Cells and Tissues Chapter 3

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

Nuclear envelope (membrane) ▫Barrier of the nucleus ▫Consists of a double membrane ▫Contains nuclear pores that allow for exchange of material

The Nucleus Nucleoli ▫Nucleus contains one or more nucleoli ▫Sites of ribosome assembly ▫Ribosomes migrate into the cytoplasm through nuclear pores

The Nucleus Chromatin ▫Composed of DNA and protein ▫Present when the cell is not dividing ▫Scattered in the nucleus ▫Condenses to form chromosomes when the cell divides

Comparing a Cell to a School Use pages to complete the chart comparing a cell to a school Fill in the cell organelle that best fits the described person or place Write out the function of this organelle in a cell

Plasma Membrane Barrier for cell contents Double phospholipid layer ▫Hydrophilic heads ▫Hydrophobic tails Also contains proteins, cholesterol, and glycoproteins

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 Membrane junctions ▫Tight junctions  Impermeable junctions  Bind cells together into leak-proof sheets ▫Desmosomes  Anchoring junctions that prevent cells from being pulled apart (Think ANCHORS) ▫Gap junctions  Allow communication between cells (GAPS)

Plasma Membrane Specializations

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

Cytoplasm Cytosol  Fluid that suspends other elements Organelles  “Little organs” that perform functions Inclusions  Stored nutrients or cell products

Cytoplasmic Organelles

Mitochondria ▫“Powerhouses” of the cell ▫Carry out reactions: oxygen used to break down food ▫Provides ATP

Cytoplasmic Organelles Ribosomes ▫Sites of protein synthesis ▫Found at two locations:  Free in cytoplasm  Part of the Rough ER

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

Cytoplasmic Organelles Rough ER  Studded with ribosomes  Synthesizes proteins Smooth ER  Lipid metabolism and detoxification of drugs and pesticides

Cytoplasmic Organelles Golgi apparatus ▫Modifies and packages proteins:  Secretory vesicles  Cell membrane components  Lysosomes

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

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) ▫Replicate by pinching in half

Cytoplasmic Organelles Cytoskeleton ▫Network of protein structures that extend throughout the cytoplasm ▫Internal framework/structure

Cytoplasmic Organelles Cytoskeleton ▫Three different types:  Microfilaments (largest)  Intermediate filaments  Microtubules (smallest)

Cytoplasmic Organelles Centrioles ▫Rod-shaped bodies made of 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  Located in the respiratory system to move mucus Flagella: propel the cell  The only cell in the human body with flagella is sperm

Human Cheek Cells Unstained

Human Cheek Cells Stained – Low

Human Cheek Cells Stained – High

Human Cheek Cells Stained – High (Labeled)

Other Cell Examples SkinMuscle (cardiac)