Cell division

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  • Created by: Hindleyc
  • Created on: 02-03-18 11:41
What is the the case with cells in multicellular organisms?
Not all cells retain the ability to divide
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What is needed by the cells for multicellular organisms to grow and develop?
Cells must divide and then specialise
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What do Eukaryotic cells that do retain the ability to divide show?
Cell cycle
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When does DNA replication occur?
During interphase of Cell cycle
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What is Mitosis?
Part of the cell cycle- Eukaryotic cell (parent cell) divides to produce 2 daughter cells each with the identical copies of DNA produced by the parent cell during DNA replication. Division of cells to produce 2 genetically identical daughter cells
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What are the daughter cells and parent cells?
Genetically identical to each other
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What happens in interphase?
Chromosome are copied, genetic information is checked, cell increases in size, produces new organelles and stores energy for another division.
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What happens if cell is going divide again?
DNA is replicated during interphase just before chromosomes condense and become visible
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What happens in Prophase?
Chromosomes now visible with optical microscope - they coil and becomes shorter and fatter. Nuclear envelope disappears, protein fibres form a spindle in the cetrll- spindle fibres attach to middle (cenomere) of each chromosomes
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What happens in Metaphase?
The spindle fibres pull the chromosomes to the middle (equator) of the cell
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What happens in Anaphase?
The centromere holding each pair of sister chromatids together divides. Spindle fibres shorten and pull the chromatids to opposite poles of the cell. The chromatids are now called chromosomes again.
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What happens in Telophase?
The two sets of chromosomes group together at each pole and a nuclear envelope forms around each group, the chromosomes uncoil becoming chromatin again.No longer visible with optical microscope, Cytoplasm divides resulting in 2 new cells- cytokinesis
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What is chromatin
DNA and structural proteins
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What is the cell cycle?
Complete life of a cell from moment created until it splits again into 2 new cells
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What is mitosis in relation to cell cycle?
Only small party of cell cycle
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What is the rest of the cell cycle known as?
Interphase when chromosomes are copied and genetic information is checked. Also inc in size, produce new organelles and stores energy for a new division. if cell going to divide again DNA replicated during Interphase before Chromosomes condense
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What are cells in for most of time? What happens during interphase?
Interphase. Nucleus intact- membrane can be seen. Chromosomes not viable- DNA spread out. Genes being expressed- used to make proteins
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What is the mitotic index?
Ratio showing proportion of cells undergoing mitosis in piece of tissue- visible chromosomes- no. cells undergoing mitosis/ no cells in sample
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How many phases are there of the cell cycle?
4
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What is G1?
New proteins and organelles formed. Cell inc in volume as new cytoplasm made, Cell may prepare to replicate its DNA
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What is S phase?
DNA replicated and around of chromatin doubled. If cell is going to divide, it enters S phase in which it synthesises (replicates) its DNA
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What is G2?
Cell continues to grow and synthesises the enzymes and structures needed for mitosis.
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What is M phase?
Nucleus of cell divides by mitosis (PMAT)
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What stages of cell cycle is interphase?
G1,S,G2
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What happens once mitosis is complete?
Cell divides into 2 cells during cytokinesis
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What is Cancer?
When mitosis goes wrong- Genes controlling cell cycle mutate= uncontrolled cell division which can lead to formation of tumours and cancers
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Whats a benign tumour?
Slow growing, don't spread to other parts of body- not classed as cancer
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What is a Malignant tumour?
Grow quick, often spread, cells can break off and start up new tumours in other parts of the body- classed as cancer
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What do cancerous cells go through?
Cell cycle faster than normal cells so disrupting cell cycle can control rate of cell division and target cancer cells but can affect normal cells
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What are the 3 approaches to cancer treatment?
Surgery-removal of tumour but hard to remove all cancerous cells. Radiotherapy- radiation damages DNA. Chemotherapy- drugs to kill cancer cells prevent them from dividing or damaging them so they kill themselves
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What are the approaches of chemotherapy (eg of drug action)?
Block enzymes involved in DNA synthesis (G1). Prevent DNA unwinding so can't replicate. Inhibit synthesis of nucleotides. Prevent development of spindle.
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Other cards in this set

Card 2

Front

What is needed by the cells for multicellular organisms to grow and develop?

Back

Cells must divide and then specialise

Card 3

Front

What do Eukaryotic cells that do retain the ability to divide show?

Back

Preview of the front of card 3

Card 4

Front

When does DNA replication occur?

Back

Preview of the front of card 4

Card 5

Front

What is Mitosis?

Back

Preview of the front of card 5
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