BIOL-141 Final Exam Study Guide: Core Concepts in Biology

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Chapter 1: Evolution, the Themes of Biology, and Scientific Inquiry

Cell Theory

The cell theory is a fundamental concept in biology stating that all living organisms are composed of cells, and that the cell is the basic unit of life. All cells arise from pre-existing cells.

All organisms are made of cells.
The cell is the basic unit of structure and function in living things.
All cells come from pre-existing cells.

Prokaryotic vs. Eukaryotic Cells

Prokaryotic cells lack a nucleus and membrane-bound organelles (e.g., Bacteria and Archaea).
Eukaryotic cells have a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).
Similarities: Both have DNA, cytoplasm, ribosomes, and a plasma membrane.
Differences: Eukaryotes are generally larger, have a nucleus, and possess organelles.

Scientific Inquiry Process

Observation: Gathering information about phenomena.
Hypothesis: A testable explanation for an observation.
Prediction: What you expect to happen if the hypothesis is correct.
Testing: Experimentation or further observation to test the hypothesis.

Variables in Experiments

Independent variable: The factor that is changed or controlled by the experimenter.
Dependent variable: The factor that is measured or observed.

Chapter 2: The Chemical Context of Life

Atomic Structure

Atomic number: Number of protons in an atom.
Mass number: Sum of protons and neutrons.
Isotopes: Atoms of the same element with different numbers of neutrons.

Electron Shells and Ions

Valence shell: The outermost electron shell.
Valence electrons: Electrons in the valence shell.
Atoms gain or lose electrons to complete their valence shell, forming ions:
- Cation: Positively charged ion (loses electrons).
- Anion: Negatively charged ion (gains electrons).

Chemical Bonds

Ionic bonds: Formed when electrons are transferred from one atom to another.
Covalent bonds: Formed when atoms share electrons.
Hydrogen bonds: Weak attractions between a hydrogen atom and an electronegative atom (important in water molecules).

Chapter 3: Water and Life

Properties of Water

Lower density as a solid: Ice floats on water.
High heat of evaporation: Requires much energy to vaporize.
High specific heat: Water resists temperature change.
Solvent for hydrophilic molecules: Dissolves polar and ionic substances.
Cohesion and adhesion: Water molecules stick to each other and to other surfaces.

Hydrophilic vs. Hydrophobic

Hydrophilic: Water-loving; substances that dissolve in water.
Hydrophobic: Water-fearing; substances that do not dissolve in water.

pH and Hydrogen Ion Concentration

pH: Measure of hydrogen ion concentration;
Acidic: pH < 7; higher [H+]
Basic: pH > 7; lower [H+]
Neutral: pH = 7
Each pH unit change = 10-fold change in [H+]

Acids and Bases

Acid: Increases [H+] in solution.
Base: Decreases [H+] in solution (increases [OH-]).

Chapter 4: Carbon and the Molecular Diversity of Life

Isomers

Isomers: Molecules with the same molecular formula but different structures.

Functional Groups

Hydroxyl (-OH)
Amine (-NH2)
Carboxyl (-COOH)
Carbonyl (C=O)
Methyl (-CH3)
Phosphate (-PO42-)
Sulfhydryl (-SH)

Chapter 5: The Structure and Function of Large Biological Molecules

Monomers and Polymers

Carbohydrates: Monomer = monosaccharide
Proteins: Monomer = amino acid
Nucleic acids: Monomer = nucleotide
Lipids: Not true polymers, but built from fatty acids and glycerol

Polysaccharides

Polysaccharide	Function	Organism
Starch	Energy storage	Plants
Cellulose	Structural	Plants
Glycogen	Energy storage	Animals
Chitin	Structural	Fungi, Arthropods

Lipids

Saturated fatty acids: No double bonds; solid at room temperature.
Unsaturated fatty acids: One or more double bonds; liquid at room temperature.

Protein Structure

Primary: Sequence of amino acids.
Secondary: Alpha helices and beta sheets (hydrogen bonding).
Tertiary: 3D folding due to side chain interactions.
Quaternary: Multiple polypeptide chains.

Denaturation

Denaturation: Loss of protein structure (and function) due to heat, pH, or chemicals.

DNA vs. RNA

DNA: Double-stranded, deoxyribose sugar, bases A-T-C-G.
RNA: Single-stranded, ribose sugar, bases A-U-C-G.

