Cell BiologyCell Biology

Cells and OrganellesCells and Organelles

Two Types of CellsTwo Types of Cells Prokaryotic CellsProkaryotic Cells

Simplest and most abundant cells on EarthSimplest and most abundant cells on Earth Contain no nucleus or organelles (except Contain no nucleus or organelles (except

ribosomes)ribosomes) All bacteria are prokaryotesAll bacteria are prokaryotes

Eukaryotic CellsEukaryotic Cells Larger than prokaryotic cellsLarger than prokaryotic cells Contain organelles and a nucleusContain organelles and a nucleus Make up animals, plants, fungi and protistsMake up animals, plants, fungi and protists

Eukaryotic Cells:Eukaryotic Cells:Animal vs PlantAnimal vs Plant

Animal CellsAnimal Cells Circular shapeCircular shape Have lysosomes and centrioles that plants do Have lysosomes and centrioles that plants do

notnot Have several small vacuolesHave several small vacuoles

Plant CellsPlant Cells Square shapeSquare shape Have chloroplasts and a cell wall that animals Have chloroplasts and a cell wall that animals

do notdo not Have a large central vacuoleHave a large central vacuole

Cell OrganellesCell Organelles Organelles are membrane bound Organelles are membrane bound

structures that perform special functions structures that perform special functions within the cell.within the cell.

Each organelle performs a specific task Each organelle performs a specific task that contributes to the homeostasis of the that contributes to the homeostasis of the cellcell

Organelles – A Closer Organelles – A Closer LookLook1.1. Nucleus Nucleus

- contains the genetic information of - contains the genetic information of the cell (DNA)the cell (DNA) - control center of the cell- control center of the cell - surrounded by a double layered - surrounded by a double layered porous membrane called the porous membrane called the nuclear nuclear membrane (or envelope)membrane (or envelope)

Nucleus continuedNucleus continued Chromatin: material consisting of DNA Chromatin: material consisting of DNA

and proteins; visible as individual and proteins; visible as individual chromosomes in a dividing cellchromosomes in a dividing cell

Nucleolus: non-membranous organelle Nucleolus: non-membranous organelle involved in production of ribosomes; a involved in production of ribosomes; a nucleus has one or more nucleolinucleus has one or more nucleoli

2. Cell Membrane (also called 2. Cell Membrane (also called plasma plasma membranemembrane)) - Encloses the cell contents and - Encloses the cell contents and separates them from the outsideseparates them from the outside

- Layer between the inside and - Layer between the inside and outside of the celloutside of the cell

- Selectively permeable- Selectively permeable

3.Cytoplasm3.Cytoplasm - jelly – like substance that fills the cell and - jelly – like substance that fills the cell and supports the other organellessupports the other organelles

4. Endoplasmic Reticulum (ER)4. Endoplasmic Reticulum (ER) - transfers materials to different parts of the cell- transfers materials to different parts of the cell- active in membrane synthesis- active in membrane synthesis- rough (ribosome studded) and smooth- rough (ribosome studded) and smooth

5. Ribosomes5. Ribosomes - synthesize proteins- synthesize proteins - found on the endoplasmic reticulum- found on the endoplasmic reticulum - composed of two sub units.- composed of two sub units.

6. Mitochondria6. Mitochondria - the “powerhouse” of the cell- the “powerhouse” of the cell - makes energy- makes energy

7. Golgi Body7. Golgi Body - also called Golgi Apparatus- also called Golgi Apparatus - packages material inside the cell - packages material inside the cell

and transfers it out.and transfers it out.

8. Centrosome8. Centrosome- Region where the cell’s microtubules are Region where the cell’s microtubules are

initiatedinitiated- In an animal cell, contains a pair of In an animal cell, contains a pair of

centriolescentrioles

9. Vacuoles9. Vacuoles - “storehouses”- “storehouses” - contain food, water, waste or cell - contain food, water, waste or cell

materialmaterial- In plant cells, there is only - In plant cells, there is only one central one central

vacuolevacuole

PLANT CELLS ONLYPLANT CELLS ONLY10. Chloroplast10. Chloroplast

- performs photosynthesis to produce - performs photosynthesis to produce food for the cellfood for the cell- sunlight energy- sunlight energygets converted gets converted into chemical into chemical energy stored in energy stored in sugar moleculessugar molecules

PLANT CELLS ONLYPLANT CELLS ONLY

11. Cell Wall11. Cell Wall - made of cellulose, proteins and other - made of cellulose, proteins and other

polysaccharidespolysaccharides - rigid outer membrane that gives structure - rigid outer membrane that gives structure

and supportand support

ANIMAL CELLS ONLYANIMAL CELLS ONLY

12. Lysosomes12. Lysosomes - breakdown food and digest - breakdown food and digest

wastes and old cell partswastes and old cell parts

ANIMAL CELLS ONLYANIMAL CELLS ONLY

13. Flagellum 13. Flagellum movement organelle present in only some movement organelle present in only some

animal cellsanimal cells composed of microtubulescomposed of microtubules

14. Microvilli14. Microvilli Projections that increase the cell’s surface Projections that increase the cell’s surface

areaarea