Cell Structure and Function.pdf

8/11/2019 Cell Structure and Function.pdf

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Cell Structure and Function

Eukaryot ic Cell : Neuron


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Eukaryot ic Cel ls :

Blo od Cells


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Prokaryo t ic Cells: Bacteria


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All living organisms are made of cells. A

cell is a small, membrane enclosed

structure filled with an aqueous solution

where organelles and other subcellularstructures are found.

Cells are of different size and shape

The cells size and shape can be related to

its specific function.


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From Prokaryotes to Eukaryotes


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From Prokaryotes to Eukaryotes

It is thought that all organisms living now onEarth are derived from a single cell born 3,500millions of years (my) ago.

This primordial cell was defined by an outermembrane ? one of the crucial events leadingto the establishment of life on Earth

Simple organic molecules are likely to have

been produced in the conditions that existed onthe Earth in its infant state (approximately duringits first billion years)


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Unicellular vs. Multicellular

Organisms

Why unicellular?

Why multicellular? Unicel lu lar - Am oeba proteus

Multicellular


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Can we see cells?

Ye

sNo

50%50%

1. Yes

2. No


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Can We See Cells?


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Structural Features of Cells:

Outside Covers

All cells have a

plasma or cell

membrane, which

contains the cell Plant cells and most

bacteria have an

outermost additional

layer, theplant cellwall and the bacterial

cell wall respectively

Plant Cell Wall

Adipo se Cells (Ad)


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Outside Covers: The Plant Cell

Wall The plant cell wall is the

outermost layer of plantcells

It provides extra

protection to the plantand cohesiveness amongneighbor plant cells. Whydo plants need theseextra features?

Cell walls of adjacentplant cells are in closecommunication throughplasmodesmata


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Structural Features of Cells: Inner

Structures of Prokaryotic Cells

No nuc leus or membrane-enclosed organel les in prok aryot ic cel ls .

R ibosomes p resen t .


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Structures of Prokaryotic Cells

Electron Microg raph of Bacteria (Cross and

Long itudinal Sections)


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Which one of these would not be

found in a prokaryotic cell?

ribosom

es

cellm

embrane

nucleus D

NA

25% 25%25%25%1. ribosomes

2. cell membrane

3. nucleus4. DNA


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cellulose: plasmodesmata :protection and

cohesiveness: outermost cell cover

anim

alcellm

embrane

prokary

oticcell

me...

plantcell

membrane

33% 33%33%

1. animal cellmembrane

2. prokaryotic cellmembrane

3. plant cell membrane


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Structures of Eukaryotic Cells

Pancreatic Cell : In Eukaryotic Cells, Nucleus, Cytoplasm , andMembrane- bound ed Organel les Are Present


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Inner Structures of Eukaryotic

Cells: The Nucleus The nucleus of eukaryotic cells

is contained by the nuclearenvelope, which is made oftwo membranes (inner andouter) decorated withporecomplexes

Inside the nucleus, chromatin(DNA + DNA associatedproteins) and a nucleolus arepresent

The nuclear lamina (made ofintermediate filaments) covers

the inner nuclear membrane,helping in the maintenance ofnuclear shape

The nucleus hosts the geneticmaterial (DNA and RNA)


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Cells: The Nucleus

Ribosom es are present in the outer nuc lear memb rane


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Cells: The Nucleus

Transmis sion Electron Micrograph (TEM) ofHemocyte Nuc leus

Freeze Fracture Replica of a Nucleus: Outer

Membrane and Pore Complexes


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Some Eukaryotic Cells Lose Their

Nucleus as They Mature

TEM of Human Enuc leated Erythro cytes (Er)


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Nuclear envelope refers to:

outer

nuclearmembrane

nuclearporecomplexes

outer

andinner

nucl...

none

oftheabo

ve

25% 25%25%25%

1. outer nuclear membrane2. nuclear pore complexes

3. outer and inner nuclearmembrane and porecomplexes

4. none of the above

I St t f E k ti C ll


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Inner Structures of Eukaryotic Cells:

Cytoplasmic Membrane- bounded

Organelles

An imal Cell Plant Cell


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Different Cytoplasmic Organelles

Perform Distinct Cell Functions

Production, circulation,

storage, and delivery of

substances produced or

taken by the cell (those

organelles constitute theendomembrane system)

Production of energy

Movement and

maintenance of the cellsshape

Chloro plasts in Plant

Cells


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Organel les of Anim al Cel ls


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Organel les of Plant Cells


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Organelles of the

Endomembrane System


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Organelles of the Endomembrane

System: Endoplasmic Reticulum (ER)

The ER is const i tu ted o f smooth (SER) and rou gh (RER) regions.

Both animal and plant cel ls have SER and RER


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System: Endoplasmic Reticulum (ER) The ER is a membrane bounded

organelle. The smooth and roughregions of the ER areinterconnected

Smooth ER lacks ribosomes. It isa network of pipe-likeinterconnected tubes. Functionsof the SER include synthesis oflipids, processing of sugars, anddetoxification of drugs andpoisons

Rough ER has bound ribosomesattached to the outside. The RERis in fact an extension of the outernuclear membrane. Functions ofthe RER include anchorage ofnewly synthesize proteins, and thefinishing of proteins


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System: Endoplasmic Reticulum (ER)

Pancreatic Cell : In Eukaryotic Cells, Nucleus, Cytoplasm , andOrganelles Are Present. ER, Endoplasmic Reticulum


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System: Golgi Apparatus

The Golg i App aratus is a s ing le m embrane-bounded o rganel le

con st i tu ted of pi led sac- l ike cisternae. Both animal and plant

ce l ls have Golg i Apparatus


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The Golgi Apparatus receives, packs, and ships vesicles comingfrom the ER, or from other parts of the cell back to the ER

