Cell Division Flashcards
Cell continuity
All cells come from pre-existing cells
Chromosomes
Structures within the Nucleus, made of DNA & Protein. People have 46 of them
Gene
Short section of DNA. Humans have 20-30,000 genes
Genome
All genes in an organism
Haploid
Has one set of chromosomes Ie has only one of each type of chromosome in the nucleus. E.g human Sperm = 23 Egg = 23
Diploid Cell
Two sets of chromosomes. I.e It has two of each type of chromosome in the nucleus. 2n = Diploid
Body cells are always diploid
Cell cycle structure
Interphase is big piece of diagram
Cell is smaller piece
- Cytokinesis
- Mitosis
Interphase
Longest phase, 90% of cells life, chromatin, everything duplicated
Mitosis
PART of cell division, division of NUCLEUS.
Prophase
At the end of the interphase chromosomes contract and become more visible. Each chromosome is in a duplicated strand. Spindle fibres appear in cytoplasm at poles. Nuclear membrane breaks down
Metaphase
Nuclear membrane broke down. Chromosomes line up across the cells equator. Spindle fibres attach to chromosomes. Each chromosome has 2 fibres attached (1 for each side)
Anaphase
Spindle fibres contract. Chromosomes pulled apart. Each strand is pulled to the opposite end of the cell. Hence an identical set of genes pulled to each end of the cell
Telophase
Nuclear membrane forms around each of the 2 sets of chromosomes. Chromosomes elongate back to chromatin within nuclei. Mitosis is done. Then cytokinesis commences
Function of mitosis
In unicellular organisms
Asexual reproduction
Function of mitosis in multicellular organisms
Produces more/new cells to allow us to grow.
Cancer
Group of disorders in which certain cells lose their ability to control both the rate of mitosis and number of times it takes place.
Benign tumour
Not life threatening
Malignant tumour
Uncontrolled multiplication of abnormal cells. Other word for cancer. Movement of these cells is metastasis
Causes of cancer
Carcinogens (cancer causing agents)
E.g ultraviolet radiation, chemicals in cigarettes, x-rays
Genetic mutations
Meiosis
Form of nuclear division in which the daughter nuclei contains half the chromosome number of parent nuclei
Functions of meiosis
- Produces haploid sex cells (sperm, egg)
- Allows for sexual reproduction without increasing the chromosome number in the offspring
- Allows for new combinations of genes. Therefore variation in offspring
Cytokinesis
When the actual cell splits in two
Cytokinesis in animal cells
The deepened cleavage furrow. Then the cell splits in two
Cytokinesis in plant cells
- Vesicles - bags of cellulose
- Cell plate forms new cells walls to separate the cell into two
(In between is the middle lomella)
