4B. The Eukaryotic cell cycle

interphase

the first stage of the eukaryotic cell cycle which involves cellular growth and duplication of chromosomes. Composed of three phases: G1, S, and G2

chromosome

a structure composed of DNA tightly wrapped around histone proteins. Carries the genetic information (genes) of a cell

mitosis

the second stage of the eukaryotic cell cycle, which involves the complete separation of sister chromatids and nuclei

sister chromatids

the two identical halves of a replicated chromosome

cytokinesis

the division of the cytoplasm and formation of two daughter cells

chromatin

chromosomes (DNA and proteins) that have been unwound and loosely packed during interphase

quiescent

dormant cells which can re-enter the cell cycle

terminally differentiated

cells that have fully specialised and have exited the cell cycle permanently and can not reenter division

chromatid

one half of a doublestranded chromosome

centromere

the structure which holds sister chromatids together

somatic cells

any cell that is not a reproductive cell (not a sperm nor egg cells). Somatic cells contain two sets of chromosomes - one inherited from each parent

diploid

cells or organisms that have two sets of chromosomes (2n)

daughter cell

the formation of a new cell following cell replication

Prophase

condensation of chromatin around histones into distinct chromosomes, so that they become visible under a microscope. Simultaneously, the centrioles migrate towards opposite ends (or poles) of the cell, and spindle fibres begin to form. The nuclear membrane breaks down and the nucleolus disappears.

Metaphase

the spindle fibres fully form and attach to the centromere of each chromosome. This allows the spindle fibres to guide the chromosomes towards the equator of the cell where they line up.

Anaphase

The spindle fibres contract, splitting the centromere and pulling sister chromatids to opposite ends of the cell.

Telophase

The chromosomes densely pack together at either end of the cell, and new nuclear membranes form, producing two genetically identical nuclei. The spindle fibres disintegrate and the chromosomes decondense.

Cytokinesis

the cytoplasm divides and the organelles evenly distribute themselves before separating into two daughter cells.

chromosome condensation

the shortening and thickening of chromosomes, as DNA is tightly wrapped around histone proteins

centrioles

cylindrical structures composed of protein which form and organise the spindle fibres during mitosis and meiosis

spindle fibres

structures which aid in the movement of chromosomes to either pole of the cell during mitosis and meiosis

equator

the centre line between opposite ends of the cell that the chromosomes line up on during metaphase

cleavage furrow

an indentation of the plasma membrane during cytokinesis in animals

cell plate

Forms in plant cells during cytokinesis eventually developing into a new cell wall

G1 Phase

The first phase of the cell cycle, consisting of growth and the synthesis of organelles and proteins necessary for DNA replication

S Phase

The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.

G2 Phase

The second growth phase of the cell cycle, consisting of continued growth in preparation for mitosis

G0 Phase

A nondividing state in which a cell has left the cell cycle: the resting stage for cells not undergoing replication