Microbiology Exam 1 Key Concepts

Prokaryotes have usually a circular chromosome in the nucleoid and may have plasmids. Eukaryotes have linear chromosomes inside a nucleus.

Replication: DNA to DNA.
Transcription: DNA to RNA.
Translation: RNA to protein.

Coccus: round.
Bacillus: rod-shaped.
Spirillum: spiral.
Spirochete: flexible spiral.

Acts as a selective permeability barrier, controlling what enters and leaves the cell.

A strong mesh-like cell wall material made of repeating sugars (NAG and NAM) cross-linked to provide strength and shape.

Gram-positive: thick peptidoglycan, contains teichoic acid, stains purple.
Gram-negative: thin peptidoglycan, outer membrane with LPS, stains pink/red.

Lipopolysaccharide (LPS) is in the Gram-negative outer membrane; its lipid A portion acts as an endotoxin.

Lysozyme breaks down peptidoglycan, weakening bacterial cell walls and potentially killing bacteria.

Protective slime coats that help with attachment, prevent drying, aid biofilm formation, evade phagocytosis, and increase virulence.

Fimbriae: attachment structures.
Pili: often involved in DNA exchange (conjugation) and motility (type IV pili).

Flagella are made of flagellin and enable movement. Arrangements include polar, lophotrichous (tuft at one pole), amphitrichous (both ends), and peritrichous (all around).

Movement of bacteria in response to chemical stimuli; positive toward attractants, negative away from repellents.

Endospores are survival structures formed by some bacteria (e.g., Bacillus, Clostridium) to withstand harsh conditions, not for reproduction.

All chemical reactions in a cell. Catabolism breaks down molecules to release energy; Anabolism uses energy to build cellular components.

ATP is the cell's usable energy currency, like cash that powers cellular processes.

Chemoorganotroph: energy from organic chemicals.
Chemolithotroph: energy from inorganic chemicals.
Phototroph: energy from light.

Autotrophs use CO₂ as carbon source.
Heterotrophs use organic carbon like sugars or proteins.

Enzymes are proteins made of amino acids. Temperature and pH can denature them, changing their shape and stopping function.

The region where the substrate binds, often described as a lock and key fit.

Glycolysis breaks glucose into 2 pyruvate molecules, producing a net of 2 ATP.

Without oxygen: fermentation regenerates NAD⁺.
With oxygen: pyruvate enters Krebs cycle and electron transport chain.

To regenerate NAD⁺ so glycolysis can continue, producing acids, gases, or alcohols as end products.

Oxidizes carbon compounds and produces electron carriers NADH and FADH₂ for the electron transport chain.

A buildup of H⁺ ions on one side of a membrane, storing energy like water behind a dam, used to make ATP.

By oxidative phosphorylation using the electron transport chain and proton gradient.

Minimum, optimum, and maximum temperatures at which a microbe can grow.

Psychrophiles: cold-loving microbes.
Mesophiles: moderate temperature lovers, e.g., E. coli.

A microbial community attached to a surface, producing a matrix and often harder to treat medically.

Lag (adjustment), exponential (active growth), stationary (no net growth), death (decline).

A virus that infects bacteria, e.g., T4 and lambda phages infecting E. coli.

Attachment → Penetration → Synthesis → Assembly/Maturation → Release.

Lytic: virus replicates, lyses host.
Lysogenic: viral DNA integrates into host genome as prophage, host survives.

A virus with RNA genome that uses reverse transcriptase to make DNA from RNA, e.g., HIV.