Biology Vocabulary Cell cycle

Genome:

The complete set of DNA; Every cell has a full copy.

Gene:

A section of DNA that codes for one specific protein.

Chromosome:

A single long DNA molecule, tightly wound up w/ helper molecules.

23 pairs of chromosomes (46 in total).

Chromatin:

DNA that’s loose and partially unwound.

Homologous chromosomes:

Each pair (two chromosomes) one came from each parent. They’re not identical, but they carry the same genes.

Sister chromatids:

Two identical copies (one parent).

Centromere:

The pinch point in the middle that holds them together.

Homologous:

A pair of chromosomes from different parts.

Mitosis:

The division of the nucleus, in eukaryotic cells. It produces 2 genetically identical “daughter nuclei”. Identical meaning the new cells get an exact copy of the DNA.

Used for growth, repair, and regeneration.

The Cell Cycle:

1. Interface (“getting ready”), longest time

G1: The cell grows and prepares

S: DNA replication, the “S” stands for synthesis.

G2: more growth and prep for division

no visible chromosomes, in chromatin form, nuclear membrane intact.

2. Mitosis & Cytokinesis

Mitosis: division of nucleus

Cytokinesis: division of cytoplasm

G0: some cells leave the cycle and never divide again.

Ex: Neutrons, muscle cells, and red blood cells.

Pro-Phase: “pack up”

Chromatin condenses into visible chromosomes.

The nuclear membrane breaks down.

Spindle fibers attach to centromeres.

Metaphase: “middle”

Spindle fibers pull the chromosomes to line up at the cell equator.

Anaphase: “apart”

The spindle fibers (microtubules) pull the sister chromatids apart.

Each chromatid now counts as it’s own chromosomes, moving towards opposite ends of the cell.

Telophase: “two nuclei”

Two new nuclear membranes form, one at each end.

Chromosomes unwind back into chromatin.

Opposite of prophase

Cytokinesis:

Cytokinesis divides the rest of the cell. It begins during telophase.

Cleavage:

Filaments tighten around the middle, pinching the cell in two.

Cell Plate:

Plants have a rigid cell wall, so they can’t pinch. Instead, a cell plate forms in the middle and develops into new cell walls that split the cell.