

What are the free ends of a nucleic acid chain called?

A
  • Free 5’ end
  • Free 3’ end
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9
Q

True or False: DNA is double-stranded while RNA is mostly single-stranded.

A

True

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10
Q

Which base pairing is stronger in DNA, G:C or A:T?

A

G:C bonding is stronger than A:T

GC = 3 hydrogen bonds
AT = 2 hydrogen bonds

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11
Q

What structural feature helps form the DNA double helix?

A

Complementary hydrogen bonds

Reinforced by the sugar phosphat ebackbone and complementary bases.

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12
Q

What is the approximate length of genomic DNA in a mammalian genome?

A

~2 meters long

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13
Q

What is the diameter of the nucleus in which DNA is packaged?

A

6-10 microns

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14
Q

What protein is genomic DNA packaged around?

A

Histones

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15
Q

How many types of histone sub-units are critical for the histone octamer?

A

4 types

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16
Q

What is the composition of a histone octamer?

A
  • 2x Histone H2A
  • 2x Histone H2B
  • 2x Histone H3
  • 2x Histone H4
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17
Q

How many base pairs of DNA are wrapped around the histone octamer?

A

147 bp

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18
Q

What is formed when DNA wraps around histones?

A

Nucleosome

19
Q

What is the range of linker DNA between nucleosomes?

A

~10-80 bp

20
Q

What histone binds to each nucleosome?

A

H1 histone

21
Q

What structure is formed by multiple stacked nucleosomes?

A

30 nm fibre (or solenoid fibre)

22
Q

What term is used to refer to the nucleosomes made of DNA and histones?

A

Chromatin

23
Q

What is the final condensed structure of chromatin called?

A

Chromosomes

24
Q

How does the condensed nature of chromatin impact gene expression?

A

It is variable and impacts gene expression.

25
Q

What are the effects of additions of methyl groups and acyl groups to histones?

A

Impact chromatin and gene expression

These modifications can influence the accessibility of DNA for transcription and other processes.

26
Q

What diseases are targeted for drug development in relation to DNA packaging?

A

Parasites like Fasciola hepatica and cancer

This highlights the importance of DNA packaging mechanisms in both health and disease.

27
Q

What is the cancer incidence rate in male dogs?

A

99.3 per 100,000

This statistic provides insight into the prevalence of cancer in canine populations.

28
Q

What is the cancer incidence rate in female dogs?

A

272.1 per 100,000

This indicates a significantly higher incidence of cancer in female dogs compared to males.

29
Q

Why is DNA replication necessary?

A

To produce more cells and offspring

DNA replication is essential for growth, development, and reproduction.

30
Q

What is the most important enzyme in DNA replication?

A

DNA polymerase

DNA polymerase synthesizes new DNA strands during replication.

31
Q

In which direction does DNA replication occur?

A

From 5’ to 3’ end

This directional nature is crucial for the fidelity of DNA replication.

32
Q

What initiates DNA replication?

A

Origin of replication

This is the specific location on the DNA where replication begins.

33
Q

What is the function of helicases?

A

Aid in the unwinding of DNA at replication forks

Unwinding is necessary to allow access to the DNA strands for replication.

34
Q

What is the role of primase in DNA replication?

A

Synthesizes short RNA sequences called primers

Primers are essential for initiating DNA synthesis.

35
Q

What is the role of DNA gyrase?

A

Prevents supercoiling during DNA replication

This enzyme is crucial for maintaining the structure of DNA as it replicates.

36
Q

What distinguishes prokaryotic DNA gyrase from eukaryotic topoisomerases?

A

Quinolones target bacterial DNA gyrases

This difference is exploited in antibiotic treatments.

37
Q

What is PCR?

A

An amplification technique of DNA

PCR is widely used in various applications, including diagnostics and research.

38
Q

List the main components required for PCR.

A
  • Template DNA
  • Free dNTPs (dATP, dGTP, dCTP, dTTP)
  • 2 specific primers (18-25 bases long)
  • Taq polymerase
  • Buffer

Each component plays a vital role in the PCR process.

39
Q

What is the first step in the PCR process?

A

Heat DNA to 94°C to separate the strands (denature)

Denaturation is necessary to allow the primers to anneal to the single-stranded DNA.

40
Q

What happens during the annealing step of PCR?

A

Cool DNA to ~60°C to allow primers to anneal

This step ensures that primers bind specifically to the target DNA sequences.

41
Q

What is the temperature for DNA polymerization during PCR?

A

72°C

This is the optimal temperature for Taq polymerase activity.

42
Q

How does PCR help in veterinary diagnostics?

A

Used to determine infections (species, strain, etc.)

PCR provides a rapid and specific method for identifying pathogens.

43
Q

What is the purpose of running a PCR mix on an agarose gel?

A

To separate by size and visualize the presence/absence of DNA

Gel electrophoresis allows for the analysis of PCR products.

PRIS (CLB) (27 decks)

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