04 lecture presentation

© 2010 Pearson Education, Inc.

Lectures by Chris C. Romero, updated by Edward J. Zalisko

PowerPoint® Lectures forCampbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean DickeyCampbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey

Chapter 4Chapter 4

A Tour of the Cell

Biology and Society: Drugs That Target Bacterial Cells

• Antibiotics were first isolated from mold in 1928.

• The widespread use of antibiotics drastically decreased deaths from bacterial infections.


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Figure 4.00


• Most antibiotics kill bacteria while minimally harming the human host by binding to structures found only on bacterial cells.

• Some antibiotics bind to the bacterial ribosome, leaving human ribosomes unaffected.

• Other antibiotics target enzymes found only in the bacterial cells.


THE MICROSCOPIC WORLD OF CELLS

• Organisms are either

– Single-celled, such as most prokaryotes and protists or

– Multicelled, such as plants, animals, and most fungi


Microscopes as Windows on the World of Cells• Light microscopes can be used to explore the structures and

functions of cells.

• When scientists examine a specimen on a microscope slide

– Light passes through the specimen

– Lenses enlarge, or magnify, the image

Light Micrograph (LM)(for viewing living cells)

Light micrograph of a protist, Paramecium

LM

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Scanning Electron Micrograph (SEM)(for viewing surface features)

Scanning electron micrograph of Paramecium

TYPES OF MICROGRAPHS

Transmission Electron Micrograph (TEM)(for viewing internal structures)

Transmission electron micrograph of Paramecium

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Figure 4.1

Light Micrograph (LM)(for viewing living cells)

Light micrograph of a protist, Paramecium

LM

Figure 4.1a

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Scanning Electron Micrograph (SEM)(for viewing surface features)

Scanning electron micrograph of ParameciumFigure 4.1b

Transmission Electron Micrograph (TEM)(for viewing internal structures)

Transmission electron micrograph of Paramecium

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Figure 4.1c


• Magnification is an increase in the specimen’s apparent size.

• Resolving power is the ability of an optical instrument to show two objects as separate.


• Cells were first described in 1665 by Robert Hooke.

• The accumulation of scientific evidence led to the cell theory.

– All living things are composed of cells.

– All cells come from other cells.


• The electron microscope (EM) uses a beam of electrons, which results in better resolving power than the light microscope.

• Two kinds of electron microscopes reveal different parts of cells.


• Scanning electron microscopes examine cell surfaces.


• Transmission electron microscopes (TEM) are useful for internal details of cells.


• The electron microscope can

– Magnify up to 100,000 times

– Distinguish between objects 0.2 nanometers apart

Figure 4.2

10 m

1 m

10 cm

1 cm

1 mm

100 mm

10 mm

Human height

Chicken egg

Frog eggs

Length of somenerve andmuscle cells

Un

aid

ed e

ye

Lig

ht

mic

rosc

op

e

Plant andanimal cells

Most bacteriaNucleus

Mitochondrion1 mm

100 nm

10 nm

1 nm

0.1 nm

Smallest bacteria

Viruses

Ribosomes

Proteins

Lipids

Small molecules

Atoms

Ele

ctro

n m

icro

sco

pe

Figure 4.3


The Two Major Categories of Cells• The countless cells on earth fall into two categories:

– Prokaryotic cells — Bacteria and Archaea

– Eukaryotic cells — plants, fungi, and animals

• All cells have several basic features.

– They are all bound by a thin plasma membrane.

– All cells have DNA and ribosomes, tiny structures that build proteins.


• Prokaryotic and eukaryotic cells have important differences.

• Prokaryotic cells are older than eukaryotic cells.

– Prokaryotes appeared about 3.5 billion years ago.

– Eukaryotes appeared about 2.1 billion years ago.


• Prokaryotes

– Are smaller than eukaryotic cells

– Lack internal structures surrounded by membranes

– Lack a nucleus

– Have a rigid cell wall


• Eukaryotes

– Only eukaryotic cells have organelles, membrane-bound structures that perform specific functions.

– The most important organelle is the nucleus, which houses most of a eukaryotic cell’s DNA.

