a tour of the cell · chapter 6 a tour of the cell powerpoint lectures are originally from campbell...

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

Chapter 6

A Tour of the Cell

PowerPoint lectures are originally from Campbell / Reece Media Manager

and Instructor Resources for BIOLOGY, 7th & 8th Edition by N. A.

Campbell & J. B. Reece Copyright 2005 & 2008 Pearson Education,

Inc. Publishing as Benjamin Cummings


In the Late 1600s.

• The English scientist

Robert Hooke first

observed plant cells

with a crude

microscope.


Robert Hooke

• Observed thin slices of

cork

• Reminded him about

the cells of the monks


In the 1830s

• All living things are

composed of cells.

Matthais Schleiden

Theodor Schwann


In the 1800s

• The cells arise only

from other cells.

• All disease conditions

of the organism can

be attributed to

diseased changes of

the body cells.

Rudolf Virchow


Overview: The Importance of Cells

• All organisms are made of cells

• The cell is the simplest collection of matter

that can live.


The Cell Theory

• The cell is an organism’s basic unit of

structure and function.

• All cells come from preexisting cells.


Cell Diversity

• The human body has:

– 50 to 100 trillion cells.

– Over 200 different

types of cells

• Types of cells differ in

size, shape, subcellular

components, and

functions

LE 6-2

Measurements

1 centimeter (cm) = 10–2 meter (m) = 0.4 inch

1 millimeter (mm) = 10–3 m

1 micrometer (µm) = 10–3 mm = 10–6 m

1 nanometer (nm) = 10–3 µm = 10–9 m

10 m

1 m

Human height

Length of some

nerve and

muscle cells

Chicken egg

0.1 m

1 cm

Frog egg

1 mm

100 µm

Most plant and

animal cells

10 µm Nucleus

1 µm

Most bacteria

Mitochondrion

Smallest bacteria

Viruses 100 nm

10 nm

Ribosomes

Proteins

Lipids

1 nm

Small molecules

Atoms 0.1 nm

Un

aid

ed

eye

Lig

ht m

icro

sco

pe

Ele

ctr

on

mic

rosco

pe


Concept 6.1: To study cells, biologists use microscopes and the tools of biochemistry

• Though usually too small to be seen by the

unaided eye, cells can be complex


Microscopy

• Scientists use microscopes to visualize cells too

small to see with the naked eye

• In a light microscope (LM), visible light passes

through a specimen and then through glass

lenses, which magnify the image


The Path of Light in the Light Microscope

• http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab2/IMAGES/BRIGHTFIELD

%20SCOPE%20DIAGRAM.JPG

http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab2/IMAGES/BRIGHTFIELD SCOPE DIAGRAM.JPG

http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab2/IMAGES/BRIGHTFIELD SCOPE DIAGRAM.JPG


Microscopy

• The quality of an image depends on:

– Magnification, the ratio of an object’s image size to its real size

– Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points

– Contrast, visible differences in parts of the sample


Microscopy / Magnification

Magnification, the ratio of an object’s image size to its real size.

LMs can magnify effectively to about 1,000 times the size of the actual specimen


Microscopy / Resolution

Resolution, the measure of the clarity of the image, or the minimum distance of two distinguishable points


Microscopy / Resolution

• The minimum resolution of a LM is about 200 nanometers (nm), the size of a small bacterium.

• The practical resolution limit of the electron microscope is closer to about 2 nm

• Most subcellular structures, or organelles, are too small to be resolved by a LM


Microscopy / Contrast

- Contrast, visible differences in parts of the sample

- Various techniques enhance contrast and enable

cell components to be stained or labeled

Brightfield (unstained

specimen)

50 µm

Brightfield (stained

specimen)

Phase-contrast Fluorescence


Electron Microscopes

• Electrons are used instead of light.

