04


Chapter 4
A Tour of the Cell

PowerPoint? Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey

Lectures by Chris C. Romero, updated by Edward J. Zalisko
? 2010 Pearson Education, Inc.

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.

? 2010 Pearson Education, Inc.

Figure 4.00

Colorized TEM

? 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.

? 2010 Pearson Education, Inc.

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

? 2010 Pearson Education, Inc.

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

? 2010 Pearson Education, Inc.

TYPES OF MICROGRAPHS Light Micrograph (LM) (for viewing living cells)
LM

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

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

Light micrograph of a protist, Paramecium

Scanning electron micrograph of Paramecium

Transmission electron micrograph of Paramecium

Figure 4.1

Light Micrograph (LM) (for viewing living cells)
LM

Light micrograph of a protist, Paramecium
Figure 4.1a

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

Scanning electron micrograph of Paramecium
Figure 4.1b

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

Transmission electron micrograph of Paramecium
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.

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

? Scanning electron microscopes examine cell surfaces.

? 2010 Pearson Education, Inc.

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

? 2010 Pearson Education, Inc.

? The electron microscope can
– Magnify up to 100,000 times

– Distinguish between objects 0.2 nanometers apart

? 2010 Pearson Education, Inc.

Figure 4.2

10 m Human height 1m Length of some nerve and muscle cells Chicken egg 1 cm Frog eggs 1 mm Light microscope Electron microscope

10 cm

100 mm

Plant and animal cells
10 mm Nucleus Most bacteria Mitochondrion

1 mm

100 nm

Smallest bacteria Viruses Ribosomes

10 nm

Proteins Lipids

1 nm

Small molecules Atoms

0.1 nm

Unaided eye

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.

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

? Prokaryotes
– Are smaller than eukaryotic cells

– Lack internal structures surrounded by membranes
– Lack a nucleus – Have a rigid cell wall

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

Plasma membrane (encloses cytoplasm) Cell wall (provides Rigidity)

Capsule (sticky coating) Prokaryotic flagellum (for propulsion) Ribosomes (synthesize proteins) Nucleoid (contains DNA) Pili (attachment structures)
Colorized TEM

Figure 4.4

Plasma membrane (encloses cytoplasm) Cell wall (provides rigidity)

Capsule (sticky coating) Prokaryotic flagellum (for propulsion)

Ribosomes (synthesize proteins)
Nucleoid (contains DNA) Pili (attachment structures)
Figure 4.4a

Colorized TEM

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.

? 2010 Pearson Education, Inc.

? Unlike animal cells, plant cells have
– Protective cell walls

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

Blast Animation: Animal Cell Overview

Blast Animation: Plant Cell Overview
? 2010 Pearson Education, Inc.

Ribosomes Cytoskeleton

Centriole Lysosome Flagellum

Not in most plant cells

Plasma membrane Nucleus Mitochondrion Rough endoplasmic reticulum (ER)

Golgi apparatus Idealized animal cell Central vacuole Cell wall

Smooth endoplasmic reticulum (ER)

Cytoskeleton

Mitochondrion
Nucleus Rough endoplasmic reticulum (ER) Ribosomes Smooth endoplasmic reticulum (ER) Idealized plant cell

Not in animal cells

Chloroplast

Plasma membrane Channels between cells Golgi apparatus

Figure 4.5

Ribosomes Cytoskeleton

Centriole Lysosome Flagellum

Not in most plant cells

Plasma membrane

Nucleus

Mitochondrion

Rough endoplasmic reticulum (ER) Golgi apparatus

Smooth endoplasmic reticulum (ER)
Figure 4.5a

Idealized animal cell

Cytoskeleton Central vacuole Cell wall Chloroplast

Mitochondrion Nucleus Rough endoplasmic reticulum (ER)

Not in animal cells

Ribosomes

Plasma membrane Smooth endoplasmic reticulum (ER) Golgi apparatus Idealized plant cell

Channels between cells

Figure 4.5b

MEMBRANE STRUCTURE
? The plasma membrane separates the living cell from its nonliving surroundings.

