Miss lee - The cell cycle + mitosis Flashcards
What is the Cell Cycle
- The cell cycle is the process (series of stages) that all body cells (in multicellular organisms) use to grow and divide.
- It starts with a cell that has already been produced by cell division and ends with this cell dividing to produce 2 genetically identical daughter cells.
What are the two ways that cells can divide
Mitosis: division into two daughter cells that are genetically identical to each other and to the parent cell. Meiosis: division into four unique daughter cells with half the chromosomes of the parent cell.
What is mitosis
Mitosis is the division of two daughter cells that are genetically identical to each other and to the parent cell
What is a diploid cell
A diploid cell is two copies of each chromosome
What is a haploid cell
A haploid cell is one copy from each chromosome
What is the importance of the cell cycle
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Produces genetically identical daughter cells (i.e. clones – maintains same number of chromosomes as the parent cell).
Growth of tissue/organism (not of cells)
Replacement of worn out/damaged cells Repairofbodytissues(e.g.bone,muscleetc) Asexualreproduction/cloning
What are the two stages of cell cycle
Interphase (‘preparation phase’): • G1 (‘Growth phase 1) • S (‘synthesis’) • G2phases(‘Growthphase2’) M Phase (‘dividing phase’): • Mitosis • Cytokinesis
What are the three interface stages and what happens in each stage
G1 – First growth phase of cell, synthesis of proteins, organelles replicate e.g. mitochondria, ribosomes etc. Cell increases in size.
End of G1 checkpoint.
S – Synthesis phase. Replication of each chromosome in the nucleus.
G2 – Second growth phase, cell continues to grow in size. Duplicated DNA is checked for errors. Energy stores (i.e. ATP molecules) are increased.
End of G2 checkpoint.
Where are the cell cycle checkpoints
The first checkpoint is the first growth phase. The second checkpoint is it the second growth phase. And the third and final checkpoint is the spindle assembly/metaphase checkpoint
What is the resting state
The resting stage is where the sale leaves the cell cycle either temporarily or permanently this happens as a replicated cell does not pass the checkpoints and is damaged or broken
If there are no checkpoints what might happen to the DNA
There could be mutations in the DNA sequence, faulty DNA produced, error in copying daughter cells, daughter cells are not receive identical genetic information, proteins not made or do not function properly
Which stage does the cell actually divide
The cell divides during the mitosis and cytokinesis stages
What are homologous chromosomes
A pair of chromosomes – one maternal (from mother) and one paternal (from father)
The chromosomes carry the same genes but may carry different forms of the genes. A alternate form of the same gene is called an allele.
E.g. gene is eye colour, alleles could be brown, green, blue etc.
What are the sister chromatids
Sister Chromatids: identical, carry the same versions of all their genes because one was produced as an exact copy of the other.
What is the Difference between sister chromatids and homologous chromosomes
A homologous pair of chromosomes contain one maternal and one paternal chromatid. They carry the same genes although may have different alleles of these genes, Position (loci) and size are the same. Members of a homologous pair pair up during meiosis.
What is the chromosome structure
Chromosomes are only visible during cell division. Each chromosome consists of two chromatids joined somewhere along its length at the centromere. Genetic information (genes/alleles) carried on each chromatid is identical.
What are the 4 stages of mitosis (PMAT)
Prophase, metaphase, anaphase And telophase
What is prophase
Chromosomes condense and thicken ( and therefore become visible). Consists of sister chromatids joined at the centromere. To centrioles migrate to opposite poles of the cell (in animal and some plant cells). Spindle fibres attached to specific areas on the centromere and start to move the chromosomes to the centre (equator) of the cell. Nuclear envelope disappears.
What is metaphase
This is a brief phase. Individual chromosomes are moved by the spindle fibres to align at the metaphase plate/equator at the centre of the cell. Chromosomes are attached to the spindle fibres by the centromere.
What is anaphase
Anaphase is where the centromeres are holding the pair of chromatids in each Chromosome divides. The chromatids separate the spindle fibres then contracts (fibres shorten). Each chromatid is pulled to the centromere to the opposite poles of the cell
What is telophase
Telophase is where the chromatids have reached opposite poles of the cell. They uncoil and become long and thin again. They are now called chromosomes then the spindle fibres disappear and the nuclear envelope reforms and encloses around the chromosomes at each pole
What is cytokinesis
This is the phase where the cytoplasm divides. In animal cells a “cleavage furrow“ forms. In plants cells a “cell plate“ forms. This results in to genetically identical daughter cells being formed.
What happens during the interphase
The DNA is copied.