• Two basic types of electron microscopes (EMs)

are used to study subcellular structures

1. Transmission electron microscopes (TEMs)

focus a beam of electrons through a specimen

• TEMs are used mainly to study the internal

ultrastructure of cells


Transmission Electron Microscope (TEM)


Scanning Electron Microscope (SEM)

2. Scanning electron microscopes (SEMs) focus a

beam of electrons onto the surface of a specimen,

providing images that look 3D

LE 6-4 1 µm

1 µm

Scanning electron microscopy (SEM) Cilia

Longitudinal section of cilium

Transmission electron microscopy (TEM)

Cross section of cilium


Isolating Organelles by Cell Fractionation

• Cell fractionation takes cells apart and separates

the major organelles from one another

• Cell fractionation enables scientists to determine

the functions of organelles


Pellet rich in nuclei and cellular debris

Pellet rich in mitochondria (and chloroplasts if cells are from a plant)

Pellet rich in “microsomes” (pieces of plasma membranes and cells’ internal membranes)

Pellet rich in

ribosomes

150,000 g 3 hr

80,000 g 60 min

20,000 g 20 min

1000 g (1000 times the force of gravity)

10 min

Supernatant poured into next tube


Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions

• Every organism has one of two types of cells:

– prokaryotic or

– eukaryotic

• Only organisms of the domains Bacteria and

Archaea consist of prokaryotic cells

• Protists, fungi, animals, and plants all consist of

eukaryotic cells


Basic features of all cells

• All cells have the following features in common:

– Plasma membrane

– Cytoplasm

– Chromosomes (carry genes in the form of

DNA)

– Ribosomes (make proteins according to

instructions from the genes)


Comparing Prokaryotic and Eukaryotic Cells

• Prokaryotic cells are characterized by having

– No nucleus

– DNA in an unbound region called the nucleoid

– No membrane-bound organelles

– Cytoplasm bound by the plasma membrane


Prokaryotic Cells

Fimbriae

Nucleoid

Ribosomes

Plasma membrane

Cell wall

Capsule

Flagella

Bacterial chromosome

(a) A typical rod-shaped bacterium

(b) A thin section through the bacterium Bacillus coagulans (TEM)

0.5 µm


Eukaryotic cells

• Eukaryotic cells are characterized by having

– DNA in a nucleus that is bounded

by a membranous nuclear envelope

– Membrane-bound organelles

– Cytoplasm in the region between the plasma

membrane and nucleus

• Eukaryotic cells are generally much larger than

prokaryotic cells


Cytoplasm’s Components of Eukaryotic Cells

The cytoplasm consists of:

– Organelles

– Cytosol

Organelles:

• Specific entities, each carries out a specific function for the cell.

Cytosol:

• The viscous, semitransparent fluid in which other cytoplasmic elements are suspended.

• Largely water with dissolved protein, salts, sugars, and other solutes.


Why Cells are Small?

• A smaller cell has a higher surface area to

volume ratio, which facilitates the exchange of

materials into and out of the cell.

• Larger organisms do NOT generally have

larger cells than smaller organisms – simply

more cells

LE 6-7

Total surface area

(height x width x

number of sides x

number of boxes)

6

125 125

150 750

1

1

1

5

1.2 6 6

Total volume

(height x width x length

X number of boxes)

Surface-to-volume

ratio

(surface area volume)

Surface area increases while

Total volume remains constant


A Panoramic View of the Eukaryotic Cell

• Every cell is surrounded by a plasma

membrane.

• The plasma membrane is a selective barrier that

allows sufficient passage of oxygen, nutrients,

and waste to service the volume of the cell

• Eukaryotic cells have internal membranes that

partition the cell into organelles

• Plant and animal cells have most of the same

organelles

LE 6-9a

Flagellum

Centrosome

CYTOSKELETON

Microfilaments

Intermediate filaments

Microtubules

Peroxisome

Microvilli

ENDOPLASMIC RETICULUM (ER

Rough ER Smooth ER

Mitochondrion Lysosome

Golgi apparatus

Ribosomes:

Plasma membrane

Nuclear envelope

NUCLEUS

In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)

Nucleolus

Chromatin

LE 6-9b

Rough endoplasmic reticulum

In plant cells but not animal cells: Chloroplasts Central vacuole and tonoplast Cell wall Plasmodesmata

Smooth endoplasmic reticulum

Ribosomes (small brown dots)

Central vacuole

Microfilaments


Microtubules

CYTOSKELETON

Chloroplast

Plasmodesmata

Wall of adjacent cell

Cell wall

Nuclear envelope

Nucleolus

Chromatin

NUCLEUS

Centrosome

Golgi apparatus

Mitochondrion

Peroxisome

Plasma membrane


Concept 6.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes

• The nucleus contains most of the genes (DNA) in

a eukaryotic cell.

