Cell Cycle/mitosis Flashcards
State the 2 forms of cell division and how they differ
Mitosis, produces 2 daughter cells with the same number of chromosomes as parent cell. Meiosis, produces 4 daughter cells, each with half the amount of chromosomes as the parent cell
Mitosis full definition
The process of nuclear division where 2 genetically identical daughter nuclei are produced, that are also genetically identical to the parent cell nucleus (same number of chromosomes)
Describe the stage of prophase
1) chromosomes condense and become visible, exist as a pair of chromatids joined by centromere 2) centrioles move to opposite poles of cell 3) spindle fibres develop from the centrioles which span cell 4) nucleolus disappears and nuclear envelope breaks down
Describe the stage of metaphase
Centrioles reach opposite poles and spindle fibres continue to extend from them, chromosomes line up at the equator of the spindle and the spindle fibres attach to the centromeres
Describe the stage of anaphase
Chromatids are separated at the centromere and are pulled to opposite poles by the spindle fibres (energy for this is from mitochondria)
What happens in the stage of telophase
Chromosomes arrive at opposite poles and chromosomes decondense/become longer and thinner and become indistinct. Spindle fibres disintegrate, nuclear envelope and nucleoli reform
What happens in cytokines
The cytoplasm divides, producing 2 new cells
Why is mitosis important
Increase size of tissue during development (growth) replace dead and worn out cells (repair)
What is the process of cell division in prokaryotic cells called
Binary fission
Describe binary fission
Circular dna molecule replicates and both copies attach to the cell membrane, plasmids also replicate. Cell membrane begins to grow in between the 2 dna molecules, dividing the cytoplasm. A new cell wall forms between the 2 molecules of dna, dividing the cell to produce 2 daughter cells
What can viruses not do
Undergo cell division, as they are non living
How is viral genetic material replicated
They attach to a host cell, using their attachment proteins. They inject their nucleus acid into the host cell. The host cells metabolic processes start producing the viral components (including nucleic acid, enzymes, structural proteins) these are then assembled into a new viruses
Not all cells, within multicellular organisms retain the ability to what?
Divide
What are the 3 stages of the cell cycle
interphase (biggest, no division takes place) nuclear division and cytokines
How long is the typical mammalian cell cycle and what % is interphase
24 hours,interphase is 90%
Eukaryotic cells that do not retain the ability to divide show what
A cell cycle
What are the 3 phases of interphase
G1, S and G2
What happens in g1 of interphase
Dna in nucleus replicates, cells make rna, enzymes and other proteins
What happens in s in interphase
Synthesis of dna
What happens in g2 of interphase
Cell continues to increase in mass and size, new dna made is checked for errors
What generally happens in interphase
Cell increases in mass and size, synthesis of proteins and replication of dna
What is cancer
When there is damage to cells that regulate mitosis, leads to uncontrollable growth and division which makes tumours
The difference between malignant and benign tumours
Malignant grow rapidly, less compact and more likely to be life threatening. Benign grow slower, more compact and less life threatening
How do drugs like chemotherapy disrupt the cell cycle
By preventing dna from replicating and inhibiting metaphase of mitosis (by interfering with spindle formation)
What is the problem with cancer- inhibiting drugs
They disrupt the cell cycle of normal cells, especially those which divide rapidly like hair producing cells because they drugs are more effective against rapidly diving cells (cancer cells)
