Chapter 3Section 1

Pg. 50

Robert Hooke

• English scientist• Discovered cells in 1665

Anton van Leeuwenhoek

• Looked at water under a microscope.• Found many living creatures and

called them “animalcules”• Today, we know that he saw

organelles.

Characteristics of a Microscope

• Light Microscope- light passes through one or more lenses to produce an enlarged image of specimen.• Electron Microscope- uses a beam of electrons rather than light.• Magnification- ability to make an image appear larger than its actual

size.• Resolution- a measure of clarity of an image.

Compound Light Microscope

• Uses two lenses, the objective lens and the and the ocular lens (10X).

Electron Microscope

• Can magnify up to 200,000X.• Electron beam and specimen

must be placed in a vacuum chamber so that electrons in the beam will not bounce off of gas particles in the air.

Other Microscopes

• Scanning electron microscope- specimen is coated with thin layer of metal and electron beam bounces off of it.• Scanning tunneling microscope- uses a needle like probe to measure

differences in voltage cause by electrons that leak from the surface of the object being viewed.

Chapter 3Section 2

Pg. 55

The Cell Theory

1838- Mattias Schleiden concluded that cells make up every part of the plant.1839- Theodor Schwann claimed that animals are also made up of cells.1858- Rudolph Virchow determined cells come from other cells.

From these guys, we have formed THE CELL THEORY

The Cell Theory

1. All living things are made of one or more cells.2. Cells are the basic unit of structure and function in organisms.3. All cells arise from existing cells.

Cells must be small

• Smaller cells function more efficiently than large cells.• 100 trillion cells in the human body.• Surface area to volume ratio• Substances do not have to travel far to reach the center of a small

cell.

Common Features

• Cell membrane or plasma membrane• Cytoplasm- cell interior• Cytoskeleton- microscopic fibers• Ribosomes- proteins are made on these. • DNA-deoxyribonucleic acid

Prokaryotic Cells

• Single-celled organism that lacks a nucleus and other internal parts.• Smallest and simplest type of cell.• The genetic material is a single, circular molecule of DNA

Characteristics of Bacteria

• Prokaryotic• Some do not need oxygen to survive• DNA is suspended within the cell, usually in the center.• They lack an internal supporting skeleton, so have to have strong cell

wall. • Some have a capsule (made of polysaccharides) which allows them to

stick to things like teeth, skin, and food.

Characteristics of Bacteria

• Many have flagella, which are like tails that enable movement.• Think of them as propellers

Eukaryotic Cells are Organized

• Eukaryote- organism that has a nucleus.• Nucleus- houses the cell’s DNA.• Organelle- a structure in the cell that carries out a specific function.• Short hair-like structures called cilia protrude from the surface. Help

propel through their environment OR help move things on the surface of the cell.

Eukaryotic Cells are Organized

• Cytoplasm- everything inside the cell, outside the nucleus. The “fluid” of the cell. • Cytoskeleton- holds the cell

together and keeps the membrane from collapsing or folding. • Microtubules (larger)• Microfilaments (smaller)

Cell Membrane as a Barrier

• Phospholipid Bilayer- polar heads and non-polar tails• Inside repels water

Cell Membrane as a Barrier

• Proteins are embedded into the cell membrane.• Marker Proteins• Receptor Proteins• Enzymes• Transport Proteins

Chapter 3Section 3

Pg. 61

Cell Organelles

• Nucleus is surrounded by a double membrane called the nuclear envelope.• Nuclear pores are little channels or openings on the surface of the

nuclear envelope.• DNA is stored in the nucleus.

Cell Organelles

• Endoplasmic Reticulum (ER)- move proteins through the cell. • Rough ER have ribosomes on them. Transports proteins made by the

ribosomes.• Smooth ER do not have ribosomes attached. Makes lipids.

• Vesicle- small, membrane bound sac that transports things in the cell.• Golgi Apparatus-flattened sac that packages and distributes things in

the cell. • Lysosome- contain cell’s digestive enzyme. “death sentence”• Copy steps on pg. 63 in notes.

Cell Organelles

• Mitochondria-gets energy from organic compounds to produce ATP for energy. • Outer membrane• Inner membrane

Plant Cell Differences• Cell Wall- surrounds the cell membrane. Helps support and maintain

cell shape.• Chloroplasts- use light energy to make carbohydrates from CO2 and

H20. This makes plants green.• Central Vacuole- large, membrane bound space. It stores water and

may contain other substances.