16749450
Description
Flashcards by Sam Gunnell, updated more than 1 year ago
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Created by Sam Gunnell
almost 7 years ago
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| Question | Answer |
| What happens during interphase of meiosis? | The DNA replicates so each chromosome contains two chromatids |
| What happens during early prophase of meiosis? | The nuclear envelope breaks down and centrioles move to poles and form spindle fibres made of microtubles |
| What happens during late prophase in meiosis? | Homologous pairs from bilavents (where one paternal and one maternal chromosome bind throuhgh crossing over)Crossing over occurs |
| What is crossing over? | Chromosomes cross over at a point called the chaismata and DNA is swapped |
| What is a bilavent? | A pair of homologous chromosomes held together by at least one DNA crossover |
| What happens during metaphase 1 of meiosis? | The bilavents randomly line up at the equator and spindle fibres attach to the centromeres |
| What happens during anaphase 1 of meiosis? | The homologous pair of chromosomes of each bilavent are pulled away from eachother to the poles by spindle fibres The centromoeres don't divide, each chromosome still has two chromatids |
| What happens during telophase 1 of meiosis? | In animal cells, the nuclear envelope will reform and cytokinesis may start |
| What happens during prophase 2 of meiosis? | The centrioles replicate, and nuclear envelope disintergrates The chromosomes (each have two chromatids) recondense |
| What happens during metaphase 2 of meiosis? | Chromosomes randomly line up at the equator and centromeres attach to the spindle fibres |
| What happens during anaphase 2 of meiosis? | The centromeres divide and the chromatids are pulled to opposite poles |
| What happens during telophase 2 of meiosis? | The chromatids (now chromosmes) have reached the poles and the nuclear envelope reforms, forming four seperate nuclei |
| How many daughter cells are produced through meiosis? Are these daughter cells haploid or diploid? | Four daughter cells are produced Haploid |
| How does crossing over cause genetic variation? | When chromosomes cross over, they have the same genes, but may have different alleles, causing variation |
| When during meiosis does crossing over occur? | Prophase 1 |
| How does independent assortment of chromosomes cause genetic variation? | Each bilavent behaves independently so it could face either way so any combination of maternal or paternal chromosomes could end up in each gamete produced |
| When during meiosis does independent assortment take place? | Metaphase 1 |
| What other causes of variation are there? | Random ferilisation (any sperm can fertilise egg) Independent assortment of chromatids |
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