Plasma membrane(encloses cytoplasm)

Cell wall (providesRigidity)

Capsule (stickycoating)

Prokaryoticflagellum(for propulsion)

Ribosomes(synthesizeproteins)

Nucleoid(contains DNA)

Pili (attachment structures)

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Figure 4.4

Plasma membrane(encloses cytoplasm)

Cell wall (provides rigidity)

Capsule (sticky coating)

Prokaryoticflagellum(for propulsion)

Ribosomes(synthesizeproteins)

Nucleoid(contains DNA)

Pili (attachment structures)Figure 4.4a

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Figure 4.4b


An Overview of Eukaryotic Cells• Eukaryotic cells are fundamentally similar.

• The region between the nucleus and plasma membrane is the cytoplasm.

• The cytoplasm consists of various organelles suspended in fluid.


• Unlike animal cells, plant cells have

– Protective cell walls

– Chloroplasts, which convert light energy to the chemical energy of food

Blast Animation: Plant Cell Overview

Blast Animation: Animal Cell Overview

CytoskeletonRibosomes Centriole

LysosomeFlagellum

Nucleus

Plasmamembrane

Mitochondrion

Roughendoplasmic

reticulum (ER)Golgi

apparatus

Smoothendoplasmicreticulum (ER)

Idealized animal cell

Idealized plant cell

Cytoskeleton

Mitochondrion

Nucleus

Rough endoplasmicreticulum (ER)

Ribosomes

Smoothendoplasmic

reticulum (ER)

Golgi apparatus

Plasmamembrane

Channels betweencells

Not in mostplant cells

Centralvacuole

Cell wall

Chloroplast

Not in animal cells

Figure 4.5

Cytoskeleton

Ribosomes CentrioleLysosome

Flagellum

Nucleus

Plasmamembrane

Mitochondrion

Roughendoplasmic

reticulum (ER)

Golgiapparatus

Smoothendoplasmicreticulum (ER)

Idealized animal cell

Not in mostplant cells

Figure 4.5a

Idealized plant cell

Cytoskeleton

Mitochondrion

Nucleus

Rough endoplasmicreticulum (ER)

Ribosomes

Smoothendoplasmic

reticulum (ER)

Golgi apparatus

Plasmamembrane

Channels betweencells

CentralvacuoleCell wallChloroplast

Not inanimal cells

Figure 4.5b


MEMBRANE STRUCTURE• The plasma membrane separates the living cell from its nonliving

surroundings.

The Plasma Membrane: A Fluid Mosaic of Lipids and Proteins

• The membranes of cells are composed mostly of

– Lipids

– Proteins



• The lipids belong to a special category called phospholipids.

• Phospholipids form a two-layered membrane, the phospholipid bilayer.

Animation: Tight Junctions

Animation: Gap Junctions

Animation: Desmosomes

(a) Phospholipid bilayer ofmembrane

(b) Fluid mosaic model ofmembrane

Outside of cell Outside of cell

Hydrophilichead

Hydrophobictail

Hydrophilicregion of

protein

Hydrophilichead

Hydrophobictail

Hydrophobicregions of

protein

Phospholipidbilayer

Phospholipid

Proteins

Cytoplasm (inside of cell)


Figure 4.6

(a) Phospholipid bilayer of membrane

Outside of cell

Hydrophilichead

Hydrophobictail

Phospholipid


Figure 4.6a

(b) Fluid mosaic model of membrane

Outside of cell

Hydrophilicregion of

protein

Hydrophilichead

Hydrophobictail

Hydrophobicregions of

protein

Phospholipidbilayer

Proteins


Figure 4.6b


• Most membranes have specific proteins embedded in the phospholipid bilayer.

• These proteins help regulate traffic across the membrane and perform other functions.


• The plasma membrane is a fluid mosaic:

– Fluid because molecules can move freely past one another

– A mosaic because of the diversity of proteins in the membrane


The Process of Science: What Makes a Superbug?

• Observation: Bacteria use a protein called PSM to disable human immune cells by forming holes in the plasma membrane.

• Question: Does PSM play a role in MRSA infections?

• Hypothesis: MRSA bacteria lacking the ability to produce PSM would be less deadly than normal MRSA strains.


• Experiment: Researchers infected

– Seven mice with normal MRSA

– Eight mice with MRSA that does not produce PSM

• Results:

– All seven mice infected with normal MRSA died.

– Five of the eight mice infected with MRSA that does not produce PSM survived.


