AP EXAM 1 Review

Features of All Life

• Reproduction: The biological process through which living organisms produce new individuals, ensuring the continuation of their species. Can be sexual or asexual.

• Growth: The process where organisms increase in size, which may involve cell division and differentiation, leading to the development of complex structures.

• Responsiveness: The ability of an organism to detect changes in their environment and respond appropriately. This includes movements toward or away from stimuli (e.g., light, temperature, and touch).

• Metabolism: A collection of biochemical reactions that occur within organisms to maintain life. These reactions involve converting food into energy, synthesizing complex molecules, and breaking down waste.

• Cellular: All living organisms are composed of one or more cells, which are the basic units of life. Cells carry out essential functions and exhibit organization.

Things Needed by Humans

• Water: Serves as a solvent for biochemical reactions, helps regulate body temperature through sweating, and acts as a transport medium for nutrients and waste.

• Food: Provides essential nutrients, including carbohydrates, proteins, fats, vitamins, and minerals. These nutrients supply energy and serve as chemical building blocks for the growth and repair of tissues.

• Atmospheric Oxygen: A vital component for cellular respiration, the biochemical process that extracts energy from food. Oxygen plays a crucial role in converting glucose into usable energy (ATP) for cellular functions.

• Heat: Thermal energy that is essential for maintaining optimal body temperature. Enzymatic reactions and other metabolic processes function best within a narrow temperature range.

• Pressure: The force exerted over an area, crucial for various physiological processes. Includes exterior pressure, like atmospheric pressure, which is necessary for breathing, and internal pressure, such as hydrostatic pressure in blood vessels, which facilitates circulation and nutrient exchange.

Homeostasis

• Definition: Homeostasis is the process used to maintain ideal conditions for an organism, ensuring optimal functioning of physiological processes.

Components of Homeostasis

• Needs:

  • Sensor: Often located in the integument (skin), detects changes in the environment.

  • Control Center: Typically the central nervous system, processes information and determines the response needed.

  • Effector: The mechanism that carries out the response, frequently muscles and glands that enact change.

Negative Feedback

• Set Point: The ideal condition or targeted physiological level.

• Counteractions: Mechanisms that counteract deviations from the set point, helping to restore balance.

• Overcompensation: Can lead to a series of adjustments that show an oscillatory pattern around the set point, maintaining stability.

Body Cavities and Features

• Cranial Cavity: Houses the brain, protected by the skull.

• Vertebral Canal: Encases the spinal cord, formed by the vertebrae.

• Thoracic Cavity: Contains the heart and lungs, protected by the rib cage.

  • Diaphragm: A muscular structure that separates the thoracic cavity from the abdominopelvic cavity.

• Abdominopelvic Cavity:

  • Abdominal Cavity: Houses digestive organs, kidneys, and spleen.

  • Pelvic Cavity: Contains the bladder, reproductive organs, and rectum.

  • Relationship: There is no real separation between the abdominal and pelvic cavities; they are part of a continuous space.

  • Quadrants: The abdominopelvic cavity is often divided into quadrants for clinical reference (right upper, left upper, right lower, left lower).

Serous Membranes

• Visceral versus Parietal Membranes:

  • Visceral Membrane: A thin membrane that covers the organs within a cavity.

  • Parietal Membrane: Lines the walls of the body cavity and does not cover the organs.

• Pleural Membranes and Cavities:

  • The pleurae are the serous membranes surrounding the lungs.

  • Pleural Cavity: The space between the visceral and parietal pleura that contains pleural fluid to reduce friction during respiration.

• Pericardial Membranes and Cavity:

  • The pericardium is the serous membrane surrounding the heart.

  • Pericardial Cavity: The space between the visceral and parietal pericardium that contains pericardial fluid for lubrication.

• Peritoneal Membranes and Cavity:

  • The peritoneum is the serous membrane lining the abdominal cavity and covering the abdominal organs.

  • Peritoneal Cavity: The space between the visceral peritoneum and the parietal peritoneum, containing peritoneal fluid.

Organs and Organ Systems

• Major Organs and Their Importance

  Adrenal Glands

  • Location: Situated atop each kidney.

  • Function: Produce hormones such as cortisol, adrenaline, and aldosterone, which are essential for stress response, metabolism regulation, and electrolyte balance.

  Appendix

  • Location: A small, tube-like structure attached to the large intestine, specifically the cecum.

  • Function: Although its exact function is debated, it may play a role in gut flora management and the immune response.

  Bladder

  • Location: Located in the pelvis, behind the pubic bone.

  • Function: Stores urine produced by the kidneys until it is excreted from the body.

