kelas berrtaraf internasional smak penabur gading serpong 2012/2013 cell structure and function...

Kelas Berrtaraf Internasional SMAK PENABUR Gading Serpong 2012/2013

CELL STRUCTURE AND FUNCTION

CHAPTER 1

Leonardus, S.Si.


Content

• The microscope in cell studies

• Cells as the basic units of living organisms

• Detailed structure of typical animal and plant cells, as seen under the electron microscope

• Outline functions of organelles in plant and animal cells

• Characteristics of prokaryotic and eukaryotic cells


Learning Outcomes

Candidates should be able to:

• (a) [PA] use an eyepice graticule and stage micrometer to measure cells and be familiar with units (millimetre, micrometre, nanometre) used in cell studies;

• (b) explain and distinguish between resolution and magnification, with reference to light microscopy and electron microscopy;


Learning Outcomes

• (c) describe and interpret drawings and photographs of typical animal and plant cells, as seen under the electron microscope, recognising the following membrane systems and organelles: rough and smooth endoplasmic reticula, Golgi apparatus, mitochondria, ribosomes, lysosomes, chloroplasts, plasma/cell surface membrane, nuclear envelope, centrioles, nucleus and nucleolus;

• (d) outline the functions of the membrane systems and organelles listed in (c);


Learning Outcomes

• (e) [PA] compare and contrast the structure of typical animal and plant cells;

• (f) [PA] draw and label low power diagrams of tissues (including a transverse section of a stems, roots, and leaves) and calculate the linear magnification of drawings;

• (g) describe the structure of a prokaryotic cell and compare and contrast the structure of prokaryotic cells with eukaryotic cells;

• (h) use the knowledge gained in this section in new situations or to solve related problems.


Introduction

Overview: The Importance of Cells

• All organisms are made of cells

• The cell is the simplest collection of matter that can live

• Cell structure is correlated to cellular function


Brief history

• R. Hooke (1665), an English scientist: cell

• A. v. Leeuwenhoek (1675), a Dutch lens maker: microscope, in the 150 years after his work, microscope lenses improved and scientists were able to observe and understand more parts of the cell.


Brief history

• In the mid-19th century, three different scientists working separately each published important conclusions about cells.

1. In 1838, Dutch botanist Matthias Schleiden concluded that all plants are composed of cells.

2. One year later, a German zoologist by the name of Theodor Schwaan postulated that animals are also composed of cells.

3. And in 1855, Rudolph Virchow, a German doctor, asserted that all cells must come from other cells by the process of cell division.


Cell Theory (based on 200+ years of discoveries)

• A. all living things are composed of cells

• B. cells are the basic unit of structure & function of all living things

• C. new cells are produced from existing cells


Why cells?

• Because cells are the most basic unit of life that all organisms share, understanding cells is the key to learning about life itself.


Microscope

• Cell biology: study of cells: cytology

• To study cells, biologists use microscopes as the tools

• Scientists use microscopes to visualize cells too small to see with the naked eye

• Type of microscopes:

1. light microscope (uses light as a source of radiation)

2. electron microscope (uses electrons)


Microscope

• Light microscopes (LM)

– Pass visible light through a specimen

– Magnify cellular structures with lenses


Microscope

– Use different methods for enhancing visualization of cellular structures

TECHNIQUE RESULT

Brightfield (unstained specimen). Passes light directly through specimen. Unless cell is naturally pigmented or artificially stained, image has little contrast. [Parts (a)–(d) show a human cheek epithelial cell.]

(a)

Brightfield (stained specimen). Staining with various dyes enhances contrast, but most staining procedures require that cells be fixed (preserved).

(b)

Phase-contrast. Enhances contrast in unstained cells by amplifying variations in density within specimen; especially useful for examining living, unpigmented cells.

(c)

50 µm


Microscope

Differential-interference-contrast (Nomarski). Like phase-contrast microscopy, it uses optical modifications to exaggerate differences indensity, making the image appear almost 3D.

Fluorescence. Shows the locations of specific molecules in the cell by tagging the molecules with fluorescent dyes or antibodies. These fluorescent substances absorb ultraviolet radiation and emit visible light, as shown here in a cell from an artery.

Confocal. Uses lasers and special optics for “optical sectioning” of fluorescently-stained specimens. Only a single plane of focus is illuminated; out-of-focus fluorescence above and below the plane is subtracted by a computer. A sharp image results, as seen in stained nervous tissue (top), where nerve cells are green, support cells are red, and regions of overlap are yellow. A standard fluorescence micrograph (bottom) of this relatively thick tissue is blurry.

