AS111 Biology PowerPoint

AS111 Biology

The Scientific Study of Living Organisms

Lesson Outline

  • Levels of Biological Organization

  • Cell Anatomy

  • Homeostasis

Levels of Biological Organization

  • Atom

    • Definition: The fundamental unit of matter

  • Molecule

    • Definition: A group of atoms joined by chemical bonds

  • Cell

    • Definition: The fundamental unit of living organisms

  • Tissue

    • Definition: A group of similar cells

  • Organ

    • Definition: A body part made of several tissues that work together to perform specific functions

  • Organ System

    • Definition: A group of body parts that work together to perform complex functions

  • Organism

    • Definition: An individual animal or plant

  • Population

    • Definition: A group of individuals of the same kind

  • Community

    • Definition: All of the living organisms in a defined area

  • Ecosystem

    • Definition: The living organisms and the nonliving physical components in a defined area

Vet Medicine Examples of Biological Levels

  • Atoms in Veterinary Medicine: Examples include measuring and correcting blood electrolytes (Na+, K+, Cl-) in patients with Addison’s disease.

  • Ecosystems in Veterinary Medicine: Example: The reintroduction of wolves into Yellowstone in 1995 increased the population of aspen trees. A related resource is available from National Geographic.

Cell Anatomy

  • Introduction to Cells: Refers to a video connecting students to the fundamentals of cell anatomy.

Anatomy of the Animal Cell

Endomembrane System
Cell Membrane (Plasma Membrane)

  • Definition: A flexible, elastic barrier between the inner cytoplasm and the outside environment.

  • Structure:

    • Phospholipid Bilayer (Lipid Bilayer):

    • Hydrophilic heads on the outside

    • Hydrophobic (fatty acid) tails on the inside

Membrane Proteins

  • Integral Proteins:

    • Position: Within the bilayer

    • Function: Create channels through which other molecules can pass

  • Peripheral Proteins:

    • Function: May act as enzymes to catalyze specific chemical reactions; involved in changing the cell’s shape; bound to the inside or outside surface of the cell membrane.

  • Glycocalyx:

    • Made of glycoprotein and glycolipids that form a “sugar coating” on some cells.

    • Function: Improves cell-to-cell adhesions and intercellular recognition (includes Cell Adhesion Molecules and Membrane Receptors).

Cilia and Flagella

  • Definition: Extensions of the plasma membrane that extend into extracellular space.

  • Structure: Energetic, motile hair-like structures, originating from basal bodies at the cell periphery.

Cilia

  • Definition: Short and numerous

  • Function: Move synchronously, creating waves of motion to propel fluid, mucus, and debris across the cellular surface.

    • Examples of Function:

    • Lines the respiratory tract to move mucus, bacteria, and inhaled particles away from the lungs

    • Lines the oviduct to move ova toward the uterus

Flagella

  • Definition: Usually single or in pairs, significantly longer than cilia.

  • Function: Propel individual cells forward by undulating (whip-like motion).

    • Examples:

    • Spermatozoa: only mammalian cell propelled by a single flagellum

    • Single-celled organisms: Giardia lamblia

Microvilli

  • Definition: Finger-like projections formed from the cell membrane itself, which are non-motile.

  • Function: Increase the surface area to enhance the movement of substances in and out of the cell by approximately 20 times.

    • Examples of Location:

    • Lining of intestines for nutrient absorption

    • Lining of kidney tubules for urine production

Cytoplasm and Cytosol

  • Cytoplasm:

    • Definition: Inner substance of a cell, excluding the nucleus; includes cytosol, cytoskeleton, organelles, and inclusions.

  • Cytosol:

    • Definition: Clear, viscous fluid of the cell composed primarily of water, proteins, and lipids, suspending the organelles.

Cytoskeleton

  • Definition: Provides the frame or structure of the cell’s shape.

