12.6 Cell Cycle And Cell Division Flashcards
Interphase
Period between divisions
What 3 stages is interphase in?
- G1 phase
- S phase
- G2 Phase
G1 phase
Cell increases in size and new biomass is made
S phase
DNA replicates by semi conservative replication
G2 phase
Cell prepares for division, synthesis and stores of ATP and new organelles synthesised
Nuclear division (mitosis and meiosis)
Period when the nucleus divides into 2 (mitosis) or 4 (meiosis)
Cell division (cytokinesis)
Cytoplasm divides to produce 2 new cells or 4 new cells
Not all cells go through all parts of cell cycle particularly…
Differentiated cells
Gene is…
A section of dna that codes for one specific polypeptide
Chromosome
Independent DNA molecule which has been supercoiled into a condensed form (contains many different genes)
Centromere
2 genetically identical copies of the DNA molecule are made and attached at this central point
Each of DNA copies…
Supercoil using histone proteins to help them coil in eukaryotes
Chromosome number js represented by
n
homologous chromosomes
Same genes in the same gene loci but different alleles of the genes (one maternal and one paternal)
Prophase
Chromosomes supercoil and become visible
1) nuclear membrane breaks down
2) centrioles start to move to the poles of the cell and make spindle fibres
3) chromosomes supercoil and condense/shorten/thicken and become visible
4) each chromosome appear as 2 identical sister chromatids joined at the centromere
Metaphase
Chromosomes line up on the equator of cell
1) centrioles complete the production of spindle fibres
2) chromosomes are attached to spindle fibres by their centromere
3) chromosomes align down the equator of the cell
Anaphase
Spindles get shorter, centromere splits identical sister chromatids separate
1) spindle fibres shorter
2) centromere splits
3) identical sister chromatids are pulled to opposite poles
4) making a “V” shape
telophase
two nuclei
1) nuclear membrane starts to reform around each set of chromosomes
2) chromatids/chromosomes unwind become longer/thinner and become invincible
Describe the appearance and behaviour of chromosomes during mitosis (5marks)
- During prophase chromosomes supercoil and condense to become visible
- Chromosomes appear as 2 identical sister chromatids joined by centromere
- During metaphase chromosomes line up on the equator of the cell
- Chromosomes attach to spindle fibres
- By their centromeres
- During anaphase, centromere splits
- Sister chromatids are pulled to opposite poles of the cell making V shape
- During telophase chromatids uncoil and become thinner
Allele
one of a number of alternative forms of the same gene
As cells are produced…
The differentiate and produce various tissues, organs and organ systems and the whole organism
once tissues have been formed…
Cell divisions stopped
Tumour suppressor genes
Codes for proteins that slow down the cell cycle
Proto-onco genes
Codes for proteins that speed up cell cycle
Example of control genes
- tumour suppressor genes
- proto-onco genes
If a mutation occurs in one of these control genes…
Cell division continues uncontrolled
Describe uncontrolled division
It’s often rapid and cells produced are abnormal.
Tumour develops
If cells start to spread into the tissue/body, the tumour is regarded as a cancer
How cancer is treated
Drugs to inhibit cell division
These drugs may stop:
DNA replication, spindle formation, cytokinesis or other processes linked to mitosis
Binary fission
Replication of Circular DNA
Division of cytoplasm
Replication of Plasmids
What 2 solutions does the plant need to be soaked into before observation
50 °C Hydrochloric acid
Ethano-orcein stain
Why add Ethano-orcein stain
To stain the chromosomes (adds contrast) so they can be viewed under the microscope.
why add 50 °C Hydrochloric acid
To break down the cellulose cell walls, ensuring the stain can enter and the tissue and the root tissue can be squashed into a layer one cell thick so that light passes through the thin sample of tissue /cells.
How do you calculate mitotic index
MI= number of cells in PMAT / total number of visible cells
Serial dilution formula
M1 X V1 = M2 X V2
M1 = Desired diluted concentration (mol dm-3)
V1 = Desired Volume (cm3)
M2 = Original concentration (mol dm-3)
V2 = Unknown Volume of stock solution (cm3)
