Biology Chapter on Bonds and Cell Membranes

Biology Exam Review - Gr. 12

• This document is a high school biology review, specifically from Canada.

Bio Chemistry - The Cell & It's Components

• Organelle: Mitochondria - breaks down molecules converting stored energy into usable energy.
• Organelle: Chloroplasts - chlorophyll absorbs light energy, converts carbon dioxide and water into energy-rich molecules.
• Organelle: Endoplasmic Reticulum - folds and processes proteins, packages them into vesicles and synthesizes lipids.
• Organelle: Golgi Apparatus - responsible for packaging, processing, sorting, distributing proteins, lipids, and other substances within the cell.
• Organelle: Nucleus - contains DNA, RNA, and proteins; nucleolus manufactures ribosomes, controls most of the cell's activity.
• Organelle: Ribosomes - responsible for synthesis of polypeptides in cytoplasm and on the surface of the rough endoplasmic reticulum.
• Organelle: Vesicle - for transport and storage of substances in the cell.
• Organelle: Lysosome - breakdown macromolecules into smaller molecules for reuse or breakdown parts of the cell that are no longer needed.
• Organelle: Cytoskeleton (microtubule) - maintaining cell shape, facilitating movement of organelles and assisting in cell division.

Structure & Function of Eukaryotic Cell: The Cell Membrane

• The cell membrane separates the cell from the extracellular fluid.
• It is a semi-fluid phospholipid bilayer with embedded molecules.
• Phospholipids have hydrophilic heads and hydrophobic tails; heads cluster in water.
• The tails are held together by hydrophobic interactions.
• Cell membrane fluidity depends on temperature, tail length, and cholesterol.
• Peripheral proteins are loosely attached to the inside or outside of the membrane.
• Integral proteins are permanently embedded in the membrane and often involved in substance transport.
• Carbohydrate chains act as identification tags.

The Transport of Substances Across the Cell Membrane

• Passive Transport: Movement of ions or molecules across a cell membrane from higher to lower concentration without energy input.
• Diffusion: The net movement of ions or molecules from an area of higher concentration to an area of lower concentration. Diffusion stops when concentration is equal.
• Facilitated Diffusion: The transport of ions or molecules across the membrane by means of membrane proteins that move with the concentration gradient.
• Osmosis: Movement of water from an area of higher water concentration to an area of lower water concentration, across a semipermeable membrane; solute concentrations may differ.
• Tonicity: Comparative concentration of solutes inside and outside the cell; affects material transport. (Hypertonic, Hypotonic, Isotonic)
• Active Transport: Movement of ions or molecules against a concentration gradient, requiring energy input (ATP).
  • Primary Active Transport: Uses ATP to directly move molecules or ions against a gradient, from low to high concentrations.
  • Secondary Active Transport: Uses a difference in charge to move other molecules against a concentration gradient.

Chemical Fundamentals: Basics of the Periodic Table

• Isotopes: Atoms with different numbers of neutrons but the same number of protons.
• Atomic Mass: Average mass of all isotopes of an atom, considering their relative abundance.
• Covalent Bonds: Electrons are shared between atoms; polar bonds involve unequal sharing. Nonpolar involve equal sharing.
• Ionic Bonds: Atoms transfer electrons creating oppositely charged ions; electronegativity differences greater than 1.7.
• Intermolecular Bonds: Weak forces that exist between various atoms and molecules.
• London Forces: Weakest intermolecular force—exists between all atoms and molecules.
• Dipole-Dipole Interactions: Hold polar molecules to each other.
• Hydrogen Bonds: Strongest intermolecular bond, only occurs between H and another electronegative atom (O, N, F).

Functional Groups

• Functional groups are specific groups of atoms that determine the chemical and physical properties of molecules.
• Hydroxyl: -OH
• Carboxyl: -COOH
• Amino: -NH2
• Sulfhydryl: -SH
• Phosphate: -PO4
• Carbonyl: -COH
• Carbonyl: -CO-

The Chemicals of Life - Macromolecules

• Carbohydrates: Contain C, H, and O in a 1:2:1 ratio.
• Fats (Lipids): Contain C, H, and O; energy-rich C-H bonds.
• Proteins: Contain C, H, O, and N; polymers made up of amino acid monomers.
• Hydrolysis: Breakdown of a molecule by adding water; breaks bonds in carbohydrates (e.g., disaccharides) and proteins (e.g., peptides).
• Condensation: Synthesis reaction where larger molecules are formed from smaller ones, releasing water.
• Dehydration Synthesis: Specific type of condensation reaction.

Macromolecules: Carbohydrates

• Monosaccharide: Single sugar
• Disaccharide: Two sugar molecules
• Polysaccharide: Many sugar molecules Isomers - are one of two or more molecules that have the same chemical formula but have a different stereochemical arrangement of their atoms. Examples: glucose, galactose, fructose, maltose, sucrose, lactose
• Polysaccharides: Starch, glycogen (animal), cellulose.

Lipids - Triglycerides

• Saturated: Solid at room temperature, no double bonds.
• Unsaturated: Liquid at room temperature, one or more double bonds.
• Types of Fats: Saturated, Unsaturated, Trans fat, Polyunsaturated, Omega-3 (Good and Bad).
• Sources of Triglycerides: Animals, Plants.

Proteins

• Structure: Polymers of amino acid monomers, called polypeptides.
• 4 Levels of Protein Structure: Primary, Secondary, Tertiary, and Quaternary.
• Primary Structure: Linear sequence of amino acids.
• Secondary Structure: Coiled (alpha helix) or folded (beta pleated sheet) patterns due to hydrogen bonds.
• Tertiary Structure: Three-dimensional shape due to various interactions (e.g., hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bridges).
• Quaternary Structure: Multiple polypeptide chains bonded to form a functional protein.

