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Cells & the Unity of life

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“You are what you eat”

This is literally, biochemically TRUE

Each piece of each cell in your body

originated in the food that you ate

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Organization of body

• Atoms: the smallest unitsof matter

 –  Atoms bond with eachother to form molecules.

• Molecules: groups of atoms bonded in specificconfigurations.

 –  for example: water is H2O,carbon dioxide is CO2

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Organization of body

• Cells link together to formtissues

• Tissue: group of cells actingtogether to perform acommon function.

 – Ex: muscle tissue, nerve tissue

• Organ: a sophisticatedorganization of tissues thatperform a specific function

 –  Ex: stomach, heart, brain

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Cellular basis of life

•Cells are microcosms of YOU –  Your individual cells do everything you do:

• Drink

• Make food (plants)

• Eat

• Digest

• Harvest energy from food

• Grow & reproduce

 –  Cells have specialized organelles (“little organs”)that perform each of these functions

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Some important organelles

• Nucleus: regulates cellmetabolism

• Ribosomes: Make structural

molecules & enzymes(proteins)

• Chloroplasts: make food(carbohydrates)

•Mitochondria: Harvest energy(ATP) from ingested foods

• Cell membrane: regulateshomeostasis

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Cells communicate with each other

• Using Signals - hormones (proteins, fats) &

ionic minerals (Na+, K+)

• And Receivers - Receptor proteins

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Cells membrane anatomy

• Cell membrane: outer layer (skin) enclosing eachcell of the body.

 –  Composed of 2 layers of phospholipid molecules

 – 

Hydrophobic phospholipid “tails” face each othertoward interior of the membrane

 –  Hydrophilic phospholipid “heads” line exterior

surfaces of the membrane

 –  Cholesterol stiffens the membrane

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Movement of Nutrients

Cell

membrane

Movement of nutrients & wastes into & out of cells typicallyoccurs by simple diffusion or active transport.

Carrier loads

nutrient on

outside of cell . . .

Energy

ACTIVE

TRANSPORT

FACILITATED

DIFFUSION

SIMPLE

DIFFUSION

Energy

. . . and then

releases it on

inside of cell.

Outside

cell

Inside

cell

Carrier loads

nutrient on

outside of cell . . .

. . . and then

releases it on

inside of cell.

Cell membrane is selectively permeable. Controls passage

of materials into and out of the cell

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