Chapter 3 Cells and Tissues

Cells and Tissues 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 Life – It’s all about the cell! Cells are not all the same but all cells share general structures and some functions Metabolism Reproduction Irritability Mobility Ability to Grow Cells are organized into three main regions Nucleus Cytoplasm Plasma membrane Figure 3.1a

The Nucleus Control center of the cell Three regions Contains genetic material (DNA) Three regions Nuclear membrane Nucleolus Chromatin Figure 3.1b

Nuclear Membrane Barrier of nucleus Contain nuclear pores that allow for exchange of material with the rest of the cell

Nucleolus Site of ribosome production Ribosomes then migrate to the cytoplasm through nuclear pores

Chromatin Composed of DNA and protein Scattered throughout the nucleus Chromatin condenses to form chromosomes when the cell divides

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

Plasma Membrane Figure 3.2

Plasma Membrane Specializations Microvilli Finger-like projections that increase surface area for absorption Figure 3.3

Plasma Membrane Specializations Membrane junctions Tight junctions Bind cells together Desmosomes Anchoring junctions Gap junctions Allow chemicals to pass for communication Figure 3.3

Cytoplasm Material outside the nucleus and inside the plasma membrane Cytosol Fluid that suspends other elements Organelles Little organs Metabolic machinery of the cell

Cytoplasmic Organelles Figure 3.4

Cytoplasmic Organelles Ribosomes Site of protein synthesis Found at two locations Free in the cytoplasm Attached to rough endoplasmic reticulum

Cytoplasmic Organelles Endoplasmic reticulum (ER) Assembles materials for inside and outside the cell Two types Rough ER (with ribosomes) Smooth ER (without ribosomes)

Cytoplasmic Organelles Rough Endoplasmic Reticulum Assembles proteins made by the ribosomes to be exported out of the cell Usually found close to the nucleus Smooth Endoplasmic Reticulum No ribosomes on the surface Makes lipids for cell membrane Detoxification of drugs

Cytoplasmic Organelles Golgi apparatus Modify, sort and package proteins from the rough ER to be secreted out of the cell or stored in the cell “Customization shop” – the finishing touches

Cytoplasmic Organelles Figure 3.5

Cytoplasmic Organelles Lysosomes Filled with enzymes Digestion or breakdown of lipids, carbohydrates, and proteins into small molecules that the cell can use “The cleaners” Peroxisomes Membranous sacs of oxidase enzymes Detoxify harmful substances Break down free radicals (highly reactive chemicals)

Cytoplasmic Organelles Mitochondria “Powerhouses” of the cell Convert energy stored in food to chemical compounds the cell can use (ATP)

Cytoplasmic Organelles Cytoskeleton Bones and muscles of the cell Network of protein structures that extend throughout the cytoplasm Provides the cell with an internal framework

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

Cell Diversity Figure 3.7; 1, 2

Cell Diversity Figure 3.7; 3

Cell Diversity Figure 3.7; 4, 5

Cell Diversity Figure 3.7; 6, 7