• Conclusions:

– MRSA strains appear to use the membrane-destroying PSM protein, but

– Factors other than PSM protein contributed to the death of mice

MRSA bacteriumproducing PSMproteins

Methicillin-resistantStaphylococcus aureus (MRSA)

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Figure 4.7-1



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PSM proteinsforming holein humanimmune cellplasmamembrane Plasma

membrane

PSMprotein

Pore

Figure 4.7-2



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PSM proteinsforming holein humanimmune cellplasmamembrane Plasma

membrane

PSMprotein

Pore

Cell bursting,losing itscontentsthroughthe pores

Figure 4.7-3


Cell Surfaces• Plant cells have rigid cell walls surrounding the membrane.

• Plant cell walls

– Are made of cellulose

– Protect the cells

– Maintain cell shape

– Keep the cells from absorbing too much water


• Animal cells

– Lack cell walls

– Have an extracellular matrix, which

– Helps hold cells together in tissues

– Protects and supports them

• The surfaces of most animal cells contain cell junctions, structures that connect to other cells.

THE NUCLEUS AND RIBOSOMES:GENETIC CONTROL OF THE CELL

• The nucleus is the chief executive of the cell.

– Genes in the nucleus store information necessary to produce proteins.

– Proteins do most of the work of the cell.



Structure and Function of the Nucleus• The nucleus is bordered by a double membrane called the

nuclear envelope.

• Pores in the envelope allow materials to move between the nucleus and cytoplasm.

• The nucleus contains a nucleolus where ribosomes are made.

Ribosomes Chromatin Nucleolus PoreNuclearenvelope

Surface of nuclear envelope Nuclear pores

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Figure 4.8

Ribosomes Chromatin Nucleolus PoreNuclearenvelope

Figure 4.8a

Surface of nuclear envelope

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Figure 4.8b

Nuclear pores

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Figure 4.8c


• Stored in the nucleus are long DNA molecules and associated proteins that form fibers called chromatin.

• Each long chromatin fiber constitutes one chromosome.

• The number of chromosomes in a cell depends on the species.

DNA molecule

Chromosome

Proteins

Chromatinfiber

Figure 4.9


Ribosomes• Ribosomes are responsible for protein synthesis.

• Ribosome components are made in the nucleolus but assembled in the cytoplasm.

Ribosome

Protein

mRNA

Figure 4.10


• Ribosomes may assemble proteins:

– Suspended in the fluid of the cytoplasm or

– Attached to the outside of an organelle called the endoplasmic reticulum

Ribosomes incytoplasm

Ribosomes attachedto endoplasmicreticulum

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Figure 4.11


How DNA Directs Protein Production• DNA directs protein production by transferring its coded

information into messenger RNA (mRNA).

• Messenger RNA exits the nucleus through pores in the nuclear envelope.

• A ribosome moves along the mRNA translating the genetic message into a protein with a specific amino acid sequence.

Synthesis ofmRNA in thenucleus

Nucleus

DNA

mRNA

Cytoplasm

Figure 4.12-1


Nucleus

DNA

mRNA

Cytoplasm

mRNAMovement ofmRNA intocytoplasmvianuclear pore

Figure 4.12-2


Nucleus

DNA

mRNA

Cytoplasm

mRNAMovement ofmRNA intocytoplasmvianuclear pore

Ribosome

Protein

Synthesis ofprotein in thecytoplasm

Figure 4.12-3

THE ENDOMEMBRANE SYSTEM: MANUFACTURING AND DISTRIBUTING CELLULAR PRODUCTS• Many membranous organelles forming the endomembrane

system in a cell are interconnected either

– Directly or

– Through the transfer of membrane segments between them



The Endoplasmic Reticulum• The endoplasmic reticulum (ER) is one of the main

manufacturing facilities in a cell.

• The ER

– Produces an enormous variety of molecules

– Is composed of smooth and rough ER

Nuclearenvelope

Smooth ERRough ER

Ribosomes

Ribosomes

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Figure 4.13

Nuclearenvelope

Smooth ERRough ER

Ribosomes

Figure 4.13a

Ribosomes

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Rough ERSmooth ER

Figure 4.13b


Rough ER

• The “rough” in the rough ER is due to ribosomes that stud the outside of the ER membrane.

• These ribosomes produce membrane proteins and secretory proteins.

• After the rough ER synthesizes a molecule, it packages the molecule into transport vesicles.

Proteins areoften modified inthe ER.

Secretoryproteins depart intransport vesicles.

Vesicles bud offfrom the ER.

A ribosomelinks amino acidsinto apolypeptide.

