Biology Unit 1 - Reproduction

Cell cycle

stages in which a cell is either carrying out normal functions and/or preparing to divide

Interphase

Longest period of a cells life

Cells grow, develop & carry out metabolic functions

Cells will make their first copy of DNA (if it will divide)

Mitosis

Cell division

Produces 2 genetically identical daughter cells

Diploids (2n) - full set of 46 chromosomes

Somatic (body) cells

Reasons for cell division

repair, growth, reproduction

Chromosome

A threadlike, DNA-carrying structure found in the nucleus.

Chromatin

Loosely grouped DNA (like spaghetti)

When cell is not yet dividing

Chromosome

compact, condensed DNA

Organised in prep for replication and division

sister chromatid

A pair of identical chromosomes created before a cell divides

After DNA copies itself

each copy = sister chromatid

centromere

Region of a chromosome that holds sister chromatids together

centriole

cytoskeleton structures

assist in forming Spindle fibres during mitosis

Prophase

1st phase of mitosis:

Chromosomes become visible when they condense into sister chromatids

Centrioles move to opposite ends of the cell

Spindle begins to form

Nuclear membrane begins to break down

Metaphase

2nd phase of mitosis

Chromosomes line up in the middle

Spindle fibres attach to centromeres

Anaphase

3rd phase of mitosis

Spindle fibres attached to centromeres pull sister chromatids apart

Chromosomes move to opposite ends of the cell

Telophase

Nuclear membrane forms at each end of the cell around the chromosomes

Two separate nuclei

Chromosomes become chromatin

PMAT

the phases of mitosis

Prophase, Metaphase, Anaphase, Telophase

Cytokinesis

division of the cytoplasm

Cytoplasm of the cell and organelles separate into 2 new, genetically identical daughter cells

In animal cells: a groove called the cleavage furrow pinches parent cell into 2

In plant cells: cell plate forms as a separating membrane, the site for forming new cell walls