  • Structure: A meshwork of fine protein fibers, consisting of:

    • Microtubules

    • Intermediate fibers

    • Microfilaments

  • Function:

    • Support and shape of the cell

    • Anchors organelles

    • Enables movement

    • Provides direction for metabolic activity

Mitochondria

  • Definition: The powerhouse of the cell.

  • Function: Produces 95% of the energy (ATP) that fuels the cell through cellular respiration (oxygen consumption leads to CO2 production).

  • Observation: Active cells with high-energy demands contain more mitochondria than inactive cells.

Ribosomes

  • Definition: The site of protein synthesis.

  • Function:

    • Makes various proteins including:

    • Membrane proteins

    • Structural proteins

    • Antibodies

    • Hormones

Endoplasmic Reticulum

  • Rough Endoplasmic Reticulum:

    • Function: Involved in protein synthesis; consists of a series of folded membranes studded with ribosomes (presence gives it a "rough" appearance).

  • Smooth Endoplasmic Reticulum:

    • Function: Involved in lipid synthesis and storage (includes:

    • Membrane phospholipids

    • Fatty acids

    • Steroid hormones).

    • Connected to the Rough ER; consists of tubule-forming membranes.

Golgi Apparatus

  • Function: Modifies, packages, and distributes proteins that were formed in the endoplasmic reticulum; consists of smooth folded membranes.

Vacuoles

  • Definition: Membrane-bound sacs formed from other membranes.

  • Function: Stores and transports substances including:

    • Incoming nutrients

    • Outgoing waste products.

Lysosomes

  • Definition: Specialized vesicles that break down nutrient molecules and digest intracellular debris.

  • Function: Fuses with vacuoles containing engulfed substances (e.g., bacteria, nutrients) and digests them.

Centrioles

  • Function: Active role in cell division by organizing the spindle fibers; form basal bodies of cilia and flagella.

  • Structure: Hollow cylinders of microtubules located in the centrosome, found near the nucleus.

Nucleus

  • Definition: The genetic control center of the cell.

  • Parts:

    • Chromatin: Long, loose fibers of DNA

    • Chromosomes: Tight coiled fibers of DNA

    • Nucleoli: Clusters of DNA and RNA involved in the production of ribosome subunits

    • Nuclear Envelope: Double-layer membrane containing many large pores for protein and RNA transport.

  • Function:

    • DNA directs all cell activity and determines heredity

    • Note: Some cells lose their nuclei during maturation (e.g., avian erythrocytes versus mammalian erythrocytes).

Cell Physiology

  • Introduction to Cell Physiology: Connection to a video covering fundamentals of cell physiology.

Homeostasis

  • Definition: The regulation of internal environments to maintain stable conditions (equilibrium) in living cells.

  • Processes Involved:

    • Absorption of essential materials:

    • Nutrients

    • Electrolytes

    • Oxygen

    • Excretion of cell products:

    • Metabolic waste

    • Carbon dioxide

    • Hormones, digestive enzymes, etc.

  • Mechanisms across Cell Membrane:

    • Active transport: Requires ATP

    • Passive transport: Does not require ATP

Transport Mechanisms

Diffusion

  • Definition: The passive movement of a substance from an area of high concentration to an area of low concentration (down the concentration gradient).

  • Concept: Molecules spread uniformly due to kinetic energy.

  • Membrane Regulation: Plasma membrane acts as a selective barrier to diffusion:

    • Small molecules can freely pass.

    • Lipid-soluble molecules (e.g., O2, CO2, alcohol) diffuse directly through the phospholipid bilayer.

    • Charged ions (e.g., Cl-) may require protein pores for crossing.

Facilitated Diffusion

  • Definition: Molecules move passively across the membrane down a concentration gradient with the help of a carrier protein.

  • Function: Carrier protein binds specific large molecules to assist passage.

  • Example: Glucose transport.

Osmosis

  • Definition: The passive movement of water through a semi-permeable membrane from a dilute solution into a more concentrated solution.

Tonicity

  • Definition: The concentration of solute particles in a fluid compared to the concentration of particles in the cytosol of a cell.