? 2010 Pearson Education, Inc.

The Plasma Membrane: A Fluid Mosaic of Lipids and Proteins
? The membranes of cells are composed mostly of
– Lipids – Proteins

? 2010 Pearson Education, Inc.

? The lipids belong to a special category called phospholipids. ? Phospholipids form a two-layered membrane, the phospholipid bilayer.

Animation: Desmosomes

Animation: Gap Junctions

Animation: Tight Junctions
? 2010 Pearson Education, Inc.

Outside of cell
Hydrophilic head Hydrophobic tail

Hydrophilic region of protein Hydrophilic head Hydrophobic tail

Outside of cell

Proteins

Phospholipid bilayer

Phospholipid

Cytoplasm (inside of cell)

(a) Phospholipid bilayer of membrane

Hydrophobic regions of protein

Cytoplasm (inside of cell)

(b) Fluid mosaic model of membrane

Figure 4.6

Outside of cell Hydrophilic head

Hydrophobic tail

Phospholipid Cytoplasm (inside of cell) (a) Phospholipid bilayer of membrane
Figure 4.6a

Outside of cell Hydrophilic region of protein

Proteins

Hydrophilic head Hydrophobic tail

Phospholipid bilayer

Hydrophobic regions of protein

Cytoplasm (inside of cell)

(b) Fluid mosaic model of membrane
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.

? 2010 Pearson Education, Inc.

? 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

? 2010 Pearson Education, Inc.

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.

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

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

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

? 2010 Pearson Education, Inc.

MRSA bacterium producing PSM proteins
Methicillin-resistant Staphylococcus aureus (MRSA)

Colorized SEM

Figure 4.7-1

MRSA bacterium producing PSM proteins
Methicillin-resistant Staphylococcus aureus (MRSA)

PSM proteins forming hole in human immune cell plasma membrane

PSM protein Plasma membrane Pore

Colorized SEM

Figure 4.7-2

MRSA bacterium producing PSM proteins
Methicillin-resistant Staphylococcus aureus (MRSA)

PSM proteins forming hole in human immune cell plasma membrane

PSM protein Plasma membrane Pore

Cell bursting, losing its contents through the pores

Colorized SEM

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

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

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.

? 2010 Pearson Education, Inc.

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.

? 2010 Pearson Education, Inc.

Ribosomes

Chromatin

Nuclear envelope

Nucleolus

Pore

TEM

Surface of nuclear envelope

Nuclear pores

TEM

Figure 4.8

Ribosomes

Chromatin

Nuclear envelope

Nucleolus

Pore

Figure 4.8a

TEM

Surface of nuclear envelope
Figure 4.8b

Nuclear pores
Figure 4.8c

TEM

? 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.

? 2010 Pearson Education, Inc.

DNA molecule

Proteins

Chromatin fiber

Chromosome

Figure 4.9

Ribosomes
? Ribosomes are responsible for protein synthesis. ? Ribosome components are made in the nucleolus but assembled in the cytoplasm.

? 2010 Pearson Education, Inc.

Ribosome

mRNA

Protein

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

? 2010 Pearson Education, Inc.

TEM

Ribosomes in cytoplasm

Ribosomes attached to endoplasmic reticulum

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.

? 2010 Pearson Education, Inc.

DNA

Synthesis of mRNA in the nucleus

mRNA

Nucleus

Cytoplasm

Figure 4.12-1

DNA

Synthesis of mRNA in the nucleus

mRNA

Nucleus

Cytoplasm

Movement of mRNA into cytoplasm via nuclear pore

mRNA

Figure 4.12-2

DNA

Synthesis of mRNA in the nucleus

mRNA

Nucleus

Cytoplasm

Movement of mRNA into cytoplasm via nuclear pore
Synthesis of protein in the cytoplasm

mRNA Ribosome

Protein
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

? 2010 Pearson Education, Inc.