  Bone

  • Function: Provides structure and support to the body, protects vital organs, facilitates movement by serving as levers for muscles, and is a major site for hematopoiesis (blood cell production).

  Brain

  • Location: Enclosed within the cranial cavity of the skull.

  • Function: The central control unit of the body, responsible for processing sensory information, regulating bodily functions, and enabling cognitive abilities, emotions, and memory.

  Esophagus

  • Location: A muscular tube running from the throat (pharynx) to the stomach.

  • Function: Transports food and liquids from the mouth to the stomach through coordinated muscle contractions known as peristalsis.

  Gallbladder

  • Location: Situated beneath the liver.

  • Function: Stores and concentrates bile produced by the liver, releasing it into the small intestine to aid in the digestion of fats.

  Heart

  • Location: Located in the thoracic cavity, between the lungs.

  • Function: Pumps blood throughout the body, supplying oxygen and nutrients while removing waste products, and plays a crucial role in maintaining blood circulation.

  Kidneys

  • Location: Located on either side of the spine, just below the rib cage.

  • Function: Filter blood to remove waste products and excess fluids, regulate electrolyte balance, and maintain acid-base balance, producing urine in the process.

  Large Intestine

  • Location: Extends from the small intestine to the anus, encircling the small intestine.

  • Function: Absorbs water and electrolytes from indigestible food matter, compacts waste into stool, and facilitates its elimination from the body.

  Liver

  • Location: Located in the right upper quadrant of the abdomen.

  • Function: Performs various functions, including detoxification of harmful substances, synthesis of proteins,production of biochemicals necessary for digestion, and regulation of metabolism.

  Lungs

  • Location: Paired organs located in the thoracic cavity on either side of the heart.

  • Function: Essential for gas exchange, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled from the body during respiration.

  Muscle

  • Function: Comprises three types (skeletal, smooth, cardiac) and enables movement of the body, supports posture, and circulates blood through contractions.

  Pancreas

  • Location: Located in the abdominal cavity behind the stomach.

  • Function: Functions as both an endocrine and exocrine gland, producing insulin and glucagon to regulate blood sugar levels, and digestive enzymes to assist in food breakdown.

  Skin

  • Function: The body's largest organ, serving as a protective barrier, regulating temperature, and facilitating sensory perception, hydration, and expression of emotions.

  Small Intestine

  • Location: Extends from the stomach to the large intestine.

  • Function: Main site of digestion and absorption of nutrients, with three segments (duodenum, jejunum, ileum) that contribute to the digestive process.

  Spinal Cord

  • Location: Extends from the base of the brain through the vertebral canal of the spinal column.

  • Function: Transmits signals between the brain and the rest of the body, facilitating reflex actions and coordination of movement.

  Spleen

  • Location: Situated in the upper left abdomen, near the stomach and pancreas.

  • Function: Plays a role in filtering blood, recycling iron from red blood cells, and combating infections as part of the immune system.

  Stomach

  • Location: Located in the upper left abdomen, between the esophagus and the small intestine.

  • Function: Responsible for the breakdown of food through mechanical churning and enzymatic action, creating a semi-liquid substance known as chyme for digestion in the small intestine.

  Thyroid Gland

  • Location: Located in the neck, just below the Adam's apple.

  • Function: Produces hormones that regulate metabolism, heart rate, and body temperature, playing a crucial role in growth and development.

  Trachea

  • Location: A tube that connects the larynx (voice box) to the bronchi of the lungs.

  • Function: Provides a clear airway for air to enter and exit the lungs and is lined with cilia and mucus to trap and expel debris.

  • Body Regions

    • Body Region Terminology: Familiarize yourself with the following terms, as they are likely to show up on the exam:

      • Otic: Pertaining to the ear.

      • Nasal: Related to the nose.

      • Oral: Concerning the mouth.

      • Cervical: Relating to the neck.

      • Acromial: Referring to the bony prominence of the shoulder.

      • Axillary: Pertaining to the armpit.

      • Brachial: Related to the arm.

      • Antecubital: Referring to the front of the elbow.

      • Abdominal: Pertaining to the abdomen.

      • Antebrachial: Relating to the forearm.

      • Carpal: Concerning the wrist.

      • Palmar: Referring to the palm of the hand.

      • Digital: Related to the fingers or toes.

      • Genital: Pertaining to the reproductive organs.

      • Patellar: Referring to the kneecap.

      • Tarsal: Pertaining to the ankle.

      • Cephalic: Related to the head.

      • Frontal: Referring to the forehead region.

      • Orbital: Pertaining to the bony cavity that houses the eye.

      • Buccal: Related to the cheek.

