Chapter 7Section 1

Section 1• Before microscope

were invented, people believed that diseases were caused by curses and supernatural spirits.

• Microscopes enable scientists to view and study cells, the basic unit of life.

• Compound light microscope: uses a series of lenses to magnify objects in steps.

• Electron microscope: uses a beam of electrons instead of light to magnify structures up to 500,000 times their actual size.

–Transmission electron microscope: allows scientists to study the structures contained within a cell.

–Scanning electron microscope: helps find the three-dimensional shape of the cell by scanning the surface of the cell.

The Cell Theory1. All organisms are

composed of one or more cells.

2. The cell is the basic unit of living things.

3. All cells come from preexisting cells.

Theodor Schwann made the fundamental

ideas of the cell theory.

                                                           

                                                           

                                                           

                                                           

                                                           

                                                           

                                               

Two basic cell types1. Prokaryotes: Cells that do not contain

any membrane bound organelles.

2. Eukaryotes: Contains a true nucleus and membrane bound organelles. Can be one cell or multicellular.

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Prokaryotes

Eukaryotes

The organelle that manages or controls cellular functions is called the nucleus.

Section 2• The plasma membrane allows a

steady supply of nutrients to come into the cell no matter what the external conditions are.

• Waste and other products also leave the cell through the PM

• Homeostasis

How does it maintain homeostasis???

Through selective permeability. This is a process in which a membrane allows some molecules to pass through while keeping others out.Water can pass in and out – sodium and ions are regulated

Structures of the Plasma Membrane

Structure of the Plasma Membrane

• Lipids are large biomolecules that are composed of glycerol and 3 fatty acids.

•Phospholipids are liquid with an attached phosphate group.

The phospholipid bilayer

• The phosphate group is critical for the formation and function of the plasma membrane.

• The fatty acid tail is non-polar and the phosphate head is polar

• Water is a key component of living organisms – both inside and out.

• The polar phosphate group allows the CM to interact with the water because water is also polar.

• The fatty acid tail avoids water.• The 2 layers make a sandwich

and create a barrier.

• The F.M. Model is a structure model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

•Transport proteins move needed substances or waste material through the plasma membrane.

•See page 178

Model of the plasma membrane is called the Fluid Mosaic Model

Components of the plasma membrane.

• Cholesterol – stabilizes the phospholipids by preventing the fatty acid tails from sticking

• Proteins are in the lipid membrane

• Transport proteins – move needed substances through the plasma membrane

Section 3 – Parts of the Cell

Plant Animal

Cell Wall

• Most commonly found in plant cells & bacteria

• Supports & protects cells

Cell Membrane• Outer membrane

of cell that controls movement in and out of the cell

• Double layer

Cytoplasm

• Gel-like mixture

• Surrounded by cell membrane

• Contains hereditary material

Chloroplast

• Usually found in plant cells

• Contains green chlorophyll

• Where photosynthesis takes place

Ribosomes• Each cell

contains thousands

• Make proteins

• Found on ribosomes & floating throughout the cell

Mitochondria• Produces energy

through chemical reactions – breaking down fats & carbohydrates

• Controls level of water and other materials in cell

• Recycles and decomposes proteins, fats, and carbohydrates

Endoplasmic Reticulum• Moves materials

around in cell

• Smooth type: lacks ribosomes

• Rough type (pictured): ribosomes embedded in surface

Golgi Bodies

• Protein 'packaging plant'

• Move materials within the cell

• Move materials out of the cell

Vacuoles

• Membrane-bound sacs for storage, digestion, and waste removal

• Help plants maintain shape

Lysosome

• Contains digestive proteins

• Transports undigested material to cell membrane for removal

• Cell breaks down if lysosome explodes

Nucleus

• Directs cell activities

• Separated from cytoplasm by nuclear membrane

• Contains genetic material - DNA

Parts cont.• Plasma membrane- maintains homeostasis. • Chromatin- strands of DNA that direct the

making of proteins.• Chloroplast- produces food.• Cytoskeleton- provides internal structure.

-Microtubules- thin, hollow cylinders made of protein.

-Microfilaments- smaller, solid protein fibers.

• Plastids- storage.

• Cilia- short, numerous projections, look like hair that aid in locomotion.

• Flagella- longer projections that move with a whip-like motion.