Genetics - topic 3 (pg 20-28) paper 1 Flashcards

1
Q

meiosis

A

produces four daughter cells each with half the number of chromosomes
only in gamete producing cells, producing genetically different haploid gametes

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2
Q

haploid

A

one set of chromosomes (me-1-osis)

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3
Q

stages of meiosis

A

the parent cell is a diplod cell (two pairs of chromosomes –> parent cell dividesin two then two again

  • before the parent cell divides, each chromosome is copied
  • each daughter cell gets a copy of one chromosome form each pair
  • each daughter cell has one different haploid set of chromosomes
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4
Q

DNA

A

Deoxyribonucleic acid - genetic material found in the chromosomes in the nucleus of cells

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5
Q

gene

A

short piece of DNA that codes for a specific protein, codes for a characteristic

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6
Q

structure of DNA

A

molecule formed from two strands twisted together in a double helix

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7
Q

DNA bases

A

A(adenine) T(thymine)

C(cytosine) G(guanine)

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8
Q

what hols DNA strand together

A

weak hydrogen bonds

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9
Q

DNA structure

A

DNA is a polymer made of monomers called nucleotides joined together

Phosphate (circle)
        deoxyribose sugar (pentagon)       Base (square)
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10
Q

when gametes fuse they form a

A

diploid zygote

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11
Q

allele

A

different versions of the same gene

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12
Q

chromosomes of the same pair have

A

the same genes in the same order

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13
Q

heterozygous

A

different alleles of the same gene

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14
Q

homozygous

A

same alleles on both chromosomes

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15
Q

genotype

A

shows the alleles in each individual - punnet squares

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16
Q

phenotype

A

the characteristics that are produced - punnet squares

17
Q

dominant

A

will show when one allele is present in the genotype

18
Q

recessive

A

will only show when two alleles are present in the genotype

19
Q

pedigree analysis

A

used to study inheritance of dominant and recessive alleles

predict the chance of someone inheriting a specific allele

20
Q

carriers

A

have one copy of a faulty allele

21
Q

genotype XX

A

female chromosomes

22
Q

genotype XY

A

male chromosomes

23
Q

at fertilisation there is an equal chance of

A

producing a male or a female

24
Q

variation factors can be

A

genetic and environmental

25
phenotypic features
hair colour, eye colour | caused by many genes
26
genetic variation
hair colour | eye colour
27
environmental variation
scars | ability to ride a bike
28
genetic and environmental variation
weight | skin colour
29
mutation is created
when subsequent bases in a gene is changed
30
mutations however
- most genetic mutations have no effect on phenotype - some have a small effect - a single mutation rarely, significantly affects the phenotype
31
a mutation may cause
- a large change in protein produced - a small change - no change
32
mutation in non coding DNA can
increase or decrease ability of RNA polymerase to bind to DNA
33
The Human Genome Project
collaboration between scientists to decode the human genome (order of bases on all human chromosomes) - completed quickly due to number of scientists working at the same time - published in 2003 - used for new medicines
34
advantages of the human genome project
- alerting people they are at risk of particular diseases - distinguishing between differences in diseases like leukaemia, some drugs are beneficial for different forms - allowing doctor to 'tailor treatments' for some diseases to the individual
35
disadvantages of the human genome project
people who were at risk of certain disease like cancer could have claimed more life insurance - may not be useful to tell someone the risk of a condition with no cure currently