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Origin and Diversity of Life > Genetics > Flashcards

Genetics Flashcards

1
Q

Genes

A

units of DNA coding for a particular piece of information

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2
Q

Chromosomes

A

segments of DNA which also contain proteins

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3
Q

Cell cycle

A
  • contains interphase and division
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4
Q

Interphase

A
  • G1: cell makes components that allows the cell to divide to make two identical cells
  • S: DNA is synthesised as each cell has to have its own copy of genetic material
  • G2: cell continues to grow
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5
Q

Prophase

A
  • chromosomes condense

- each chromosome made from 2 chromatids joined at a region called the centromere

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6
Q

Telomere

A
  • region at the end of a chromosome

- protects chromosome from damage

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7
Q

Metaphase

A
  • chromosomes line up along the metaphase plate of the cell as a spindle has formed
  • fibres extend down from opposite poles to the middle of the cell and grab hold of the centromere
  • spindle fibres attach to the kinetochore
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8
Q

Kinetochore

A
  • complex of proteins surrounding the centromere

- where spindle fibres attach to

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9
Q

Spindle fibres

A
  • forms of proteins called microtubules

- initiated from opposite poles of the cell

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10
Q

Anaphase

A
  • once spindle fibres attach to kinetochore, microtubules contract and pulls them apart to opposite sides
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11
Q

Telophase

A
  • 2 nuclei are produced

- 2 daughter cells are formed

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12
Q

Meiosis

A

Meiosis I

  • each chromosome is replicated so sister chromatids are formed
  • homologous chromosomes form bivelant with each other
  • spindles form, attach to centromeres, pull chromosomes apart

Meiosis II
- starts with 2 products which have one copy of each chromosome
- spindle fibres form and attach to centromere
fibres shorten and pull apart chromatids
- 4 haploid products are formed

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13
Q

Diplotene

A
  • stage during Prophase I
  • there are regions within bivelants where sister chromatids interact
  • parts of sister chromatids break and rejoin by crossing over
  • forms chiasma
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14
Q

Independent assortment

A
  • allows different products to be formed from different combinations of chromosomes
  • bivelants assort independently
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15
Q

Wild-type

A

common form of a character (normal)

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16
Q

Mutant

A

rare form of a character (affected)

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17
Q

Homozygous

A

2 identical alleles

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18
Q

Heterozygous

A

2 different alleles

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19
Q

Phenotype

A

the appearance controlled by combination of alleles

20
Q

Dominant inheritance

A

if an affected individual has an affected parent

21
Q

Test cross

A

used to determine genotype of an individual who is showing the dominant feature phenotype

22
Q

Pleitropy

A

a single gene mutation influences multiple phenotypes and characteristics

23
Q

Expressivity

A

variation in degree to which the phenotype is shown

24
Q

Penetrance

A

individual in one generation can have the mutant genotype, but do not express the phenotype

25
Q

Incomplete dominance

A
  • form of inheritance where one allele for a specific trait is not completely expressed over its paired allele
  • results in third phenotype which physical trait is a combination of both
26
Q

Complete dominance

A
  • form of dominance in heterozygotes

- allele regarded as dominant completely overrides effect of allele that is recessive

27
Q

Sex linked chromosomes

A

genes on the X chromosome are said to be sex linked

28
Q

Epistasis

A

interaction of phenotypes controlled by different genes, but affect the same character

29
Q

Complementation test

A
  • genetic experiment that indicates whether two mutations affect one gene or two different genes
  • one gene = no complementation
  • two genes = complementation
30
Q

Pseudo-autosomal region

A
  • regions at each end of the Y chromosome, which allow it to align with the X chromosome
31
Q

SRY gene

A
  • determines male development
32
Q

Aneuploidy

A
  • when there is an abnormal number of chromosomes
  • eg. down syndrome has 47 chromosomes as there are 3 copies of chromosome 21
    1 copy - monosomy
    2 copies - disomy
    3 copies - trisomy
    4 copies - tetrasomy
33
Q

Trisomy

A
  • results in death in other chromosomes apart from 13, 18 and 21
  • occurs through problem in meiosis
  • non-dysjunction is failure to separate either homologous chromosomes or sister chromatids
34
Q

Barr bodies

A

dark staining region representing inactive x chromosome

35
Q

X chromosome inactivation

A
  • known as dosage compensation
  • prevents females having too much of same gene expressed
  • one copy of each gene is switched off in either chromosome
36
Q

Polyploids

A
  • organisms with extra copy of chromosomes
  • fatal in humans, acceptable in plants
  • results in larger appearance
37
Q

Mutations

A

occur when DNA sequence is changed

38
Q

Epigenetics

A

study of change in activity of genes that do not result from changes in DNA sequence

39
Q

Genomic imprinting

A
  • expression of different genes is determines by with parent it is inherited from
  • imprint is erased in germline cells
  • imprint is maintained in somatic cells
40
Q

Epigenetic mark

A

mechanism that switches off X chromosome

41
Q

Cell autonomous phenotype

A
  • determined by the genotype of the cell it has formed from

- only cells with mutant genotype show mutant phenotype

42
Q

Cell non-autonomous phenotype

A
  • cells can show mutant phenotype regardless of their genotype
43
Q

Hardy Weinberg equilibrium

A
  • no change in allele frequency from one generation to another
    p2 + 2pq + q2 = 1
44
Q

Hardy Weinberg true if:

A 
- there is random mating 
there is no selection
- there is no migration
- there is no mutation
- population is large
45
Q

Anisogamy

A

gametes differ in size

46
Q

Hermaphroditism

A
  • organism has both male and female gametes

- favoured if mate searching efficiency is low

Origin and Diversity of Life (3 decks)

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