The Cellular Basis of Life

Chapter 3Part 1

The Magic School Bus: Goes Cellular

Introduction to Cell Biology

– Chemical in the cells• Major Elements

– Carbon (C)– Oxygen (O)– Hydrogen (H)– Nitrogen (N)

“Biology is the search for chemistry that works.”

Trace Elements

– Calcium (Ca)- blood clotting

– Iron (Fe)- hemoglobin– Iodine (I)- controls

metabolism– Electrolytes- carry an

electrical charge

http://www.ehu.es/biomoleculas/PROT/hemoglobin.jpg

Iodine Deficiency

http://www.mja.com.au/public/issues/178_01_060103/li10764_fm-4.jpghttp://carondelet.net/PeriodicTable/I/iodized%20salt.jpg

Water in the Cell

– Cells are 60% water– Interstitial fluid

• Dilute, saltwater around cells• Site of all exchanges between cells and blood

Variations in Cells- Length

http://www.acticare.com/conditions/images/sciatic_nerve2.jpg

http://www.iss.k12.nc.us/schools/shs/jmcCartney/redcell.jpg

2 micrometersOver 1 meter

Variations in Cells- Shape

• Red Blood Cells- disk shaped

• Nerve Cells- spindle shaped

• Smooth Muscle Cells- Threadlike

• Epithelial Cells- Cubes

http://www.idahoptv.org/dialogue4kids/season3/brain/Images/neuronlabels.gif

Variations in Cells- Function

• Over 200 cell types found in the body

The Generalized Cell

– Demonstrates the basic parts that all cells contain

– Has three parts• Nucleus• Plasma Membrane• Cytoplasm

http://www.cse.ucsc.edu/~sugnet/documentation/biology_starter/images/animal_cell_580_915.jpg

The Nucleus

– Nuclear Envelope• The membrane of the

Nucleus– Nucleoli

• Where ribosomes are assembled

• Round, dark staining bodies

– Chromatin• DNA combined with

protein• When the cell divides the

DNA condenses into chromosomes

Plasma Membrane

• Fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment

– Lipid Bilayer– Proteins– Glycoproteins

Lipid Bilayer

• Phospholipid• Cholesterol

http://www.biology.arizona.edu/chh/problem_sets/kidneysmetals/graphics/bilayer.gif

Proteins

• scatter the surface of the plasma membrane– Receptors for hormones– Transport Proteins

http://www.nirgal.net/graphics/coli_protein.jpghttp://www.science.org.au/nobel/1996/images/picture-0.jpg

Glycoproteins

• Blood type• Cell-cell

communication

http://www.funhousefilms.com/glycolip.jpg

Specializations

• Microvilli– finger-like projections to

increase cell’s surface area

Specializations

• Tight Junctions– impermeable junctions that bind

cells together into leak-proof sheets

• Desmosomes– Anchoring junctions that prevent

cells subjected to mechanical stress from falling apart

• Gap Junctions– Allow communication– Connexons- hollow cylinders

composed of proteins that span the entire width of the abutting membrane

Cytoplasm

– Cellular material outside the nucleus and inside the plama membrane

– Site of most cellular activities (factory)– Three Elements

• Cytosol- semitransparent fluid• Organelles- parts that have specific functions• Inclusions- non-functioning units

Cytoplasmic Organelles

Cytoplasmic Organelles

• Mitochondria– Enzymes break down

food and capture the energy in ATP molecules

– Liver and muscle cells have hundreds of mitochondria

http://www.cbs.dtu.dk/staff/dave/roanoke/mitochon.gif

Cytoplasmic Organelles

• Ribosomes– Made of proteins and rRNA– Site of protein synthesis

• Endoplasmic Reticulum– System of fluid-filled

cisterns that coil and twist through the cytoplasm

– Rough ER- studded with ribosomes

– Smooth ER- cholesterol synthesis and breakdown, fat metabolism, and detoxification http://dragon.seowon.ac.kr/~bioedu/bio/ohp/t-021.jpg

Cytoplasmic Organelles

– Golgi Apparatus– stack of flattened sacs– Modifies and packages proteins

Cytoplasmic Organelles

– Lysosomes– Sacs of powerful

digestive enzymes– Digests wornout cell

structures and most foreign substances

– Peroxisomes– Sacs that contain

powerful oxidase enzymes

– Detoxify poisonous substances and disarm free radicals

http://www.cs.utexas.edu/~s2s/latest/cell1/src/tutorial/lysosome.html

Cytoplasmic Organelles

• Cytoskeleton– Provides cells framework

and cells shape– Microfilaments- cell

motility and makes changes in cell shape

– Intermediate Filaments- form desmosomes and resists pulling forces

– Microtubule- overall shape of a cell and important in cell shape

Cytoplasmic Organelles

– Centrioles– Rod-shaped bodies that are at right angles

– Other Cell Structures– Cilia- whiplike cellular extensions that move substances

along the cell surface– Flagella- Longer projection that moves the cell

Cell Diversity

• Trillions of cells in the body, 200 different cell types

Cells that connect body parts

• Fibroblast- secretes cable-like fibers• Erythrocyte (red blood cell)- carries oxygen in the

blood stream

Cells that cover and line body organs

– Epithelial cell- pack together into sheets

Cells that move organs and body parts

• Skeletal and Smooth Muscle cells- contract in order to move bones or internal organs

Cell that stores nutrients

• Fat cell- stores a lipid droplet

Cell that fights disease

• Macrophage- digest infectious microorganisms

Cell that gathers information and controls body functions

• Nerve cell (neuron)- send electrical signals

Cells of reproduction

• Oocyte- female egg cell• Sperm- male cell with flagellum