power point presentation of cells

8/3/2019 Power Point Presentation of CELLS

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The microscope was invented in the 17thcentury

Using a microscope, Robert Hooke discoveredcells in 1665: cellulae

INTRODUCTION TO THE WORLDOF THE CELL


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The light microscope enables us to see the overallshape and structure of a cell

Microscopes: windows to the world of thecell

Image seen by viewer

Eyepiece

Ocular

lens

Objective lensSpecimen

Condenser lens

Light source


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Electron microscopes were invented in the 1950s

They use a beam of electrons instead of light

The greater resolving power of electron

microscopes

allows greater magnification

reveals cellular details


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Scanningelectron

microscope(SEM)

Scanning

electronmicrograph ofcilia


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Transmissionelectron

microscope(TEM)

Transmission

electronmicrograph ofcilia


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The cell theorystates:

All organisms are composed of one or more cells.

Cells are the basic unit of structure and function inorganisms.

All cells come only from other cells.


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Cells are smallso they can exchange materials

with their surroundings.

Surface area relative to the volume decreases assize of cell increases.

- limits the size of cells


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Sizes of living things


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All cells have:

Plasma membrane

Region where DNA is stored Cytoplasm

2 Types:

- Prokaryotic

- Eukaryotic

Cells


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Domains: Archaebacteria and Eubacteria

Kingdom Monera

DNA is NOT enclosed in nucleus

Generally the smallest, simplest cells

No membrane bound organelles

Prokaryotic cells


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A prokaryotic cell is enclosed by a plasmamembrane and is usually encased in a rigid cell

wall

The cell wallmay be

covered by asticky capsule RibosomesCapsule

Cell wall

Plasma

membrane

Prokaryotic

flagella

Nucleoid region

(DNA)Pili

Inside the cell

are its DNAand otherparts


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Domain Eukarya

Plantae

Animalia

Protista

Fungi

Larger and more complex than prokaryotic cells Have a nucleus and other organelles

Eukaryotic cells


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An animal cell

Plasma membrane

Golgiapparatus

Ribosomes

NucleusSmooth

endoplasmic

reticulumRoughendoplasmic

reticulum

Mitochondrion

Not in

most

plant

cells

Cytoskeleton

Flagellum

Lysosome

Centriole

Peroxisome

Microtubule

Intermediate

filament

Microfilament


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Plant cells have structures that animal cells

lacks:

Chloroplasts

A rigid cell wall composed of cellulose

vacuole


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Nucleus

Golgi

apparatus

Not in

animal

cells

Centralvacuole

Chloroplast

Cell wall

Mitochondrion

Peroxisome

Plasma membrane

Rough

endoplasmic

reticulum

Ribosomes

Smooth

endoplasmic

reticulum

Cytoskeleton

Microtubule

Intermediate

filament

Microfilament


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Eukaryotic cells living factories

A Tour of the Cell


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Cell Function

Cells are the building blocks of all plants and animals

Cells are produced by the division of preexistingcells

Cells are the smallest units that perform all vitalphysiological functions

Each cell maintains homeostasis at the cellular

level

Homeostasis at higher levels reflects combined,coordinated action of many cells


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Cytology-the study of the structure and

function of cells

Cell biology

The human body contains both somatic and sex cells


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The Anatomy of a Representative Cell


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Is surrounded by extracellular fluid, which is the

interstitial fluid of the tissue

A typical cell

Has an outer boundary called the cell membrane

or plasma membrane


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A Typical Cell

1. Has structural components - cytoskeleton(made up of protein filaments)

2. Has organelles that perform specificfunctions in the cell (Mitochondria

-produces energy)

3. Has certain active genes to give the cell aspecific function (heart cells, liver cells,brain cells, etc)

4. Has the information to perpetuate thewhole organism as well as its specificfunction (Nucleus - DNA)


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Nonmembranous organelles are not enclosed by

a membrane and always in touch with the cytosol

Organelles

Cytoskeleton, microvilli, centrioles, cilia,ribosomes, proteasomes

Membranous organelles are surrounded by lipidmembranes

Endoplasmic reticulum, Golgi apparatus,

lysosomes, peroxisomes, mitochondria


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Different Types of Cell Movement (related tostructural components)

Internal - movement of proteins, molecules,organelles

External - movement of molecules into or out of the cellDetermined by cell membrane function and dynamics

Determined by cytoskeleton dynamics


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Physical isolation

Cell membrane functions include:

Regulation of exchange with the environment

Changes in ECF, pH, receptorrecognition

Structural support


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The cell membrane is a phospholipid bilayer with

proteins, lipids and carbohydrates.

