cell structure

Our School

Under the Guidance of

Sanjukta

Mishra

Our Science Teacher

Swasti Panda

Presents……

Definition of Cell…

A cell is the smallest unit that

is capable of performing life

functions.

The Cell Theory…

All living things are made up of cells.

Cells are the smallest working units of all living things.

All cells come from pre-existing cells through cell division.

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

The Two Major Categories of Cells….

The countless cells on earth fall into two categories:

Prokaryotic cells — Bacteria and Archaea

Eukaryotic cells — plants, fungi, and animals

Prokaryotes and Eukaryotes

PROKARYOTIC

They are the simplest form of life.

No nucleus.

Do not have structures surrounded by membranes (organelles)

Few internal structures

They are unicellular_(One-celled organisms).

Example: Bacteria

ribosomes

cell wall

plasma membrane

food granule

prokaryoticflagellum

cytoplasm

nucleoid (DNA)

are the most complex form of life.

They have nucleus

Contain organelles surrounded by membranes

They are multicellular organisms (composed of many cells).

Most living organisms

Examples: animals and plants.

Eukaryotic

EUKARYOTIC

Plant Animal

Prokaryotes & Eukaryotes…

Similarities & differences

Both surrounded by plasma membrane, but very different

Prokaryotes – Archaebacteria and Eubacteria

Eukaryotes – everything else

“TYPICAL” ANIMAL CELL

“Typical” Plant Cell

Similarities in Plant & Animal Cell…

Both constructed from eukaryotic cells

Both contain similar organelles

Both surrounded by cell membrane

Difference Between Plant & Animal Cells…

Plants haveCell wall – provides strength & rigidityHave chloroplasts, photosynthetic

Animals haveOther organelle not found in plants (lysosomes formed from Golgi)Centrioles, important in cell division

Surrounding the Cell

Plasma (Cell) Membrane

All living cells (eukaryotes and prokaryotes) have cell membranes Made mainly of phospholipids and

proteins▪ Animal cell membranes contain cholesterol

Functions:▪ Separate the cell from the external

environment▪ Controls passage in and out of cell

Cell Membrane

Outer membrane of cell that controls movement in and out of the cell

Double layer

Membrane Structure

Cell Wall

Rigid structure outside cell membrane• Found in plants, fungi, bacteria,

some protists (not animals)• Made of cellulose (plants), chitin

(fungi) or other material (bacteria)• Supports and protects cell

Inside the Cell

ORGANELLESCell Parts

CELL STRUCTURE AND FUNCTION

Cell Organells

nuclearpores

nuclearpore

nuclear envelopenucleolus

histone protein

chromosome

DNANucleus Function

protects DNA Structure

nuclear envelope double membrane membrane fused in spots to create pores

allows large macromolecules to pass through

What kind of molecules need to pass through?

Nucleolus Function

ribosome production▪ build ribosome subunits from rRNA &

proteins▪ exit through nuclear pores to cytoplasm &

combine to form functional ribosomes

smallsubunit

large subunit

ribosome

rRNA &proteins

nucleolus

smallsubunit

largesubunitRibosomes

Function protein production

Structure rRNA & protein 2 subunits combine 0.08mm

RibosomesRoughER

SmoothER

membrane proteins

Types of RibosomesFree ribosomes

◦ suspended in cytosol◦ synthesize proteins that

function in cytosolBound ribosomes

◦ attached to endoplasmic reticulum

◦ synthesize proteins for export or for membranes

Endoplasmic Reticulum (ER)

Function • processes proteins• manufactures membranes• synthesis & hydrolysis of many compounds

Structure• membrane connected to nuclear envelope &

extends throughout cell

Types of ER

Rough ER (RER) – Has ribosomes attached Site of protein synthesis

Smooth ER (SER) Complex molecules built here Continuous with RER

Smooth ER function Membrane production Many metabolic processes

• synthesis synthesize lipids

oils, phospholipids, steroids & sex hormones

• hydrolysis hydrolyze glycogen into glucose

in liver detoxify drugs & poisons

in liver ex. alcohol & barbiturates

Rough ER function Produce proteins for export out of cell

• protein secreting cells• packaged into transport vesicles for export

Golgi ApparatusFunction

finishes, sorts, tags & ships cell productsships products in vesicles

membrane sacsStructure

Stack of flattened membranes“pita bread” like

transport vesicles

secretoryvesicles

Golgi Apparatus

Vesicles Transport…

ER contents pinch off into vesicles - membrane-bound sacs that store and transport substances in cells

vesiclebuddingfrom roughER

fusionof vesiclewith Golgiapparatus

migratingtransportvesicle

protein

ribosome

Bulk Transport & ATP The movement of macromolecules such

as proteins or polysaccharides into or out of the cell is called bulk transport. There are two types of bulk transport, exocytosis and endocytosis, and

both require the expenditure of energy

(ATP).

Mitochondria Produces energy through

chemical reactions – breaking down fats & carbohydrates

Controls level of water and other materials in cell

Recycles and decomposes proteins, fats, and carbohydrates

CytoplasmCytosol (cytoplasm)

Cellular fluid surrounding organellesSite of many cellular reactionsFound between cell membrane and nucleus

Lysosomes

Lysosomes – special vesicles that store and transport powerful digestive enzymes and other reactive substances within a cell Double membrane protects cell from being

digested Break down

Food particles Unneeded proteins, carbohydrates, etc.. Disease-causing microorganisms

Vacuoles

Large membranous storage sacs found mainly in plants. Stores water, nutrients, waste products

and pigments○ Give certain plants bright colors (beets,

carrots, flowers)

CILIA AND FLAGELLA…

Hairlike organelles that extend from the surface of the cell

Assist in movement Cilia – short and

present in large numbers

Flagella – long and less numerous

Chromosomes…

In nucleus Made of DNA Contain

instructions for traits & characteristics

Chloroplast

Usually found in plant cells

Contains green chlorophyll

Where photosynthesis takes place

Building Proteins

21/07/2014

video B.avi

21/07/2014

Any Questions!!

Thanks ...For giving Your Valuable Time…