Unit 5.1 Test Review Notes

virus

A nonliving particle made of proteins and nucleic acids that can only replicate inside a living cell.

capsid

The protein coat surrounding the nucleic acid core of a virus.

lytic cycle

A viral replication cycle in which the virus replicates rapidly, kills the host cell, and releases new viruses.

lysogenic cycle

A viral replication cycle in which the virus's nucleic acid becomes integrated into the host cell's chromosome, and the host cell is not immediately destroyed.

retrovirus

A virus that contains RNA as its genetic material and uses reverse transcriptase to synthesize DNA.

reverse transcriptase

An enzyme that catalyzes the synthesis of DNA from an RNA template.

prokaryote

A unicellular organism that lacks a nucleus and other membrane-bound organelles.

extremophile

An organism that lives in extreme environments, such as hot springs, salt lakes, or acidic conditions.

peptidoglycan

A network of polysaccharide chains cross-linked by short peptides that forms the rigid cell wall of bacteria.

Gram-positive

A bacterium with a thick peptidoglycan layer in its cell wall that retains Gram stain.

Gram-negative

A bacterium with a thin peptidoglycan layer in its cell wall surrounded by an outer membrane that does not retain Gram stain.

binary fission

A method of asexual reproduction in bacteria in which the cell divides into two identical daughter cells.

endospore

A thick-walled, dormant structure formed by some bacteria that is highly resistant to heat, radiation, and other harsh conditions.

conjugation

The transfer of genetic material between two bacterial cells that are temporarily joined.

nitrogen fixation

The conversion of atmospheric nitrogen gas into a form usable by plants, carried out by certain bacteria.

pathogen

A disease-causing agent, such as a bacterium, virus, fungus, or protist.

Germ Theory of Disease

The principle that infectious diseases are caused by microorganisms.

vaccine

A preparation of weakened or killed pathogens that stimulates the immune system to produce antibodies and immunity.

antibiotic

A substance that kills or inhibits the growth of bacteria.

emerging disease

A disease that is newly identified or has recently increased in incidence or geographic range.

photoautotroph

An organism that uses light energy to synthesize organic compounds from carbon dioxide and water.

chemoautotroph

An organism that obtains energy by oxidizing inorganic substances.

aerobe

An organism that requires oxygen for respiration.

anaerobe

An organism that does not require oxygen for respiration.

facultative anaerobe

An organism that can survive in the presence or absence of oxygen.

protist

A diverse group of eukaryotic microorganisms, including protozoa, algae, and slime molds.

alternation of generations

A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte.

spore

A haploid reproductive cell that develops into a new organism without fusion with another cell.

fungi

A group of eukaryotic organisms that includes molds, yeasts, and mushrooms.

chitin

A structural polysaccharide found in the cell walls of fungi and the exoskeletons of arthropods.

hyphae

A filament of fungal cells.

fruiting body

The reproductive structure of a fungus, such as a mushroom.

mycelium

The network of hyphae that forms the body of a fungus.

lichen

A symbiotic association between a fungus and a photosynthetic organism, such as an alga or cyanobacterium.

mycorrhizae

A symbiotic association between a fungus and the roots of a plant.

plant

A multicellular, eukaryotic organism that is typically photosynthetic and has cell walls made of cellulose.

germination

The process by which a seed sprouts and begins to grow.

pollen

A structure produced by seed plants that contains the male gametophyte.

root

An organ of a plant that anchors it in the ground, absorbs water and nutrients, and stores food.

stem

An organ of a plant that supports the leaves and flowers and transports water and nutrients.

leaf

An organ of a plant that is the primary site of photosynthesis.

green algae

Photosynthetic protists that are thought to be the ancestors of plants.

bryophyte

Nonvascular plants that lack true roots, stems, and leaves, such as mosses.

tracheophyte (vascular seedless plants)

Vascular plants that do not produce seeds, such as ferns.

gymnosperm

Seed plants that do not produce flowers, such as conifers.

seed

A structure produced by seed plants that contains an embryo and a food supply, enclosed in a protective coat.

angiosperm

Flowering plants that produce seeds enclosed in a fruit.

fruit

A mature ovary that contains seeds.

xylem

Vascular tissue that transports water and minerals from the roots to the rest of the plant.

phloem

Vascular tissue that transports sugars from the leaves to the rest of the plant.

stomata

Pores on the surface of a leaf that allow for gas exchange.

guard cells

Cells that surround the stomata and control their opening and closing.

transpiration

The evaporation of water from the leaves of a plant.

Lytic Cycle Steps

1. Attachment: Virus attaches to host cell.
2. Entry: Viral DNA enters the cell.
3. Replication: Viral DNA replicates using host cell machinery.
4. Assembly: New viral particles are assembled.
5. Lysis: Host cell lyses, releasing new viruses.

Lysogenic Cycle Steps

1. Attachment: Virus attaches to host cell.
2. Entry: Viral DNA enters the cell.
3. Integration: Viral DNA integrates into the host cell's chromosome, becoming a prophage.
4. Replication: The prophage is replicated along with the host cell's DNA during cell division.
5. Induction (optional): Under

Virus Structure

A virus particle consists of:

• Nucleic Acid: DNA or RNA (single- or double-stranded).
• Capsid: A protein coat that surrounds and protects the nucleic acid.
• Envelope (in some viruses): A lipid layer derived from the host cell membrane.

Three Main Structures of Bacteria

1. Cocci (spherical): Spherical-shaped bacteria.

   • Example: Streptococcus.

2. Bacilli (rod-shaped): Rod-shaped bacteria.

   • Example: Bacillus

3. Spirilla (spiral): Spiral-shaped bacteria.

   • Example: Spirillum.