Chapter 3

Cells and Tissues

Cells and TissuesCells 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 CellAnatomy 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 membraneFigure 3.1a

The NucleusThe Nucleus

Control center of the cell

Contains genetic material (DNA)

Three regions

Nuclear membrane

Nucleolus

Chromatin Figure 3.1b

Nuclear MembraneNuclear Membrane

Barrier of nucleus

Contain nuclear pores that allow for exchange of material with the rest of the cell

NucleolusNucleolus Site of ribosome

production

Ribosomes then migrate to the cytoplasm through nuclear pores

ChromatinChromatin

Composed of DNA and protein

Scattered throughout the nucleus

Chromatin condenses to form chromosomes when the cell divides

Plasma MembranePlasma Membrane Barrier for cell contents

Double phospholipid layer Hydrophilic heads

Hydrophobic tails

Other materials in plasma membrane Protein

Cholesterol

Glycoproteins

Plasma MembranePlasma Membrane

Figure 3.2

Plasma Membrane SpecializationsPlasma Membrane Specializations Microvilli

Finger-like projections that increase surface area for absorption

Figure 3.3

CytoplasmCytoplasm

Material outside the nucleus and inside the plasma membrane Cytosol

Fluid that suspends other elements

Organelles

Little organs

Metabolic machinery of the cell

Cytoplasmic OrganellesCytoplasmic Organelles

Figure 3.4

Cytoplasmic OrganellesCytoplasmic Organelles Ribosomes

Site of protein synthesis

Found at two locations Free in the cytoplasm

Attached to rough endoplasmic reticulum

Cytoplasmic OrganellesCytoplasmic Organelles Endoplasmic reticulum (ER)

Assembles materials for inside and outside the cell

Two types Rough ER (with ribosomes) Smooth ER (without ribosomes)

Cytoplasmic OrganellesCytoplasmic 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 OrganellesCytoplasmic 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 OrganellesCytoplasmic Organelles

Figure 3.5

Cytoplasmic OrganellesCytoplasmic 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 OrganellesCytoplasmic Organelles

Mitochondria

“Powerhouses” of the cell

Convert energy stored in food to chemical compounds the cell can use (ATP)

Cytoplasmic OrganellesCytoplasmic 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 ProjectionsCellular Projections

Not found in all cells

Used for movement

Cilia moves materials across the cell surface

Flagellum propels the cell

Cell DiversityCell Diversity

Figure 3.7; 1, 2

Cell DiversityCell Diversity

Figure 3.7; 3

Cell DiversityCell Diversity

Figure 3.7; 4, 5

Cell DiversityCell Diversity

Figure 3.7; 6, 7