Chapter 4 A Tour of the Cell...2012/10/04 · Figure 4.1A Figure 4.1B 10 m 1 m 100 mm (10 cm) 10 mm...

© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko

PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey

Chapter 4 A Tour of the Cell

Plans:

Day 1) Notes: 4.1-4.4/ HW Packet, Assign project and talk about cell cake

Day 2) Cards

Day 3) Cards

Day 4) Review cards

Day 5) Card Matching Game

Day 6) Quiz

Day 7) Cell Cake

Day 8) test

Do Now: What is life? Describe the characteristics of all living things.

1) Nutrition

2) Respiration

3) Regulation

4) Reproduction

5) Synthesis

6) Transport

7) Excretion

8) Growth

Introduction

Cells are the simplest collection of matter that can live.

Cells were first observed by Robert Hooke in 1665.

Working with more refined lenses, Antoni van Leeuwenhoek later described

– blood,

– sperm, and

– organisms living in pond water.

© 2012 Pearson Education, Inc.

Introduction

Since the days of Hooke and Leeuwenhoek, improved microscopes have vastly expanded our view of the cell.


Figure 4.0_1

Introduction to the Cell The Nucleus and Ribosomes

The Endomembrane System

Energy-Converting Organelles

The Cytoskeleton and Cell Surfaces

Chapter 4: Big Ideas

Figure 4.0_2

INTRODUCTION TO THE CELL


1)LIGHT MICROSCOPE

Common?

Maximum Magnification?

Magnification:

Resolution:

The most frequently used

Light passes through a specimen, then through glass lenses, and finally light is projected into the viewer’s eye.

– Magnified up to 1,000 times

Magnification is the increase in the apparent size of an object.

Resolution is a measure of the clarity of an image. In other words, it is the ability of an instrument to show two close objects as separate.

Limited detail


Figure 4.1A

Figure 4.1B 10 m

1 m

100 mm (10 cm)

10 mm (1 cm)

1 mm

Human height

Length of some nerve and muscle cells

Chicken egg

Frog egg

Human egg Paramecium

100 µm

10 µm

1 µm

100 nm

10 nm

Most plant and animal cells

1 nm

0.1 nm

Nucleus Most bacteria Mitochondrion

Smallest bacteria Viruses

Ribosome

Proteins Lipids

Small molecules

Atoms

Una

ided

eye

Ligh

t mic

rosc

ope

Elec

tron

mic

rosc

ope

2) ELECTRON MICROSCOPE (EM)

How it works?

Maximum magnification?

limitiation?


1950s, scientists started using them to view the ultrastructure of cells.

– Instead of light, EM uses a beam of electrons.

Electron microscopes can

– resolve biological structures as small as 2 nanometers and

– magnify up to 100,000 times.

– Specimen must be dead


Figure 4.1E

3) Scanning Electron Microscope (SEM)

What can you study?

How does it work?

Scanning electron microscopes (SEM) study the detailed architecture of cell surfaces.

– An electron beam to scan the surface which is usually coated in gold,

– beam excites electrons on the surface

– an image is translated

Figure 4.1C

4) Transmission Electron Microscope (TEM)

What is it used for?

How does it work?

Transmission electron microscopes (TEM) study the details of internal cell structure.

– Aims an electron beam through a thin section

– Section is stained with heavy metals

– Electrons that scatter create an image

– Uses electromagnets instead of lenses to bend pathway of electron, magnifying specimen

.


Figure 4.1D

5) CELL THEORY/ SIZE

What is the cell theory?

Why are cells small?

In the 1800s, these studies led to cell theory, which states that

– all living things are composed of cells and

– all cells come from other cells. Cell size must

– be large enough to house DNA, proteins, and structures needed to survive and reproduce, but

– remain small enough to allow for a surface-to-volume ratio that will allow adequate exchange with the environment.

Figure 4.2A

3

3

1

1

Total volume

Total surface area Surface-to- volume ratio

2

54 units2

27 units3 27 units3

162 units2

6

6) PLASMA MEMBRANE (CELL MEMBRANE)

What is the cell membrane like? Where are the proteins?

How does it control the traffic of molecules across it?

What things pass over easily?

What things need help? How are they helped?