RibosomeTransportvesicle

Polypeptide

ProteinRough ER

Figure 4.14


Smooth ER

• The smooth ER

– Lacks surface ribosomes

– Produces lipids, including steroids

– Helps liver cells detoxify circulating drugs


The Golgi Apparatus• The Golgi apparatus

– Works in partnership with the ER

– Receives, refines, stores, and distributes chemical products of the cell

Video: Euglena

“Receiving” side of Golgi apparatus

New vesicle forming

Transport vesiclefrom rough ER

“Receiving” sideof Golgiapparatus

Newvesicleforming

Transportvesiclefrom theGolgi

Plasmamembrane

“Shipping” sideof Golgi

apparatus

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Figure 4.15

Transport vesiclefrom rough ER

“Receiving” side ofGolgi apparatus

Newvesicleforming

Transportvesiclefrom theGolgi

Plasmamembrane

“Shipping” side ofGolgi apparatus

Figure 4.15a

“Receiving” side of Golgi apparatus

New vesicle forming

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Figure 4.15b


Lysosomes• A lysosome is a sac of digestive enzymes found in animal cells.

• Enzymes in a lysosome can break down large molecules such as

– Proteins

– Polysaccharides

– Fats

– Nucleic acids


• Lysosomes have several types of digestive functions.

– Many cells engulf nutrients in tiny cytoplasmic sacs called food vacuoles.

– These food vacuoles fuse with lysosomes, exposing food to enzymes to digest the food.

– Small molecules from digestion leave the lysosome and nourish the cell.

Animation: Lysosome Formation

Plasma membrane Digestive enzymes

Lysosome

Digestion

Food vacuole

Lysosome

Digestion

(a) Lysosome digesting food (b) Lysosome breaking down the molecules of damaged organelles

Vesicle containingdamaged organelle

Vesicle containing twodamaged organelles

Organelle fragment

Organelle fragment

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Figure 4.16

Plasma membrane Digestive enzymes

Lysosome

Digestion

Food vacuole

(a) Lysosome digesting food

Figure 4.16a

Lysosome

Digestion

(b) Lysosome breaking down the molecules of damaged organelles

Vesicle containing

damaged organelle

Figure 4.16b

Vesicle containing twodamaged organelles

Organelle fragment

Organelle fragment

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Figure 4.16c


• Lysosomes can also

– Destroy harmful bacteria

– Break down damaged organelles


Vacuoles• Vacuoles are membranous sacs that bud from the

– ER

– Golgi

– Plasma membrane


• Contractile vacuoles of protists pump out excess water in the cell.

• Central vacuoles of plants

– Store nutrients

– Absorb water

– May contain pigments or poisons

Video: Cytoplasmic Streaming

Blast Animation: Vacuole

Video: Paramecium Vacuole

Vacuole filling with water

Vacuole contracting

(a) Contractile vacuole in Paramecium

(b) Central vacuole in a plant cell

Central vacuoleC

olo

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d T

EM

LM

LM

Figure 4.17

Figure 4.17a

Vacuole filling with water

Vacuole contracting

(a) Contractile vacuole in Paramecium

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EM

(b) Central vacuole in a plant cell

Central vacuole

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Figure 4.17b


• To review, the endomembrane system interconnects the

– Nuclear envelope

– ER

– Golgi

– Lysosomes

– Vacuoles

– Plasma membrane

Blast Animation : Vesicle Transport Along Microtubules

Video: Chlamydomonas

Golgi apparatus

Transport vesicle

Plasma membrane

Secretory protein

New vesicle forming

Transport vesicle fromthe Golgi

Vacuoles store somecell products.

Lysosomes carrying digestiveenzymes can fuse with other vesicles.

Transport vesicles carry enzymesand other proteins from the roughER to the Golgi for processing.

Some productsare secretedfrom the cell.

Golgi apparatus

Rough ER

Vacuole

Lysosome

Transportvesicle

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Figure 4.18

Golgiapparatus

Transportvesicle

Plasmamembrane

Secretoryprotein

Vacuoles store somecell products.

Lysosomes carryingdigestive enzymes canfuse with other vesicles.

Transport vesiclescarry enzymes andother proteins fromthe rough ER to theGolgi for processing.

Some productsare secretedfrom the cell.

Rough ER

Vacuole

Lysosome

Transportvesicle

Figure 4.18a

New vesicle forming

Transport vesicle fromthe Golgi

Golgi apparatus

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Figure 4.18b

CHLOROPLASTS AND MITOCHONDRIA: ENERGY CONVERSION

• Cells require a constant energy supply to perform the work of life.