The Cell Membrane


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Membrane StructureMembrane Structure

Primarily made up of lipids

With lipids

With carbohydrates

1. Lipids are the most abundant

Membrane called phospholipid bilayer

Outermost portions - hydrophilic

Innermost layers - hydrophobic

P bilit


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The ease with which substances can cross the cell membrane

Permeability

Nothing passes through an impermeable barrier

Anything can pass through a freely permeable

barrier

Cell membranes are selectively permeable

Selective permeability is based on size, electrical charges, molecular

shape, and lipid solubility.

Transport of substances across the membrane can be Passive or ActiveActive transport requires energy to occur

Passive transport does not require energy

Diffusion, Osmosis and Active Transport are different types of movement

Diff i h C ll M b


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Diffusion across the Cell Membrane


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Cell Motility

The movement of whole cells is made possible throughthe membrane pliability and the rearrangement of thecytoskeleton and internal components

C t k l t id t th fl ibilit d


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Microfilaments(6nm) -

1. anchor cytockeleton to integral proteins,2. determine the consistency of the cytoplasm,

3. interacts with myosin to produce movement

Cytoskeleton provides strength, flexibility andmotility

Intermediate filaments (7-11 nm)- Protein compositionvaries between cell types.

1. Strengthen cell and help maintain shape;

2. Stabilize the position of organelles

3. Stabilize the position of the cell with respect to surrounding cells thru

specialized membrane attachments


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Microtubules (up to 25nm)all cells contain microtubules, made up ofprotein tubulin. Largest cytoskeletal component

Functions:

1. Primary cytoskeletal component

2. Disassembly of microtubules provides a mechanism forchanging the shape of the cell and assisting in movement

3. Used to transport other proteins around the cell in association

with motor proteins kinesin and dynein

4. Forms spindle apparatus during cell division

5. Form structural cell components such as cilia and centrioles

Th C t k l t


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The Cytoskeleton

Th E d l i R ti l


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The Endoplasmic Reticulum

Site of protein and lipid synthesis

Th G l i A t


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The Golgi Apparatus

Forms secretory vesicles

Forms new membrane components

F ti f th G l i A t


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Functions of the Golgi Apparatus

L a d P i


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Lysosomes are

Lysosomes and Peroxisomes

Filled with digestive enzymes

Responsible for autolysis of injured cells

Peroxisomes

Carry enzymes that neutralize toxins

Lysosome Functions


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Lysosome Functions

Mitochondria


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Responsible for ATP production through aerobicrespiration

Mitochondria

Matrix = fluid contents of mitochondria

Cristae = folds in inner membrane

The nucleus is the center of cellular operations


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Surrounded by a nuclear envelope

The nucleus is the center of cellular operations

Perinuclear space

Communicates with cytoplasm through

nuclear pores

The Nucleus


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The Nucleus

Contents of the nucleus


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A supportive nuclear matrix

Contents of the nucleus

One or more nucleoli

Chromosomes

DNA bound to histones

Chromatin

Chromosome Structure


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Chromosome Structure

The genetic code


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The cells information storage system

The genetic code

Triplet code

A gene contains all the triplets needed to codefor a specific polypeptide

Gene activation and protein synthesis


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Gene activation initiates with RNA polymerasebinding to the gene

Gene activation and protein synthesis

Transcription is the formation of mRNA fromDNA

mRNA carries instructions from the nucleusto the cytoplasm


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The Cell Life Cycle


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DNA Replication


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DNA Replication

Early Prophase -


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Early Prophase Mitosis Begins

Duplicated chromosomes begin to condense

Nucleoli dissappear

centrosome(with centriole pairs)

Late Prophase


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Late Prophase

One centriole pair of thecentrosome is moved toward

opposite pole of spindle

Mitotic spindle forms Spindle fibers attach to

sister chromatids

Nuclear envelope starts to

break up

centriole

Mitotic

spindle

kinetochore

Metaphase


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Metaphase

All chromosomes arelined up at the

metaphase plate(equator)

Chromosomes aremaximally condensed

Anaphase


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Anaphase

Sister chromatids arepulled apart at thecentromere

Once separated, eachchromatid is achromosome

Each identical

chromosome movestoward opposite poles

Telophase


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Telophase

Chromosomes uncoil,

return to chromatin

Two nuclear membranesform, one around each set of

new chromosomes

Nucleoli reappear


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INTERPHASE PROPHASE

Centrosomes(with centriole pairs)

Chromatin

Nucleolus Nuclearenvelope

Plasmamembrane

Early mitoticspindle

Centrosome

CentromereChromosome,consisting of twosister chromatids

Fragmentsof nuclearenvelope

Kinetochore

Spindlemicrotubules


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METAPHASE TELOPHASE AND CYTOKINESIS