50 µm

50 µm

(d)

(e)

(f)


Microscope

• Electron microscopes (EM)

– Focus a beam of electrons through a specimen (TEM) or onto its surface (SEM)


Microscope

• The scanning electron microscope (SEM)

– Provides for detailed study of the surface of a specimen

TECHNIQUE RESULTS

Scanning electron micro-scopy (SEM). Micrographs takenwith a scanning electron microscope show a 3D image of the surface of a specimen. This SEM shows the surface of a cell from a rabbit trachea (windpipe) covered with motile organelles called cilia. Beating of the cilia helps moveinhaled debris upward toward the throat.

(a)

Cilia1 µm


Microscope

• The transmission electron microscope (TEM)

– Provides for detailed study of the internal ultrastructure of cells

Transmission electron micro-scopy (TEM). A transmission electron microscope profiles a thin section of a specimen. Here we see a section through a tracheal cell, revealing its ultrastructure. In preparing the TEM, some cilia were cut along their lengths, creating longitudinal sections, while other cilia were cut straight across, creating cross sections.

(b) Longitudinalsection ofcilium

Cross sectionof cilium

1 µm


Units of measurement in cell studies

• International System of Units (SI Units)

Fraction of a metre Unit Symbol

One thousandth = 0.001 = 1/1000 = 10-3 millimetre mm

One millionth = 0.000001 = 1/1000000 = 10-6

micrometre µm

One thousandth millionth = 0.000000001 = 1/1000000000 = 10-9

nanometre nm


Size of some biological structures


Size of some biological structures

Una

ide

d e

ye

1 m

0.1 nm

10 m

0.1 m

1 cm

1 mm

100 µm

10 µ m

1 µ m

100 nm

10 nm

1 nm

Length of somenerve and muscle cells

Chicken egg

Frog egg

Most plant and Animal cells

Smallest bacteria

Viruses

Ribosomes

Proteins

Lipids

Small molecules

Atoms

NucleusMost bacteriaMitochondrion

Lig

ht m

icro

sco

pe

Ele

ctro

n m

icro

sco

pe

Ele

ctro

n m

icro

sco

pe

Human height

Measurements1 centimeter (cm) = 102 meter (m) = 0.4 inch1 millimeter (mm) = 10–3 m1 micrometer (µm) = 10–3 mm = 10–6 m1 nanometer (nm) = 10–6 mm = 10–9 m


Measuring cells – eyepiece graticule



stage micrometer scale (marked in 0.01 mm and 0.1 mm divisions

eyepice graticule scale (arbitrary units)



eyepiece graticule in the eyepiece of the microscopes

cheek cells on a slide on the stage of the microscope


Magnification dan resolution

• Magnification: the number of times larger an images is compared with the real size of the object

size of image

actual size of specimen

• Resolution: the ability to distinguish between to separate points

magnification =


Cell Types

• Two types of cells make up every organisms

– Prokaryotic

– Eukaryotic


Cell Types

• All cells have several basic features in common

– They are bounded by a plasma membrane

– They contain a semifluid substance called the cytosol

– They contain chromosomes

– They all have ribosomes


Prokaryotic cells

• Prokaryotic cells

– Do not contain a nucleus (do not have a nuclear membrane)

– Have their DNA located in a region called the nucleoid


Prokaryotic cells

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

Pili: attachment structures onthe surface of some prokaryotes

Nucleoid: region where thecell’s DNA is located (notenclosed by a membrane)

Ribosomes: organelles thatsynthesize proteins

Plasma membrane: membraneenclosing the cytoplasm

Cell wall: rigid structure outsidethe plasma membrane

Capsule: jelly-like outer coatingof many prokaryotes

Flagella: locomotionorganelles ofsome bacteria

(a) A typical rod-shaped bacterium

0.5 µmBacterial

chromosome


Prokaryotic cells


Eukaryotic cells

• Eukaryotic cells

– Contain a true nucleus, bounded by a membranous nuclear envelope

– Are generally quite a bit bigger than prokaryotic cells

– Have extensive and elaborately arranged internal membranes, which form organelles

– Have internal membranes that compartmentalize their functions


Eukaryotic cells: Plant and animal cell

• A side-by-side view of an animal and plant cell. Plant cells contain special organelles called chloroplasts and an outer covering called a cell wall. Animal cells lack both of these structures.


