CELLS AND TISSUES Carry out all chemical activities needed

to sustain life 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 Cells are organized into three main

regions Nucleus Cytoplasm Plasma membrane

Figure 3.1a

THE NUCLEUS Control center of

the cell Contains

genetic material (DNA)

Three regions Nuclear

membrane Nucleolus Chromatin

Figure 3.1b

NUCLEAR MEMBRANE Nuclear Membrane

Barrier of nucleus Consists of a double phospholipid membrane Contain nuclear pores that allow for

exchange of material with the rest of the cell Nucleoli Nucleus contains one or more nucleoli Sites 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

Also contains protein, cholesterol, and glycoproteins

Microvilli Finger-like projections that increase surface

area for absorption

PLASMA MEMBRANE

Figure 3.2

Extracellular fluid(watery environment)

Sugargroup

Polar heads ofphospholipidmolecules

Bimolecularlipid layer containingproteins

Nonpolar tailsof phospholipidmolecules

Glycoprotein

Proteins Filaments ofcytoskeleton Cytoplasm

(watery environment)

Channel

CholesterolGlycolipid

Plasmamembranes ofadjacent cells

Desmosome(anchoring junction)

Tight(impermeable) junction

Microvilli

Gap(communicating) junction

Extracellularspace betweencells

Underlyingbasementmembrane

Connexon

Figure 3.3

CYTOPLASM Material outside the nucleus and inside

the plasma membrane Cytosol

Fluid that suspends other elements Organelles

Metabolic machinery of the cell “Little organs”

Inclusions Non-functioning units (stored nutrients, cell

products, etc.)

Ribosomes

Golgi apparatus

Secretion being releasedfrom cell by exocytosisMicrotubule

Centrioles

Mitochondrion

Lysosome

Cytosol

Smooth endoplasmicreticulum

Chromatin

NucleolusNuclear envelope

Nucleus

Plasmamembrane

Roughendoplasmicreticulum

Intermediatefilaments

Peroxisome

Figure 3.4

CYTOPLASMIC ORGANELLES Ribosomes

Made of protein and RNA Sites of protein synthesis Found at two locations

Free in the cytoplasm Attached to rough endoplasmic reticulum

CYTOPLASMIC ORGANELLES Endoplasmic reticulum (ER)

Fluid-filled tubules for carrying substances Two types of ER

Rough Endoplasmic Reticulum Studded with ribosomes Site where building materials of cellular

membrane are formed Smooth Endoplasmic Reticulum

Functions in cholesterol synthesis and breakdown, fat metabolism, and detoxification of drugs

Figure 3.5, step 1

Ribosome mRNA

Rough ER

Protein

As the protein is synthesized on theribosome, it migrates into the rough ERcistern.

1

1

Figure 3.5, step 2

In the cistern, the protein folds into itsfunctional shape. Short sugar chainsmay be attached to the protein (forminga glycoprotein).

As the protein is synthesized on theribosome, it migrates into the rough ERcistern.2

Ribosome mRNA

Rough ER

Protein

21

1

Figure 3.5, step 3

In the cistern, the protein folds into itsfunctional shape. Short sugar chainsmay be attached to the protein (forminga glycoprotein).

The protein is packaged in a tinymembranous sac called a transportvesicle.

As the protein is synthesized on theribosome, it migrates into the rough ERcistern.

32

1

Ribosome mRNA

Rough ER

Transportvesicle buds off

Protein

3

2

1

Figure 3.5, step 4

In the cistern, the protein folds into itsfunctional shape. Short sugar chainsmay be attached to the protein (forminga glycoprotein).

The protein is packaged in a tinymembranous sac called a transportvesicle.

The transport vesicle buds from therough ER and travels to the Golgiapparatus for further processing.

As the protein is synthesized on theribosome, it migrates into the rough ERcistern.

32

1

Ribosome mRNA

Rough ER

Transportvesicle buds off

Protein insidetransport vesicle

Protein

43

2

1

4

CYTOPLASMIC ORGANELLES Golgi apparatus

Modifies and packages proteins Produces different types of packages

Secretory vesicles Cell membrane components Lysosomes

Figure 3.6

Golgi vesicle containingdigestive enzymesbecomes a lysosome

Pathway 3

Pathway 2

Secretory vesicles

Proteins

Secretion byexocytosis

Golgi vesicle containingproteins to be secretedbecomes a secretoryvesicle

Golgiapparatus

Pathway 1

Transportvesicle

Membrane

Proteins in cisternaCisternaRough ER

Lysosome fuses withingested substances

Golgi vesicle containingmembrane componentsfuses with the plasmamembrane

Plasma membrane

Extracellular fluid

CYTOPLASMIC ORGANELLES Lysosomes

Contain enzymes that digest nonusable materials within the cell

Packaged by Golgi apparatus Peroxisomes

Membranous sacs of oxidase enzymes Detoxify harmful substances Break down free radicals

(highly reactive chemicals) Replicate by pinching in half

CYTOPLASMIC ORGANELLES Mitochondria

“Powerhouses” of the cell Change shape continuously Carry out reactions where oxygen is used

to break down food Provides ATP for cellular energy

CYTOPLASMIC ORGANELLES Cytoskeleton

Network of protein structures that extend throughout the cytoplasm

Provides the cell with an internal framework

Figure 3.7a

Figure 3.7a-c

(a) Microfilaments (b) Intermediate filaments (c) Microtubules

Actin subunit

7 nm 10 nm

Fibrous subunitsTubulin subunits

25 nm

Microfilaments form the bluenetwork surrounding the pinknucleus.

Intermediate filaments formthe purple batlike network.

Microtubules appear as goldnetworks surrounding thecells’ pink nuclei.

CYTOPLASMIC ORGANELLES Centrioles

Rod-shaped bodies Direct formation of mitotic spindle during

cell division

CELLULAR PROJECTIONS Not found in all cells Used for movement

Cilia moves materials across the cell surface

Flagellum propels the cell

CELL DIVERSITY

Figure 3.8a–b

CELL DIVERSITY

Figure 3.8c

CELL DIVERSITY

Figure 3.8d–e

CELL DIVERSITY

Figure 3.8f–g