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

? 2010 Pearson Education, Inc.

Nuclear envelope

Ribosomes
Rough ER Smooth ER

TEM

Ribosomes
Figure 4.13

Nuclear envelope

Ribosomes Rough ER

Smooth ER
Figure 4.13a

Rough ER
TEM

Smooth ER

Ribosomes

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.

? 2010 Pearson Education, Inc.

Proteins are often modified in the ER.

Secretory proteins depart in transport vesicles.

Vesicles bud off from the ER.

Ribosome

Transport vesicle

Protein A ribosome links amino acids into a polypeptide. Rough ER

Polypeptide
Figure 4.14

Smooth ER
? The smooth ER
– Lacks surface ribosomes

– Produces lipids, including steroids
– Helps liver cells detoxify circulating drugs

? 2010 Pearson Education, Inc.

The Golgi Apparatus
? The Golgi apparatus
– Works in partnership with the ER

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

Video: Euglena
? 2010 Pearson Education, Inc.

“Receiving” side of Golgi apparatus

Transport vesicle from rough ER

“Receiving” side of Golgi apparatus New vesicle forming

“Shipping” side of Golgi apparatus

Transport vesicle from the Golgi

Plasma membrane

New vesicle forming

Figure 4.15

Transport vesicle from rough ER

“Receiving” side of Golgi apparatus

New vesicle forming

Transport vesicle from the Golgi “Shipping” side of Golgi apparatus Plasma membrane
Figure 4.15a

“Receiving” side of Golgi apparatus
Colorized SEM

New vesicle forming
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

? 2010 Pearson Education, Inc.

? 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
? 2010 Pearson Education, Inc.

Plasma membrane

Digestive enzymes

Lysosome Digestion Food vacuole

Lysosome

Vesicle containing damaged organelle

Digestion

(a) Lysosome digesting food

(b) Lysosome breaking down the molecules of damaged organelles Organelle fragment

Vesicle containing two damaged organelles

Organelle fragment

TEM

Figure 4.16

Plasma membrane

Digestive enzymes

Lysosome Digestion Food vacuole

(a) Lysosome digesting food

Figure 4.16a

Lysosome

Digestion Vesicle containing damaged organelle (b) Lysosome breaking down the molecules of damaged organelles

Figure 4.16b

Organelle fragment

Vesicle containing two damaged organelles

Organelle fragment

TEM

Figure 4.16c

? Lysosomes can also
– Destroy harmful bacteria

– Break down damaged organelles

? 2010 Pearson Education, Inc.

Vacuoles
? Vacuoles are membranous sacs that bud from the
– ER

– Golgi
– Plasma membrane

? 2010 Pearson Education, Inc.

? 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: Paramecium Vacuole

Blast Animation: Vacuole

Video: Cytoplasmic Streaming
? 2010 Pearson Education, Inc.

Vacuole filling with water

Vacuole contracting

(a) Contractile vacuole in Paramecium
Colorized TEM

Central vacuole

(b) Central vacuole in a plant cell
Figure 4.17

LM

LM

Vacuole filling with water

Vacuole contracting

(a) Contractile vacuole in Paramecium
Figure 4.17a

TEM

TEM

Central vacuole

(b) Central vacuole in a plant cell
Figure 4.17b

Colorized TEM

? To review, the endomembrane system interconnects the
– Nuclear envelope

– ER
– Golgi – Lysosomes

– Vacuoles
– Plasma membrane

Video: Chlamydomonas

Blast Animation : Vesicle Transport Along Microtubules
? 2010 Pearson Education, Inc.

Rough ER Transport vesicle Golgi apparatus

Transport vesicle
Transport vesicles carry enzymes and other proteins from the rough ER to the Golgi for processing. Plasma membrane Vacuole Secretory protein Lysosomes carrying digestive enzymes can fuse with other vesicles.

Lysosome
Some products are secreted from the cell. Vacuoles store some cell products.

