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Biology: Cell Biology And Genetics > Mutagens > Flashcards

Mutagens Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Name two forms of mutations.

A

Spontaneous and induced

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2
Q

What causes induced mutations?

A

Mutagens.

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3
Q

Mention three common types of mutagens.

A
  • physical
  • chemical
  • induced
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4
Q

List chemical mutagens.

A
  • deaminating agents
  • alkylating agents
  • base analogues
  • bulky addition products
  • intercalating agents
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5
Q

What do deaminating agents cause?

A

The removal of amino groups from nitrogenous based.

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6
Q

Give an example of the work of a deaminating agent.

A

Removing the Amino group from cytosine leaving it as uracil.

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7
Q

State a change in base pairing this may cause starting from CG.

A

CG-UA-AT

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8
Q

What is the name of the substance that delaminates cytosine to form uracil?

A

Nitrous acid

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9
Q

State what alkylating agents do.

A

These mutagens add alkyl groups to nitrogenous bases.

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10
Q

Give examples of alkyl groups.

A

CH3, CH2CH3

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11
Q

What may the addition of alkyl groups lead to?

A

Deletion of such bases, especially the purines adenine and guanine.
Or mispairing of bases.

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12
Q

Name a disease deaminating agents age linked to.

A

Gastric cancer

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13
Q

Give examples of alkylating agents.

A

Dimethylsulphate
Diethylsulphate
Ethylmethane sulphate

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14
Q

Give on illustration of an alkylation taking place.

A

Ethyl methane sulphate generates ethylation at the O-4 position of thymine. The modified thymine will mispair with guanine leading to TA-GC transition.

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15
Q

Name some conditions alkylating agents are linked to.

A

Bladder, bronchial and blood cancer.

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16
Q

What are base analogues?

A

Mutagens that look like normal bases thus confusing the DNA replication system.

17
Q

Give 2 examples of base analogues. And state what they are analogues of.

A

5- bromouracil an analogue of thymine

2-amino purine an analogue of adenine

18
Q

Give an example of the effect of a base analogue.

A

5-bromouracil, an analogue of thymine, will pair with guanine. When affected DNA replicates, it produces the change TA-5bromouracil/guanine-GC

19
Q

What are bulky addition products??

A

Large molecules able to covalently bond to purines leading to deletion of such purines from the affected DNA.

20
Q

Name one bulk addition mutagen and where it is found.

A

Aflatoxin B1 a carcinogen found in seed crops such as groundnuts and maize.

21
Q

Name what the previous bulk addition mutagen is linked to. (2)

A

Liver cancer

Hepatitis B

22
Q

The attachment of a bulky addition product, such as Aflatoxin B1 will disturb things in what way.

A

Deletion of affected purine, in this case guanine leaving an apurinic site.

23
Q

What is an apurinic site?

A

Location in DNA that is neither a purine or pyrimidine. Caused spontaneously or due to damage.

24
Q

What does the repair system usually do and what change does it lead to.

A

Repair system usually inserts guanine in site of deletion.

Leads to change CG-C*-CA-TA

25
Q

What’s an intercalating agent?

A

Molecules that have three rings which mimic base pairs.

26
Q

How will intercalating agents affect DNA?

A

Insert themselves between base pairs in the affected DNA double helix, causing frame shift mutations.

27
Q

Give three examples of intercalating agents.

A
  • proflavin (antiseptic antibacterial and urinary)
  • acridine orange (dye used in lab detection of mycobacterium)
  • ethidium bromide (fluorescent dye)
28
Q

Mention the two most important physical mutagens.

A
  • UV radiations

- ionization radiations

29
Q

What do UV radiations do??

A

Generates the pyrimidine (thymine) dimers which cause cancer e.g melanoma and keratosis.

30
Q

List three examples of ionization radiations.

A
  • X rays
  • Gamma rays
  • neutrons
  • alpha rays
31
Q

What do ionization radiations lead to? What do they cause

A

Generation of free radicals which cause breaks in DNA

32
Q

What’s the ultimate result of ionization radiations?

A

Results in deletions and other types of mutations in affected DNA

33
Q

Liste three examples of biological mutagens.

A

Viruses
Transposable elements
Some bacteria

34
Q

Explain how mutagenic viruses work.

A

When a viral infection is acquired, the virus attatches to a cell and transfers genetic material into the cell thus altering the original gene causing mutation.

35
Q

Give one example of a DNA viral mutagen and an RNA virus.

What disease can they cause?

A

DNA-hepatitis B
RNA-hepatitis C

Liver cancer

36
Q

Give three more examples of mutagenic viruses.

A
  • human herpes virus
  • SV40
  • human papilloma virus
37
Q

Transposable elements also cause mutations. Explain how they disturb functions.

A

Segment of DNA able to move from one position to another in the same chromosome or from one chromosome to another. When inserted into a new position on chromosomal DNA it disrupts function of genes.

38
Q

What does mutagenic bacteria do?

A

Causes inflammation during which oxidative species are produced. Causes DNA damage by reducing efficiency of DNA repair systems thereby increasing mutations.

39
Q

Give one example of mutagenic bacteria.

A

Helicobacter pylori

Biology: Cell Biology And Genetics (2 decks)

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