The Nucleus

Cell theory

all living things are composed of cells, cells arise from preexisting cells, each cell maintains its own homeostasis

gametes

sex cells

somatic cells

all other cells in the human body; diploid

The Nucleus

stores and organizes genetic material, site of DNA replication and transcription

The Nuclear Envelope

double membrane that has nuclear pores that regulate passage of proteins and RNA

The nucleus contains:

nucleoplasm, nucleoli, and nucleosomes

nucleoli

nuclear organelles that synthesize ribosomal RNA

Nucleosomes

bundles of DNA molecules wrapped around histone proteins

Chromosomes

Highly condensed DNA/protein only found in cells during division

Chromatin

loosely coiled tangle of DNA/protein complexes found in cells not going through division

transcription factors

cause DNA to unwind from histones; regulated by internal and external signals

stem cells

maintain the cell population through repeated cycles of cell division

mitosis

cell division which produces somatic cells

Tissue growth occurs when ______________________

the rate of division exceeds the rate of cell death

Growth factors

stimulates division in certain tissues

Cancer

the loss of cell cycle control results in uncontrolled tissue growth

benign tumors

remain in place

metastatic tumors

travel through blood vessels and establish new tumors

Differentiation

specialization of cell structure and function