The Cellular Basis Of Life 525yb

The Cellular Basis of Life

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

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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 Over 1 meter 2 micrometers

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Variations in Cells- Shape • Red Blood Cells- disk shaped • Nerve Cells- spindle shaped • Smooth Muscle CellsThreadlike • Epithelial CellsCubes

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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

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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

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

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Glycoproteins • Blood type • Cell-cell communication

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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

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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

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

– Peroxisomes – Sacs that contain powerful oxidase enzymes – Detoxify poisonous substances and disarm free radicals

Cytoplasmic Organelles • Cytoskeleton – Provides cells framework and cells shape – Microfilaments- cell motility and makes changes in cell shape – Intermediate Filamentsform 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