Biology Midterm Review
Midterm Review Notes
Overview
Review topics: Chapters 1, 7, 2 to 4, 24.1, 24.2 and Supplemental Materials
Chapter 1: Introduction to Biology
Key Questions and Concepts
What is biology?
Biology is the study of life and living organisms, encompassing various scientific disciplines.
What is anatomy and physiology?
Anatomy refers to the structure of body parts, while physiology focuses on the functions of those parts.
Property of life questions:
which of the following is NOT a property of life? Answers include:
A) Populations of organisms rarely change over time.
B) Living things exhibit complex but ordered organization.
C) Organisms take in energy and use it to perform all of life’s activities.
D) Organisms reproduce their own kind.
Homeostasis and Ecosystems
Homeostasis:
Definition: The maintenance of stable internal conditions in an organism despite changes in external conditions.
Ecosystem:
Definition: A biological community of interacting organisms and their physical environment.
Population:
Definition: A group of individuals of the same species that live in the same area at the same time.
Taxonomy and Life Domains
Taxonomy:
The scientific classification of living things; a mnemonic rhyme can help remember it.
Three domains of life:
Archaea, Bacteria, Eukarya.
Differentiation:
Archaea: Prokaryotic, extremophiles.
Bacteria: Prokaryotic, diverse habitats.
Eukarya: Eukaryotic, includes complex organisms.
Kingdoms in Eukarya:
Protista, Fungi, Plantae, Animalia.
Energy Flow in Ecosystems
Recycling in ecosystems:
Identify which resources are not recycled but change form within ecosystems:
A) Nitrogen
B) Energy (correct answer)
C) Magnesium
D) Carbon
Macromolecules and Organ Systems
Food Web Roles:
Discuss roles in ecosystems: producers, consumers, decomposers.
Human Organ Systems:
Circulatory, respiratory, digestive, nervous, musculoskeletal, immune, endocrine, urinary, reproductive.
Four main macromolecules:
Carbohydrates, proteins, lipids, nucleic acids.
Negative Feedback:
Mechanism whereby a change in a physiological variable triggers a response which counteracts the initial fluctuation.
Chapter 7: Evolution
Key Concepts
Evolution:
The process by which populations of organisms change over generations.
Adaptation:
An inherited characteristic that enhances an organism's ability to survive and reproduce in its environment.
Genetic Variation:
Differences in DNA among individuals, crucial for natural selection.
Natural Selection:
The differential survival and reproduction of individuals due to differences in phenotype.
Darwin’s Theory Principles:
Variation, heritability, differential survival, competition, reproduction, change over time.
Micro vs Macroevolution:
Microevolution: Small evolutionary changes within a species. Macroevolution: Large-scale changes that occur at or above the level of species.
Genetic Mechanisms
Mutations:
Permanent alteration in the DNA sequence. They can occur due to errors in DNA replication or environmental factors.
Migration:
Movement of individuals into or out of a population, which can affect genetic diversity.
Bottleneck Effect:
A sharp reduction in population size, leading to a loss of genetic diversity.
Chapter 2: Chemistry and Water
Water Structure and Properties
Structure of Water:
Comprised of two hydrogen atoms bonded to one oxygen atom (H₂O).
Types of Bonds:
Within a water molecule: Covalent bonds; between water molecules: Hydrogen bonds.
Polar Molecules:
Molecules with an uneven distribution of charge (water is polar).
Life-supporting Properties:
Cohesion, adhesion, ice formation, solvent properties, specific heat.
States of Matter:
Solid, liquid, gas.
Organic Molecules and Importance
Organic Molecules:
Molecules that contain carbon and are found in living organisms.
Naturally Occurring Elements:
There are 92 naturally occurring elements.
Four Elements of Human Body:
Oxygen, carbon, hydrogen, nitrogen (comprise 96% of body weight).
Macromolecules:
Four types: Carbohydrates, proteins, lipids, nucleic acids.
Reactions and Protein Structure
Dehydration Synthesis Reaction:
Process of joining two molecules, or compounds, together following the removal of water.
Hydrolysis Reaction:
A reaction involving the breaking of a bond in a compound by addition of water.
Protein Structure:
Proteins are composed of 20 different amino acids.
Functions: Enzymatic, structural, transport, signaling.
Levels of Structure:
Primary (sequence of amino acids), secondary (alpha-helix or beta-pleated sheet), tertiary (3D shape), and quaternary (complex of multiple polypeptides).
Denaturation:
The process whereby proteins lose their native structure due to external stressors, which often leads to loss of function.
Nucleic Acids and Carbohydrates
Types of Nucleic Acids:
DNA and RNA.
Structure of Nucleic Acids:
DNA is double-stranded with bases A, T, C, G; RNA is single-stranded with bases A, U, C, G.