Chloroplasts• Most of the living world runs on the energy provided by

photosynthesis.

• Photosynthesis is the conversion of light energy from the sun to the chemical energy of sugar.

• Chloroplasts are the organelles that perform photosynthesis.


• Chloroplasts have three major compartments:

– The space between the two membranes

– The stroma, a thick fluid within the chloroplast

– The space within grana, the structures that trap light energy and convert it to chemical energy

Inner and outermembranes

Space betweenmembranes

Stroma (fluid in chloroplast) Granum

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Figure 4.19

Inner and outermembranes


Stroma (fluid in chloroplast)

Granum

Figure 4.19a

Stroma (fluid in chloroplast)

Granum

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Figure 4.19b


Mitochondria• Mitochondria are the sites of cellular respiration, which produce

ATP from the energy of food molecules.

• Mitochondria are found in almost all eukaryotic cells.


• An envelope of two membranes encloses the mitochondrion. These consist of

– An outer smooth membrane

– An inner membrane that has numerous infoldings called cristae

Blast Animation: Mitochondrion

Outermembrane

Innermembrane

Cristae

Matrix


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Figure 4.20

Outermembrane

Innermembrane

Cristae

Matrix


Figure 4.20a

Outermembrane

Innermembrane

Cristae

Matrix


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Figure 4.20b


• Mitochondria and chloroplasts contain their own DNA, which encodes some of their proteins.

• This DNA is evidence that mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past.

THE CYTOSKELETON: CELL SHAPE AND MOVEMENT

• The cytoskeleton is a network of fibers extending throughout the cytoplasm.



Maintaining Cell Shape• The cytoskeleton

– Provides mechanical support to the cell

– Maintains its shape


• The cytoskeleton contains several types of fibers made from different proteins:

– Microtubules

– Are straight and hollow

– Guide the movement of organelles and chromosomes

– Intermediate filaments and microfilaments are thinner and solid.

(a) Microtubulesin the cytoskeleton

(b) Microtubulesand movement

LM

LM

Figure 4.21

(a) Microtubulesin the cytoskeleton

LM

Figure 4.21a

(b) Microtubules and movement

LM

Figure 4.21b


• The cytoskeleton is dynamic.

• Changes in the cytoskeleton contribute to the amoeboid motion of an Amoeba.


Cilia and Flagella• Cilia and flagella aid in movement.

– Flagella propel the cell in a whiplike motion.

– Cilia move in a coordinated back-and-forth motion.

– Cilia and flagella have the same basic architecture.

Animation: Cilia and Flagella

Video: Paramecium Cilia

Video: Prokaryotic Flagella (Salmonella typhimurium)

Video: Euglena

(a) Flagellum of a human sperm cell

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(b) Cilia on a protist

(c) Cilia lining therespiratory tract

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Figure 4.22

(a) Flagellum of a human sperm cell

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Figure 4.22a

(b) Cilia on a protist

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Figure 4.22b

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(c) Cilia lining the respiratory tractFigure 4.22c


• Cilia may extend from nonmoving cells.

• On cells lining the human trachea, cilia help sweep mucus out of the lungs.

Evolution Connection:The Evolution of Antibiotic Resistance

• Many antibiotics disrupt cellular structures of invading microorganisms.

• Introduced in the 1940s, penicillin worked well against such infections.

• But over time, bacteria that were resistant to antibiotics were favored.

• The widespread use and abuse of antibiotics continues to favor bacteria that resist antibiotics.


Figure 4.23

Figure 4.23a

Figure 4.23b

Figure 4.UN1

Figure 4.UN2

Figure 4.UN3

Figure 4.UN4

Figure 4.UN5

Figure 4.UN6

Figure 4.UN7

Figure 4.UN8

Figure 4.UN9

Figure 4.UN10

Figure 4.UN11

Prokaryotic Cells Eukaryotic Cells

• Smaller

• Simpler

• Most do not have organelles

• Found in bacteria and archaea

• Larger

• More complex

• Have organelles

• Found in protists, plants,

fungi, animals

CATEGORIES OF CELLS

Figure 4.UN12

Outside of cell


Protein

Phospholipid

Hydrophilic

Hydrophilic

Hydrophobic

Figure 4.UN13

Light energy

Chloroplast

Mitochondrion

Chemicalenergy(food)

ATPPHOTOSYNTHESISCELLULAR

RESPIRATION

Figure 4.UN14