Functions of the nucleus:

1. The nucleus controls cellular activities by making

proteins.

2. In the nucleus, DNA replication takes place to

transmit information from parents to offspring.


The Nucleus: Genetic Library of the Cell

The nucleus is made of

the following parts:

1. The nuclear envelope: a double

membrane with pores enclosing the

nucleus,.

2. The nucleolus: Where components

of ribosomes are synthesized and

assembled to form ribosomal

subunits.

3. The chromatin: the fibrous material

in the nucleus of a nondividing cell,

made of DNA and associated

proteins.

LE 6-10

Close-up of nuclear envelope

Nucleus

Nucleolus

Chromatin

Nuclear envelope:

Inner membrane

Outer membrane

Nuclear pore

Pore

complex

Ribosome

Pore complexes (TEM) Nuclear lamina (TEM)

1 µm

Rough ER

Nucleus

1 µm

0.25 µm

Surface of nuclear envelope


Ribosomes: Protein Factories in the Cell

• Ribosomes are particles made of ribosomal RNA and

protein

• Ribosomes carry out protein synthesis in two locations:

– In the cytosol. Free ribosomes synthesize proteins

that function within the cytosol.

– On the outside of the endoplasmic reticulum (ER) or

the nuclear envelope. Bound ribosomes synthesize

proteins that:

a. Build membranes

b. Are to be exported from the cell.

LE 6-11

Ribosomes

0.5 µm

ER Cytosol

Endoplasmic

reticulum (ER)

Free ribosomes

Bound ribosomes

Large

subunit

Small

subunit

Diagram of

a ribosome

TEM showing ER

and ribosomes


Concept 6.4: The endomembrane system regulates protein traffic and performs metabolic functions in the cell

• In the cell, the endomembrane system is the membranous components that are either in direct contact or connected via transfer by vesicles.

• These components make up the endomembrane system that includes the:

– Nuclear envelope

– Endoplasmic reticulum

– Golgi apparatus

– Lysosomes

– Vacuoles

– Plasma membrane


The Endomembrane System

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi

Plasma

membrane


The Endoplasmic Reticulum: Biosynthetic Factory

• The endoplasmic reticulum (ER) accounts for

more than half of the total membrane in many

eukaryotic cells

• The ER membrane is continuous with the nuclear

envelope

• There are two distinct regions of ER:

– Smooth ER, which lacks ribosomes

– Rough ER, with ribosomes studding its surface

LE 6-12

Ribosomes

Smooth ER

Rough ER

ER lumen

Cisternae

Transport vesicle

Smooth ER Rough ER

Transitional ER

200 nm

Nuclear

envelope


Functions of Smooth ER

• The smooth ER

– Synthesizes lipids

– Metabolizes carbohydrates

– Stores calcium ions necessary for muscle

contraction.

– Detoxifies poisons and drugs


Functions of Rough ER

• The rough ER

– Has bound ribosomes

– Is a membrane factory for the cell

– Produces proteins that:

a.Build membranes

b.Are to be exported from the cell.


• The Golgi apparatus consists of flattened

membranous sacs called cisternae

The Golgi Apparatus: Shipping and Receiving Center



• Functions of the Golgi apparatus:

– Modifies products of the ER

– Manufactures certain macromolecules,

including some polysaccharides.

– Sorts and packages materials into transport

vesicles

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.20

Protein- containing

vesicles pinch off rough ER

and migrate to fuse with

membranes of Golgi

apparatus.

Proteins are modified within

the Golgi compartments.

Proteins are then packaged within different vesicle types, depending on their ultimate

destination.

