Biology Unit 4

Positive Feedback

A process that amplifies a signal or response (e.g., oxytocin during childbirth).

Negative Feedback

A process that decreases or counteracts a stimulus to maintain homeostasis (e.g., insulin regulation of blood sugar).

Interphase

The longest phase of the cell cycle where the cell grows, performs normal functions, and duplicates its DNA.

G1 Phase:

The phase of cell growth and preparation for DNA replication.

S Phase:

The phase where DNA replication occurs.

G2 Phase

• The phase where the cell prepares for mitosis by producing proteins and organelles.

M Phase:

The phase of mitosis, where the cell divides its chromosomes and cytoplasm.

Cytokinesis

The division of the cytoplasm to form two separate daughter cells.

Cyclins

Regulatory proteins that control the progression of the cell cycle.

Cyclin-Dependent Kinases (CDKs):

• Enzymes that, when bound to cyclins, activate processes required for cell cycle progression.

MPF (Maturation Promoting Factor):

A cyclin-CDK complex that triggers the cell to proceed past the G2 checkpoint.

Oncogenes:

Genes that, when mutated, promote cell division and contribute to cancer.

cAMP

amplifies signals in cells by activating protein kinases