Animal cell

Rough ER Smooth ER

Centrosome

CYTOSKELETON

Microfilaments

Microtubules

Microvilli

Peroxisome

Lysosome

Golgi apparatus

Ribosomes

In animal cells but not plant cells:LysosomesCentriolesFlagella (in some plant sperm)

Nucleolus

Chromatin

NUCLEUS

Flagellum

Intermediate filaments

ENDOPLASMIC RETICULUM (ER)

Mitochondrion

Nuclear envelope

Plasma membrane


Plant cell

In plant cells but not animal cells:ChloroplastsCentral vacuole and tonoplastCell wallPlasmodesmata

CYTOSKELETON

Ribosomes (small brwon dots)

Central vacuole

Microfilaments


Microtubules

Rough endoplasmic reticulum

Smooth endoplasmic reticulum

ChromatinNUCLEUS

Nuclear envelope

Nucleolus

Chloroplast

PlasmodesmataWall of adjacent cell

Cell wall

Golgi apparatus

Peroxisome

Tonoplast

Centrosome

Plasma membrane

Mitochondrion


Outside of cell

Inside of cell

Hydrophilicregion

Hydrophobicregion

Hydrophilicregion

(b) Structure of the plasma membrane

Phospholipid Proteins

TEM of a plasmamembrane. Theplasma membrane,here in a red bloodcell, appears as apair of dark bandsseparated by alight band.

(a)

0.1 µm

Plasma Membrane

• Functions as a selective barrier

• Allows food, oxygen, & water into the cell & waste products out of the cell.

• Outer covering, protective layer around all cells

Carbohydrate side chain

back


The Nucleus: Genetic Library of the Cell

• The nucleus

– Contains most of the genes in the eukaryotic cell

• Directs all cell activities

• Contains instructions for everything the cell does

• These instructions are found on a hereditary material called DNA

• Usually the largest organelle

back


The Nuclear Envelope

• Encloses the nucleus, separating its contents from the cytoplasm

• controls movement of materials in & out of nucleus Nucleus

NucleusNucleolus

Chromatin

Nuclear envelope:Inner membraneOuter membrane

Nuclear pore

Rough ER

Porecomplex

Surface of nuclear envelope.

Pore complexes (TEM). Nuclear lamina (TEM).

Close-up of nuclearenvelope

Ribosome

1 µm

1 µm0.25 µm

back


Nucleolus

• “little nucleus”

• Found in the nucleus

back


Chromatin

• contains genetic code that controls cell

• made of DNA & proteins

back


Ribosomes: Protein Factories in the Cell

• Are particles made of ribosomal RNA and protein

• Float freely or attached to the endoplasmic reticulum (ER)

• made in the nucleolus

• Carry out protein synthesis


Ribosomes Cytosol

Free ribosomes

Bound ribosomes

Largesubunit

Smallsubunit

TEM showing ER and ribosomes Diagram of a ribosome

0.5 µm

Ribosomes: Protein Factories in the Cell

Endoplasmic reticulum (ER)

ER

back


The Endoplasmic Reticulum: Biosynthetic Factory

• The endoplasmic reticulum (ER)

– Accounts for more than half the total membrane in many eukaryotic cells

– A series of folded membranes that move materials (proteins) around in a cell

– like a conveyor belt

– Smooth ER – ribosomes not attached to ER

– Rough ER – ribosomes attached to ER



• The function of smooth ER

– Synthesizes lipids

– Metabolizes carbohydrates

– Stores calcium

– Detoxifies poison



• The function of rough ER

– Produces proteins and membranes, which are distributed by transport vesicles



Smooth ER

Rough ER

ER lumen

Cisternae

RibosomesTransport vesicle

Smooth ER

Transitional ER

Rough ER 200 µm

Nuclearenvelope

back

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

• The Golgi apparatus

– Receives many of the transport vesicles produced in the rough ER

– Consists of flattened membranous sacs called cisternae

• Functions of the Golgi apparatus include:

– Sort and package proteins

The Golgi Apparatus: Shipping and Receiving Center

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

The Golgi Apparatus: Shipping and Receiving Center

cis face(“receiving” side ofGolgi apparatus)

Vesicles movefrom ER to Golgi Vesicles also

transport certainproteins back to ER

Vesicles coalesce toform new cis Golgi cisternae

Cisternalmaturation:Golgi cisternaemove in a cis-to-transdirection

Vesicles form andleave Golgi, carryingspecific proteins toother locations or tothe plasma mem-brane for secretion

Vesicles transport specificproteins backward to newerGolgi cisternae

Cisternae

trans face(“shipping” side ofGolgi apparatus)