Plasma membrane

Secretion by exocytosis

Vesicle becomes lysosome

Golgi apparatus

Rough ER ER membrane

Phagosome

Proteins in cisterna

Pathway B:

Vesicle membrane to be incorporated

into plasma membrane Pathway A:

Vesicle contents destined for exocytosis Extracellular fluid

Secretory vesicle

Pathway C:

Lysosome containing acid hydrolase

enzymes

1

3

2



Lysosomes: Digestive Compartments

• Lysosomes are membranous sacs of hydrolytic enzymes

that digest macromolecules such as proteins, fats,

polysaccharides, and nucleic acids.

• Functions of lysosomes:

• Intracellular digestion: Lysosomes can fuse with food vacuoles containing food items brought into the cell by phagocytosis.

• Recycle cell’s own organic material: Lysosomes use enzymes to recycle organelles and macromolecules, a process called autophagy.

• Programmed cell destruction in multicellular organisms or apoptosis

LE 6-14a

Phagocytosis: lysosome digesting food

1 µm

Plasma

membrane

Food vacuole

Lysosome

Nucleus

Digestive

enzymes

Digestion

Lysosome

Lysosome contains active hydrolytic enzymes

Food vacuole fuses with lysosome

Hydrolytic enzymes digest food particles

LE 6-14b

Autophagy: lysosome breaking down damaged organelle

1 µm

Vesicle containing damaged mitochondrion

Mitochondrion fragment

Lysosome containing two damaged organelles

Digestion

Lysosome

Lysosome fuses with vesicle containing damaged organelle

Peroxisome fragment

Hydrolytic enzymes digest organelle components


Vacuoles: Diverse Maintenance Compartments

• Vesicles and vacuoles (larger versions of vesicles) are membrane-bound sacs with varied functions

• A plant cell or fungal cell may have one or several

vacuoles


Types of vacuoles in various cells:

• Food vacuoles are formed by phagocytosis

• Contractile vacuoles, found in many freshwater

protists, pump excess water out of cells

• Central vacuoles, found in many mature plant

cells. The membrane surrounding the central

vacuole is called the tonoplast.

LE 6-15

5 µm

Central vacuole

Cytosol

Tonoplast

Central

vacuole Nucleus

Cell wall

Chloroplast


Functions of the Central Vacuole:

• Stockpiling proteins and inorganic ions.

• Storing pigments.

• Storing defensive compounds against

herbivores.

• Increasing the surface area to volume ratio for

the whole cell.


The Endomembrane System: A Review

• The endomembrane system regulates protein

traffic and performs metabolic functions in the

cell

LE 6-16-1

Nuclear envelope

Nucleus

Rough ER

Smooth ER


The endomembrane system:

- regulates protein traffic within the cell

- performs metabolic functions in the cell

LE 6-16-2

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi


LE 6-16-3

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi

Plasma

membrane



Concept 6.5: Mitochondria and chloroplasts change energy from one form to another

• Mitochondria and chloroplasts are not part of the endomembrane system.

• Both organelles have:

1- Small quantities of DNA

2- Their own ribosomes

3- Double membranes.


Mitochondria: Structure

• Mitochondria are in nearly all eukaryotic cells

• They have a smooth outer membrane and an inner membrane folded into cristae

• The inner membrane creates two compartments: intermembrane space and mitochondrial matrix


Mitochondria: Make ATP

• Mitochondria are the sites of cellular respiration , generating energy for the cell in the form of ATP.

• Cristae present a large surface area for enzymes that synthesize ATP

LE 6-17

Mitochondrion

Intermembrane space

Outer

membrane

Inner

membrane

Cristae

Matrix

100 nm Mitochondrial

DNA

Free

ribosomes

in the

mitochondrial

matrix


Chloroplasts: Capture of Light Energy

• Chloroplasts contain the green pigment

chlorophyll, as well as enzymes and other

molecules that function in photosynthesis.

• In photosynthesis, the plants make sugar by

using light energy, carbon dioxide and

water.

• Chloroplasts are found in the leaves and

other green organs of plants and in algae

LE 6-18

Chloroplast

Chloroplast

DNA

Ribosomes

Stroma

Inner and outer

membranes

Granum

Thylakoid 1 µm

Chloroplast structure includes:

-Thylakoid membranes:

membranous sacs that are stacked

in some regions like poker chips into

grana (singular is granum)

- Stroma, the internal fluid

surrounding the thylakoid

membanes.


