S9) Introduction to DNA Mutation Flashcards

1
Q

What is a mutation?

A

A mutation is a heritable alteration in a gene or chromosome (a change in the sequence of nucleotides) and also the process that produces the alteration

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2
Q

Identify two sources of exogenous mutations

A
  • Ionising radiation/particles and free radicals
  • Mutagenic chemicals and anti-cancer agents
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3
Q

What is the general effect of exogenous mutagens?

A

Exogenous mutagens lead to defective/error-prone DNA repair in the body

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4
Q

identify 6 processes/substances which lead to the formation of free radicals

A
  • UV light
  • Ionising radiation
  • Smoking
  • Air pollution
  • Inflammation
  • Metabolism
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5
Q

What are the two sources of endogenous mutations?

A
  • DNA replication errors
  • Transposable elements
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6
Q

What are transposable elements?

A

A transposable element is a DNA sequence that can change its position within a genome, sometimes creating or reversing mutations and altering the cell’s genetic identity and genome size

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7
Q

Identify 4 types of micro mutations (DNA)

A
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8
Q

Identify 5 types of macro mutations (chromosomal)

A
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9
Q

What are the four different types of single nucleotide changes?

A
  • Mutations that change gene products
  • Mutations that change the amount of gene product
  • Mutations that change the polypeptide length
  • Mutations that have no effect
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10
Q

What are missense mutations?

A

Missense mutations are mutations which change the gene product due to a change in amino acid

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11
Q

Identify some types of mutations which change the polypeptide length

A
  • Frameshift mutations
  • Mutations of stop codon
  • Nonsense mutations
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12
Q

Mutations that change the amount of gene product affect transcription and/or translation.

Identify some examples

A
  • Alter promoter activity
  • Alter translation initiation at AUG
  • Prevent mRNA splicing
  • Reduce mRNA stability
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13
Q

What are silent mutations?

A

Silent/neutral mutations are mutations which have no effect

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14
Q

What are the different types of substitutions?

A
  • Transition: change to same type of base e.g. purine to purine (A ⇒ G)
  • Transversion: change to different type of base e.g. purine to pyrimidine (A/G ⇒ T/C )
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15
Q

What is sickle cell anaemia?

A

Sickle cell anaemia is a haemoglobinopathy which arises due to a single base mutation in the β-chain of haemoglobin (Glu ⇒ Val) causing the blood cells to become rigid and sickle (HbS protein)

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