Topic 2-Cell Division Flashcards
What is interphase?
A period of cell growth and DNA replication
What are the three growth phases of interphase?
G1 S and G2
What happens in Gap phase 1
The cell grows (vol of cytoplasm) and new organelles and proteins are made.
What happens in the synthesis phase?
The cell replicates its DNA (semi-conservitively), this leads to 2 identical chromatids joined at a centromere
What happens in Gap phase 2
The cell keeps growing and proteins needed for cell division are made.
Describe in detail the three main events that occur during interphase.
- DNA is unravelled and replicated to double genetic content
-Organelles are replicated so it has spare ones
-ATP content is increased as it is needed for cell division
Describe prophase in mitosis.
The chromosomes condense getting dhorther and fatter as ting bundles of proteins being the centrioles move to oppposite ends of the cell forming a network of protein fibres across it called the spindle. The nuclear envelope around the nucleus breaks down and the chromoseomes lie free in the cytoplasm.
Describe metaphase in mitosis.
The chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere.
Describe anaphase in mitosis.
The centometres divide, seperating each pair of sister chromatids. The spindles contracts, pulling chromatids to opposite poles (ends) of the spindle, centrometre first. Thsi makes the chromatids appear v- shaped.
Describe telephase in mitosis.
The chromatids reach the opposite poles on the spindle. They uncoil and become long and thin again. They are now called chromosomes again. A nuclear envelope forms around each group of chromsomes, so now there are two nuclei. Then cytokineseis occures.
Describe cytokinesis
Startes during anaphase and finishes in telephase and is the division of cytoplasm. At the end of it therre are now two daughter cells that are genetically indentical to the origional cell and to eachother. Then each daughter cell starts interphase to do it all over again.
Why are there sister chromatids on the chromosome before mitosis begins?
Because during interphase, each chromosome has already made an identical copy of itself?
What is a sister chromatid?
Two strands of the same chromosome.
Give three uses of mitosis
Growth
Repair
Asexual reproduction
What is cancer?
A tumour that invades surroumnding tissue cause by uncontrolled cell division from a mutation in a gene that controlls cell division.
Why is cancer treatment more likely to kill cancerous cells than normal cells?
Because cancer cells divide much more frequently than normal cells.
Dscribe how some cancer treatments target cell cycles.
During g1 chemotherapy prevents the sythesis of enzymes needed for synthesis causing it to kill itself.
During synthesis radiation and some DNA drugs damage DNA and if sever damage id detected, the cell will kill istelf both preventing tumour growth.
In what stage of the cell cycle does all the DNA unravel.
The S phase.
What os the mitotic index?
The proportion of cells in a tissue sample that are undergoing mitosis.
State the formula to work put the mitotic index
mitotic index = number of cells with visible chromosomes ÷ total number of cells
Give the formula for calculating actual size
Actual Size =Image size (with ruler)÷Magnification
State a 2 suitable stains that can be used to investigate mitosis.
Toludoine
Ethano-orcein
State the abbreviagtion of formula used to calculate magnification.
IAM
What does the name ‘Binary Fission’ refer to
Division in Prokaryotic cells