      • Mental: Pertaining to the chin.

      • Sternal: Referring to the breastbone area.

      • Pectoral: Pertaining to the chest.

      • Umbilical: Related to the navel.

      • Inguinal: Referring to the groin area.

      • Coxal: Pertaining to the hip.

      • Crural: Related to the leg.

      • Pedal: Referring to the foot.

      • Occipital: Pertaining to the back of the head.

      • Vertebral: Related to the spine.

      • Dorsal: Pertaining to the back.

      • Cubital: Related to the elbow.

      • Lumbar: Referring to the lower back.

      • Sacral: Pertaining to the region between the hips.

      • Gluteal: Related to the buttocks.

      • Perineal: Referring to the area between the anus and the genitals.

      • Femoral: Related to the thigh.

      • Popliteal: Referring to the area behind the knee.

      • Plantar: Pertaining to the sole of the foot.

Terms of Relative Position

• Anterior (Ventral): Refers to the front of the body.

• Posterior (Dorsal): Refers to the back of the body.

• Superior: Refers to a position above or higher than another part of the body.

• Inferior: Refers to a position below or lower than another part of the body.

• Medial: Refers to a position closer to the midline of the body.

• Lateral: Refers to a position farther away from the midline of the body.

• Proximal: Refers to a position closer to the trunk of the body or point of attachment.

• Distal: Refers to a position farther from the trunk of the body or point of attachment.

• Superficial: Refers to a position closer to the surface of the body.

• Deep: Refers to a position farther from the surface of the body.

Body Sectioning

• Transverse: A horizontal plane that divides the body into superior and inferior parts.

• Sagittal: A vertical plane that divides the body into right and left parts.

• Coronal (Frontal): A vertical plane that divides the body into anterior and posterior parts.

• Oblique: A plane that divides the body at an angle, not parallel to the axes of the body.

Basic Chemistry

Electrostatic Attraction/Repulsion

• The attractive or repulsive force that occurs between charged molecules or particles due to their electric charge.

• Opposite charges (positive and negative) attract each other, resulting in a force that draws them together, while like charges (positive-positive or negative-negative) repel each other, pushing them apart. This principle is fundamental in understanding chemical bonding and molecular interactions across different states of matter.

Atomic Structure

• Basic Structure of the Atom: The atom consists of a dense nucleus surrounded by electron shells.

  • Nucleus:

    • Contains protons and neutrons.

    • Proton: A positively charged particle, fundamental to the identity of the atom, with its number determining the atomic number of the element.

    • Neutron: A neutral particle that contributes to the atomic mass; it helps stabilize the nucleus. The relative number of protons to neutrons affects the stability of the atom. If there are too many or too few neutrons, it can lead to radioactive decay, allowing the nucleus to become unstable and eject particles or energy. This process is critical in nuclear chemistry and understanding radioactive isotopes.

  • Electron Shells/Orbitals: Regions around the nucleus where electrons are likely to be found. The arrangement of these electrons plays a significant role in the chemical behavior of an atom.

• Subatomic Particles:

  • Protons: Define the chemical identity of an element (e.g., hydrogen has 1 proton; carbon has 6 protons).

  • Neutrons: Their number can vary among isotopes of the same element (e.g., carbon-12 has 6 neutrons, while carbon-14 has 8). These variations influence atomic stability and the process of radioactive decay.

  • Electrons: Negatively charged particles found in the electron shells; they determine the atom's chemical bonding properties and reactivity.

• Locations and Charges of Subatomic Particles:

  • Atomic Number: Identifies an element; equals the number of protons in the nucleus (e.g., Z = 6 for carbon).

  • Atomic Mass: Refers to the total number of protons and neutrons in the nucleus, typically expressed in atomic mass units (amu).

  • Atomic Charge: The net charge of an atom, calculated by subtracting the number of electrons from the number of protons. If an atom has an equal number of protons and electrons, the charge is neutral (0).

• Illustration of Electrons in an Atom: Be able to visually represent electrons in their respective shells, noting the maximum capacity and arrangement according to the shell model (e.g., 2 electrons in the first shell, 8 in the second, etc.).

Isotopes and Ions

• Isotopes: Variants of a particular chemical element that have the same number of protons but differ in the number of neutrons; they may have different physical properties and stability (e.g., Carbon-12 vs. Carbon-14).

• Ions: Atoms or molecules that have gained or lost one or more electrons, resulting in a net charge. Cations are positively charged ions (loss of electrons), while anions are negatively charged ions (gain of electrons). You should be able to identify ions when given the number of protons and electrons.

Electron Shells

• Predicting Electron Shells: Understand the electron configuration of an atom and the number of shells based on its position in the periodic table.