0.1 0 µm16

5

2

3

4

Golgiapparatus

TEM of Golgi apparatus

back


Lysosomes: Digestive Compartments

• A lysosome

– Is a membranous sac of hydrolytic enzymes

– Can digest all kinds of macromolecules such as food or break down the cell when it dies

• Lysosomes carry out intracellular digestion by

– Phagocytosis

– Autophagy


(a) Phagocytosis: lysosome digesting food

1 µm

Lysosome contain active hydrolytic enzymes Food vacuole fuses with lysosome Hydrolytic enzymes digest food particles

Digestion

Food vacuole

Plasma membrane

Lysosome

Digestiveenzymes

Lysosome

Nucleus

Lysosomes: Phagocytosis


(b) Autophagy: lysosome breaking down damaged organelle

Lysosome containingtwo damaged organelles 1 µ m

Mitochondrionfragment

Peroxisomefragment

Lysosome fuses with vesicle containingdamaged organelle

Hydrolytic enzymesdigest organelle components

Vesicle containingdamaged mitochondrion

Digestion

Lysosome

Lysosomes: Autophagy

back


The Endomembrane System: A Review

• The endomembrane system

– Is a complex and dynamic player in the cell’s compartmental organization


Plasma membrane expandsby fusion of vesicles; proteinsare secreted from cell

Transport vesicle carriesproteins to plasma membrane for secretion

Lysosome availablefor fusion with anothervesicle for digestion

4 5 6

Nuclear envelope isconnected to rough ER, which is also continuous

with smooth ER

Nucleus

Rough ER

Smooth ERcis Golgi

trans Golgi

Membranes and proteinsproduced by the ER flow in

the form of transport vesiclesto the Golgi Nuclear envelop

Golgi pinches off transport Vesicles and other vesicles

that give rise to lysosomes and Vacuoles

1

3

2

Plasmamembrane

The Endomembrane System: A Review

• Relationships among organelles of the endomembrane system


Mitochondria: Chemical Energy Conversion

• Mitochondria

– Are found in nearly all eukaryotic cells

– Are the sites of cellular respiration

• Mitochondria are enclosed by two membranes:

– A smooth outer membrane

– An inner membrane folded into cristae


Mitochondria: Chemical Energy Conversion

Mitochondrion

Intermembrane space

Outermembrane

Freeribosomesin the mitochondrialmatrix

MitochondrialDNA

Innermembrane

Cristae

Matrix

100 µm

back


Peroxisomes: Oxidation

• Peroxisomes

– Produce hydrogen peroxide and convert it to water

ChloroplastPeroxisome

Mitochondrion

1 µmback


The Cytoskeleton

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


The Cytoskeleton

• The cytoskeleton

– Is a network of fibers extending throughout the cytoplasm

Microtubule

0.25 µm Microfilaments


Roles of the Cytoskeleton: Support, Motility, and Regulation

• The cytoskeleton

– Gives mechanical support to the cell


Roles of the Cytoskeleton: Support, Motility, and Regulation

– Is involved in cell motility, which utilizes motor proteins

VesicleATP

Receptor formotor protein

Motor protein(ATP powered)

Microtubuleof cytoskeleton

(a) Motor proteins that attach to receptors on organelles can “walk”the organelles along microtubules or, in some cases, microfilaments.

Microtubule Vesicles 0.25 µm

(b) Vesicles containing neurotransmitters migrate to the tips of nerve cell axons via the mechanism in (a). In this SEM of a squid giant axon, two vesicles can be seen moving along a microtubule. (A separate part of the experiment provided the evidence that they were in fact moving.)


Components of the Cytoskeleton

• There are three main types of fibers that make up the cytoskeleton

back


Microtubules

• Microtubules

– Shape the cell

– Guide movement of organelles

– Help separate the chromosome copies in dividing cells

back


Centrosomes and Centrioles

• The centrosome

– Is considered to be a “microtubule-organizing center”


Centrosomes and Centrioles

– Centrosome contains a pair of centrioles

Centrosome

Microtubule

Centrioles

0.25 µm

Longitudinal sectionof one centriole

Microtubules Cross sectionof the other centriole

back


Cilia and Flagella

• Cilia and flagella

– Contain specialized arrangements of microtubules

– Are locomotor appendages of some cells


Cilia and Flagella

• Cilia and flagella share a common ultrastructure

(a)

(c)

(b)

Outer microtubuledoublet

Dynein arms

Centralmicrotubule

Outer doublets cross-linkingproteins inside

Radialspoke

Plasmamembrane

Microtubules

Plasmamembrane

Basal body

0.5 µm

0.1 µm

0.1 µm

Cross section of basal body

Triplet


Cilia and Flagella

• The protein dynein

– Is responsible for the bending movement of cilia and flagella

Microtubuledoublets ATP

Dynein arm

Powered by ATP, the dynein arms of one microtubule doublet grip the adjacent doublet, push it up, release, and then grip again. If the two microtubule doublets were not attached, they would slide relative to each other.

