Mitosis Flashcards
Three phases of interphase
- G1 - first growth phase
- S - synthesis phase
- G2 - second growth phase
Two parts of the cell cycle
- Interphase
- Mitosis
Occurs during G1 phase of interphase
- Cell growth
- preparation for DNA replication
Occurs during S-phase of interphase
DNA replicated (chromatid duplication)
Parts of a duplicated chromosome
- Two sister chromatids
- Centromere
Inefficient if surface area to volume ration is too small
Nutrient and waste exchange by the cell
Reason for cell division by mitosis
- Growth - cells divide forming more cells for growth
- Repair - repair and renew injured, old or worn out cells
- Reproduction - bacteria and protists reproduce asexually by binary fission or budding
Location of mitosis in plants
Apical and lateral meristem in plants
Animal tissues continuously replaced by mitosis
- Epithelium and connective tissues
- Fairly frequently for repair: liver, skin
Two division processes necessary for cell division
- Karyokinesis - nucleus division
- Cytokinesis - cytoplasm division
Four phases of mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Features of prophase in animal cells
- Centrosomes start to form spindle
- Centrosomes start to move towards poles
- Chromosomes made of two chromatids condense to become visible
- Nuclear membrane starts to break down
Features of prophase in plant cells
- Spindle forms without centrosomes
- Chromosomes with two chromatids condense
- Nuclear membrane starts to break down
Features of metaphase
- Nuclear membrane has disappeared
- Chromosomes line up along equator region
- Chromosomes attached to spindle fibre
Features of anaphase
- Chromatids of chromosome separate
- Spindle fibres pull daughter chromosomes to opposite poles
Features of telophase in animal cells
- Nuclear membrane starts to form in each daughter cell
- Chromosomes start to form chromatin network
- Cytokinesis starts by the cell membrane constricting
Features of telophase in plant cells
- Nuclear membrane starts to form in each daughter cell
- Chromosomes form chromatin network
- Cytokinesis starts by cell plate formation at the equator
Different kinds of cancer
- Carcinomas - epithelium
- Leukaemia - blood and lymph
- Sarcomas - other connective tissue
a cancer cell
- A cell with its cell cycle control system disrupted
- These cells divide uncontrollably
Tumour
A mass of cancer cells
Two types of tumour
- Benign - stay in one location
- Malignant - cells of tumour spread to other locations in the body
Metastasis
The process of a malignant tumour leaving the first site of cancer and invading other organs and tissues
Carcinogen
A factor causing cancer
Example carcinogens
- Faulty genes (inherited)
- Radiation
- Smoking
- Hormonal imbalances
- Processed foods
- Pollutants and pesticides
- Viruses
Three common methods of treating cancer
- Surgery
- Chemotherapy
- Radiotherapy
Surgery as a treatment for cancer
Cut out tumour cells with a scalpel or laser
Chemotherapy as a treatment for cancer
- Chemicals that kill cancer cells or
- Stop their DNA from making new cells
- injections or tablets
Radiotherapy as a treatment for cancer
- Machines emitting radiation
- Injections of radioactive compounds
- Capsules of radioactive substances
Complementary therapy
- Alternative treatments that can be used together with other treatments in treating a disease.
- They do not negatively effect each other or harm the patient.
- E.g. Teas to alleviate nausea during chemotherapy
cell phase
anaphase
- spindle fibres separate sister chromatids
- retract pullting them towards poles
cell phase
late prophase of mitosis
- nulear membrane still disappearing
- chromosomes condensed and clearly visible
cell phase
metaphase of mitosis
- chromosomes lined up along equator
cell phase
telophase of mitosis
- chromosomes at opposite ‘poles’
- cytokinesis starting
- two nuclear membranes forming
cell phase
early prophase of mitosis
- spindle apparatus just starting to form
- chromosomes start condensing
- nuclear membrane starts to break down