Metaphaseplate

Spindle Daughter chromosomes

Cleavagefurrow

Nucleolusforming

Nuclearenvelopeforming

ANAPHASE

Two Mechanisms of Cytokinesis


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Cytokinesis is thedivision of the cytoplasm

In animals, cytokinesisoccurs by cleavage

This process pinches thecell apart

Two Mechanisms of Cytokinesis

Cleavagefurrow

Cleavagefurrow

Contracting ring ofmicrofilaments

Daughter cells

Cell plate Wall of Daughter


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In plants, amembranous cellplate splits the cell intwo

pforming parent cell

gnucleus

Results of Mitosis


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Results of Mitosis

Two daughter nuclei

Each with same

chromosome number asparent cell

Each cell is geneticallyidentical

Review of the functions of mitosis:


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Multicellular organisms

Growth

Cell replacement

Some protistans, fungi, plants, animals

Asexual reproduction


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When the cell cycle operates normally, mitoticcell division functions in:

Growth (seen here in an onion root)

Cell eplacement (seen he e in skin)


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Cell replacement (seen here in skin)

Deadcells

Dividingcells

Epidermis,the outerlayer of theskin

Dermis

Asexual reproduction (seen here in a hydra)


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Asexual reproduction (seen here in a hydra)

Budding of a

new hydra

Growth factors signal the cell cycle control system


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Proteins within the cell control the cell cycle

growth factors deliver signals that determinewhether the cell will go through a complete

cycle and divide

Growth factors signal the cell cycle control system

G1 checkpoint

M checkpoint G2 checkpoint

Controlsystem

Th bi di f th f t t ifi


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The binding of growth factors to specificreceptors on the plasma membrane is usuallynecessary for cell division

Growth factor

Cell cyclecontrolsystem

Plasma membrane

Receptorprotein

Signaltransduction

pathway

G1 checkpointRelayproteins

Cancer:


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Cancer cells have abnormal cell cycles

They divide excessively and can form abnormal

masses called tumors

Cancer cells ignore the control signals of normalcells - ignore STOP signals

Radiation and chemotherapy are effective ascancer treatments because they interfere with celldivision

cells growing out of control

Malignant tumors can invade other tissues and


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Malignant tumors can invade other tissues andmay lead to death

Tumor

Glandulartissue

1 2 3A tumor growsfrom a singlecancer cell.

Cancer cells invadeneighboring tissue.

Lymphvessels

Cancer cells spreadthrough lymph andblood vessels to otherparts of the body.

Metastasis

cell division


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Cell division is the reproduction of cells

cell division

Apoptosis is the genetically controlled death ofcellsMitosis is the nuclear division of somatic cells

Meiosis produces sex cells

Differentiation


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Process of specialization

Differentiation

Results from inactivation of particular genes

Produces populations of cells with limitedcapabilities

Differentiated cells form tissues

Quiz


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1. Name the stages of the cell cycle in order of

occurrence.2. What happens in the S stage of interphase?

3. What are the two main stages of cell division inthe cell cycle?

4. What are the main stages of mitosis (M phase)of the cell cycle?

5. What mechanism do animal cells use incytokinesis?

6. Why is cancer considered a disease of the cellcycle?

QUIZ:


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I. FILL IN THE BLANK

1. The first person to describe microscopic organisms and livingcells was

__________________________. 2. Short, hair-likeorganelles that can move and may cover a unicellular organism orline the respiratory tract are called

__________________________. 3. Some ribosomes arefree in the cytoplasm, while others line the membrane of the

_________________________. 4. Everything between the

cell membrane and the nucleus is the cell's____________________. 5. All cells, from all organisms, aresurrounded by a _________________________. 6. Theorganelle that stores DNA and synthesizes RNA

______________________. 7. The organelle that processesand packages substances produced by the cell

___________________________. 8. The_______________________is the control center of the cell.9. The DNA in the form of a long strand is called

_____________________. 10. Scientist call the modern viewof the cell membrane structure the

_________________________________.

QUIZ CONT


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11. During cell division, _________________________strands coil and condense into thick structures called12._______________________. 13. Organisms whose cellsnever contain a membrane bound nucleus are called_______________________. 14. Suspended in the cell'scytosol are tiny _______________________. 15. When a

cell prepares to reproduce the _______________________disappears. 16. In eukaryotic cells, most organelles aresurrounded by a _____________________. 17. Organismswhose cells always or usually contain a nucleus or nuclei arecalled __________________18. Unicellular organisms suchas bacteria and their relatives are___________________________. 19. Where are poisonsand waste detoxified in a cell?______________________20. A cell synthesizes protein byusing organelles called _____________________.

power point presentation of cells

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