The plasma membrane forms a flexible boundary between the living cell and its surroundings.

Phospholipids form a two-layer sheet called a phospholipid bilayer in which

– hydrophilic heads face outward, exposed to water, and

– hydrophobic tails point inward, shielded from water.

Membrane proteins are

– attached to the membrane surface or

– embedded in the phospholipid bilayer.

Some proteins form channels or tunnels that allow ions and other hydrophilic/polar molecules through

O2 and CO2 are nonpolar and pass right over

Other proteins serve as pumps, using energy to actively transport molecules into or out of the cell.


Figure 4.2B

Outside cell

Hydrophilic heads

Hydrophobic tails

Phospholipid Inside cell

Channel protein Proteins

Hydrophilic region of a protein

Hydrophobic region of a protein

7) PROKARYOTIC CELL

Types of organisms?

Common with eukaryotic cells?

Different?

What do they have on the outside?

Attach to other things?

Move?

What do they lack?

Bacteria and archaea

– Prokaryotic and eukaryotic cells have

– a plasma membrane

– chromosomes, ribosomes and cytoplasm

The DNA is coiled into a region called the nucleoid, but no membrane surrounds DNA

The surface of prokaryotic cells may

– be surrounded by a complex cell wall,

– have a capsule surrounding the cell wall,

– have short projections that help attach to other cells or the substrate,

– have longer projections called flagella (swim)

– no true membrane bound organelles.


Figure 4.3

Fimbriae Ribosomes

Nucleoid

Plasma membrane

Cell wall

Capsule

Flagella A TEM of the bacterium Bacillus coagulans

Bacterial chromosome

A typical rod-shaped bacterium

Figure 4.3_1 Fimbriae

Ribosome

Nucleoid

Plasma membrane

Cell wall

Capsule

Flagella

Bacterial chromosome

A typical rod-shaped bacterium

Figure 4.3_2

Ribosome

Nucleoid

Plasma membrane

Cell wall

Capsule

A TEM of the bacterium Bacillus coagulans

8) EUKARYOTIC CELL

What does it have that is missing in prokaryotes?

What are the four functions?

How are they achieved?

membrane-bound nucleus and

number of other organelles.

The structures/organelles perform four basic functions.

1. The nucleus and ribosomes are involved in the genetic control of the cell.

2. The endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes are involved in the manufacture, distribution, and breakdown of molecules.

3. Mitochondria in all cells and chloroplasts in plant cells are involved in energy processing.

4. Structural support, movement, and communication between cells are functions of the cytoskeleton, plasma membrane, and cell wall.


9) Plant and Animal Cell

What does an animal cell have that is missing in a plant?

What does a plant have that is missing in an animal?

What are the chemical reactions in the cell called?

What are the little organs called?

Organelles: are the small structures with specific functions

Cellular metabolism: the many chemical activities of cells, occurs within organelles

Animals only: Lysosomes and centrioles

Plant only: a rigid cell wall, chloroplasts, and a central vacuole.


Figure 4.4A

Smooth endoplasmic reticulum

Rough endoplasmic reticulum

NUCLEUS: Nuclear envelope Chromatin Nucleolus

Ribosomes

Golgi apparatus

Mitochondrion

Plasma membrane

Peroxisome

CYTOSKELETON: Microtubule Intermediate filament Microfilament

Lysosome Centriole

NOT IN MOST PLANT CELLS:

Figure 4.4B

NUCLEUS: Nuclear envelope Chromatin Nucleolus

Golgi apparatus

Rough endoplasmic reticulum

Ribosomes

Peroxisome

Central vacuole

NOT IN ANIMAL CELLS:

Chloroplast Cell wall Plasmodesma

Mitochondrion

Plasma membrane

Cell wall of adjacent cell

Smooth endoplasmic reticulum

CYTOSKELETON: Microtubule Intermediate filament Microfilament

THE NUCLEUS AND RIBOSOMES


10) NUCLEUS

Function?

What is inside?

How is it kept separate?

What organelle is inside? Function?

- contains most of the cell’s DNA and

– controls the cell’s activities by directing protein synthesis by making messenger RNA (mRNA).

DNA is associated with many proteins in structures called chromosomes. (46 for humans) / unorganized chromatin

The nuclear envelope

– is a double membrane

– has pores that allow material in and out

The nuclear envelope is attached to cellular membranes called the endoplasmic reticulum.

