113969
Description
Flashcards by sammi_taylor01, updated more than 1 year ago
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Created by sammi_taylor01
over 11 years ago
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| Question | Answer |
| What happens during: 1) meiosis one? 2) meiosis two? | 1- The parent cell separates into two homologous chromosomes in different cells. 2- The chromatids move apart so four cells are formed. |
| In which two ways does meiosis bring about genetic variation between offspring? | 1- recombination of homologous chromosomes by crossing over 2- independent segregation of homologous chromosomes |
| Describe the independent segregation of chromosomes. | Each chromosome lines up next to its homologous partner (randomly arranged. One chromatid from each chromosome then will pass into the daughter cell. |
| What is the same in each member of a pair of homologous chromosomes? | They have the exact same genes and therefore determine the same characteristics. |
| How does variation occur in genetic combinations? | The haploid gametes fuse in fertilisation to become the diploid state. Each gamete has a different genetic make up and the random fusion therefore produces variety in offspring. |
| What happens in genetic recombination by crossing over? | The chromatids of each pair become twisted round one another, tensions are created and portions of the chromatid breaks off, they rejoin with the chromatids of its homologous partner |
| What is produced from crossing over? | new genetic combinations |
| What is a: 1) gene? 2) locus? 3) allele? | 1) section of DNA that codes for a polypeptide 2) the position of a gene on a chromosome or DNA molecule 3) different forms of a particular gene |
| What does meiosis produce? | Four daughter nuclei with half the genetic material (chromosomes) as the parent cell. Also known as haploid cells. |
| When haploid cells fuse at fertilisation, what occurs? | The diploid number of chromosomes is restored. |
| How many nuclear divisions does meiosis have and when do they occur? | Two nuclear divisions which normally occur one after the other. |
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