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Unit 5

Cell Structure & Transport

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Cell Theory

• All living things are composed of cells

• Cells are the basic unit of structure and function in living things

• New cells are produced from pre-existing cells

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Cells come in many shapes and sizes!

Specialized Cells

1.bone cells

2.skin cells

3.blood cells

4.nerve cells

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Some organism are made up of only ONE cell !!

Uni-cellular Organisms

1.E. coli bacteria

2.Amoeba

3.Paramecium

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Biologist divide cells into two categories:

Prokaryotes and Eukaryotes

Prokaryotes Eukaryotes

Small & Simple Mostly found in large organisms.

Cell Membranes Cell Membranes

Cytoplasm Cytoplasm & Specialized Structures

NO Nucleus Nucleus

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Cell StructuresName Description &

FunctionImage

1. Cell

Membrane

A thin flexible barrier around a cell that regulates what enters and leaves the cell.

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Name Description & Function

Image

2.

Cell Wall

Only found in plant cells. Offers protection and rigidity to all plant cells.

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Name Description & Function

Image

3.

Nucleus

Controls most cell processes and contains the hereditary information found on the DNA

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Name Description & Function

Image

4.

Cytoplasm

The material inside the cell membrane. It offers support to all the other cell structures in the cell.

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Name Description & Function

Image

5.

Ribosome

Small particles in the cell on which proteins are assembled.

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Name Description & Function

Image

6.

Endoplasmic Reticulum

Components of the cell membrane are assembled here.

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Name Description & Function

Image

7.

Golgi

Apparatus

The place where enzymes attach carbohydrates and lipids to proteins.

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Name Description & Function

Image

8. Lysosomes

Filled with enzymes and breaks down lipids, carbohydrates, and proteins. Animal cell only

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Name Description & Function

Image

9.

Vacuoles

Store materials like water, and salts

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Name Description & Function

Image

10.

Chloroplasts

Found only in plants. The site of photo-synthesis

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Name Description & Function

Image

11.

Mitochondria

Releases the energy stored in glucose molecules.

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Generalized

Animal Cell

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Generalized Plant Cell

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Movement through the Membrane1.The membrane is important because it

separates the cell from its surroundings.

2.It regulates what enters and leaves the cell and also provides protection and support.

3.Membrane Design:

It is a called a lipid bi-layer which is actually a double layer membrane made up of proteins and lipid molecules.

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Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel

Lipid bi-layer

Carbohydratechains

Cell membrane

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Moving Materials Across the Cell Membrane

1.Molecules DO NOT just cross into or out of a cell randomly.

2.Two factors determine if a molecule will cross the membrane.

• Size of the molecule

• Concentration of the molecules on one side of the membrane as compared to the concentration on the other side of the membrane

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Passive Transport

1.The movement of materials across the membrane without the cell needing to expend any energy to make it happen.

2.Three different types:

• Diffusion

• Facilitated Diffusion

• Osmosis

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Diffusion

1.Molecules move from a region of high concentration to a region of lower concentration.

• high to low is the easy way to go

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Facilitated Diffusion

1.Movement of larger molecules across cell membranes through transport protein channels.

HighConcentration

LowConcentration

CellMembrane

Proteinchannel

Glucosemolecules

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Osmosis

1.It is the diffusion of water molecules across the membrane.

2.Sometimes molecules are simply too big to move across the membrane. In

these cases Water will move across the membrane so that a balanced concentration can be reached.

(This is called equilibrium)

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What is Tonicity?

•Tonicity is a measure of the water pressure inside of a cell as compared to the water pressure outside of the cell.

•Tonicity is influenced only by substances that cannot cross the membrane.

•Substances able to freely cross the membrane do not affect tonicity because they will always be in equal concentrations on both sides of the membrane.

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Isotonic Solution

The size of the cell remains the same!

Plant Cell

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Isotonic Animal Cell

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Hypotonic Solution

The size of the cell increases!

Plant Cell

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Hypotonic Animal Cell

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Hypertonic Solution

The Size of the cell decreases!

Plant Cell

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Hypertonic Animal Cell

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Active Transport

1.The movement of materials from an area of lower concentration to an area of greater concentration.

2.It requires a special energy from the cell known as ATP energy.

3.Movment is against the concentration gradient.(Think of it as trying to swim upstream agaisnt the current!!!!)

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Low Concentration

High Concentration

Cell membrane

Low Concentration

High Concentration

Cell membrane

Active Transport of molecules against a concentration gradient requires the use of transport proteins in the cell membrane and ATP energy from the cell.

Molecule to be carried

Molecule being carried

Energy