The nucleolus is

– a prominent structure in the nucleus

– the site of ribosomal RNA (rRNA) synthesis


Figure 4.5

Two membranes of nuclear envelope

Nucleus

Chromatin Nucleolus

Pore

Endoplasmic reticulum

Ribosomes

11) RIBOSOMES

What do they do?

What are they made up of? Who makes them?

Where are they found?

Ribosomes are involved in the cell’s protein synthesis.

– Ribosomes are synthesized from rRNA produced in the nucleolus.

– Cells that must synthesize large amounts of protein have a large number of ribosomes.

– Free ribosomes are

– suspended in the cytoplasm

– make proteins that function in cytoplasm.

– Bound ribosomes are

– attached to the endoplasmic reticulum (ER)

– associated with proteins packed in organelles or exported


Figure 4.6

Ribosomes ER Cytoplasm

Endoplasmic reticulum (ER) Free ribosomes Bound ribosomes

Diagram of a ribosome Protein

mRNA

Colorized TEM showing ER and ribosomes

THE ENDOMEMBRANE SYSTEM


Many of the membranes within a eukaryotic cell are part of the endomembrane system Some are physically connected and some are

related by the transfer of membrane segments by tiny vesicles (sacs made of membrane). Many of these organelles work together in the

– synthesis, – storage, and – export of molecules.

The endomembrane system includes

– the nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, vacuoles, and the plasma membrane.


12) Rough Endoplasmic Reticulum

What does it do?

What does it have on it?

Steps:

Has ribosomes attached

Rough ER makes

– additional membrane

– ER ribosomes synthesize, modify, and package proteins to be transported to other organelles or secreted by cell

– Steps

1. Polypeptide synthesized by ribosomes according to mRNA, as it enters it takes on its 3D shape

2. Short sugars(address) added creating a glycoprotein

3. Packaged into a vesicle

4. Off to the Golgi


Figure 4.8B

Transport vesicle buds off

mRNA

Ribosome

Polypeptide Glycoprotein

Rough ER

Sugar chain

Secretory protein inside transport vesicle

4

3

2

1

13) Smooth Endoplasmic Reticulum

3 functions?

1. Produces enzymes important in the synthesis of lipids, oils, phospholipids, and steroids.

2. Other enzymes help process drugs, alcohol, and other potentially harmful substances.

3. Some smooth ER helps store calcium ions.


Figure 4.8A

Smooth ER

Rough ER

Ribosomes

Nuclear envelope

Figure 4.8A_1

Smooth ER Rough ER Ribosome

14) Golgi Apparatus

Function?

Steps?

Serves as a molecular warehouse and finishing factory for products (proteins) manufactured by the ER.

1. Products travel in transport vesicles from the ER to the Golgi apparatus.

2. One side of the Golgi apparatus functions as a receiving dock for the product and the other as a shipping dock.

3. Products are modified by enzymes as they go from one side of the Golgi apparatus to the other and travel in vesicles to other sites.

– Change sugars, add molecular tags like P to help sort proteins


Figure 4.9

Golgi apparatus Golgi apparatus

Transport vesicle from the Golgi

“Shipping” side of Golgi apparatus

Transport vesicle from ER

“Receiving” side of Golgi apparatus

1

2

3

4

4

15) Lysosome

What is it?

How is it created?

Steps?

Membranous sac containing digestive enzymes.

– The enzymes and membrane are produced by the ER and transferred to the Golgi apparatus for processing.

– Safely isolate these potent enzymes

Digests food particles engulfed by a cell

1. A food vacuole binds with a lysosome.

2. The enzymes in the lysosome digest the food.

3. The nutrients are then released into the cell.

Remove or recycle damaged parts of a cell.


Figure 4.10A_s1

Digestive enzymes

Lysosome

Plasma membrane

Figure 4.10A_s2

Digestive enzymes

Lysosome

Food vacuole

Plasma membrane

Figure 4.10A_s3

Digestive enzymes

Lysosome

Food vacuole

Plasma membrane

Figure 4.10A_s4

Digestive enzymes

Lysosome

Food vacuole

Plasma membrane

Digestion

Figure 4.10B_s1

Lysosome

Vesicle containing damaged mitochondrion

Figure 4.10B_s2

Lysosome


Figure 4.10B_s3

Lysosome


Digestion

16)VACUOLES

Functions in protists

Functions in plants:

Variety of functions.

