Biology 2.1.6 Meiosis

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A level Biology (2.1.6 Cell division and diversity ) Flashcards on Biology 2.1.6 Meiosis, created by Sam Gunnell on 11/02/2019.
Sam Gunnell
Flashcards by Sam Gunnell, updated more than 1 year ago
Sam Gunnell
Created by Sam Gunnell over 5 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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