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Biology - Genetics > Evolution - Causes > Flashcards

Evolution - Causes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Mutagenesis

A

This is the process of mutation formation

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2
Q

What are the endogenous causes of mutagenesis?

A

DNA replication
Failure in DNA repair
Spontaneous deamniation
Abundant ROS
Abasic sites

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3
Q

Why might mutagenesis occur in DNA replication?

A

Varying polymerase fidelity

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4
Q

How many bases do polymerase makes per generation?

A

10^8 with minimal error rates

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5
Q

How might errors occur by polymerases in replication?

A

In tandem with mismatch repair mechanisms, by insertions/deletaions by replication slippage

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6
Q

What are the repair pathways?

A

Mismatch Repair
Base-excision repair
Nucleotide-excision repair
Translesion
Non-homologous end joining

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7
Q

What disease does failure in DNA repair often result in?

A

cancer.

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8
Q

What does NER pathway mutation cause?

A

Xeroderma pigmentosum which makes people prone to skin cancer.

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9
Q

Why might translesion repair system result in mutation?

A

It increases polymerase active site to bypass DNA lesions with expense of increased error rate due to lower fidelity

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10
Q

Fidelity

A

A polymerase ability to accurately replicate a template.

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11
Q

Why does translesion repair reduce polymerase fidelity?

A

Because high fidelity polymases struggle to pass damaged bases, stalling DNA replication.

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12
Q

What happens in spontaneous deamination?

A

An amine is lost resulting in NT change.

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13
Q

What are examples in deamination nucleotide change?

A

C to U, adenine to hypoxanthine, guanine to xanthine, 5-methyl cytosine to thymine

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14
Q

What does cytosine damination result in?

A

A;T mutaiton

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15
Q

How many SNT hereditary diseases result from deamination?

A

33%

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16
Q

How are ROS naturally produced?

A

By ETC, important in many cell processes, with high quantities damaging DNA.

17
Q

What is an example of ROS damage?

A

8’ carbon guanine forming 8-oxoguanine with incorrect pairing with adenine instead of cytosine

18
Q

What diseases are abundant ROS often involved in?

A

Alzheimers, cancer and heart failure

19
Q

Why does ROS result in alheimers?

A

Mitochondrial autophagy results in ROS increasing due to nutrient deprivation and oxygen

20
Q

How are abasic sites formed?

A

Spontaneous hydrolysis or DNA glycolyase cleavge, often repaired by TLS

21
Q

What are the EXOGENOUS mutagenic causes?

A

Ionizing Radiation
Ultraviolet Radiation
Alkylating agents
Polycyclic aromatic hydrocarbons
Aflatoxin

22
Q

How does ionizing radiation cause mutagenesis?

A

Induce DNA breaks as well as radiolysis of H2O producing ROS.

23
Q

How does UV induce mutagenesis?

A

Pyrimidine dimerisation and pyrimidine photoproducts with DNA helical distortion

24
Q

What can UV damage be repaired by?

A

NER and TLS

25
Q

What do alkylating agents cause?

A

Abasic site formation due to their affinity for nitrogen.

26
Q

What are examples of alkylating agnets?

A

Methyl methanosulfonate
Nitrogen mustard gas
Ethyl methanosulfonate

27
Q

Alkylating agents

A

These have capabilites to prevent DNA replication, reacting with nucleophiles forming covalent bond

28
Q

How does mustard gas prevent DNA replication?

A

Induces cross-linkage

29
Q

Ethyl methanosulfonate

A

This results in guanine alkylation producing point mutations

30
Q

CytochromeP450 system

A

A hemeprotein metabolising a variety of drugs and xenobiotics.

31
Q

How might aromatic amines cause alkylating agent formation?

A

When metabolised by cytochromeP450 system

32
Q

What does aromatic amine metabolism cause?

A

C8 guanine lesions and frameshift/base mutations

33
Q

Polycyclic Aromatic Hydrocarbons

A

Contain two or more aromatic rings, found in tobacco smoke, automobile exhausts, and fossils fuels

34
Q

DNA adducts

A

DNA segments bound to cancer causing chemicals

35
Q

Alfatoxing

A

Metabolised by CYP450 forming adducts with guanine N7

36
Q

What is alfatoxin the main cause of?

A

Hepatocellular carcinoma

Biology - Genetics (14 decks)

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