Cell Structure and Function

Chapter 7

Conversion Review

K H D ___ d c m

12.4m = ________cm

0.765L = ________mL

10,432ms = ________s

Going Further

1 Milimeter (mm) = 0.001m 1 micrometer (μm) = 0.00001m (10-6m) 1 nanometer(nm)=0.00000001m

(10-9m)

7.1 Life is CellularSizes of Objects and Magnifying Power of Microscopes

Compound Light Microscope

Guidelines for using Light Microscopes Carry the microscope with one hand holding

the arm and the other hand supporting the base.

Never slide the microscope across the lab table.

Clean lenses with lens paper only. Always begin AND end with the lowest power

objective in place and the stage at its lowest level.

Use the coarse adjustment knob on low power objectives.

Use ONLY the fine adjustment knob on high power objectives.

The Discovery of the Cell

Robert Hooke • Looked at cells in cork and named them cells

Anton van Leeuwenhoek• Observed pond water

Schleiden and Schwann• All plants and animals are made of cells

Oken and Virchow• Cells are produced from division of existing cells

Three Parts of the Cell Theory:

1. All living things are made up of cells.

2. The cell is the most basic unit of life.

3. New cells are produced from existing cells.

Why are cells so small?

Small cells function more efficiently than large cells.• All substances that enter and leave the cell

must cross the cell surface.

• Cells need a high surface area to volume ratio in order to exchange substances more readily.

Prokaryotes

Single-celled organism that lacks a nucleus and other internal compartments.

Bacteria are common prokaryotes.

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Common Features of Cells• Cell membrane – thin flexible barrier that

encloses and separates the cell from it’s external environment.

• Cytoplasm – the cell’s interior

• Ribosomes – where proteins are made

• Genetic Material – instructions for making proteins, regulate cellular activities, and enable reproduction

Eukaryotes

Cells that contain a nucleus and internal compartments called organelles.

Eukaryotic organisms can be one-celled (unicellular) or contain many cells (multicellular).

7.2 Cell Structure

supports and shapes cell helps position and transport organelles provides strength assists in cell division aids in cell movement

Three types of cytoskeleton fibers:• Microfilaments – made up of protein and actin

• Microtubules – made up of protein and tubulin

• Intermediate fibers – thick ropes of protein

The Cytoskeleton

The Nucleus

Controls most functions of the cell.

Most of the cell’s DNA is contained in the nucleus.

Surrounded by the nuclear envelope, which separates the nucleus from the cytoplasm.

• The nuclear envelope contains small channels called nuclear pores which allow substances to move in and out of the nucleus.

Nucleolus

Region inside the nucleus where ribosomes are assembled.

Nucleolus

Ribosomes

Located free in the cytoplasm or attached to the rough endoplasmic reticulum

Produce proteins

2 types of endoplasmic reticulum (ER):

• Rough ER – has attached ribosomes and thus has a rough appearance.– Helps transport proteins from ribosomes in

vesicles.

• Smooth ER – performs various functions such as making lipids and breaking down toxic substances.

Rough ER

Smooth ER

Golgi Apparatus

Modifies proteins received in vesicles from the ER.• Some vesicles will

remain in the cytoplasm and become lysosomes, which work to remove waste in the cell.

Vesicle

Vacuoles

Used for storage of water, salts, proteins, and sugars.

Mitochondria

Harvest energy from organic compounds to make ATP.

Cell Membrane

Made of a double layer of phospholipids• lipid bilayer

Protects and supports the cell

Regulates what enters and leaves the cell• Selectively permeable

Unique features of plant cells

Cell wall • thick layer of protein and cellulose

surrounding the cell membrane. Chloroplast

• use light energy to make carbohydrates from carbon dioxide and water.

Central vacuole • takes up much of the plant cell’s volume

• Stores water and nutrients.

Plant Cells

Plant Cell

Cell Specialization• Cell Diversity