DNA and RNA Comparison:
DNA contains deoxyribose; RNA contains ribose. DNA uses thymine, RNA uses uracil.
Example Nucleotide Sequence:
DNA: A T C C G G G G A A T T C G A; Complementary DNA strand: T A G G C C C C T T A A G C T.
Carbohydrates:
Chemical structure includes carbon, hydrogen, and oxygen.
Monosaccharides vs Disaccharides:
Monosaccharides: Single sugar molecules (e.g., glucose). Disaccharides: Two monosaccharides joined together (e.g., sucrose).
Complex Carbs:
Polysaccharides made up of various monosaccharide units.
Fiber:
A type of complex carbohydrate that is not digestible, aiding in digestion.
Lipid Categories and Functions
Three Main Types of Lipids:
Triglycerides, phospholipids, and steroids.
Triglycerides:
Composed of glycerol and three fatty acids.
Found in oils, fats, and food items like butter.
Essential Fatty Acids:
Fatty acids that the body cannot synthesize and must be obtained from the diet.
Functions of Cholesterol:
Integral to cell membrane structure and fluidity, precursor to steroid hormones.
Phospholipids:
Composed of glycerol, two fatty acids, and a phosphate group; a major component of cell membranes.
Micronutrients
Types of Micronutrients:
Vitamins and minerals.
Essential Vitamins:
13 essential vitamins identified.
Essential Minerals:
Approximately 16 essential minerals acknowledged.
Water-Soluble vs Fat-Soluble Vitamins:
Water-soluble: Easily dispersed in water; e.g., Vitamin C.
Fat-soluble: Stored in body tissue; e.g., Vitamins A, D, E, K.
Chapter 3: The Cell
Cell Types
Prokaryotic Cells:
Simpler and smaller cells that lack a nucleus and organelles; examples include bacteria.
Eukaryotic Cells:
Larger and more complex cells containing organelles; the largest organelle is the nucleus.
Cell Theory and Structure
Principles of Cell Theory:
All living organisms are composed of cells.
The cell is the basic unit of life.
All cells arise from pre-existing cells.
Basic Structures in All Cells:
Plasma membrane, cytoplasm, ribosomes, genetic material (DNA).
Age Comparison:
Prokaryotic cells are older than eukaryotic cells due to evolutionary history.
Plasma Membrane Composition
Makeup and Role of Plasma Membrane:
The membrane structure is a phospholipid bilayer embedded with proteins; it regulates what enters and exits the cell.
Fluid Component:
The fluid mosaic model describes the plasma membrane's dynamic nature.
Hydrophilic vs Hydrophobic:
Hydrophilic: Water-attracting (polar). Hydrophobic: Water-repelling (non-polar).
Proteins, Carbohydrates, and Lipids in Membranes
Roles of Carbohydrates, Lipids, and Proteins in Plasma Membrane:
Carbohydrates: Involved in cell recognition and signaling.
Lipids: Form the structure of the membrane, providing fluidity and barrier.
Proteins: Act as transporters, receptors, and enzymes.
Cell Organelles and Functions
Labeling Cells:
Eukaryotic and prokaryotic cells contain organelles such as the nucleus, mitochondria, and lysosomes.
Organelle Definitions:
Structure and specific functions such as energy production, protein synthesis, and waste disposal.
Chromosome Count and Protein Synthesis
Human Chromosome Count:
Humans typically have 46 chromosomes.
Process of Protein Synthesis:
DNA transcription (nucleus).
mRNA processing (nucleus).
Translation (ribosome in cytoplasm).
Types of Proteins:
Intracellular (within cells) vs extracellular (secreted proteins).
3.6 - Plasma Membrane Transport
Passive and Active Transport
Simple Diffusion:
The movement of molecules from high to low concentration without energy expenditure.
Factors Affecting Diffusion Rates:
Temperature, concentration gradient, surface area, and distance.
Osmosis:
Movement of water through a semipermeable membrane.
Definitions:
Solute: Substance dissolved in a solvent.
Solvent: The substance in which solutes are dissolved.
Tonicity Definitions:
Hypotonic: Lower concentration of solutes compared to another solution.
Isotonic: Equal concentration of solutes in two solutions.
Hypertonic: Higher concentration of solutes compared to another solution.
Facilitated Diffusion and Active Transport
Facilitated Diffusion:
The passive movement of molecules via membrane proteins without energy usage.
Active Transport Types:
Primary Active Transport: Direct use of ATP to transport molecules against their concentration gradient.
Secondary Active Transport: Utilizes the energy from the primary transport to move a second molecule against its gradient.
Endocytosis:
Process of cell engulfing material from the external environment.
Exocytosis:
Process of expelling materials from a cell into the external environment.
