Intercellular JunctionsTight junctions• close space between cells• located among cells that form linings

Desmosomes•form “spot welds” or “rivet” between cells

•Except it works more like “velcro”

•located among outer skin cells

Gap junctions• tubular channels

between cells• located in cardiac

muscle cells

These molecules are also known as Cellular Adhesion Molecules (CAMS)

Cytoskeleton•thin rods and tubules

•support cytoplasm•allows for movement of organelles

Cytoplasmic Organelles

Inclusions

•temporary nutrients and pigments

Nucleus: the control center of our cells!

Nuclear envelopeNuclear envelope•porous double membrane

•separates nucleoplasm from cytoplasm

NucleolusNucleolusdense collection of RNA and proteinssite of ribosome productionChromatinChromatin•fibers of DNA and proteins•stores information for synthesis of proteins

Cytoplasmic OrganellesEndoplasmic Endoplasmic ReticulumReticulum•connected, membrane-bound sacs, canals, and vesicles

•transport systemRough ERRough ER•studded with ribosomes

•protein synthesisSmooth ERSmooth ER•lipid synthesis•added to proteins arriving from rough ER

•break down of drugs

RibosomesRibosomes•free floating or connected to ER•provide structural support

Cytoplasmic OrganellesGolgi apparatus• stack of flattened,

membranous sacs• modifies, packages

and delivers proteins

Vesicles• membranous sacsmembranous sacs• store substances store substances

MitochondriaMitochondria• membranous sacs

with inner partitions• generate energy

Figure 3-4 Mitochondria are the power plants of the cells.

Golgi apparatus• stack of flattened,

membranous sacs• modifies, packages and

delivers proteins

Cytoplasmic OrganellesLysosomes•enzyme-containing sacs

•digest worn out cell parts or unwanted substances

Peroxisomes•enzyme-containing sacs

•break down organic molecules

Centrosome•two rod-like centrioles

•used to produce cilia and flagella

•distributes chromosomes during cell division

• Cell division is the reproduction of cells

• Apoptosis is the genetically controlled death of cells

• Mitosis is the nuclear division of somatic cells

• Meiosis produces sex cells

Cell Division

Cell Cycle• Interphase (G1, S, and G2 phases)

• Mitosis (M phase)• The splitting of one mother cell into two

identical daughter cells.• Four phases of mitosis: prophase,

metaphase, anaphase, and telophase.

• Most somatic cells spend the majority of their lives in this phase

• Interphase includes

•G0

•G1

•S

•G2

Interphase

Figure 3.27

Fig. 3-25a, Stage 1, p. 97

Fig. 3-25b, Stages 2 and 3, p. 97

Fig. 3-25b, Stage 4, p. 98