Cell Structure and Composition

Cell Structure and Cell Structure and CompositionComposition

Prepared by:Ms. Bernabeth Jo T. Tendero

Major Parts of the CellMajor Parts of the CellNucleusCytoplasmCell Surface

NucleusNucleusRegion of the cell where the

genetic material is locatedGenerally oval-shaped or

spherical shapedMost conspicuous part of the cellRegulates and coordinates all the

activities of the cellDenser than surrounding

cytoplasm

Parts of the NucleusParts of the Nucleus

Parts of the NucleusParts of the NucleusChromosomes

- in form of chromatin- contains genetic information- Composed of DNA- Thicken for cellular division- Set number per species (i.e. 23 pairs for human)

ChromosomesChromosomes

ChromatinChromatin

Nuclear MembraneNuclear MembraneSurrounds the nucleusDouble membraneHas numerous opening called

nuclear pores which serves as pathways for exchange of materials between the nucleus and the cytoplasm

Nuclear MembraneNuclear Membrane

NucleolusNucleolusSpherical shapeVisible when cell is not dividingContains RNA for protein

manufacture

NucleolusNucleolus

CytoplasmCytoplasmProtoplasm found outside the

nucleusCollective term for cytosol and

organellesColloidal suspensionCytosol composed mainly of

water with free floating molecules

Viscosity constantly changes

OrganellesOrganellesDiscrete structures of a cell

having specialized functions

Centrioles: Helper in Cell Centrioles: Helper in Cell DivisionDivision

Paired cylindrical organelles near nucleus

Composed of nine tubes, each with three tubules

Involved in cellular divisionLie at right angles to each other

CentriolesCentrioles

Cytoskeleton: Framework of Cytoskeleton: Framework of the Cellthe Cell

Composed of microtubulesSupports and provides shapeAids movement of materials in

and out of cellsMicrotubules provide pathways

for certain cellular molecules to move about

CytoskeletonCytoskeleton

Endoplasmic Reticulum: Endoplasmic Reticulum: Manufacturers and Builders Manufacturers and Builders

of the Cellof the CellTubular network fused to nuclear membrane

Goes through cytoplasm onto cell membrane

Stores, separates and serves as cell’s transport system

Endoplasmic ReticulumEndoplasmic Reticulum

Endoplasmic Reticulum: Endoplasmic Reticulum: Manufacturers and Builders Manufacturers and Builders

of the Cellof the Cell2 types Rough Endoplasmic Reticulum (RER) - occurs as flattened sheets studded on its outer surface with small spherical bodies called ribosomes- aids in protein synthesis- prevalent in cells that specializes in secreting proteins

Rough Endoplasmic Rough Endoplasmic ReticulumReticulum

Endoplasmic Reticulum: Endoplasmic Reticulum: Manufacturers and Builders Manufacturers and Builders

of the Cellof the Cell2 types Smooth Endoplasmic Reticulum (SER) - occurs as tubes of membranes without

ribosomes attached- site for fat metabolism and forms vesicles for transporting large molecules to other cell parts

Smooth Endoplasmic Smooth Endoplasmic ReticulumReticulum

Golgi Apparatus: Packaging Golgi Apparatus: Packaging Counters of the CellCounters of the Cell

Discovered and named after Camillo Golgi in 1898 by observing nerve cells of an owl

A system of membrane-bound sacs that look like a stack of pancakes

Believe to be part of ER and where new membranes for the ER are manufactured

Believe to prepare proteins for secretion after they are released from the ER

Golgi ApparatusGolgi Apparatus

Lysosomes: Suicide Bags of Lysosomes: Suicide Bags of the Cellthe Cell

“Lyso” – dissolving power and “some” – body

Discovered in 1952Contains hydrolytic/digestive

enzymes for proteins, lipids and carbohydrates

Transports undigested material to the cell membrane for removal

Destroys cells when lysosomes burst

LysosomesLysosomes

Mitochondria: Powerhouses Mitochondria: Powerhouses of the Cellof the Cell

2nd largest organelle with its own DNA (mtDNA)

Double layered outer membrane with inner folds called cristae

Energy-producing chemical reactions (produces ATP) takes place on cristae

Controls level of water and other materials in cell

Recycles and decomposes proteins, fats and carbohydrates, and forms urea

MitochondriaMitochondria

MitochondriaMitochondria

Ribosomes: Protein Factories Ribosomes: Protein Factories of the Cell of the Cell

Composed of nucleic acids (RNA) and proteins

Numerous in cellsManufacture proteins

RibosomesRibosomes

RibosomesRibosomes

Vacuoles: Storage Tanks of Vacuoles: Storage Tanks of the Cellthe Cell

Membrane-bound sacs for storage, digestion and waste removal

Contains water solutionContractile vacuoles for water

removal

VacoulesVacoules

PeroxisomePeroxisomeContain enzymes that transfer

hydrogen to various substrate of oxygen to produce hydrogen peroxide

Use oxygen to break fats to use as fuel for cellular respiration

Detoxify alcohol and other harmful compounds

PeroxisomesPeroxisomes

Chloroplast: Site of Chloroplast: Site of PhotosynthesisPhotosynthesis

Plastid found in plant cellsContains green chlorophyll where

photosynthesis takes placeHas its own DNA and ribosomesDouble membrane bound

organelleMobile and move around the cell

through cytosleleton

ChloroplastChloroplast

Cell SurfaceCell SurfaceProtectively surrounds the cellPlasma membraneCell wallPlasmodesmata

Plasma MembranePlasma MembraneDouble layer of phospholipid

moleculesEach phospholipid is composed of

fats, phosphate and carbohydrates (oligosaccharide)

Protein molecules are embedded in phospholipids

Because of its structure the membrane has a semi-permeable property that allows only chosen substances to enter and leave the cell

Plasma MembranePlasma Membrane

Cell WallCell WallLies outside the plasma

membraneCompose of celluloseProtects the cells and provide

rigid structure for cellsRemains intact even after the

rest of the cell has died

Cell WallCell Wall

Cell WallCell Wall

Cell WallCell Wall

PlasmodesmataPlasmodesmatasmall channels that directly

connect the cytoplasm of neighboring plant cells to each other, establishing living bridges between cells

allow certain molecules to pass directly from one cell to another and are important in cellular communication

PlasmodesmataPlasmodesmata

PlasmodesmataPlasmodesmata