Plant Cell Features:
Cell walls, chloroplasts, and large vacuoles are characteristic structures.
Energy and the Cell
Energy Concepts
Energy Definition:
The capacity to perform work.
Types of Energy:
Kinetic Energy: Energy of motion.
Potential Energy: Stored energy due to position or structure.
Types of Reactions:
Exergonic Reactions: Reactions that release free energy.
Endergonic Reactions: Reactions that absorb free energy.
ATP and Enzymes
ATP (Adenosine Triphosphate):
The primary energy carrier in cells.
Phosphorylation:
The addition of a phosphate group to a molecule, often activating it for use.
Enzymes:
Biological catalysts that speed up chemical reactions by lowering the activation energy required.
Metabolism:
The sum of all biochemical reactions occurring in an organism.
Catabolic Reaction:
A biochemical reaction that breaks down molecules into smaller units and releases energy.
Anabolic Reaction:
A biochemical reaction that builds larger molecules from smaller units, requiring energy.
Chapter 4: Cellular Respiration
Overview
Cellular Respiration:
The process by which cells convert glucose and oxygen into energy, occurring in the mitochondria.
Caloric Yield:
Each macromolecule provides the following calories:
Carbohydrates: 4 calories per gram.
Proteins: 4 calories per gram.
Fats: 9 calories per gram.
Balanced Chemical Equation:
Aerobic Nature:
Cellular respiration is considered aerobic because it requires oxygen.
Glycolysis and Metabolic Pathways
Glycolysis:
The metabolic process occurring in the cytoplasm where glucose is broken down into pyruvate, yielding 2 ATP.
Krebs Cycle:
Occurs in the mitochondria, processes pyruvate into acetyl-CoA, producing electron carriers (NADH, FADH₂) and ATP.
ATP Production:
Total ATP produced during cellular respiration is typically 36-38 ATP molecules depending on efficiency.
Anaerobic Respiration:
Respiration in the absence of oxygen, leading to fermentation processes instead of full glucose oxidation.
Photosynthesis Overview
Photosynthesis:
Process by which plants convert light energy into chemical energy stored in glucose.
Location of Photosynthesis:
Occurs in chloroplasts.
Major Pigments Involved:
Chlorophyll a and Chlorophyll b.
Photosynthetic Reactions
Light-Dependent Reactions:
Convert solar energy into chemical energy (ATP and NADPH).
Light-Independent Reactions (Calvin Cycle):
Utilize ATP and NADPH to convert CO₂ into glucose.
Photosynthesis Balanced Equation:
Chapter 24.1 and 24.2: Bacteria and Viruses
Bacteria Structure and Function
Normal Flora Bacteria:
Beneficial bacteria that reside in the body, aiding processes such as digestion.
Bacterial Cell Structure:
Composed of a cell wall, plasma membrane, cytoplasm, and genetic material (often circular DNA).
Gram Staining:
Gram-Positive: Thick peptidoglycan layer; retains crystal violet stain.
Gram-Negative: Thinner peptidoglycan layer; does not retain violet stain but takes up counterstain (pink).
Prokaryotic Fission:
Process of asexual reproduction in bacteria creating two identical daughter cells.
Gene Transfer in Bacteria
Three Types of Bacterial Gene Transfer:
Transformation, transduction, and conjugation.
Three Main Shapes of Bacterial Cells:
Cocci (spherical), bacilli (rod-shaped), spirilla (spiral).
Types of Bacterial Respiration
Three Main Types of Bacterial Respiration:
Aerobic, anaerobic, and facultative anaerobic respiration.
Antibiotic Resistance:
The ability of bacteria to survive and grow despite the presence of antibiotics due to genetic changes.
Viruses Overview
Are Viruses Alive?
Viruses are not considered alive as they cannot reproduce independently or perform metabolic processes.
Virus Structure:
Consists of nucleic acid (DNA or RNA) surrounded by a protein coat (capsid).
Shapes of Viruses:
Helical, icosahedral, complex, and enveloped.
Size Comparison:
Viruses are typically much smaller than both prokaryotic and eukaryotic cells.
DNA Virus vs RNA Virus:
DNA viruses include herpesvirus; RNA viruses include influenza virus.
Viral Life Cycle
The Lytic Cycle:
1. Attachment to host cell.
2. Entry of viral genome.
3. Replication and assembly of new virions.
4. Lysis of the host cell and release of new virions.
The Lysogenic Cycle:
Viral DNA integrates into host genome and replicates with host cell until induced to enter the lytic cycle.
Methods of Viral Entry into Cells:
Direct penetration, membrane fusion, or receptor-mediated endocytosis.
Vaccines:
Work by preparing the immune system to recognize and fight pathogens without causing the disease directly.