Peroxisomes

• Peroxisomes are specialized metabolic

compartments bounded by a single membrane

• Peroxisomes produce hydrogen peroxide and

convert it to water.

• Peroxisomes in the liver detoxify alcohol and other

harmful compounds.

Peroxisome

1 µm


Concept 6.6: The cytoskeleton is a network of fibers that organizes structures and activities in the cell

• The cytoskeleton is a network of fibers extending

throughout the cytoplasm

• It helps to support the cell and maintain its shape

• It interacts with motor proteins to produce motility

• Inside the cell, vesicles can travel along “monorails” provided by the cytoskeleton

• It is composed of three types of molecular structures:

– Microtubules

– Microfilaments

– Intermediate filaments


Microtubules

• Microtubules are the thickest of the three components of

the cytoskeleton


Microtubules / Maintenance of Cell Shape


Microtubules / Chromosome Movement in Cell Division

Vesicle

Receptor for

motor protein

Microtubule

of cytoskeleton

Motor protein

(ATP powered)

ATP

Microtubules / Organelle Movements


Microtubules / Organelle Movements


Microtubules in Cellular Structures

• The following cellular structures have

microtubules as a basic component:

– Centrioles

– Cilia and flagella


Centrosomes and Centrioles

• In many cells, microtubules grow

out from a centrosome near the

nucleus

• The centrosome is a “microtubule-

organizing center”

• In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring. Centrioles have (9 + 0) arrangement of microtubules.


Centrosomes


Microtubules / Centrioles

0.25 µm

Microtubule

Centrosome

Centrioles

Longitudinal section of one centriole

Microtubules Cross section of the other centriole


Microtubules / Centrioles

Figure 3.25a

Centrosome matrix

(a)

Centrioles

Microtubules


Microtubules / Cilia and Flagella



Cilia and flagella are extensions of the plasma

membrane that share a common ultrastructure:

– A core of microtubules sheathed by the plasma

membrane. Cilia and flagella have (9 + 2)

arrangement of microtubules.

– A basal body that anchors the cilium or

flagellum with a (9 + 0) arrangement of

microtubules.



0.5 µm

Microtubules

Plasma

membrane Basal body

Plasma

membrane

0.1 µm

Cross section of basal body

Triplet

Outer microtubule

doublet 0.1 µm

Dynein arms

Central

microtubule

Cross-linking

proteins inside

outer doublets

Radial

spoke

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.27

(a) Phases of ciliary motion.

(b) Traveling wave created by the activity of

many cilia acting together propels mucus

across cell surfaces.

Power, or propulsive, stroke

Layer of mucus

Cell surface

Recovery stroke, when cilium is returning to its initial position

1 2 3 4 5 6 7

Cilia and flagella differ in their beating patterns


Components of the Cytoskeleton / Microfilament

• Microfilaments, also called actin filaments, are

the thinnest components


Microfilaments (Actin Filaments)

Microfilaments are solid rods

built as a twisted double

chain of actin subunits

• The structural role of microfilaments is to bear tension, resisting pulling forces within the cell

• They form a 3D network just inside the plasma membrane to help support the cell’s shape


Microfilaments in Microvilli

• Bundles of microfilaments make up the core of microvilli of intestinal cells

Microvillus

Actin

filaments


Microfilaments / Changes in Cell Shape and Cell Motility (as in Pseudopodia)


Microfilaments / Muscle Contraction

Muscle cell

Actin filament

Myosin filament

Myosin arm

Myosin motors in muscle cell contraction


Microfilaments / Animal Cell Division (Cleavage Furrow Formation)


Microfilaments / Cytoplasmic Streaming

http://www.youtube.com/watch?v=n841Ab2c83Q

http://www.youtube.com/watch?v=n841Ab2c83Q


Intermediate Filaments

• Intermediate filaments are fibers with diameters

in a middle range between microtubules and

microfilaments.