• Electron Capacity: Know that an electron shell can hold a maximum number of electrons given by the formula 2n² (where n is the shell level). For example, the first shell can hold 2 electrons, the second shell can hold 8, and so on.

• Drawing Electron Configuration: Be able to draw and represent electron shells and their arrangement in an atom, using dots or circles to denote electrons in each shell.

Major and Trace Elements in Living Organisms

• Major Elements: The most abundant elements in living organisms are Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) - often referred to as CHON. These elements form the backbone of biological molecules like proteins, nucleic acids, carbohydrates, and lipids.

• Trace Elements: These are elements required in small amounts that play crucial roles in various biological processes. Examples include:

  • Iron (Fe): Vital for oxygen transport in hemoglobin.

  • Zinc (Zn): Important for immune function and enzymatic reactions.

  • Copper (Cu): Plays a role in energy production and iron metabolism.

  • Iodine (I): Essential for the production of thyroid hormones.

Covalent Bonds

Chemical Reactions

• Products vs. Reactants:

  • Reactants: Starting substances that undergo change during a chemical reaction.

  • Products: Substances formed as a result of a chemical reaction.

• Direction of the Reaction:

  • Indicates the progress of a reaction, typically represented by an arrow (→) that points from reactants to products.

Valence Electron Shell and Its Significance

• The valence electron shell consists of the outermost electrons of an atom, which play a crucial role in chemical bonding.

• Atoms strive to achieve full valence shells to attain stability, which significantly influences their chemical behavior.

“Duet” and “Octet” Rules

• Duet Rule: For very light elements like hydrogen and helium, the goal is to achieve two electrons in their outer shell.

• Octet Rule: For most other elements, atoms are most stable when they have eight electrons in their valence shell, resembling the electron configuration of noble gases.

Covalent Bonds and the Sharing of Electrons

• How and Why Covalent Bonds are Formed:

  • Covalent bonds are formed when two atoms share one or more pairs of electrons to achieve full valence shells, enhancing their stability.

  • This bond formation is driven by the need for atoms to complete their electron shells according to the duet and octet rules.

• Predicting the Number of Covalent Bonds:

  • The number of covalent bonds an atom can form typically relates to the number of electrons it needs to achieve a full valence shell.

  • For example, oxygen, which needs two electrons, can form two covalent bonds.

• Understanding Why Sharing Electrons Holds Atoms Together:

  • Shared electrons create an attractive force between the positively charged nuclei of the atoms and the negatively charged electrons, stabilizing the bond.

Singly, Doubly, and Triply Covalent Bonds

• Covalent Bonds Representation:

  • Illustrated by dashes:

    • Single Covalent Bond: One pair of shared electrons (e.g., H-H).

    • Double Covalent Bond: Two pairs of shared electrons (e.g., O=O).

    • Triple Covalent Bond: Three pairs of shared electrons (not in the examples but significant to note).

• Examples without Dashes:

  • Sometimes the dashes are omitted for simplicity, e.g.,

    • H2 for a single bond,

    • O2 for a double bond,

    • H2O or HOH for water.

• Electron Sharing Representation:

  • Each dash represents two shared electrons, or one shared pair of electrons, visually indicating the bond strength and electron sharing between atoms.

Ionic Bonds

Ionic Bonds and the Transferring of Electrons

• Formation of Ionic Bonds as a Multistep Process:

  • Transfer of Electrons: One atom donates electrons, resulting in a positive ion (cation), while another atom accepts these electrons, resulting in a negative ion (anion).

  • Attraction Between the Ions: The electrostatic attraction between the oppositely charged ions forms the ionic bond.

• Predicting Electron Transfer: Be able to determine how many electrons an atom will transfer or receive based on its position in the periodic table and its electronegativity.

• Representation of Ionic Compounds: In an ionic molecule, the bond is generally not shown. The atomic symbols are simply written next to one another (e.g., NaCl).

  • This can be confusing since covalent compounds are sometimes represented in a similar manner.

Polar Covalent Bonds

• Nature of Polar Covalent Bonds:

  • Result from the unequal sharing of electrons between different atoms in a bond.

  • This unequal sharing leads to the development of partial charges on either side of the molecule.

• Electrostatic Attraction: The partial charges can create attractions that bond molecules together.

  • Hydrogen Bonds:

    • Involve the attraction between partial charges arising in the following polar covalent bonds:

      • O-C

      • O-H

      • N-H

    • Represented by a series of small dots between the molecules that are hydrogen-bonded.

• Significance of Hydrogen Bonding:

  • Hydrogen bonding is extensive between water molecules and plays a crucial role in the behavior of water and dissolved substances, affecting its physical and chemical properties.