Vesicles arriving from the ER (on cis side) coalesce in the Golgiapparatus, where they mature and form new vesicles that would beshipped (from trans side) to other cell locations


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Golg i Apparatus in Neuron


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System: Vesicles and Lysosomes

Transpor t and Secre tory Ves ic les (s ing le membrane-

bou nded organel les) . Both animal and plant cel ls havet rans o rt ves ic les


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System: Vesicles

Pancreat ic Secretory Cell : Basal and Apical Parts


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System: Vesicles and Lysosomes

Lyso som es are typical of animal cel ls ; lysosom es are vesic les that contain hydrolyt ic

enzymes. Tay-Sachs is an autosomal recessive disease caused by mutat ions inlysosomal enzymes


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How Do Vesicles, Lysosomes, and

Vacuoles Move?

Cytoskeletal e lements and m otor prote ins interact with the vesic le s sur face

receptor proteins. Such interaction leads to vesicle mo vement.


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System: Central Vacuole

Mature plants generallycontain a large centralvacuole that may occupy50-90% of the cells

interior The central vacuole is asingle membrane-bounded organelle. Suchcell membrane is termed

tonoplast The central vacuole

stores a variety of organicand inorganic compounds


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System

Plasma Membrane and Nuclear Envelope

Endoplasmic Reticulum (SER, RER)

Golgi Apparatus Transport, Secretory Vesicles, and

Vacuoles

Lysosomes (only in animal cells) Central Vacuole (only in plant cells)

O ll f th d b t t l


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Organelles of the endomembrane system control

production, circulation, storage, and delivery of

substances produced or taken by the cell

True

False

50%50%

1. True

2. False


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trans side : sorting of vesicles

:secretion of vesicles

SER

RER

Golgi

apparatus

centralvacuole

25% 25%25%25%

1. SER

2. RER

3. Golgi apparatus

4. central vacuole


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cell storage: tonoplast

:endomembrane system

SER

RER

Golgiapparatus

centralvacuole

25% 25%25%25%1. SER

2. RER

3. Golgi apparatus4. central vacuole


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Energy- Producing Organelles


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Energy- Producing Organelles:

Mitochondria

Mitocho ndria are dou ble membrane- bou nded organelles present in nearly al l

eukaryotic cel ls (plant, animals, fungi, etc.). Mitocho ndria proc ess

macromolecules to obtain energy throu gh a process termed aerobic

respiration . Mitocho ndria have their own DNA (mito cho ndrial DNA, mDNA)

and ribosomes in thei r matr ix .


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O


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Chloroplasts

Chloroplast areplastids that contain the green pigment chlorophyllalong with other photosynthetic pigments. Chloroplasts performphotosynthesis

Chloroplasts are double membrane-bounded organelles present inplant cells.

In the stroma, chloroplast DNA and ribosomes can be found

E P d i O ll


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Chloroplasts

If ll did t h it h d i


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If a cell did not have mitochondria,

it would be unable to:

move

produceenergy

synthe

tizelipids

an...

allofth

eabo

ve

25% 25%25%25%

1. move

2. produce energy3. synthetize lipids and move

vesicles

4. all of the above


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Select the choice that indicates organelles

bounded by a double membrane

Golgiapparatus

&ve...

SER&RER

mito

chondria&chlor

...

allofth

eabo

ve

25% 25%25%25%

1. Golgi apparatus &

vesicles

2. SER & RER

3. mitochondria &

chloroplasts

4. all of the above

E P d i O ll


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Chloroplasts


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M t P d i O ll


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Movement- Producing Organelles

and Cytoskeleton

Motion produc ed by ci l ia or f lagel la

Motion of ves ic les prov ided by c ytoske le ton

Amoebo idal movemen t p rov ided by cy toske leton

M t P d i O ll


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Movement- Producing Organelles

and Cytoskeleton

Skeleta l Muscle and Cardiac Mu scle


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Shape Maintenance and Movement- Producing

Organelles and Cytoskeleton: The Cytoskeleton


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Movement- Producing Organelles and

Cytoskeleton: The Cytoskeleton

Microtubules grow out

from a centrosome, a

microtubule-

organizing region. Inanimal cells, the

centrosome contains

a pair of centrioles

Centrioles are madeof nine triplets of

microtubules


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Cytoskeleton: Cilia and Flagella

Cil ia and flagel la are extensions of the plasma memb rane that con tain an array of nin e pairs

of peripheral mic rotub ules and a central one (9+2 array). Cil ia and flagel la are roo ted on the

basal body , con sti tuted of nine peripheral tr iplets of microtu bules. Cil ia are sho rter than

flagella

M P d i O ll d


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Cytoskeleton: Flagella

Flagella propel the

cell (flagellatedcell) in

a whip-like motion

Sperm cells ofanimals, plants, and

algae are flagellated

Sperm Cel ls in Semini ferous Tubules

M t P d i O ll d


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Cytoskeleton: Cilia

Cilia provide movementto free-swimmingeukaryotic unicellularorganisms (i.e.Paramecium)

In multicellularorganisms, they generallyconstitute ciliatedepithelia (i.e. trachea and

oviducts). What is thefunction of these ciliatedepithelia?

Ciliated Cells in Tracheal Epithelia


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Thi ll b l t th


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This organelle belongs to the

endomembrane system. Do you agree?

Yes N

o

50%50%

1. Yes

2. No

Thi ll b l t th


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This organelle belongs to the

endomembrane system. Do you agree?

Yes No

50%50%

1. Yes

2. No

Cell Structure and Function.pdf

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