Golgi apparatus

New vesicle forming

Transport vesicle from the Golgi
TEM

Figure 4.18

Golgi apparatus
Transport vesicle

Rough ER Transport vesicle

Transport vesicles carry enzymes and other proteins from the rough ER to the Golgi for processing.

Plasma membrane Secretory protein Some products are secreted from the cell.

Vacuole

Lysosomes carrying digestive enzymes can Lysosome fuse with other vesicles.

Vacuoles store some cell products.

Figure 4.18a

Golgi apparatus

New vesicle forming

Transport vesicle from the Golgi
TEM

Figure 4.18b

CHLOROPLASTS AND MITOCHONDRIA: ENERGY CONVERSION
? Cells require a constant energy supply to perform the work of life.

? 2010 Pearson Education, Inc.

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.

? 2010 Pearson Education, Inc.

? 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

? 2010 Pearson Education, Inc.

Inner and outer membranes

Space between membranes Stroma (fluid in chloroplast) Granum

TEM

Figure 4.19

Inner and outer membranes

Granum Space between membranes Stroma (fluid in chloroplast)

Figure 4.19a

Stroma (fluid in chloroplast)

Granum

TEM

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.

? 2010 Pearson Education, Inc.

? 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
? 2010 Pearson Education, Inc.

Outer membrane

Inner membrane

Cristae

Matrix
Space between membranes

Figure 4.20

TEM

Outer membrane

Inner membrane

Cristae Matrix Space between membranes
Figure 4.20a

Outer membrane

Inner membrane

Cristae Matrix

Space between membranes
Figure 4.20b

TEM

? 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.

? 2010 Pearson Education, Inc.

THE CYTOSKELETON: CELL SHAPE AND MOVEMENT
? The cytoskeleton is a network of fibers extending throughout the cytoplasm.

? 2010 Pearson Education, Inc.

Maintaining Cell Shape
? The cytoskeleton
– Provides mechanical support to the cell

– Maintains its shape

? 2010 Pearson Education, Inc.

? 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.

? 2010 Pearson Education, Inc.

LM

(a) Microtubules in the cytoskeleton

(b) Microtubules and movement
LM

Figure 4.21

(a) Microtubules in the cytoskeleton
Figure 4.21a

LM

(b) Microtubules and movement
Figure 4.21b

LM

? The cytoskeleton is dynamic. ? Changes in the cytoskeleton contribute to the amoeboid motion of an Amoeba.

? 2010 Pearson Education, Inc.

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.

Video: Euglena Video: Prokaryotic Flagella (Salmonella typhimurium)

Video: Paramecium Cilia

Animation: Cilia and Flagella
? 2010 Pearson Education, Inc.

(b) Cilia on a protist

Colorized SEM

(a) Flagellum of a human sperm cell

(c) Cilia lining the respiratory tract
Figure 4.22

Colorized SEM

Colorized SEM

(a) Flagellum of a human sperm cell
Figure 4.22a

Colorized SEM

(b) Cilia on a protist
Figure 4.22b

Colorized SEM

(c) Cilia lining the respiratory tract
Figure 4.22c

Colorized SEM

? Cilia may extend from nonmoving cells. ? On cells lining the human trachea, cilia help sweep mucus out of the lungs.

? 2010 Pearson Education, Inc.

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.

? 2010 Pearson Education, Inc.

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

CATEGORIES OF CELLS 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

Figure 4.UN12

Outside of cell

Phospholipid Hydrophilic

Protein

Hydrophobic

Hydrophilic

Cytoplasm (inside of cell)

Figure 4.UN13

Mitochondrion

Chloroplast
Light energy PHOTOSYNTHESIS Chemical energy (food) CELLULAR RESPIRATION

ATP

Figure 4.UN14


相关文档

更多相关文档

大学英语说课 Lecture Presentation
14_Lecture_Presentation
11_lecture_Presentation
13_Lecture_Presentation
10_Lecture_Presentation
电脑版