Nonpolar Covalent Bonds

• Equal Sharing of Electrons: Nonpolar covalent bonds involve the equal sharing of electrons between atoms.

• No Partial Charges Arise: Since electrons are shared equally, there are no partial charges on the atoms involved.

• Examples: C-C bonds and C-H bonds are both examples of nonpolar covalent bonds.

Water as a Solvent

• Universal Solvent: Water is often referred to as the universal solvent due to its ability to dissolve many substances.

• Polarity of Water: The polar covalent bonds of water allow hydrogen bonding between water molecules and the solutes dissolved in water.

Polar Compounds in Water

• Dissolution Process:

  • Polar compounds will dissolve in water because the partial charges of the polar molecule interact with the partial charges of water molecules.

  • Each polar molecule becomes wrapped in a shell of water.

  • Polar compounds are described as hydrophilic ("likes water").

Ions and Ionic Compounds in Water

• Dissolution of Ionic Compounds:

  • Dissolving an ionic compound breaks the ionic bond, thereby releasing individual ions into the solution.

  • Whole charges of the ions interact with the partial charges of water molecules.

  • Each ion becomes wrapped in a shell of water.

  • Ions and ionic compounds are also considered hydrophilic ("likes water").

Nonpolar Compounds in Water

• Lack of Solubility: Nonpolar compounds do not dissolve in water due to their hydrophobic ("fears water") nature.

• No Interaction with Polar Water: Nonpolar molecules do not have partial charges and therefore cannot interact well with polar water molecules, making them insoluble in water.

Acid/Base Chemistry

Auto-Ionization of Water

• Reaction: HOH ⇌ H⁺ + OH⁻

Definitions of Acidic, Neutral, and Basic Solutions

• Acidic: [H⁺] > [OH⁻]

• Neutral: [H⁺] = [OH⁻]

• Basic/Alkaline: [H⁺] < [OH⁻]

Effects of Acids and Bases on Water

• Acids: Increase the concentration of H⁺ and decrease the concentrations of OH⁻ when added to water.

• Bases: Decrease the concentration of H⁺ and increase the concentration of OH⁻ when added to water.

• Pure water is neutral with equal concentrations of H⁺ and OH⁻.

pH Scale

• pH is an estimate of [H⁺]:

  • pH < 7: Acidic

  • pH = 7: Neutral

  • pH > 7: Basic/Alkaline

Introduction to Organic Chemistry

• Organic Chemistry: The study of carbon and its compounds, which includes the structure, properties, reactions, and synthesis of carbon-containing compounds.

  • Carbon:

    • Has four valence electrons, enabling it to form four covalent bonds with other atoms, this makes it highly versatile in forming various structures.

    • Acts as a central atom in molecular scaffolds, allowing for intricate and diverse organic molecules, including chains, rings, and branched structures.

• Hydrocarbons:

  • Definition: Simplest organic molecules that consist entirely of carbon and hydrogen atoms.

  • Types:

    • Aliphatic Hydrocarbons: Composed of straight or branched chains (e.g., alkanes, alkenes, alkynes).

    • Aromatic Hydrocarbons: Contain one or more aromatic rings (e.g., benzene).

• Polar vs. Nonpolar:

  • Nonpolar Bonds:

    • Formed when atoms share electrons equally, leading to no charge difference across the molecule.

    • Example: Hydrocarbons, where carbon and hydrogen atoms share electrons equally due to similar electronegativities.

  • Polar Bonds:

    • Occur when two atoms with different electronegativities share electrons unequally, creating regions of partial positive and negative charge.

    • Example: Water (H2O), where oxygen is more electronegative than hydrogen, resulting in a partial negative charge on the oxygen and partial positive charges on the hydrogens.

• Hydrophobic and Hydrophilic:

  • Hydrophobic Molecules:

    • Nonpolar substances that do not interact favorably with water and do not dissolve in it.

    • Often consist of long carbon chains or hydrocarbons, which repel water (e.g., fats and oils).

  • Hydrophilic Molecules:

    • Polar or ionic substances that readily dissolve in water, interacting through hydrogen bonding or ionic interactions.

    • Examples include sugars, salts, and functionalized organic compounds that contain highly electronegative atoms (e.g., O, N).

• Functional Groups:

  • Groups of atoms that confer specific chemical properties to organic compounds.

  • Role:

    • Increase the hydrophilicity of hydrocarbons, enhancing their solubility in polar solvents like water.

    • Dictate the reactivity, behavior, and biological functions of organic molecules.

  • Common Functional Groups:

    • Hydroxyl (-OH), carbonyl (C=O), carboxyl (-COOH), amino (-NH2), phosphate (-PO4).

4 Biological Macromolecules

• Lipids:

  • Types:

    • Triglycerides: Composed of glycerol and three fatty acids, serve primarily for energy storage.

    • Phospholipids: Form cell membranes; have a hydrophilic head and two hydrophobic tails, creating a bilayer structure.

    • Steroids: Include cholesterol and hormones (e.g., testosterone, estrogen).

  • Functions:

    • Major component of cell membranes, providing structural integrity and fluidity.

    • Store energy for long-term use; provide insulation and protection to organs.

• Carbohydrates:

  • Monosaccharides: Simple sugars (e.g., glucose, fructose), the building blocks of carbohydrates.

  • Disaccharides: Formed from two monosaccharides (e.g., sucrose, lactose).

  • Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

  • Functions:

    • Provide a primary source of energy for cells.

    • Serve as energy storage molecules (e.g., glycogen in animals, starch in plants).

    • Structural components in plants (cellulose) and insect exoskeletons (chitin).

• Proteins:

  • Comprised of amino acids linked by peptide bonds, folded into specific three-dimensional shapes.

  • Functions:

    • Enzymatic: Catalyze metabolic reactions and increase reaction rates.

    • Structural: Provide support in cells and tissues (e.g., collagen in connective tissue).

    • Transport: Move molecules across cell membranes or throughout the organism (e.g., hemoglobin carries oxygen).

    • Defense: Immune system proteins (antibodies) protect against pathogens.

• Nucleic Acids:

  • Composed of nucleotide monomers (adenine, guanine, cytosine, thymine, uracil).

  • Types:

    • DNA (Deoxyribonucleic Acid): Carries genetic information; composed of two strands forming a double helix.

    • RNA (Ribonucleic Acid): Involved in protein synthesis and regulation; single-stranded.

  • Functions:

    • Serve as the blueprint for making proteins, guiding their synthesis and expression, and transmitting genetic information across generations.

Lipids

Types of Lipids

• Steroids: A class of lipids characterized by a carbon skeleton consisting of four fused rings. They play various roles in cellular processes, including being precursors for hormones.

• Waxes: Long-chain fatty acids esterified to long-chain alcohols. These lipids provide protective coatings in both plants and animals, serving functions such as waterproofing surfaces.

• Fatty Acids: Building blocks of lipids with a hydrocarbon chain and a carboxyl (acid) group.

Structure of Fatty Acids

• Nonpolar, Hydrophobic Hydrocarbon Tail: The long-chain hydrocarbon part that is hydrophobic and repels water.

• Polar, Hydrophilic, Acidic Head Group: The carboxyl group that is polar and interacts favorably with water.

• Amphipathic: Molecules that contain both hydrophobic and hydrophilic properties, leading to unique structures in aqueous environments like lipid bilayers.

Saturated vs. Unsaturated Fatty Acids

• Saturated Fatty Acids:

  • Saturated with hydrogen, meaning there are no double bonds between carbons.

  • Characterized by a straight, unbent hydrocarbon tail, often solid at room temperature (e.g., butter).

• Unsaturated Fatty Acids:

  • Contain at least one carbon-carbon double bond in the hydrocarbon tail, resulting in a kink or bend.

  • Generally liquid at room temperature (e.g., olive oil).

Phospholipids

• Main Components of Cellular Membranes: Phospholipids consist of two fatty acids attached to a very polar head group, forming a bilayer structure.

• Amphipathic Nature: Their dual nature allows them to form lipid bilayers that are essential for cell membranes.

Amphipathic Molecules

• Molecules that possess both hydrophobic and hydrophilic regions.

• Formation of Unique Structures in Water: When in an aqueous environment, amphipathic molecules can form structures like lipid bilayers, crucial to cellular architecture.

Diffusion

• The tendency of molecules to spread out, leading to spontaneous movement from areas of high concentration to low concentration.

• Net Result: Achieves uniformity in concentration across a given space.

Cell Membranes

• Semipermeable (Selective Permeability): Cell membranes allow certain molecules to diffuse across while restricting others.

  • Molecules that Can Diffuse:

    • Gases (e.g., O2, CO2)

    • Small polar molecules (including water)

    • Nonpolar molecules

  • Molecules that Cannot Diffuse:

    • Large polar molecules (e.g., glucose)

    • Ions (e.g., Na+, K+, Cl-)

Diffusion Across a Membrane

• Molecules move from an area of high concentration to an area of low concentration, equalizing concentration on either side of the membrane, known as passive diffusion or passive transport.

Osmosis

• Definition: Osmosis is the movement of water across a selectively permeable membrane when the solute is not permeable but the solvent is. The solvent is almost always water in living organisms.

• Direction of Movement: The solvent moves towards the area of high solute concentration.

• Nature: This process is spontaneous and aims to equalize the concentration of the solute on either side of the membrane.

Tonicity

• Definition: Tonicity determines the flow of the solvent (water) during osmosis.

  • Isotonic:

    • Same concentration of solute inside and outside of the cell.

    • No net flow of water, leading to stable cell conditions.

    • This is the optimal state for cells.

  • Hypotonic:

    • Lower solute concentration outside the cell.

    • Water flows into the cell, which may ultimately lead to cell lysis (bursting).

  • Hypertonic:

    • Higher solute concentration outside the cell.

    • Water flows out of the cell, resulting in crenation (shrinkage).

• Key Concept: Understand the direction of water flow and its effects on animal cells.

Facilitated Diffusion

• Definition: Facilitated diffusion is diffusion with the assistance of a protein, enabling certain molecules that cannot normally pass through the membrane (such as ions and large polar molecules) to enter the cell.

  • Mechanism: A protein forms a pore or channel in the membrane to facilitate this transport.

• Direction of Movement: Molecules move from areas of high concentration to low concentration.

• Nature: This process is spontaneous.

Active Transport

• Definition: Active transport is the movement of molecules from low concentration to high concentration, which is the reverse of passive diffusion.

  • Process: Active transport works for molecules that cannot normally pass through the membrane and requires the assistance of a specific protein.

• Nature: It is a non-spontaneous process that requires an input of energy (usually in the form of ATP).

Bulk Transport

• Endocytosis: The process by which cells internalize substances from their external environment.

  • Pinocytosis: Cell drinking; uptake of fluids and small molecules.

  • Phagocytosis: Cell eating; uptake of large particles or microorganisms.

• Exocytosis: The reverse process of endocytosis where substances are expelled from the cell.

• Vesicles: Membrane-bound sacs that transport materials within the cell and help in both endocytosis and exocytosis.

Vesicles

• Formation: Vesicles are formed by the pinching off of a section of the membrane during endocytosis. This process can be triggered by the binding of specific ligands to receptors on the cell surface, initiating invagination of the membrane and leading to vesicle formation.

• Functions:

  • Delivery: Used to transport macromolecules such as proteins, lipids, and carbohydrates to different organelles within the cell. For instance, vesicles may carry newly synthesized proteins from the rough ER to the Golgi apparatus for further modification.

  • Transport: Serve as vehicles to move molecules into and out of the cell. For example, secretory vesicles release their contents outside the cell through exocytosis.

  • Fusion: Upon reaching their target site, the vesicle membrane fuses with the target membrane (such as the plasma membrane or an organelle membrane), releasing its contents.

Filtration

• Definition: Filtration involves using force or pressure to move fluid and solutes through a membrane, effectively separating substances based on their size.

• Mechanism: In biological systems, filtration often occurs in capillary beds, where blood pressure forces water and small solutes out of the blood and into the tissue fluid, while larger molecules and cells remain in the bloodstream.

• Size-Filtration: The filtration process typically results in two components: the filtrate (the liquid that passes through the membrane) and the residue (what is left behind).

Cells

• Significance of Compartmentalization: Compartmentalization is crucial in eukaryotic cells as it allows different metabolic processes to occur simultaneously in different environments. For example, it enables the hydrolysis of macromolecules in lysosomes while respiration occurs in mitochondria, minimizing interference between incompatible reactions.

• Major Structures of the Cell:

  • Plasma Membrane: The semi-permeable outer boundary of the cell composed of a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates. The membrane regulates the movement of substances in and out of the cell through passive and active transport mechanisms.

  • Nucleus: Contains the cell's genetic material.

    • Nucleolus: A dense region within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosome subunits are assembled.

    • Nuclear Pores: Complex structures that span the nuclear envelope and allow the regulated exchange of proteins and RNA between the nucleus and the cytoplasm.

    • Nucleoplasm: The viscous fluid within the nucleus, analogous to the cytoplasm, in which the chromatin (DNA strands) and nucleolus are suspended.

  • Ribosome: Non-membranous organelles composed of ribosomal RNA and proteins. They can be found free in the cytoplasm or bound to the rough ER, playing a critical role in translating mRNA into polypeptide chains (proteins).

  • Smooth and Rough Endoplasmic Reticulum (ER):

    • Rough ER: Studded with ribosomes, it is primarily involved in protein synthesis and post-translational modifications.