  • Types of Solutions:

    • Hypertonic Solution: The outside solution is more concentrated than the cytosol; results in water moving out of the cell, causing shrinkage.

    • Hypotonic Solution: The outside solution is less concentrated than the cytoplasm; results in water moving into the cell, causing expansion.

    • Isotonic Solution: The solution outside the cell has the same concentration as the cytosol; results in no net movement of water across the membrane. Most intravenous fluids are isotonic to prevent cell damage.

Active Transport

  • Definition: Substance movement across the membrane independent of concentration gradient, requiring energy (ATP) and a carrier protein.

  • Example: Sodium-Potassium pump (Na+ K+ pump) on nerve cell membranes.

Endocytosis vs. Exocytosis

  • Endocytosis: Involves the engulfing of particles, liquids, or cells into the cell.

    • Methods include:

    • Phagocytosis: engulfs large particles; forms a vesicle (phagosome) that fuses with lysosomes for digestion.

    • Pinocytosis: engulfs small pockets of cellular fluid and dissolved substances.

  • Exocytosis: Exports substances out of the cell, such as waste (excretion) and cell products (secretion like hormones and enzymes).

Cell Reproduction

  • Purpose of Cell Division:

    • Growth requires more cells

    • Replacement of worn-out or damaged cells

    • Reproduction of the organism

  • Types:

    • Mitosis: Produces two identical "daughter" cells, identical to the "parent" cell.

    • Meiosis: Produces four cells with half as many chromosomes as the parent cell.

Mitosis

  • Definition: The method for producing new cells for growth and cell replacement.

  • Chromosome Count: Daughter cells have a complete set of chromosomes (diploid).

Mitosis Stages

  1. Interphase:

    • Cell growth and increase in size

    • Doubles organelles, including centrosomes

    • DNA replication in the nucleus (each DNA strand makes a copy)

  2. Prophase:

    • Chromosomes coiled and joined at centromeres

    • Nuclear envelope disintegration

    • Formation of spindle fibers by centrioles, connecting to chromosomes

  3. Metaphase:

    • Centrosomes migrate to opposite poles

    • Chromosomes align at the metaphase plate

    • Spindle fibers connect chromosomes to centrosomes

  4. Anaphase:

    • Centromeres split

    • Chromatids separate into daughter chromosomes

    • Spindle fibers shorten, pulling daughter chromosomes to opposite poles

  5. Telophase:

    • Chromosomes grouped at opposite poles

    • Chromosomes uncoil to chromatin

    • Disappearance of spindle fibers

    • Nuclear envelope formation around chromosomes

    • Cytoplasm pinches and divides (cytokinesis)

Meiosis

  • Definition: Results in new cells for reproduction (gametes: ova and spermatozoa).

  • Chromosome Count: Gametes have half as many chromosomes as the parent cell; diploid (2n) in body cells; haploid (n) in gametes.

Meiosis I vs. Meiosis II

Meiosis I:

  • Interphase I: Cell growth; DNA replication into paired chromatids.

  • Prophase I: Chromosomes form pairs (homologous) and join together; spindle fibers develop.

  • Metaphase I: Chromosomes align at the metaphase plate.

  • Anaphase I: Chromosome pairs separate; chromatids remain connected at centromeres.

  • Telophase I: Chromosomes grouped; nuclear envelope develops; cytokinesis yields haploid daughter cells.

Meiosis II:

  • Similar to mitosis, but results in four daughter cells:

  • Prophase II: Chromosomes already in paired chromatids.

  • Metaphase II: Chromosomes line up at the metaphase plate.

  • Anaphase II: Sister chromatids separate into daughter chromosomes.

  • Telophase II: Chromosomes grouped at opposite poles; nuclear envelope develops; cytokinesis yields haploid daughter cells.

Genetic Diversity Sources

  • Mutations: Errors during replication.

  • Crossing Over: Exchange of DNA between homologous chromatids.

  • Chromosome Sorting: During Metaphase I and II

Taxonomy

  • Definition: Classifying organisms based on evolutionary relationships, including anatomic comparisons and molecular biology.

