Cells Class IX by Prabhat Gaurav

Cell - Cell - Structure Structure

and and FunctionsFunctions

CellsCells

• Smallest living unitSmallest living unit• Most are Most are

microscopicmicroscopic

Discovery of Cells Robert HookeRobert Hooke

Observed sliver of corkObserved sliver of corkSaw “row of empty boxes”Saw “row of empty boxes”Coined the term cellCoined the term cell

Characteristics of All Characteristics of All CellsCells

A surrounding membraneA surrounding membrane Protoplasm – cell contents in thick fluidProtoplasm – cell contents in thick fluid Organelles – structures for cell functionOrganelles – structures for cell function Control center with DNAControl center with DNA

Cell TypesCell Types

• Prokaryotic

• Eukaryotic

Prokaryotic Cells

• First cell type on earth• Cell type of Bacteria and Archaea

Prokaryotic CellsProkaryotic Cells No membrane bound nucleusNo membrane bound nucleus Nucleoside = region of DNA concentrationNucleoside = region of DNA concentration Organelles not bound by membranesOrganelles not bound by membranes

Eukaryotic CellsEukaryotic CellsNucleus bound by membraneNucleus bound by membraneInclude fungi, protists, plant, Include fungi, protists, plant, and animal cellsand animal cellsPossess many organellesPossess many organelles

Animal Cell

Plant CellPlant Cell

Organelles Cellular machinery Cellular machinery Two general kindsTwo general kinds

• Derived from membranesDerived from membranes• Bacteria-like organellesBacteria-like organelles

Cell Walls►Found in plants, fungi, & many protistsFound in plants, fungi, & many protists►Surrounds plasma membraneSurrounds plasma membrane

Cell Wall Differences Plants – mostly cellulosePlants – mostly cellulose Fungi – contain chitinFungi – contain chitin

Cytoplasm Viscous fluid containing organellesViscous fluid containing organelles components of cytoplasmcomponents of cytoplasm

Interconnected filaments & fibers Interconnected filaments & fibers Organelles (not nucleus)Organelles (not nucleus) storage substancesstorage substances

NucleusNucleus

Control center of Control center of cellcell

Double membraneDouble membrane

Contains Contains – ChromosomesChromosomes– Nucleolus Nucleolus

NucleolusMost cells have 2 or moreMost cells have 2 or moreDirects synthesis of RNADirects synthesis of RNAForms ribosomesForms ribosomes

Vacuoles

Membrane bound storage sacs More common in plants than animals Contents

– Water– Food– wastes

Bacteria-Like Organelles

Release & store energy

Types Mitochondria (release energy) Chloroplasts (store energy)

ChloroplastsDerived form photosynthetic bacteriaSolar energy capturing organelle

Photosynthesis Takes place in the chloroplast Makes cellular food – glucose