DNA & inheritance Flashcards

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1
Q

What is a gene

A

section of DNA that contains a specific sequence of bases which code for a specific protein

  • length of DNA determines single characteristic of an organism
  • unit of inheritance
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2
Q

Mutation

A

sudden change in DNA of an organism

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3
Q

Gene mutation

A

change in structure of a gene

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4
Q

Chromosome mutation

A

change in number / structure of chromosome

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5
Q

Sickle cell anaemia

A

gene that codes haemoglobin undergoes mutation to produce abnormal haemoglobin
- less soluble
- tends to stick together
- distort RBC ; sickle-shaped ( half moon )
- cannot transport oxygen
- may block small capillaries ; larger diameter
- destruction of sickle cells causes severe form of anemia

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6
Q

Albinism

A

body can no longer produce melanin pigment
- white hair
- very light-coloured skin
- pink eyes

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7
Q

Down’s Syndrome

A
  • 24 chromosomes instead of 23 in ovum
  • child will have 47 chromosomes instead of 46
  • slow physical & mental development
  • broad flat face
  • shorter life span
  • extra chromosome in 21st group ; 3 instead of 2
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8
Q

Mutagens

A

agents increasing mutation rate
- change structure of gene ; altering the way it works

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9
Q

Examples of mutagens

A
  • chemicals : mustard gas & tar from cigarette smoke
  • high energy radiation : X-rays & UV light
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10
Q

Significance of mutations

A

main source of genetic variation ; new alleles of genes produced

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11
Q

Other causes of variation

A
  • meiosis
  • random mating between organisms
  • random fertilisation of gametes
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