Biology revision 0.0 / 5 ? BiologyDNA and inheritanceGCSEEdexcel Created by: Joemea123Created on: 26-04-17 22:43 Describe what happens to the genetic material during meiosis It is mixed up creating genetically different cells 1 of 27 What type of cells does meiosis produce? Haploid gametes 2 of 27 What is mitosis and meiosis? Cell division: mitosis- for growth and repair, meiosis- to make gametes 3 of 27 What is fertilisation? When the nucleus of 2 gametes fuse together 4 of 27 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 5 of 27 Describe the structure of DNA - double helix, sugar phosphate back bone, weak hydrogen bonds join complementary bases (a-t, c-g) 6 of 27 Why do you need to gently crush the 'pea' cells before extracting DNA? Break the cell walls but gently so DNA isn't damaged 7 of 27 Why is washing up liquid needed to extract DNA? To dissolve cell membrane 8 of 27 Why is protease enzyme needed to extract DNA? To digest proteins which hold DNA together 9 of 27 Why is ice cold ethanol needed to extract DNA? To clump DNA together to be able to pick out 10 of 27 What is an allele? Different version of the same gene 11 of 27 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 12 of 27 How many cells are produced it meiosis? 4 daughter cells 13 of 27 How many cells are produced in mitosis? 2 daughter cells 14 of 27 What can cause mutations? Cell division, radiation, certain chemicals 15 of 27 What does the term genome mean? Genome is the complete set of genes in and organism 16 of 27 What is continuous variation? varitation which can be measured 17 of 27 What does the term phenotype mean? The appearance/ feature an organism has because of its genotype 18 of 27 What does the term genotype mean? The alleles in an organism 19 of 27 What is a mutation? A change in the sequence of bases in DNA 20 of 27 What term is used to describe an organism that has 1 dominant and 1 recessive allele? Heterozygous 21 of 27 Name two causes of genetic variation Mutation, sexual reproduction 22 of 27 What is discontinuous variation? Variation where the data cannot be measured 23 of 27 What term is used to describe an organism that has 2 identical dominant alleles? Homozygous dominat - BB 24 of 27 What term is used to describe and organism that has 2 identical recessive alleles? Homozygous recessive - bb 25 of 27 Suggest 3 uses of the human genome project Personalise medicine, identify genes which increase risk of certain diseases, identify genetic diseases 26 of 27 What 2 sex chromosomes does a male and female have? Male: XY Female:** 27 of 27
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