Biology Chapter on Naming and Theories

Naming

• Species are named using the genus first, followed by the species.
• The name is either underlined or italicized.
• After the first use, you can use the genus initial and species name.

History - Spontaneous Generation

• Spontaneous generation is the idea that life can form from non-living matter.
• Francesco Redi disproved this by using two jars with meat. One was sealed, and one was not.
• The sealed jar stayed free of maggots, while the unsealed jar developed them.
• This further experiment showed that lack of oxygen did not prevent maggot formation.
• The experiment with a mesh covering the jar also showed that maggots did not form, as flies could not access the meat.

Biogenesis

• Biogenesis is the theory that living cells come from pre-existing living cells.

Germ Theory of Disease

• The germ theory of disease is the belief that microbes can spread diseases through the air.

Microscope Parts

• Ocular lens: Magnifies the image from the objective lens.
• Body tube: Transmits the image from the objective lens to the ocular lens.
• Arm: Supports the microscope.
• Objective lens: Primarily magnifies the specimen.
• Stage: Holds the microscope slide.
• Condenser: Focuses light through the specimen.
• Diaphragm: Controls the amount of light entering the condenser.
• Illuminator: The light source.
• Course focusing knob: Grossly adjusts the focus.
• Base: Supports the microscope.
• Fine focusing knob: Fine-tunes the focus.
• Oil: Used with the 100x objective to improve resolution. Oil has a similar refractive index to glass, reducing light scattering.

Magnification Calculation

• Multiply the objective lens magnification by 10 to get the total magnification.

Limit of Resolution

• The limit of resolution is a measure of the smallest detail that can be distinguished with a microscope.

Staining

• Staining helps visualize cell shape and arrangement, as cells are usually colorless.
• Simple stains: Use a single basic dye to stain the entire cell.
• Gram stain: Used to differentiate between Gram-positive and Gram-negative bacteria. Gram-positive cells stain purple, and gram-negative cells stain pink.
• Negative stain: The background is stained, allowing visualization of capsules surrounding the cells.
• Acid-fast stain: Used for cells with a waxy coating that can't be gram-stained; stains the cells red.

Important Concepts from Chapter four

• All cells have a plasma membrane, cytoplasm, DNA, and RNA.
• Cells acquire raw materials and energy from their environments.
• Cell shapes include diplococci.

Bacterial Morphology (Pages 3 & 4)

• Various shapes and arrangements of bacteria are shown (streptococci, staphylococci, single/diplobacilli, streptobacilli, coccobacilli, vibrio)
• Images/diagrams accompany each type.

Bacterial Structures (Page 4)

• Glycocalyx: Organized (capsule) or unorganized (slime layer); protects against dehydration and antibiotics.
• Flagella: Arrangements include peritrichous (all around), monotrichous (single), lophotrichous (tuft), and amphitrichous (on both sides--polar).

Additional Cell Structures (Page 5)

• Pili (pili): Used for DNA transfer (conjugation).
• Cell wall: Made of peptidoglycan; thick in Gram-positive, thin in Gram-negative.
• Plasma membrane: Controls what enters and exits the cell and anchors enzymes for ATP.
• Nucleoid: Bacterial chromosome.
• Ribosomes: Sites of protein synthesis (70S in prokaryotes).
• Endospores: Dormant, resistant resting cells of some bacteria.