Cells Anatomy Cells and Tissues Carry out all

Cells Anatomy

Cells and Tissues • Carry out all chemical activities • Cells are the building blocks of all living things • Tissues are groups of cells that are similar in structure and function

Anatomy of the Cell • Cells are not all the same • All cells share general structures • All cells have three main regions ▫ Nucleus ▫ Cytoplasm ▫ Plasma membrane

The Nucleus • Control center of the cell ▫ Contains genetic material (DNA)

The Nucleus • Three regions ▫ Nuclear envelope (membrane) ▫ Nucleolus ▫ Chromatin

The Nucleus

The Nucleus • Nuclear envelope (membrane) ▫ Double membrane ▫ nuclear pores - exchange of material

The Nucleus • Nucleoli ▫ Sites of ribosome assembly ▫ Ribosomes move into the cytoplasm through nuclear pores

The Nucleus • Chromatin ▫ DNA and protein ▫ Present when the cell is not dividing

Plasma Membrane • Barrier for cell contents • Double phospholipid layer ▫ Hydrophilic heads ▫ Hydrophobic tails

Plasma Membrane

Plasma Membrane Specializations • Microvilli ▫ Finger-like projections that increase surface area for absorption ▫ Do all cells have microvilli?

Plasma Membrane Specializations • Membrane junctions ▫ Tight junctions ▫ Desmosomes ▫ Gap junctions

Plasma Membrane Specializations

Cytoplasm • Cytoplasm is the material outside the nucleus and inside the plasma membrane

Cytoplasm • Cytosol • Organelles • Inclusions

Cytoplasmic Organelles

Cytoplasmic Organelles • Mitochondria ▫ “Powerhouses” of the cell

Cytoplasmic Organelles • Ribosomes ▫ Sites of protein synthesis ▫ Found at two locations:

Cytoplasmic Organelles • Endoplasmic reticulum (ER) ▫ Fluid-filled tubules for carrying substances

Cytoplasmic Organelles • Rough ER • Smooth ER

Cytoplasmic Organelles • Golgi apparatus ▫ Modifies and packages proteins:

Proteins in cisterna Rough ER Cisterna Lysosome fuses with ingested substances Membrane Transport vesicle Golgi vesicle containing digestive enzymes becomes a lysosome Pathway 3 Golgi apparatus Pathway 1 Golgi vesicle containing proteins to be secreted becomes a secretory vesicle Pathway 2 Secretory vesicles Proteins Secretion by exocytosis Golgi vesicle containing membrane components fuses with the plasma membrane Plasma membrane Extracellular fluid

Cytoplasmic Organelles • Lysosomes ▫ Contain enzymes that digest worn-out or non-usable materials within the cell

Cytoplasmic Organelles • Peroxisomes ▫ Membranous sacs of oxidase enzymes �Detoxify harmful substances �Break down free radicals (highly reactive chemicals)

Cytoplasmic Organelles • Cytoskeleton ▫ Internal framework/structure

Cytoplasmic Organelles • Cytoskeleton ▫ Three different types:

Cytoplasmic Organelles • Centrioles ▫ Rod-shaped structure made off microtubules ▫ Direct the formation of mitotic spindle during cell division

Cellular Projections • Not found in all cells • Used for movement

Cellular Projections • Cilia: move materials across the cell surface • Flagella: propel the cell