Mitosis & Meiosis Flashcards
What is a telomere?
Repeated sequences (TTAGGG) at each end of the chromosome
What is the centromere?
Connects sister chromatids, is a repetitive sequence of DNA
What 3 centromere positions are found in humans? Where is the centromere positioned in each type of chromosome?
Metacentric (middle)
Submetacentric (between middle and end)
Acrocentric (between submetacentric position and telomere)
What are the stages of mitosis after G2 of the cell cycle?
Prophase Prometaphase Metaphase Anaphase Telophase (Cytokinesis)
What occurs in prophase of mitosis?
The nuclear membrane disappears
Chromosomes condense and become visible
What occur in prometaphase of mitosis?
Microtubule spindles form and connect to centromeres of chromosomes
What occurs in metaphase of mitosis?
Chromosomes line up along the metaphase plate
What occurs in anaphase of mitosis?
Microtubule spindles pull each replicated chromosome apart
Centromere splits
Sister chromatids separate to opposite poles of the cell
What occurs in telophase of mitosis?
Spindle fibres break down and disappear
Nuclear envelope reforms around chromosomes
Cleavage furrow appears —> cytokinesis
What is produced from one cycle of mitosis?
1 diploid cell —-> 2 identical diploid daughter cells
What cells are produced as a result of meiosis?
1 diploid cell —> 4 non identical haploid cells
What is the difference between the genetic material on sister chromatids and non-sister chromatids?
Sister chromatids = same genes, same alleles
Non-sister chromatids = same genes, different alleles
Prometaphase only exists in mitosis or meiosis?
Prometaphase is only in mitosis
What happens in prophase I of meiosis?
Nuclear membrane disappears
Spindles form
Maternal/paternal chromosomes ‘find’ each other
Recombination and crossing over occurs between two of the non-sister chromatids
What occurs in metaphase I of meiosis?
Random assortment
Homologous pairs line up along the metaphase plate as a tetrad
What occurs in anaphase I of meiosis?
Homologous chromosomes are separated
What occurs in telophase I of meiosis?
Nuclear membrane reforms
Spindles disappear
What is the resulting cellular product of meiosis I? What happens next?
2 daughter cells each with 23 replicated chromosomes
Meiosis II without any dna replication stage
Which part of meiosis is nearly exactly the same as classical mitosis?
Meiosis II
What occurs in prophase II of meiosis?
Nuclear membrane disappears
Spindles form
What occurs in metaphase II of meiosis?
Chromosomes line up along the metaphase plate
What happens in anaphase II of meiosis?
Chromatids separate into separate daughter cells
What happens in telophase II of meiosis?
Nuclear membrane reforms
Spindles disappear
In what two ways is genetic variation provided by meiosis? At what stages of meiosis do these occur?
Random assortment of chromosomes (metaphase I)
Crossing over/recombination (prophase I)