Metabolic Processes

• Cellular Respiration: Catabolic pathways producing ATP; Aerobic respiration needs oxygen.
• Stages of Aerobic Respiration: Glycolysis, Pyruvate Oxidation, Krebs Cycle, Electron Transport Chain, Oxidative Phosphorylation.
• Phosphorylation: Process of adding a phosphate group to an organic compound.
  • Substrate Level Phosphorylation: Phosphate from a substrate added to ADP to make ATP.
  • Oxidative Phosphorylation: Oxidation of NADH and FADH2 produces more ATP through the electron transport chain.
• Glycolysis: 10 step process breaking down glucose to pyruvate (2 ATP, 2 NADH, 2 pyruvate).
• Pyruvate Oxidation: Pyruvate converted to Acetyl CoA, releasing CO2 and making 2 NADH.
• Krebs Cycle/Citric Acid Cycle: Acetyl CoA enters to produce reduced electron carriers (2 ATP, 6 NADH, 2 FADH2).
• Electron Transport Chain (ETC): Electrons from NADH and FADH2 transfer through membrane proteins to oxygen, creating a proton gradient for ATP production.
• Oxidative Phosphorylation (Chemiosmosis): H+ flow drives the synthesis of ATP through ATP synthase.

Photosynthesis

• Photosynthesis: Process where organisms use light energy to convert carbon dioxide and water into glucose and oxygen.
• Summary Equation: 6CO2 + 6H2O ----> C6H12O6 + 6O2
• Calvin Cycle: The light-independent reaction that produces glucose from carbon dioxide.

Homeostasis and Control Systems

• Homeostasis: The body's ability to maintain stable internal conditions.
• Sensor: Part that detects a change.
• Control Centre: Determines appropriate response.
• Effector: Part that carries out the response.
• Negative Feedback: Maintains stability.
• Positive Feedback: Amplifies changes.
• Homeostatic Systems: The body's systems cooperate to maintain homeostasis, including the nervous and endocrine systems.

The Nervous System

• Central Nervous System (CNS): Brain and spinal cord; controlling centre.
• Reflex Arc: Simple connections of neurons, responding quickly to a stimulus.
• Peripheral Nervous System (PNS): Carries sensory messages to the CNS and motor messages to muscles and glands, including voluntary (somatic) and involuntary (autonomic) divisions.
• Autonomic Nervous System: Regulates vital functions, including heart rate, breathing, and digestion. (Sympathetic and Parasympathetic)

The Endocrine System

• Endocrine Glands: Glands in the human body that secrete hormones directly into the bloodstream; regulating many bodily functions.
• Hormones: Chemical messengers; controlling growth, development, metabolism, and other functions.
• Mechanism: Hypothalamus regulating the pituitary which may stimulate or inhibit other glands for hormone production and release..
• Target Gland Response: Individual glands respond to hormones to maintain homeostasis, and create a systemic response.

Hormones Affecting Blood Sugar

• Pancreas - Regulates blood glucose levels.
  • Beta Cells: Secrete insulin, lowering blood glucose.
  • Alpha Cells: Secrete glucagon, raising blood glucose.
• Adrenal Gland: Stress response.
  • Medulla: Releases epinephrine and norepinephrine, increasing blood glucose.
  • Cortex: Produces cortisol, increasing blood glucose, and influencing other metabolic processes.

Molecular Genetics

• Genome: An organism's complete set of DNA.
• Gene: Specific DNA sequence coding for a trait or function, including regulatory sequences to control gene expression.
• DNA Structure: Double helix formed from nucleotides. Each nucleotide includes deoxyribose sugar, phosphate group, and a nitrogenous base (adenine, guanine, cytosine, or thymine).
• Base Pairing: A with T, C with G; holds the two strands together in DNA.
• DNA Replication: Process of doubling DNA. The double helix unwinds and each strand serves as a template for a new strand, resulting in two daughter molecules, identical to each other and the original molecule.
• DNA Proofreading: DNA polymerase recognizes and corrects mistakes during replication (mistakes are rare).
• Semi-Conservative: Form of DNA replication - each new double helix contains one original (parental) strand and one new strand.
• Transcription: DNA to RNA - process where a particular segment of DNA is copied into a form of RNA called mRNA which carries the genetic code to be translated.
• Translation: RNA to Protein - the process where mRNA acts as a messenger and brings the appropriate amino acids in order to produce a protein - codons are the instructions.
• Different RNA types: mRNA (messenger), tRNA (transfer), rRNA (ribosomal).
• Mutations: Changes in the DNA sequence.
• Types of Mutations: Silent, Missense, Nonsense, and Frameshift (deletion or insertion of base pairs).

Population Dynamics

• Population Size/Density: The number of individuals of a specific species in a given area or volume at a given time.
• Population Dispersion patterns: Clumped, Uniform, Random.
• Factors Affecting Population Growth: Immigration, Emigration, Birth rate, Death rate, Limiting factors, Density-dependent factors (ex: competition, predation, disease), Density-independent factors (ex: weather events, natural disasters).
• Exponential vs. Logistic Growth: Exponential growth assumes unlimited resources, while logistic growth considers carrying capacity (the maximum population size an environment can sustain).

Explore important concepts in biology related to chemical bonding and cell membranes. This quiz covers topics such as covalent bonds, ionic bonds, and various cell organelles. Test your knowledge on how these elements contribute to cell structure and function.