(a)


Outer doubletscross-linkingproteins

Anchoragein cell

ATP

In a cilium or flagellum, two adjacent doublets cannot slide far because they are physically restrained by proteins, so they bend. (Only two ofthe nine outer doublets in Figure 6.24b are shown here.)

(b)

Cilia and Flagella


Localized, synchronized activation of many dynein arms probably causes a bend to begin at the base of the Cilium or flagellum and move outward toward the tip. Many successive bends, such as the ones shown here to the left and right, result in a wavelike motion. In this diagram, the two central microtubules and the cross-linking proteins are not shown.

(c)

1 3

2

Cilia and Flagella


Flagella

• Flagella beating pattern

(a) Motion of flagella. A flagellum usually undulates, its snakelike motion driving a cell in the same direction as the axis of the flagellum. Propulsion of a human sperm cell is an example of flagellatelocomotion (LM).

1 µm

Direction of swimming

back


Cilia

• Ciliary motion

(b) Motion of cilia. Cilia have a back- and-forth motion that moves the cell in a direction perpendicular to the axis of the cilium. A dense nap of cilia, beating at a rate of about 40 to 60 strokes a second, covers this Colpidium, a freshwater protozoan (SEM).

15 µm


Cilia

• Ciliary motion

back


Microfilaments (Actin Filaments)

• Microfilaments

– Are built from molecules of the protein actin



– Are found in microvilli

0.25 µm

Microvillus

Plasma membrane

Microfilaments (actinfilaments)




• Microfilaments that function in cellular motility

– Contain the protein myosin in addition to actin

Actin filament

Myosin filament

Myosin motors in muscle cell contraction. (a)

Muscle cell

Myosin arm



• Amoeboid movement

– Involves the contraction of actin and myosin filaments

Cortex (outer cytoplasm):gel with actin network

Inner cytoplasm: sol with actin subunits

Extendingpseudopodium

(b) Amoeboid movement



• Cytoplasmic streaming

– Is another form of locomotion created by microfilaments

Nonmovingcytoplasm (gel)

Chloroplast

Streamingcytoplasm(sol)

Parallel actinfilaments Cell wall

(b) Cytoplasmic streaming in plant cellsback


Intermediate Filaments

• Intermediate filaments

– Support cell shape

– Fix organelles in place

back


The Cell Wall

• The cell wall

– Is an extracellular structure of plant cells that distinguishes them from animal cells


Central vacuoleof cell

Plasmamembrane

Secondarycell wall

Primarycell wall

Middlelamella

1 µm

Centralvacuoleof cell

Central vacuole

Cytosol

Plasma membrane

Plant cell walls

Plasmodesmata

The Cell Wall

• Plant cell walls

– Protects the cell

– Gives shape

– Are made of cellulose fibers embedded in other polysaccharides and protein

– Found in plant, algae, fungi, most bacteria

back


Chloroplasts: Capture of Light Energy

• The chloroplast

– Is a specialized member of a family of closely related plant organelles called plastids

– Contains chlorophyll

– Found in plants (leaves and other green organs) and in algae, are the sites of photosynthesis

• Chloroplast structure includes:

– Thylakoids, membranous sacs

– Stroma, the internal fluid


Chloroplasts: Capture of Light Energy

Chloroplast

ChloroplastDNA

Ribosomes

Stroma

Inner and outermembranes

Thylakoid

1 µm

Granum

back


Vacuoles: Diverse Maintenance Compartments

• A plant or fungal cell

– May have one or several vacuoles

1.Food vacuoles

– Are formed by phagocytosis

2.Contractile vacuoles

– Pump excess water out of protist cells


Vacuoles: Diverse Maintenance Compartments

• Central vacuoles

– Are found in plant cells

– Hold reserves of important organic compounds and water

Central vacuole

Cytosol

Tonoplast

Centralvacuole

Nucleus

Cell wall

Chloroplast

5 µm

back


Plasmodesmata

• Plasmodesmata

– Are channels that perforate plant cell walls

Interiorof cell

Interiorof cell

0.5 µm Plasmodesmata Plasma membranes

Cell walls

Figure 6.30

back


Two fundamentally different types of cell

kelas berrtaraf internasional smak penabur gading serpong 2012/2013 cell structure and function...

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