Chapter 03 Lecture and Animation Outline Copyright © The McGraw-Hill Companies, Inc. Permission...

Chapter 03Lecture and

Animation Outline

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3.1 Cellular Organization

A.Introduction• Three main parts of a cell

a.Plasma membrane – surrounds the cell, keeps it intact, and regulates passage into and out of the cell

b.Nucleus – control centerc. Cytoplasm – gelatinous, semi-fluid of water and

suspended and dissolved substances

Introduction, cont

2.Organelles (little organs) are scattered throughout the cytoplasm and have various functions

3.The cytoskeleton maintains cell shape and allows the cell and its content to move

A typical animal cell

B.Plasma Membrane• Separates the inside of the cell (cytoplasm) from the outside• Fluid-mosaic model

a. Phospholipid bilayer – hydrophilic heads point outward and hydrophobic tails point inward

b. Attached peripheral and integral proteins serve as receptors, channels, and carriers

c. Cholesterol molecules stabilize the membraned. Glycoproteins and glycolipids attached to outer surface of some

protein and lipid molecules, mark cells as belonging to a particular individual

Fluid-mosaic model of the plasma membrane

C.The Nucleus• Stores genetic information• Chromatin

a.Contains DNA, protein, and some RNAb.Coils into rod-like structures called chromosomes

before the cell dividesc. Immersed in nucleoplasm

• Nucleoli a.Dark-staining bodies containing rRNA and proteinb.Site where ribosomes are formed

The Nucleus, cont

4.Nuclear envelope separates nucleus from cytoplasma.Lipid bilayer with many nuclear poresb.Outer layer is continuous with the endoplasmic

reticulum

The Nucleus

D.Ribosomes• Composed of two subunits containing protein

and rRNA• Can be found free within the cytoplasm, singly

or in groups called polyribosomes; produce proteins that are used inside the cell

• Also found attached to the endoplasmic reticulum; produce proteins that may be secreted by the cell

E.Endomembrane System• Nuclear envelope• Endoplasmic reticulum (ER)

a.Continuous with the outer membrane of the nuclear envelope, it is a system of membranous channels and saccules

b.Rough ER1)Has attached ribosomes2)Processes proteins produced by attached ribosomes

Endomembrane system, cont

c. Smooth ER 1)Has no attached ribosomes2)Synthesizes phospholipids, detoxifies drugs, and

has other functions depending on the type of cell

Endoplasmic Reticulum

Endomembrane System, cont3.Golgi apparatus

a.Stacks of curved sacculesb.Processes, packages, and secretes various substancesc. Receives protein and/or lipid-filled vesicles from ERd.Contains enzymes that modify proteins and lipidse.Vesicles leave the Golgi apparatus and move to other

parts of the cell or to the plasma membrane for secretion

f. Produces lysosomes

Endomembrane System Function

Endomembrane system, cont4.Lysosomes

a.Contain hydrolytic digestive enzymes; nick-names “suicide sacs”

b.Autodigestion responsible for cell rejuvenation and development and removal of worn-out organelles

c. Can fuse with vesicles of material brought into the cell for destruction

d.Tay-Sach’s disease – metabolic disorder involving missing or inactive lysosomal enzymes in nerve cells

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F.Peroxisomes and Vacuoles• Peroxisomes

a.Enzyme-containing vesicles, similar to lysosomesb.Detoxify drugs, alcohol, and other toxinsc. Large numbers found in liver and kidneyd.Break down fatty acids from fats

• Vacuoles isolate substances captured inside the cell

G.Mitochondria• Rod-shaped organelle bound by a double

membrane• Inner membrane folds into cristae to increase

surface area• Site of ATP production through cellular

respiration – cell powerhouse

Mitochondrion Structure

H.The cytoskeleton

• Microtubules - help maintain the cell’s shape and anchors or assists the movement of organelles

• Intermediate filaments – involved in cell to cell junctions

• Actin filaments – involved in cell movement• Assembly regulated by the centrosome

I.Centrioles• Composed of microtubules with a 9 + 0 pattern• A pair of perpendicular centrioles are found near

the nucleus of every cell• In a area called the centrosome• Involved in cell division by forming the mitotic

spindle• Form the basal body (anchor point) for each

cilium or flagellum

Structure of basal bodies and flagella

J.Cilia and flagellum

– Cilia are hair-like projections from the free surface of a cell; beat in unison to move material along the cell surface

– Flagellum – a single whip-like extension for cell movement; sperm is the only human cell with a flagellum

Cilia and flagella

Structures in Human Cells