Unit 4 viruses and bacteria pt.1
Summary of Bacteria: Characteristics, Classification, Functions, and
Control
This content provides a comprehensive overview of bacteria, including their classification,
characteristics, modes of nutrition and respiration, reproduction methods, ecological roles, impacts
on human health, and ways to control harmful bacteria. It also compares prokaryotes and
eukaryotes and highlights the differences between major bacterial groups.
Core Concepts and Classification
Prokaryotes vs. Eukaryotes:
● Prokaryotes lack a defined nucleus and membrane-bound organelles.
● Prokaryotes include bacteria, which are divided into two main groups:
● Archaebacteria:
● Lack peptidoglycan in their cell walls.
● Have distinct membrane lipids.
● Typically live in extreme environments (e.g., hot springs, salty lakes).
● Eubacteria:
● Contain peptidoglycan in their cell walls.
● Occupy a wide range of environments.
Identification of Bacteria:
Bacteria are difficult to distinguish visually and are usually identified based on:
● Shape:
● Bacilli: Rod-shaped
● Cocci: Spherical
● Spirilla: Spiral or corkscrew-shaped
● Cell wall composition: Presence or absence of peptidoglycan.
● Movement: Motility mechanisms such as flagella.
● Energy acquisition and usage: Methods of obtaining and utilizing energy.
Bacterial Nutrition and Energy
, Unit 4 viruses and bacteria pt.1
Bacteria display diverse nutritional strategies:
● Heterotrophs: Obtain energy from other living organisms.
● Chemoheterotrophs: Rely solely on consuming organic matter.
● Photoheterotrophs: Use photosynthesis but still require organic compounds.
● Autotrophs: Produce their own food.
● Photosynthesis: Use sunlight to convert CO₂ to organic compounds.
● Chemosynthesis: Use chemical reactions to produce organic compounds.
Respiration Types:
● Aerobic respiration: Requires oxygen; produces the most ATP.
● Anaerobic respiration: Does not require oxygen; produces less ATP.
● Obligate aerobes: Must have oxygen to survive.
● Obligate anaerobes: Oxygen is toxic; rely on fermentation or anaerobic respiration.
● Facultative anaerobes: Can survive with or without oxygen, performing fermentation when
oxygen is absent.
Bacterial Reproduction and Genetic Exchange
● Binary Fission: Asexual reproduction where one cell divides into two genetically identical
daughter cells.
● Example: A bacterial cell with 4 chromosomes undergoing binary fission will produce
two daughter cells, each with 4 chromosomes.
● Conjugation: Exchange of genetic material between bacteria, enhancing genetic diversity.
● Spore Formation: Some bacteria form spores to survive harsh conditions; spores can later
germinate into active bacteria.
Ecological Roles and Human Uses
Ecological Functions:
● Decomposers: Break down dead organic material, recycling nutrients.
● Nitrogen Fixers: Convert atmospheric nitrogen into forms usable by plants (e.g., Rhizobium
associated with legumes).
Human Benefits:
Summary of Bacteria: Characteristics, Classification, Functions, and
Control
This content provides a comprehensive overview of bacteria, including their classification,
characteristics, modes of nutrition and respiration, reproduction methods, ecological roles, impacts
on human health, and ways to control harmful bacteria. It also compares prokaryotes and
eukaryotes and highlights the differences between major bacterial groups.
Core Concepts and Classification
Prokaryotes vs. Eukaryotes:
● Prokaryotes lack a defined nucleus and membrane-bound organelles.
● Prokaryotes include bacteria, which are divided into two main groups:
● Archaebacteria:
● Lack peptidoglycan in their cell walls.
● Have distinct membrane lipids.
● Typically live in extreme environments (e.g., hot springs, salty lakes).
● Eubacteria:
● Contain peptidoglycan in their cell walls.
● Occupy a wide range of environments.
Identification of Bacteria:
Bacteria are difficult to distinguish visually and are usually identified based on:
● Shape:
● Bacilli: Rod-shaped
● Cocci: Spherical
● Spirilla: Spiral or corkscrew-shaped
● Cell wall composition: Presence or absence of peptidoglycan.
● Movement: Motility mechanisms such as flagella.
● Energy acquisition and usage: Methods of obtaining and utilizing energy.
Bacterial Nutrition and Energy
, Unit 4 viruses and bacteria pt.1
Bacteria display diverse nutritional strategies:
● Heterotrophs: Obtain energy from other living organisms.
● Chemoheterotrophs: Rely solely on consuming organic matter.
● Photoheterotrophs: Use photosynthesis but still require organic compounds.
● Autotrophs: Produce their own food.
● Photosynthesis: Use sunlight to convert CO₂ to organic compounds.
● Chemosynthesis: Use chemical reactions to produce organic compounds.
Respiration Types:
● Aerobic respiration: Requires oxygen; produces the most ATP.
● Anaerobic respiration: Does not require oxygen; produces less ATP.
● Obligate aerobes: Must have oxygen to survive.
● Obligate anaerobes: Oxygen is toxic; rely on fermentation or anaerobic respiration.
● Facultative anaerobes: Can survive with or without oxygen, performing fermentation when
oxygen is absent.
Bacterial Reproduction and Genetic Exchange
● Binary Fission: Asexual reproduction where one cell divides into two genetically identical
daughter cells.
● Example: A bacterial cell with 4 chromosomes undergoing binary fission will produce
two daughter cells, each with 4 chromosomes.
● Conjugation: Exchange of genetic material between bacteria, enhancing genetic diversity.
● Spore Formation: Some bacteria form spores to survive harsh conditions; spores can later
germinate into active bacteria.
Ecological Roles and Human Uses
Ecological Functions:
● Decomposers: Break down dead organic material, recycling nutrients.
● Nitrogen Fixers: Convert atmospheric nitrogen into forms usable by plants (e.g., Rhizobium
associated with legumes).
Human Benefits:
