Cell Structure and Function

• Cells are the fundamental structural and functional units of all living organisms, where all life processes occur.

Basic Cell Parts

• Cell (Plasma) Membrane: The outer boundary of the cell.
• Cytoplasm: The gel-like substance inside the cell.
  • Cytosol: The fluid portion of the cytoplasm.
  • Organelles: Specialized structures within the cytoplasm.
• Cytoskeleton: A network of protein fibers for structural support and movement.
• Inclusions: Stored materials within the cytoplasm (e.g., glycogen, lipids).

Cell Component Identification and Functions

• Cell (Plasma) Membrane regulates the passage of materials into and out of the cell.
• Centrioles play a role in cell division.
• Cytoplasm (general) is the site of many cellular metabolic reactions.
• Endoplasmic Reticulum (ER):
  • Smooth ER: Lipid synthesis, detoxification.
  • Rough ER: Protein synthesis (due to the presence of ribosomes).
• Golgi Body (Apparatus) modifies, sorts, and packages proteins for transport.
• Lysosome contains enzymes for intracellular digestion.
• Mitochondria produces ATP (cellular energy) through cellular respiration.
• Nucleus contains DNA and controls cell activities.
• Nuclear Membrane (Envelope) surrounds the nucleus, regulating passage of materials.
• Nuclear Pores allow passage of materials between the nucleus and cytoplasm.
• Ribosomes synthesize proteins.

Surface Area to Volume Ratio

• As a cell increases in size, its volume increases at a faster rate than its surface area which limits cell size.
• Cells need sufficient surface area to exchange materials (nutrients, wastes) with their environment; transport becomes inefficient if a cell becomes too large.

Monocular Microscope Focusing

• Low Power (x10):
  • Place the slide on the stage and secure it.
  • Use the coarse adjustment knob to bring the stage close to the objective lens.
  • While looking through the eyepiece, slowly move the stage downward using the coarse adjustment knob until the image comes into focus.
  • Use the fine adjustment knob to sharpen the image.
• High Power (x40):
  • Center the object of interest in the field of view using the low power objective.
  • Rotate the revolving nosepiece to the high power objective.
  • Use only the fine adjustment knob to focus the image as the coarse adjustment should not be used at high power because it can damage the slide and objective lens.

Cell Membrane Structure (Fluid Mosaic Model)

• Cell membrane is composed of a phospholipid bilayer, with proteins embedded within.
• Phospholipids have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails, forming a bilayer.
• Proteins:
  • Channel Proteins: Form pores that allow specific substances to pass through.
  • Carrier Proteins: Bind to specific substances and change shape to transport them across the membrane.
• The membrane is "fluid" as lipids and proteins can move laterally and the membrane is a "mosaic" because of the various proteins embedded within the lipid bilayer.

Cell Membrane Functions

• Selective Permeability: Regulates the passage of materials.
• Cell Signaling: Contains receptors for hormones and other signaling molecules.
• Cell Adhesion: Holds cells together to form tissues.
• Transport: Facilitates the movement of substances across the membrane.

Differentially Permeable

• A differentially (or selectively) permeable membrane allows some substances to pass through while preventing others.

Passive vs. Active Transport

• Passive Transport:
  • Does not require cellular energy (ATP).
  • Moves substances down their concentration gradient (high to low).
• Active Transport:
  • Requires cellular energy (ATP).
  • Moves substances against their concentration gradient (low to high).

Transport Processes

• Diffusion is the movement of substances from an area of high concentration to an area of low concentration.
• Carrier-Mediated Transport uses carrier proteins to transport substances across the membrane.
• Vesicular Transport involves the formation of membrane-bound vesicles to transport large molecules.

Diffusion and Osmosis

• Diffusion: Movement of any substance from high to low concentration.
• Osmosis: Diffusion of water across a selectively permeable membrane.

Channel Proteins in Diffusion

• Channel proteins create pores in the membrane that allow specific ions or small polar molecules to diffuse across.

Facilitated Diffusion vs. Active Transport

• Facilitated Diffusion:
  • Passive transport.
  • Uses carrier proteins.
  • Moves substances down their concentration gradient.
• Active Transport:
  • Requires ATP.
  • Uses carrier proteins.
  • Moves substances against their concentration gradient.

Endocytosis and Exocytosis

• Endocytosis: The process by which a cell takes in substances by forming vesicles from the cell membrane.
  • Phagocytosis: "Cell eating" - engulfing large particles.
  • Pinocytosis: "Cell drinking" - engulfing fluids and dissolved substances.
• Exocytosis: The process by which a cell releases substances by fusing vesicles with the cell membrane.

Concentration Gradient

• A steeper concentration gradient results in a faster rate of diffusion.

Material Properties and Membrane Transport

• Size: Small molecules pass more easily.
• Polarity: Nonpolar (lipid-soluble) molecules pass more easily than polar (water-soluble) molecules.
• Charge: Ions require channel or carrier proteins.

Metabolism, Catabolism, and Anabolism

• Metabolism: The sum of all chemical reactions in the body.
• Catabolism: Breakdown of large molecules into smaller ones (e.g., cellular respiration).
• Anabolism: Synthesis of large molecules from smaller ones (e.g., protein synthesis).

Enzymes in Metabolism

• Enzymes are biological catalysts that speed up metabolic reactions.

Cellular Respiration

• Cellular respiration is a catabolic process that produces ATP.

Respiration Word Equation

• Glucose + Oxygen → Carbon Dioxide + Water + ATP

Aerobic vs. Anaerobic Respiration

• Aerobic Respiration:
  • Occurs in the mitochondria.
  • Requires oxygen.
  • Produces a large amount of ATP.
  • Products are CO2 and H2O.
• Anaerobic Respiration:
  • Occurs in the cytoplasm.
  • Does not require oxygen.
  • Produces a small amount of ATP.
  • Products can be lactic acid, or ethanol and CO2.

ATP and ADP

• ATP (adenosine triphosphate) is the cell's energy currency.
• ADP (adenosine diphosphate) is formed when ATP releases energy.
• ATP is regenerated from ADP by adding a phosphate group.

Reasons Cells Need Energy

• Muscle contraction.
• Active transport.
• Protein synthesis.
• Cell division.
• Nerve impulse transmission.

Enzyme Function

• Enzymes lower the activation energy of reactions.
• Lock and Key Principle:
  • The substrate binds to the enzyme's active site, forming an enzyme-substrate complex.
  • The enzyme then catalyzes the reaction, producing the product.
  • The enzyme is unchanged, and can be reused.

Factors Affecting Enzyme Activity

• Enzyme concentration.
• Substrate concentration.
• Product concentration.
• Temperature.
• pH.
• Cofactors and coenzymes.

Nutrient Definition

• A nutrient is a substance that provides nourishment essential for growth and the maintenance of life.

Nutrient Groups

• Water: Essential for most bodily functions.
• Carbohydrates: Primary energy source.
• Lipids (Fats): Energy storage, insulation, cell membrane component.
• Proteins: Building blocks for tissues, enzymes, hormones.
• Minerals: Inorganic substances required for various functions.
• Vitamins: Organic compounds required for various metabolic processes.

Respiratory System Labeling

• Nose, pharynx, larynx, trachea, lungs, bronchi, bronchioles, alveoli, pleural membranes, diaphragm, intercostal muscles, vocal cords.
• Each structure plays a role in conducting air to the lungs and facilitating gas exchange.

Gas Exchange

• Occurs in the alveoli.
• Oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli.

Respiratory Surface Characteristics

• Large surface area.
• Thin walls.
• Moist surface.
• Rich blood supply.

Diffusion Gradient

• Maintained by ventilation (breathing) and blood flow.

Inhaled vs. Exhaled Air

• Inhaled air: Higher oxygen, lower carbon dioxide.
• Exhaled air: Lower oxygen, higher carbon dioxide.

Breathing vs. Respiration

• Breathing (ventilation): Physical act of moving air in and out of the lungs.
• Respiration: Cellular process of producing ATP.

Mechanics of Breathing

• Inhalation: Diaphragm contracts, chest cavity expands.
• Exhalation: Diaphragm relaxes, chest cavity contracts.

Respiratory Diseases

• Emphysema, lung cancer, pneumonia, tuberculosis, and asthma all impair gas exchange by damaging lung tissue or obstructing airways.

Blood Functions

• Transport of gases, nutrients, wastes, hormones.
• Regulation of pH and temperature.
• Protection against infection.

Blood Components

• Blood cells (erythrocytes, leukocytes, thrombocytes).
• Plasma (fluid portion).

Blood Component Structure and Function

• Plasma: Fluid matrix of blood, contains dissolved substances.
• Erythrocytes (Red Blood Cells): Transport oxygen and some carbon dioxide.
• Leukocytes (White Blood Cells): Defend against infection.
• Thrombocytes (Platelets): Blood clotting.

Erythrocyte and Plasma Role in Gas Transport

• Erythrocytes: Hemoglobin binds to oxygen and carbon dioxide.
• Plasma: Dissolves some carbon dioxide.

Nutrient and Waste Transport

• Nutrients: Dissolved in plasma.
• Wastes: Dissolved in plasma.

Heart Labeling

• Chambers, valves, vessels.

Blood Flow Through the Heart

• Right atrium → right ventricle → lungs → left atrium → left ventricle → body.

Pulmonary vs. Systemic Circulation

• Pulmonary: Heart to lungs and back.
• Systemic: Heart to body and back.

Cardiac Cycle

• Alternating periods of contraction (systole) and relaxation (diastole) of the heart chambers.

Blood Vessel Structure and Function

• Arteries, arterioles, veins, venules, capillaries.

Blood Clotting

• A complex cascade of reactions involving platelets and clotting factors.

Lymphatic System Functions

• Fluid balance, fat absorption, immune defense.

Lymphatic System Components

• Lymph vessels, lymph nodes.

Phagocytic Cells

• Engulf and destroy pathogens.

Blood vs. Lymphatic Systems

• Blood: Closed system, circulates blood.
• Lymphatic: Open system, circulates lymph.

Basic Tissue Types

• Epithelial tissue.
• Connective tissue.
• Muscle tissue.
• Nervous tissue.

Tissue Type Location and Function

• Epithelial Tissue:
  • Location: Covers body surfaces, lines cavities.
  • Function: Protection, secretion, absorption.
• Connective Tissue:
  • Location: Throughout the body.
  • Function: Support, binding, storage.
• Muscle Tissue:
  • Location: Muscles.
  • Function: Movement.
• Nervous Tissue:
  • Location: Brain, spinal cord, nerves.
  • Function: Communication.

Science as a Human Endeavour

• Classification systems are based on international conventions, subject to change with new evidence through debate and resolution.
• Identification and classification of a conservation reserve requires balancing commercial, recreational, and Indigenous Peoples' usage rights.

Science Understanding

Describing Biodiversity

• Biodiversity includes the diversity of genes, species, and ecosystems. Measures rely on classification and are used for spatial and temporal comparisons.
• Biological classification is hierarchical, based on molecular sequences (DNA and protein), physical features, and reproduction (e.g., mammals: placentals, marsupials, monotremes).
• Biological classification systems reflect evolutionary relatedness, often shown with phylogenetic trees.
• Common species definitions rely on morphological or genetic similarity, or the ability to interbreed and produce fertile offspring under natural conditions, though exceptions exist.

Ecosystems

• Ecosystems are diverse, with varied habitats, biotic and abiotic factors, and can be described by their species, interactions, and abiotic environment.
• Habitats and ecosystems are often named after dominant species, typically plants; abiotic factors like climate and substrate also describe environments.
• Different habitats are determined by biotic and abiotic factors (e.g., desert vs. rainforest).
  • Differentiating terrestrial and aquatic environments focus on their abiotic factors.
• Relationships within and between species include predation, competition, symbiosis (mutualism, commensalism, parasitism), collaboration, and disease.
• Biotic components transfer energy (primarily from the sun) and matter to produce biomass. They interact with abiotic components to facilitate biogeochemical cycling (carbon and nitrogen). These interactions are represented in food webs and biomass pyramids.
• Ecological niche: An organism's importance and purpose within its ecosystem.
• Competitive exclusion principle: Describes how two species competing for the same resources cannot coexist if other ecological factors are constant.