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

Microbial Life: Prokaryotes and Protists

Prokaryotic Cell Shapes and Types

Prokaryotes are classified based on their cell shapes and structural features. These characteristics are important for identification and understanding their ecological roles.

• Bacilli: Rod-shaped bacteria.

• Cocci: Spherical bacteria.

• Spirochetes: Spiral-shaped bacteria, often motile.

Gram Staining distinguishes bacteria based on cell wall composition:

• Gram-positive: Thick peptidoglycan layer; stains purple.

• Gram-negative: Thin peptidoglycan layer and outer membrane; stains pink.

Peptidoglycan is a polymer forming the bacterial cell wall, providing structural support.

Metabolic Diversity in Prokaryotes

Prokaryotes are classified by their energy and carbon sources:

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

• Chemoheterotrophs: Obtain energy and carbon from organic compounds.

• Photoautotrophs: Use light for energy and CO2 for carbon.

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

Archaea and Extremophiles

• Methanogens: Archaea that produce methane, often found in anaerobic environments.

• Thermophiles: Archaea or bacteria thriving in high-temperature environments.

Protists: Diversity and Structure

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

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

• Brown algae: Multicellular, large seaweeds; important in marine habitats.

• Pseudopodia: Temporary extensions of cytoplasm used for movement and feeding (e.g., amoebas).

• Foraminiferans: Protists with porous shells (tests) made of calcium carbonate.

• Radiolarians: Protists with intricate silica skeletons.

• Flagella: Whip-like structures used for movement.

The Evolution of Vertebrate Diversity

Major Groups and Characteristics

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

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

• Marsupials: Mammals with pouches for developing young (e.g., kangaroo).

• Mammals: Animals with hair and mammary glands.

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

• Amniotes: Vertebrates with amniotic eggs (reptiles, birds, mammals).

Ectothermic animals rely on external sources for body heat (e.g., reptiles), while endothermic animals generate heat internally (e.g., birds, mammals).

The scientific view of birds recognizes them as descendants of theropod dinosaurs, sharing many evolutionary traits.

Evolutionary Trees

Evolutionary trees (phylogenies) illustrate relationships among groups. To interpret them:

• Identify common ancestors and branching points.

• Trace evolutionary traits and divergence.

Major defining characteristics between mammal groups include reproductive strategies, body coverings, and metabolic adaptations.

Unifying Concepts of Animal Structure and Function

Levels of Organization

Biological organization follows a hierarchy:

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

Each level builds upon the previous, increasing complexity and specialization.

Tissues: Types and Functions

Tissues are groups of cells with similar structure and function. Four major categories:

• Epithelial tissue: Covers surfaces and lines cavities; functions in protection, absorption, secretion.

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

• Muscle tissue: Enables movement; types include skeletal, cardiac, and smooth.

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

Examples of tissues: Skin (epithelial), bone (connective), heart (muscle), brain (nervous).

How to Name Epithelial Tissue

Epithelial tissues are named based on cell shape and number of layers:

• Cell shapes: Squamous (flat), cuboidal (cube-shaped), columnar (tall).

• Layers: Simple (one layer), stratified (multiple layers).

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

Types of Connective Tissues

Connective tissues vary in structure and function:

• Loose connective tissue: Most common; holds organs in place.

• Fibrous connective tissue: Dense; forms tendons and ligaments.

• Adipose tissue: Stores fat.

• Cartilage: Flexible support.

• Bone: Rigid support and protection.

• Blood: Transports substances.

Most common type: Loose connective tissue.

Muscle Tissue Types and Functions

• Skeletal muscle: Voluntary movement; attached to bones.

• Cardiac muscle: Involuntary; found in heart.

• Smooth muscle: Involuntary; found in walls of organs.

Nervous Tissue

• Neurons: Cells that transmit electrical signals.

• Nerve: Bundle of neurons.

Plasma

Plasma is the liquid component of blood, transporting nutrients, hormones, and waste.

Where Tissues Are Found

• Epithelial: Skin, lining of digestive tract.

• Connective: Tendons, ligaments, fat, bone, blood.

• Muscle: Skeletal muscles, heart, digestive organs.

• Nervous: Brain, spinal cord, nerves.

Functions of Tissue Types

• Epithelial: Protection, absorption, secretion.

• Connective: Support, transport, storage.

• Muscle: Movement.

• Nervous: Communication, control.

Control Systems and Homeostasis

Homeostasis

Homeostasis is the maintenance of stable internal conditions despite external changes.

Feedback Mechanisms

• Negative feedback: Counteracts changes to maintain equilibrium (e.g., body temperature regulation).

• Positive feedback: Amplifies changes (e.g., blood clotting, childbirth).

Examples of Feedback

• Negative feedback: Thermoregulation, blood glucose control.

• Positive feedback: Labor contractions, platelet activation.

Physiologist

A physiologist studies the functions and mechanisms of living organisms.

Organ Systems

Organs of the Respiratory System

• Nose/Nasal cavity: Filters, warms, and moistens air.

• Pharynx: Passageway for air and food.

• Larynx: Voice box.

• Trachea: Windpipe; conducts air to lungs.

• Bronchi: Branches leading to lungs.

• Lungs: Main site of gas exchange.

Summary Table: Tissue Types and Characteristics

Type	Defining Characteristics	Location	Function
Epithelial	Cell layers, shapes (squamous, cuboidal, columnar)	Skin, lining of organs	Protection, absorption, secretion
Connective	Extracellular matrix, various cell types	Bone, blood, fat, tendons	Support, transport, storage
Muscle	Contractile fibers	Skeletal muscles, heart, organs	Movement
Nervous	Neurons, glial cells	Brain, spinal cord, nerves	Communication, control

Additional info:

• Evolutionary trees are used to trace lineage and shared traits among vertebrates.

• Structure relates to function: e.g., the thinness of alveoli in lungs facilitates gas exchange.

• Feedback mechanisms are essential for maintaining homeostasis in all organ systems.