Intermediate Filaments / Anchorage of cell organelles


Intermediate Filaments / Formation of Nuclear Lamina

Nuclear lamina (TEM)


Label The Cellular Organelles and Structures


Concept 6.7: Extracellular components and connections between cells help coordinate cellular activities

• Most cells synthesize and secrete materials that

are external to the plasma membrane

• These extracellular structures include:

– Cell walls of plants

– The extracellular matrix (ECM) of animal cells

– Intercellular junctions


Cell Walls of Plants

• The cell wall is an extracellular structure that

distinguishes plant cells from animal cells

• The cell wall:

– protects the plant cell

– maintains the plant cell shape

– prevents excessive uptake of water by the cell

• Plant cell walls are made of cellulose fibers

embedded in other polysaccharides and protein


Cell Walls of Plants

• Plant cell walls may have multiple layers:

– Primary cell wall: relatively thin and flexible

– Middle lamella: thin layer between primary walls of adjacent cells

– Secondary cell wall (in some cells): added between the plasma membrane and the primary cell wall

LE 6-28

Central

vacuole

of cell

Plasma

membrane

Secondary

cell wall

Primary

cell wall

Middle

lamella

1 µm

Central

vacuole

of cell

Central vacuole

Cytosol

Plasma membrane

Plant cell walls

Plasmodesmata


Intercellular Junctions in Plants

Plasmodesmata are channels between adjacent plant

cells

• Through plasmodesmata, water and small solutes (and

sometimes proteins and RNA) can pass from cell to cell

Interior

of cell

Interior

of cell

0.5 µm Plasmodesmata Plasma membranes

Cell walls


The Extracellular Matrix (ECM) of Animal Cells

• Animal cells lack cell walls but are covered by an

elaborate extracellular matrix (ECM)

• The ECM is made up of glycoproteins and other

macromolecules


Intercellular Junctions in Animals

• Neighboring cells in tissues, organs, or organ systems often adhere, interact, and communicate through direct physical contact

• Intercellular junctions facilitate this contact.

• Animals have 3 main types of intercellular junctions:

– Tight junctions.

– Desmosomes (anchoring junctions).

– Gap (Communicating) junctions.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.5a

Interlocking

junctional proteins

Intercellular

space

Plasma membranes

of adjacent cells

Microvilli

Intercellular

space

Basement membrane

(a) Tight junctions: Impermeable junctions prevent molecules

from passing through the intercellular space.

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.5b

Intercellular space

Plasma membranes

of adjacent cells

Microvilli

Intercellular

space

Plaque

Linker glycoproteins

(cadherins)

Intermediate

filament (keratin)

(b) Desmosomes: Anchoring junctions bind adjacent cells together

and help form an internal tension-reducing network of fibers.

Basement membrane

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Figure 3.5c

Plasma membranes

of adjacent cells Microvilli

Intercellular

space

Intercellular

space

Channel

between cells

(connexon)

(c) Gap junctions: Communicating junctions allow ions and small mole-

cules to pass from one cell to the next for intercellular communication.

Basement membrane

LE 6-31

Tight junctions prevent

fluid from moving

across a layer of cells

Tight junction

0.5 µm

1 µm

0.1 µm

Gap junction

Extracellular

matrix

Space

between

cells

Plasma membranes

of adjacent cells


Tight junction

Desmosome

Gap junctions


The Cell: A Living Unit Greater Than the Sum of Its Parts

• Cells rely on the integration of structures and

organelles in order to function

• For example, a macrophage’s ability to destroy

bacteria involves the whole cell, coordinating

components such as the cytoskeleton, lysosomes,

and plasma membrane


You should now be able to:

1. Distinguish between the following pairs of terms:

magnification and resolution; prokaryotic and

eukaryotic cell; free and bound ribosomes;

smooth and rough ER

2. Describe the structure and function of the

components of the endomembrane system

3. Briefly explain the role of mitochondria,

chloroplasts, and peroxisomes

4. Describe the functions of the cytoskeleton

5. Describe four different intercellular junctions

a tour of the cell · chapter 6 a tour of the cell powerpoint lectures are originally from campbell...

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