protein at each centromere. This serves as the attachment site for spine microtubules.
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Compare and contrast mitosis and meiosis?
Mitosis produces 2 new cells/identical to part/growth and division/1 set of division , meiosis= 4, genetically varied, contains half the no. of chromosomes and has 2 sets of divsion.
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Name some examples of mitotic cells?
Bone marrow, hair follicle cells, fibroblasts, liver cells
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What is the Hayflick limit?
The number of times a normal cell can divide before cell division stops, and telomerase activity reduces.
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How many stages are in the cell cycle and name them?
4--> S stage, G2, Mitosis and G1
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What happens in G1?
Growth phase--> Cell grows and synthesises many nutrients and enzymes needed later on.
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What happens in S stage?
Synthesis and replication of DNA
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What happens in the G2 stage?
Cell finishes growing and determines if cell can go on to mitosis
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In Mitosis, what happens in Interphase?
Cells prepare to divide, Here DNA replication happens--> genetic material doubles
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In Mitosis, what happens in Prophase?
Chromosomes get thick/short--> become visible and joined by a centromere. Centrioles move to opposite sides of the cell. The nucleolus disappears and the nuclear membrane disintegrates
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In Mitosis, what happens in Metaphase?
Chromosomes arrange themselves at the equator and become attached to spindle fibres by their centromeres.
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In Mitosis, what happens in Anaphase?
The spindle fibres contract to pull chromatids to opposite poles of the cell.
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In Mitosis, what happens in Telophase?
The chromosomes uncoil, the spindle disintegrates and the centrioles replicate. The nuclear membrane reforms. This proceeds to Cytokinesis.
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State some side effects of chemotherapy?
Low white blood cell, red blood and platelet count
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Explain the important of meiosis?
Reduce the chromosome number to 23. Recombination leads to genetic diversity--> Evolution
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State the ways in which genetic diversity is achieved in meiosis?
Independent assortment and crossing over
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In Meiosis 1, what happens in Interphase 1?
Chromosomes replicate, 2 genetically identical chromatids are attached.
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In Meiosis 1, what happens in Prophase 1?
Chromosomes match up and form a tetrad. Here, crossing over occurs.
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In Meiosis 1, what happens in Metaphase 1?
Chromosomes line up at the equator in their homologous pairs
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In Meiosis 1, what happens in Anaphase 1?
Homologous chromosomes move to opposite poles.
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In Meiosis 1, what happens in Telophase 1?
Cytoplasm divides, this forms 2 daughter cells. The new cells have half the no. of chromosomes as the parent.
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In Meiosis 2, what happens in Prophase 2?
The daughter cells from a spindle, the chromosomes move to the equator.
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In Meiosis 2, what happens in Metaphase 2?
Chromosomes are positioned in the centre (equator)
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In Meiosis 2, what happens in Anaphase 2?
Centromeres of sister chromatids separate, chromosomes move to opposite poles.
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In Meiosis 2, what happens in Telophase and Cytokinesis?
Nuclei form at opposite poles, cytokinesis occurs 4 daughter cells form that are haploid.
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State the effects of non-disjunction?
Trisomy 1 (Down's syndrome). This causes some chromosome abnormalities and deletions.
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Other cards in this set
Card 2
Front
What is the kinetochore?
Back
protein at each centromere. This serves as the attachment site for spine microtubules.
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