Unit 5 Study Guide: Microbial Life, Evolution of Vertebrates, and Animal Structure & Function

Microbial Life: Prokaryotes and Protists

Major Groups of Prokaryotes

Prokaryotes are single-celled organisms lacking a nucleus, classified mainly as Bacteria and Archaea. They exhibit diverse shapes, metabolic strategies, and ecological roles.

• Bacilli: Rod-shaped bacteria. Example: Escherichia coli.

• Cocci: Spherical bacteria. Example: Staphylococcus aureus.

• Spirochetes: Spiral-shaped bacteria. Example: Treponema pallidum (causes syphilis).

• Gram-positive bacteria: Have thick peptidoglycan cell walls and retain crystal violet stain (appear purple).

• Gram-negative bacteria: Have thin peptidoglycan layers and an outer membrane; do not retain crystal violet (appear pink).

• Peptidoglycan: A polymer forming the cell wall of most bacteria, providing structural support.

Metabolic Diversity in Prokaryotes

• Chemoautotrophs: Obtain energy from inorganic chemicals and carbon from CO2.

• Chemoheterotrophs: Obtain both energy and carbon from organic molecules.

• Photoautotrophs: Use light as an energy source and CO2 as a carbon source (e.g., cyanobacteria).

• Photoheterotrophs: Use light for energy but obtain carbon from organic compounds.

Archaea: Extremophiles

• Methanogens: Archaea that produce methane as a metabolic byproduct; often found in anaerobic environments like swamps.

• Thermophiles: Thrive in extremely hot environments, such as hot springs.

Protists: Major Groups

• Diatoms: Unicellular algae with silica cell walls; important primary producers in aquatic ecosystems.

• Dinoflagellates: Mostly marine protists with two flagella; some cause red tides.

• Brown algae: Large, multicellular algae (e.g., kelp); important in marine habitats.

• Pseudopodia: Temporary extensions of the cell membrane used for movement and feeding (e.g., in amoebas).

• Foraminiferans: Protists with porous shells (tests) made of calcium carbonate; use pseudopodia for movement.

• Radiolarians: Protists with intricate silica skeletons and radiating pseudopodia.

• Flagella: Long, whip-like structures used for movement in many protists and some bacteria.

The Evolution of Vertebrate Diversity

Major Vertebrate Groups and Characteristics

Vertebrates are animals with a backbone. Their evolution includes several key adaptations.

• Monotremes: Egg-laying mammals (e.g., platypus, echidna).

• Marsupials: Mammals with a pouch for developing young (e.g., kangaroo, opossum).

• Mammals: Vertebrates with hair and mammary glands; include monotremes, marsupials, and placental mammals.

• Tetrapods: Vertebrates with four limbs (amphibians, reptiles, birds, mammals).

• Amniotes: Vertebrates with an amniotic egg, allowing reproduction on land (reptiles, birds, mammals).

• Ectothermic: Animals that rely on external sources for body heat (e.g., reptiles, amphibians).

• Endothermic: Animals that regulate body temperature internally (e.g., birds, mammals).

Scientific View of Birds

• Birds are considered a group of reptiles, specifically derived from theropod dinosaurs.

• They are endothermic and have adaptations for flight (feathers, hollow bones).

Major Defining Characteristics in Mammalian Evolution

• Evolution of hair, mammary glands, and differentiated teeth.

• Development of the placenta in most mammals.

• Transition from egg-laying to live birth in most groups.

Understanding Evolutionary Trees

• Evolutionary trees (phylogenies) show relationships among groups based on shared characteristics and ancestry.

• Nodes represent common ancestors; branches indicate evolutionary lineages.

Unifying Concepts of Animal Structure and Function

Levels of Organization in Life

Biological systems are organized hierarchically:

• Molecule → Cell → Tissue → Organ → Organ system → Organism

Tissues: Types, Naming, and Functions

• Tissue: A group of similar cells performing a specific function.

• Organ: Structure composed of multiple tissue types working together (e.g., heart, lung).

• Organ system: Group of organs working together (e.g., respiratory system).

Major Categories of Tissues

• Epithelial tissue: Covers body surfaces and lines cavities.

• Connective tissue: Supports and binds other tissues; includes bone, blood, cartilage, adipose, and loose connective tissue.

• Muscle tissue: Responsible for movement; includes skeletal, cardiac, and smooth muscle.

• Nervous tissue: Conducts electrical impulses; includes neurons and supporting cells.

How to Name Epithelial Tissue

• Based on number of layers (simple = one layer; stratified = multiple layers) and cell shape (squamous = flat, cuboidal = cube-shaped, columnar = tall).

• Example: Simple squamous epithelium (single layer of flat cells).

Types of Connective Tissues and Their Characteristics

Type	Defining Characteristics	Location/Function
Loose connective tissue	Loosely arranged fibers, most common	Binds epithelia to underlying tissues
Fibrous connective tissue	Dense collagen fibers	Tendons, ligaments
Adipose tissue	Fat storage cells	Energy storage, insulation
Cartilage	Flexible matrix	Joints, ear, nose
Bone	Mineralized matrix	Skeletal support
Blood	Liquid matrix (plasma)	Transport of substances

• Most common connective tissue: Loose connective tissue.

Types of Muscle Tissues and Their Functions

Type	Function	Location
Skeletal muscle	Voluntary movement	Attached to bones
Cardiac muscle	Pumps blood	Heart
Smooth muscle	Involuntary movement	Walls of organs (e.g., intestines, blood vessels)

Nervous Tissue

• Neurons: Nerve cells that transmit electrical signals.

• Nerve: Bundle of axons (nerve fibers) in the peripheral nervous system.

Examples and Locations of Tissues

• Epithelial: Skin, lining of gut and respiratory tract.

• Connective: Tendons, fat, bone, blood.

• Muscle: Biceps (skeletal), heart (cardiac), intestine wall (smooth).

• Nervous: Brain, spinal cord, nerves.

Homeostasis and Feedback Mechanisms

Homeostasis

Homeostasis is the maintenance of a stable internal environment despite external changes.

• Physiologist: Scientist who studies how organisms function.

Feedback Mechanisms

• Negative feedback: A process that counteracts a change, returning a system to its set point. Example: Regulation of body temperature—if body temperature rises, mechanisms like sweating lower it.

• Positive feedback: A process that amplifies a change. Example: During childbirth, contractions increase in intensity due to the release of oxytocin.

Organs and Organ Systems

Respiratory System

• Organs of the respiratory system: Nose, pharynx, larynx, trachea, bronchi, lungs.

Summary Table: Tissue Types and Functions

Tissue Type	Function	Location
Epithelial	Protection, absorption, secretion	Skin, lining of organs
Connective	Support, binding, transport	Bone, blood, fat
Muscle	Movement	Skeletal muscles, heart, digestive tract
Nervous	Signal transmission	Brain, nerves

Additional info: This guide expands on the provided outline with definitions, examples, and context to ensure a comprehensive review for exam preparation.