Cell Structure & Function

http://koning.ecsu.ctstateu.edu/cell/cell.html

Cell Theory• All living things are made up of cells. • Cells are the smallest working units of all

living things. • All cells come from preexisting cells

through cell division.

Definition of Cell

A cell is the smallest unit that is capable of performing life

functions.

Examples of CellsAmoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Cell Parts

Organelles – “little organs”

Surrounding the Cell

Plasma (Cell) Membrane• Outer membrane of cell;

control movement via selective permeability

• Structure:• Transparent, Lipid bilayer• Cholesterol to stabilize • Receptors• Binding sites• Pores and carriers• Microvilli

http://library.thinkquest.org/12413/structures.html

Plasma (Cell) Membrane• Function:• To regulate the flow

of materials both in and out

• Act as a barrier• Communication

channel between inside and outside of the cell

Inside the Cell

Nucleus

• Directs cell activities – “Headquarters”• Separated from cytoplasm by nuclear

membrane• Contains genetic material - DNA

Nucleus • 3 main structures:

1. Nuclear membrane – lipid bilayer, with pores for transport2. Nucleoli – clusters of DNA and site of ribosomal subunits3. Chromosomes – 46 present, 23 inherited from each parent, genetic materials

Nuclear Membrane• Surrounds nucleus• Is selectively permeable• Made of two layers• Openings allow material

to enter and leave nucleus

http://library.thinkquest.org/12413/structures.html

Chromosomes• In nucleus• Made of DNA• Contain instructions

for traits & characteristics

http://library.thinkquest.org/12413/structures.html

Nucleoli• Inside nucleus• Contains RNA to build

proteins

http://library.thinkquest.org/12413/structures.html

Cytoplasm• Gel-like mixture - cytosol• Surrounded by cell membrane• Contains hereditary material • Site of organelles

Endoplasmic Reticulum “network” (ER)

• “Mini circulatory system”• Smooth ER (SER): lacks

ribosomes; detox• Rough type, pictured (RER):

ribosomes embedded in surface

• Uses a cistern formation to move materials around the cell

• Ex. – pancreas for enzyme productionhttp://library.thinkquest.org/12413/structures.html

Ribosomes• Each cell contains

thousands• Make (synthesize)

proteins

http://library.thinkquest.org/12413/structures.html

Golgi Apparatus• “Traffic Director”• Protein 'packaging

plant'• Move materials in

and out of the cell• Modify and package

proteins• Think UPS

http://library.thinkquest.org/12413/structures.html

Mitochondria• “The Powerhouse”• Produces energy through

manufacturing ATP• Controls level of water and

other materials in cell• Recycles and decomposes

proteins, fats, and carbohydrates

http://library.thinkquest.org/12413/structures.html

Lysosomes• “Demolition Sites”• “Breakdown Bodies”• Breaks down worn out

cell parts and foreign substances

• Transports undigested material to the cell membrane for removal

• Cell breaks down if lysosome explodes

http://library.thinkquest.org/12413/structures.html

Vacuoles• Membrane-bound

sacs for storage, digestion, and waste removal

• Contains water solution

http://library.thinkquest.org/12413/structures.html