Cell Division Flashcards
What is cell continuity?
All cells develop from pre-existing cells.
What are chromomsomes?
Coiled threads of DNA (which form genes) and proteins that become visible in the nucleus at cell division.
What is a diploid cell?
Cell that has 2 sets of chromosomes i.e has 2 of each type of chromosome in the nucleus.
What is a haploid cell?
Cell that has one set of chromosomes i.e only has 1 of each type of chromosome in nucleus.
What is a homologous pair?
Consists of 2 chromosomes that each have genes for the same features at the same positions.
What is interphase?
Phases in the cell cycle when the cell isn’t dividing.
What is mitosis?
Form of nuclear division in which 1 nucleus divides to form 2 nuclei, each containing the same number of chromosomes with identical genes.
What is cancer?
A group of disorders in which certain cells lose their ability to control both the rate of mitosis and the number of times mitosis takes place.
What is meiosis?
Form of nuclear division in which the 4 daughter nuclei contain half the chromosome number of parent nucleus.
What are the 4 stages of mitosis?
Prophase, metaphase, anaphase and telophase.
What phases does a new cell have to go through before it can divide again?
1) . Produces material it will need
2) . Grows larger
3) . Reproduces to form new cell.
What symbolises haploid?
n
What symbolises diploid?
2n
What cells are haploid?
Sperm and egg
What does the cell do in interphase?
Produces mitochondria, chloroplasts, etc and chemicals for growth.
What happens in prophase?
1) . End of interphase, chromosomes contract and become visible.
2) . Each chromosome appears as a duplicated strand.
3) . Fibres appear in cytoplasm of cell.
4) . Nuclear membrane starts to break down.
What happens in metaphase?
1) . Nuclear membrane completely broken down.
2) . Chromosomes thicken more.
3) . Chromosomes line up across the centre of cell
4) . Spindle fibres attach to centromeres
5) . Each chromosome has 2 fibres attached, 1 each side.
What happens in anaphase?
1) . Spindle fibres contract and pulls chromosomes apart.
2) . Each strand pulled to opposite ends of cell.
3) . Identical set of genes on each side.
4) . Shortest stage.
What happens in telophase?
1) . Chromosomes at each end turn to chromatin.
2) . Spindle fibres break down.
3) . Nucleolus reforms
4) . Nuclear membrane starts to form around chromatin.
How do animal cells divide?
Cleavage furrow.
How do plant cells divide?
1) . Vesicles containing cellulose gather between 2 nuclei and join to form cell plate.
2) . 2 cell walls will form in cell plate and eventually split.
What is the function of mitosis in unicellular organisms?
1). Reproduction
What is the function of mitosis in multicellular organisms?
1) . Produce new cells
2) . Responsible for growth, renewal and repair of cells.
What are malignant tumours?
1) . Uncontrolled multiplication of abnormal cells
2) . Malignant tumours invade other cells and move around body.
3) . Cancer cells can divide indefinitely.
What is the movement of cancer cells called?
Metastasis.
Name for altered genes that form cancers?
Oncogens.
What are cancer causing agents called?
Carcinogens.
Where does meiosis occur in the body?
Testes and ovaries to produce gametes.
What are the functions of meiosis?
1) . Asexual Reproduction without increasing number of chromosomes in offspring.
2) . Allows new combinations of genes i.e variation within species.
How many cells are produced by meiosis?
4
How many cells are produced by mitosis?
2