    • Smooth ER: Lacks ribosomes and is involved in lipid synthesis, detoxification of drugs and poisons, and storage of calcium ions.

  • Golgi Apparatus: A stack of flattened membrane-bound sacs (cisternae) that further modifies, sorts, and packages proteins and lipids received from the ER for secretion or transport to other organelles.

  • Lysosomes: Membrane-bound organelles that contain hydrolytic enzymes for breaking down waste materials and cellular debris. They are involved in processes such as autophagy (cellular recycling) and phagocytosis (engulfing of large particles).

  • Mitochondria: Double-membraned organelles known as the powerhouses of the cell. They generate ATP through oxidative phosphorylation and are unique in having their own circular DNA and ribosomes, supporting the endosymbiotic theory.

  • Centrosome and Centrioles: The centrosome is the primary microtubule organizing center in animal cells, important for cell division. It contains two centrioles, cylindrical structures that help form the spindle fibers during mitosis.

  • Cilia/Flagella: Microtubule-based structures that extend from the cell surface, involved in movement. Cilia are short and numerous, often moving fluid across the cell surface, while flagella are longer and usually fewer in number, propelling the cell itself.

  • Vesicles: Membrane-bound sacs that transport materials within the cell and facilitate cellular processes like endocytosis, exocytosis, and intracellular trafficking.

Cell Division Cycle

• Nucleic Acids: DNA is the nucleic acid that comprises the genetic material in cells.

  • In humans, DNA is organized into 46 long structures called chromosomes, holding the genetic instructions for the development and functioning of the organism.

  • Chromosomes consist of two sister chromatids joined at a region known as the centromere.

• During Cell Division: Cells must:

  • Grow: Increase in size and mass to prepare for division.

  • Duplicate Genetic Material: Copy their DNA so that each daughter cell receives a complete set of chromosomes.

  • Segregate Genetic Material: Distribute the duplicated DNA to opposite poles of the cell.

  • Divide: Physically split into two daughter cells.

• Phases and Major Events:

  • Interphase: The longest phase of the cell cycle where cells prepare for division.

    • G1 Phase (Gap 1): Cells grow in size, synthesize proteins, and produce organelles.

    • S Phase (Synthesis): The DNA is replicated, resulting in the formation of sister chromatids for each chromosome.

    • G2 Phase (Gap 2): Further growth occurs, and the cell prepares for mitosis, ensuring all organelles and proteins are ready for cell division.

Mitosis

Prophase

• DNA Condensation: DNA condenses, allowing effective movement of genetic material around the cell.

• Nucleus Disintegration: The nuclear envelope disintegrates, facilitating interaction with the cytoplasm.

• Mitotic Spindle Formation: DNA becomes attached to the mitotic spindle.

  • The centrosome serves as the main microtubule organizing center of the cell, with centrioles aiding in the formation of the spindle apparatus.

  • Spindle fibers, which are protein cables, attach to the kinetochores of the chromosomes.

  • These fibers will move the DNA to the appropriate locations within the cell in subsequent phases.

Metaphase

• Chromosome Alignment: Chromosomes are aligned in the middle of the cell at the metaphase plate, ensuring they are properly positioned for separation.

Anaphase

• Chromosome Segregation: Sister chromatids are pulled apart and segregated to opposite ends of the cell, ensuring each daughter cell receives an identical set of genetic material.

• Initiation of Cytokinesis: The physical division of the cell begins, and a cleavage furrow may become apparent at this stage.

Telophase

• Completion of Cytokinesis: The process of cytoplasm division is completed, resulting in two separate daughter cells.

• Decondensation of DNA: Chromosomes begin to uncoil and decondense back into chromatin.

• Nuclear Reformation: The nuclear envelope reforms around each set of separated chromosomes, creating two distinct nuclei in the daughter cells.

Cancer and Mitosis

• Regulation of Mitosis: Mitosis is regulated by several factors including:

  • Growth Factors: Stimulate cell division and proliferation.

  • Contact Inhibition: Cells stop dividing when they come into contact with other cells, preventing overcrowding.

  • Anchorage Dependence: Cells must be attached to a substrate to grow and divide.

• Types of Tumors:

  • Benign Tumors: Non-cancerous growths that do not invade surrounding tissues or metastasize; they are typically localized and can often be removed surgically.

  • Malignant Tumors: Cancerous growths that invade surrounding tissues and have the potential to metastasize, spreading to other parts of the body.

• Metastasis: The process by which cancer cells spread from the original (primary) tumor to form new (secondary) tumors in other tissues or organs of the body.

• Key Concept: Understanding the regulation of mitosis and the characteristics distinguishing benign and malignant tumors is crucial for comprehending cancer biology.