Chapter 3 - Cells and Tissues Cell Anatomy

Cells and Tissues Carry out all chemical activities needed to sustain life Cells - the building blocks of all living things Tissues - groups of cells that are similar in structure and function

Anatomy of the Cell Cells not all the same, but share general structures 3 main regions Nucleus Cytoplasm Plasma membrane

The Nucleus Control center 3 regions Contains (DNA) Nuclear membrane Nucleolus Chromatin

Nuclear Envelope (Membrane) Barrier of nucleus Made of double phospholipid membrane Pores allow for exchange of material with rest of the cell

Nucleolus Nucleus contains 1 or more nucleoli Make ribosomes Ribosomes migrate to cytoplasm through nuclear pores

DNA – Chromatin & Chromosome Forms Composed of DNA and protein Chromatin - throughout nucleus in thread form Chromosomes -condensed DNA forms before cell divides

Cytoplasm Material outside nucleus and inside plasma membrane 1. Cytosol Fluid that suspends other elements 2. Organelles Machinery of cell 3. Inclusions Non-functioning units

Cytoplasmic Organelles

1. Ribosomes Made of protein and RNA (made in nucleolus) Sites of protein synthesis Found at two locations Free in the cytoplasm and Attached to rough endoplasmic reticulum

2. Endoplasmic reticulum (ER) Fluid-filled tubules for carrying substances Two types Rough ER Studded with ribosomes Makes parts for membranes Smooth ER Makes & breaks cholesterol Fat metabolism Detoxifies drugs

3. Golgi apparatus Modifies and packages proteins (3 types) Secretory vesicles Cell membrane components Lysosomes

4. Lysosomes 5. Peroxisomes Sacs of enzymes digest nonusable materials Sacs of oxidase enzymes Detoxify harmful substances Break down free radicals (highly reactive chemicals) Replicate by pinching in half Remember bubbling liver?

6. Mitochondria “Powerhouses” of the cell Change shape continuously Uses O2 to break down food Provides ATP for energy

7. Cytoskeleton Protein structures throughout the cytoplasm Internal framework Three different types Microfilaments Intermediate filaments Microtubules

8. Centrioles Rod-shaped bodies made of microtubules Make spindle fibers during cell division

Plasma Membrane Barrier for cell contents Double phospholipid layer Hydrophilic heads Hydrophobic tails Other materials in membrane Proteins Cholesterol Glycoproteins

Plasma Membrane Specializations Microvilli Finger-like projections Increase surface area for absorption Membrane junctions Tight junctions - impermeable Desmosomes - anchor Gap junctions - communicate

Cellular Projections Not found in all cells Used for movement Cilia move materials across the cell surface Flagellum propels the cell