  • Classification System: Continuously modified with new information; related organisms categorized into a hierarchy of groups and subgroups.

  • Taxonomic Categories:

    • Kingdom

    • Phylum

    • Subphylum

    • Class

    • Order

    • Family

    • Genus

    • Species

    • Mnemonic: King Phillip’s Son Came Over For Good Soup

Kingdoms Overview

Kingdom Monera

  • Type: Bacteria (Prokaryotes)

  • Characteristics: Single-celled organisms without a true nucleus, rigid cell wall, reproduce by mitosis.

  • Importance: Microbiology study includes both harmless and pathogenic species; antibiotics combat harmful bacteria.

Kingdom Protista

  • Type: Protists (Eukaryotes)

  • Characteristics: Single-celled with a true nucleus, capable of motility, can live singly or in colonies.

  • Importance in Veterinary Medicine: Protozoans can cause diseases and are part of normal flora in some animals.

Kingdom Fungi

  • Definition: Organisms that secrete enzymes to digest food externally and absorb small nutrient molecules; includes unicellular yeasts and multicellular molds/mushrooms.

  • Importance in Veterinary Medicine: Some fungi may infect living animals; includes yeast in moist areas and molds causing diseases like “ringworm.”

Kingdom Plantae

  • Characteristics: Use photosynthesis, have cell walls, complex multicellular structure, and organs for reproduction (flowers, seeds).

  • Veterinary Importance: Dietary plants, poisonous plants, and plant-derived pharmaceuticals.

Kingdom Animalia

  • Characteristics: Eukaryotic cells lacking cell walls, complex multicellular organisms, ingest food.

  • Taxonomy: Commonly divided into 11 phyla, including:

    • Porifera (sponges)

    • Cnidaria (corals, jellyfish)

    • Mollusca (snails, clams)

Phyla of Veterinary Parasites

  • Phylum Platyhelminthes: Includes flatworms (Trematoda - flukes; Cestoda - tapeworms).

  • Phylum Nematoda: Includes roundworms like heartworm, hookworm.

  • Phylum Arthropoda: Includes insects (lice, fleas) and arachnids (ticks, mites).

Phylum Chordata

  • Characteristics: Features include a brain and spinal cord, gill structures, a tail, and segmented spine.

  • Subphylum Vertebrata: Backbone developed with various classes:

    • Class Agnatha (lampreys)

    • Class Chondrichthyes (sharks)

    • Class Osteichthyes (bony fish)

Classes of Vertebrata

  • Amphibia: Frogs, toads; life cycle includes aquatic larval and terrestrial adult stages.

  • Reptilia: Protected by scales; lay leathery eggs.

  • Aves: Birds with feathers that contribute to insulation and flight.

  • Mammalia: Hair, milk-producing, diverse reproductive methods (placental and egg-laying).

Notable Orders in Class Mammalia

  • Order Rodentia: Includes significant reservoirs for zoonotic diseases; popular pet species include mice and hamsters.

  • Order Lagomorpha: Rabbits and hares significant in research and as pets.

  • Order Carnivora: Includes domesticated species such as dogs and cats; veterinary significance due to disease interactions.

  • Order Perissodactyla: Horses and zebras; significant in multiple working contexts (e.g., racing, military).

  • Order Artiodactyla: Includes significant livestock and species important within agriculture.

  • Order Primata: Humans, monkeys, and apes, with considerable biomedical research relevance.

Common Veterinary Species

  • Examples from Animalia Phylum with their classifications:

    • Class Reptilia: Iguanidae (Iguana); Phasianidae (Chicken, Turkey).

    • Class Mammalia: Order Rodentia (Mouse, Rat); Lagomorpha (Rabbit); Carnivora (Dog, Cat, Ferret); Perissodactyla (Donkey, Horse, Mule); Artiodactyla (Cattle, Sheep, Goat, Pig).

Conclusion

  • Anticipation for the next lesson covering Mitosis.