Biology revision

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  • Created by: Joemea123
  • Created on: 26-04-17 22:43
Describe what happens to the genetic material during meiosis
It is mixed up creating genetically different cells
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What type of cells does meiosis produce?
Haploid gametes
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What is mitosis and meiosis?
Cell division: mitosis- for growth and repair, meiosis- to make gametes
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What is fertilisation?
When the nucleus of 2 gametes fuse together
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Describe what happens during meiosis
Chromosomes copy and stay attached, Chromosomes line up in the middle of the cell, Cell divides twice forming 4 genetically identical haploid gametes
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Describe the structure of DNA
- double helix, sugar phosphate back bone, weak hydrogen bonds join complementary bases (a-t, c-g)
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Why do you need to gently crush the 'pea' cells before extracting DNA?
Break the cell walls but gently so DNA isn't damaged
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Why is washing up liquid needed to extract DNA?
To dissolve cell membrane
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Why is protease enzyme needed to extract DNA?
To digest proteins which hold DNA together
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Why is ice cold ethanol needed to extract DNA?
To clump DNA together to be able to pick out
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What is an allele?
Different version of the same gene
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Explain why chromosomes look X shaped at the start of meiosis and mitosis
Because the DNA/ chromosomes copy themselves before division, the x shape is 2 of the same chromosomes attached
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How many cells are produced it meiosis?
4 daughter cells
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How many cells are produced in mitosis?
2 daughter cells
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What can cause mutations?
Cell division, radiation, certain chemicals
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What does the term genome mean?
Genome is the complete set of genes in and organism
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What is continuous variation?
varitation which can be measured
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What does the term phenotype mean?
The appearance/ feature an organism has because of its genotype
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What does the term genotype mean?
The alleles in an organism
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What is a mutation?
A change in the sequence of bases in DNA
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What term is used to describe an organism that has 1 dominant and 1 recessive allele?
Heterozygous
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Name two causes of genetic variation
Mutation, sexual reproduction
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What is discontinuous variation?
Variation where the data cannot be measured
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What term is used to describe an organism that has 2 identical dominant alleles?
Homozygous dominat - BB
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What term is used to describe and organism that has 2 identical recessive alleles?
Homozygous recessive - bb
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Suggest 3 uses of the human genome project
Personalise medicine, identify genes which increase risk of certain diseases, identify genetic diseases
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What 2 sex chromosomes does a male and female have?
Male: XY Female:**
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Other cards in this set

Card 2

Front

What type of cells does meiosis produce?

Back

Haploid gametes

Card 3

Front

What is mitosis and meiosis?

Back

Preview of the front of card 3

Card 4

Front

What is fertilisation?

Back

Preview of the front of card 4

Card 5

Front

Describe what happens during meiosis

Back

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