AP BIO UNIT 4 REVIEW

G1 phase

The phase in the cell cycle where the cell carries out its metabolic activities.

S phase

The phase in the cell cycle where DNA replication occurs.

G2 phase

The phase in the cell cycle where proteins needed for mitosis are produced.

G0 phase

The phase where cells are in an arrested or 'dormant' state.

Chromatin

The relaxed state of chromosomes, resembling a ball of string under a microscope.

Chromatid

A single chromosome strand that carries one DNA molecule.

Replicated chromosome

A chromosome composed of two strands, carrying two DNA molecules.

Mitosis

The process that produces body cells which are genetically identical to each other.

Diploid (2n)

A cell that has two sets of chromosomes, one from each parent.

Centromere

The central point of a chromosome which splits during anaphase.

Prophase

The stage in mitosis where chromosomes coil into the 'X' shape and the nuclear membrane breaks down.

Metaphase

The stage in mitosis where replicated chromosomes align in the center of the cell.

Anaphase

The stage in mitosis where sister chromatids are pulled apart by spindle fibers.

Telophase

The stage in mitosis where new nuclear membranes form around separated chromosome groups.

G1 checkpoint

Checks if cell size is adequate and if DNA is undamaged.

G2 checkpoint

Ensures DNA is undamaged and has been fully replicated.

M checkpoint

Checks if chromosomes are properly aligned during metaphase.

Cyclin

Proteins that regulate the timing of the cell cycle by binding to kinases.

Steroid hormones

Hormones that activate gene expression by binding to receptors inside the cell.

Peptide hormones

Hormones with receptors embedded in the target cell that can activate gene expression or proteins.

Signal transduction pathway

A series of processes by which a peptide hormone activates a cellular response.

Phosphorylation

The process by which an inactive protein kinase receives a phosphate group, becoming activated.

Homeostasis

The maintenance of a constant internal environment in an organism.

Negative feedback mechanisms

Processes that maintain homeostasis by regulating physiological processes.

Positive feedback mechanisms

Processes that amplify responses in organisms, moving them away from homeostasis.

Independent variable

The variable being manipulated in an experiment.

Dependent variable

The variable being measured in an experiment.

Chi-Square Test

A statistical test used to determine if there is a significant difference between expected and observed data.

Water potential

The measure of the tendency of water to move from one area to another, influenced by solute and pressure potentials.

Hypertonic

An environment with a higher solute concentration relative to another.

Hypotonic

An environment with a lower solute concentration relative to another.

Isotonic

An environment with the same solute concentration as another.

Endocytosis

The process of transporting bulk materials into a cell.

Exocytosis

The process of transporting substances out of a cell.

Passive transport

The movement of substances down their concentration gradient without the need for energy.

Active transport

The movement of substances against their concentration gradient, requiring energy.

Osmosis

The diffusion of water across a selectively permeable membrane.