– Food vacuole

– Some fresh water protists have contractile vacuoles that help to eliminate extra water

– In plants, vacuoles may

– have digestive functions,

– contain pigments, or

– contain poisons that protect the plant

– Large central vacuole


Figure 4.11A

Contractile vacuoles

Nucleus

Figure 4.11B

Central vacuole

Chloroplast

Nucleus

17)PEROXISOME

Did it come from the EMS?

What does it do?

Do not originate from EM system

Break down fatty acids to be used as fuel

In your liver, they detox alcohol

– an enzyme adds H to oxygen to make H2O2 or hydrogen peroxide

– Other enzymes then convert this toxic substance into a water

4.12 A review of the structures involved in manufacturing and breakdown

The following figure summarizes the relationships among the major organelles of the endomembrane system.


Figure 4.12

Smooth ER

Nucleus

Transport vesicle from ER to Golgi

Golgi apparatus

Lysosome Vacuole Plasma membrane

Nuclear membrane

Rough ER

Transport vesicle from Golgi to plasma membrane

ENERGY-CONVERTING ORGANELLES


18)MITOCHONDRIA

What do they do?

How?

Compartments.

Carries out cellular respiration

Converts chemical energy in foods to chemical energy in ATP (adenosine triphosphate).

Mitochondria have two internal compartments.

1. The intermembrane space is the narrow region between the inner and outer membranes.

2. The mitochondrial matrix contains

– the mitochondrial DNA,

– ribosomes,

– many enzymes that catalyze some of the reactions of cellular respiration.


Figure 4.13

Matrix

Cristae

Inner membrane

Outer membrane

Mitochondrion

Intermembrane space

19) CHLOROPLAST

Process?

Compartments?

Photosynthesizing organelles

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

Compartments.

– Between the outer and inner membrane is a thin intermembrane space.

– Inside the inner membrane is

– a thick fluid called stroma that contains the chloroplast DNA, ribosomes, and many enzymes and

– a network of interconnected sacs called thylakoids.

– In some regions, thylakoids are stacked like poker chips. Each stack is called a granum, where green chlorophyll molecules trap solar energy.


Figure 4.14

Inner and outer membranes

Granum Stroma Chloroplast

Thylakoid

20)Endosymbiont Theory

What is it?

What organelles is it about?

Why is this thought to be true?

Mitochondria and chloroplasts have

– DNA and

– ribosomes.

The structure of this DNA and these ribosomes is very similar to that found in prokaryotic cells.

The endosymbiont theory proposes that

– mitochondria and chloroplasts were formerly small prokaryotes and they began living within larger cells.


Figure 4.15

Mitochondrion Nucleus

Endoplasmic reticulum Engulfing of

photosynthetic prokaryote

Chloroplast

Host cell

Mitochondrion

Host cell Engulfing of oxygen- using prokaryote

Some cells

THE CYTOSKELETON AND CELL SURFACES


21)CYTOSKELETON

Function:

3 types: Functions?

A network of protein fibers, which functions in structural support and motility.

Motility and cellular regulation result when the cytoskeleton interacts with proteins called motor proteins.

The cytoskeleton is composed of three kinds of fibers.

1. Microfilaments (actin filaments) support the cell’s shape and are involved in motility.

2. Intermediate filaments reinforce cell shape and anchor organelles.

3. Microtubules (made of tubulin) give the cell rigidity and act as tracks for organelle movement.


Figure 4.16

Actin subunit

Nucleus Nucleus

Microfilament Intermediate filament

Fibrous subunits

7 nm 10 nm

Tubulin subunits

Microtubule

25 nm

22)Cilia and Flagella

Function in multicellular organisms

Function in single celled eukaryotes (protists) and prokaryotes

Structure

multicellular organisms

– Cells that sweep mucus out of our lungs have cilia and animal sperm are flagellated

Protists and Prokaryotes

A flagellum, longer than cilia, propels a cell by an undulating, whiplike motion.

