Biology - Cell Divison

Define cell continuity

When cells develop from other existing cells

State the composition of a chromosome

DNA and protein

State the location of chromosomes in a cell

Nucleus

Define the term haploid cell and name an example

Has one set of chromosomes (e.g. sperm and eggs)

Define the term diploid cell and name an example

Has two sets of chromosomes (e.g. skin cells)

Define the term homologous pair

Two chromosomes with similar genes

List the two stages of the cell cycle and which one is shorter

Interphase and mitosis, mitosis is shorter

Define mitosis

When one nucleus divides into two identical nuclei

Function of mitosis in a single celled organism

asexual reproduction

Function of mitosis in a multi cellular organism

Growth and repair of cells

List the four stages of mitosis in order

Prophase, Metaphase, Anaphase, Telophase

Describe in detail the prophase

Double stranded structures, nucleolus disappears, spindle fibres appear, nuclear membrane breaks down

Describe in detail the metaphase

Spindle fibre attaches to each centromere, chromosomes line up across the equator

Define centromere

The point at which chromosomes are attached together in a double stranded structure

Describe in detail the anaphase

Spindle fibres contract, double stranded chromosomes separate

Describe in detail the telophase

Nuclear membrane forms around each mass of chromatin at each end of cell

Name the feature that allows animal cells to split in two

Cleavage furrow

Name the feature that allows plant cells to split in two

Cell plate

Define cancer

when a cell loses the ability to control the rate of mitosis. This forms a mass of cells called a tumour

Define carcinogen

Cancer causing agent

Define oncogene

Cancer causing genes

Distinguish between a benign and malignant tumor

A benign tumour does not invade other cells and stops dividing after some time, a malignant tumour invaded other cells and is an uncontrolled division of tumours

Define meiosis

Where a nucleus divides into four new nuclei that are not identical and contain only half the number of chromosomes as the parent nucleus

State two functions of meiosis

Allows sexual reproduction/ allows for greater variation within a species

Where does meiosis occur in males

Testes

Where does meiosis occur in females

Ovaries