Cilia work more like the oars of a crew boat.

Structure

Both are made of microtubules wrapped in an extension of the plasma membrane.

A ring of nine microtubule doublets surrounds a central pair of microtubules. This arrangement is

– called the 9 + 2 pattern

– anchored in a basal body with nine microtubule triplets arranged in a ring.

Cilia and flagella move by bending motor proteins called dynein feet.


Figure 4.17A

Cilia

Figure 4.17B

Flagellum

Figure 4.17C

Outer microtubule doublet

Central microtubules

Radial spoke

Dynein proteins

Plasma membrane

Figure 4.17C_1

Outer microtubule doublet Central microtubules

Radial spoke

Dynein proteins

4.18 CONNECTION: Problems with sperm motility may be environmental or genetic

In developed countries over the last 50 years, there has been a decline in sperm quality.

The causes of this decline may be

– environmental chemicals or

– genetic disorders that interfere with the movement of sperm and cilia. Primary ciliary dyskinesia (PCD) is a rare disease characterized by recurrent infections of the respiratory tract and immotile sperm.


Figure 4.18

23)Extracellular Matrix

Function:

Components:

Most Abundant?

Integrin functions

Animal cells synthesize and secrete an elaborate extracellular matrix (ECM) that

– helps hold cells together in tissues and

– protects and supports the plasma membrane.

The ECM may attach to a cell through glycoproteins that then bind to membrane proteins called integrins. Integrins span the plasma membrane and connect to microfilaments of the cytoskeleton.


Figure 4.19

EXTRACELLULAR FLUID

CYTOPLASM Microfilaments of cytoskelton

Plasma membrane

Integrin

Connecting glycoprotein

Glycoprotein complex with long polysaccharide

Collagen fiber

24) Animal Cell Junctions:

Functions:

3 Types described

Adjacent cells communicate, interact, and adhere through specialized junctions between them.

– Tight junctions prevent leakage of extracellular fluid across a layer of epithelial cells.

– Anchoring junctions fasten cells together into sheets.

– Gap junctions are channels that allow molecules to flow between cells.


Figure 4.20 Tight junctions prevent fluid from moving between cells

Tight junction

Anchoring junction

Gap junction

Plasma membranes of adjacent cells

Extracellular matrix

25) Plasmodesmata

Type of cells

Function

A plant cell has a rigid cell wall that

– protects and provides skeletal support that helps keep the plant upright against gravity and

– is primarily composed of cellulose.

Plant cells have cell junctions called plasmodesmata that serve in communication between cells.


Figure 4.21

Vacuole

Plant cell walls

Plasmodesmata

Cytoplasm

Primary cell wall Secondary cell wall Plasma membrane

4.22 Review: Eukaryotic cell structures can be grouped on the basis of four basic functions

Eukaryotic cell structures can be grouped on the basis of four functions:

1. genetic control,

2. manufacturing, distribution, and breakdown,

3. energy processing, and

4. structural support, movement, and communication between cells.


Table 4.22

Table 4.22_1

Table 4.22_2

You should now be able to

1. Describe the importance of microscopes in understanding cell structure and function.

2. Describe the two parts of cell theory.

3. Distinguish between the structures of prokaryotic and eukaryotic cells.

4. Explain how cell size is limited.

5. Describe the structure and functions of cell membranes.



6. Explain why compartmentalization is important in eukaryotic cells.

7. Compare the structures of plant and animal cells. Note the function of each cell part.

8. Compare the structures and functions of chloroplasts and mitochondria.

9. Describe the evidence that suggests that mitochondria and chloroplasts evolved by endosymbiosis.



10. Compare the structures and functions of microfilaments, intermediate filaments, and microtubules.

11. Relate the structure of cilia and flagella to their functions.

12. Relate the structure of the extracellular matrix to its functions.

13. Compare the structures and functions of tight junctions, anchoring junctions, and gap junctions.



14. Relate the structures of plant cell walls and plasmodesmata to their functions.

15. Describe the four functional categories of organelles in eukaryotic cells.


Figure 4.UN02

Figure 4.UN03

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Chapter 4 A Tour of the Cell...2012/10/04 · Figure 4.1A Figure 4.1B 10 m 1 m 100 mm (10 cm) 10 mm...

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