Nucleotide Components

Phosphate group
Pentose sugar (deoxyribose or ribose)
Nitrogenous base

Chapter 6: A Tour of the Cell

Prokaryotic vs. Eukaryotic Cells

See Chapter 1 for similarities and differences.

Plant vs. Animal Cells

Plant cells: Have cell walls, chloroplasts, and large central vacuoles.
Animal cells: Lack cell walls and chloroplasts, have small vacuoles.

Organelle Functions

Nucleus: Contains DNA, controls cell activities.
Ribosomes: Protein synthesis; found free in cytoplasm or on rough ER.
Chloroplast: Photosynthesis (plants and algae).
Mitochondria: Cellular respiration, ATP production.
Rough ER: Protein synthesis and modification.
Smooth ER: Lipid synthesis, detoxification.
Lysosome: Digestion of macromolecules and waste.

Chapter 7: Membrane Structure and Function

Phospholipid Bilayer

Hydrophilic heads: Face outward toward water.
Hydrophobic tails: Face inward, away from water.

Fluid Mosaic Model

Membranes are flexible and composed of various proteins and lipids.

Tonicity

Term	Definition	Effect on Animal Cell	Effect on Plant Cell
Hypertonic	Higher solute outside	Shrinks (crenates)	Plasmolysis
Isotonic	Equal solute	No net change	Flaccid
Hypotonic	Lower solute outside	Swells/lyses	Turgid (normal)

Transport Mechanisms

Passive diffusion: Movement down concentration gradient, no energy required.
Active transport: Movement against concentration gradient, requires energy (ATP).

Chapter 8: An Introduction to Metabolism

Energy Types

Kinetic energy: Energy of motion.
Potential energy: Stored energy.

Exergonic vs. Endergonic Reactions

Exergonic: Releases energy;
Endergonic: Requires energy input;
Catabolic: Breaks down molecules, releases energy.
Anabolic: Builds molecules, requires energy.

Enzymes

Lower activation energy of reactions.
Are not consumed in the reaction.

ATP

Main energy currency of the cell.
Energy released by breaking phosphate bonds (hydrolysis).

Chapter 9: Cellular Respiration and Fermentation

Purpose and Overview

Converts glucose and oxygen into ATP, CO2, and H2O.
Reactants: Glucose, O2
Products: CO2, H2O, ATP
Glucose is oxidized; oxygen is reduced.

Oxygen Requirement

Oxygen is the final electron acceptor in the electron transport chain.

Anaerobic Respiration/Fermentation

Glycolysis occurs without oxygen, in the cytoplasm.
Fermentation produces lactic acid (animals) or ethanol (yeast).

Chapter 10: Photosynthesis

Relationship to Cellular Respiration

Photosynthesis stores energy; cellular respiration releases it.

Overall Equation

Reactants: CO2, H2O
Products: Glucose, O2
CO2 is reduced; H2O is oxidized.

Light Reactions

Convert solar energy to chemical energy (ATP, NADPH).
Produce O2 as a byproduct.

Calvin Cycle

Uses ATP and NADPH to convert CO2 to glucose.

Leaf Color

Chlorophyll reflects green light, making leaves appear green.

Chapter 12: The Cell Cycle

Mitosis vs. Meiosis

Mitosis: Growth, repair, asexual reproduction.
Meiosis: Production of gametes (sexual reproduction).

Chromosome Terms

Sister chromatids: Identical copies of a chromosome, joined at the centromere.
Homologous chromosomes: Chromosome pairs, one from each parent, similar but not identical.

End Products of Mitosis (Humans)

2 daughter cells
Diploid (2n)
Genetically identical
46 chromosomes each

Chapter 13: Meiosis and Sexual Life Cycles

Gametes vs. Somatic Cells

Gametes: Sex cells (sperm, egg), haploid (n)
Somatic cells: Body cells, diploid (2n)

Separation Events

Homologous chromosomes separate in meiosis I.
Sister chromatids separate in meiosis II (and in mitosis).

Genetic Variation

Crossing over: Exchange of genetic material between homologous chromosomes (prophase I).
Independent assortment: Random distribution of homologous chromosomes (metaphase I).

End Products of Meiosis (Humans, Sperm)

4 daughter cells
Haploid (n)
Genetically unique
23 chromosomes each

Chapters 14/15: Mendel and the Gene Idea; Chromosomal Basis of Inheritance

Genetics Terminology

Dominant: Trait expressed if at least one allele is present (capital letter).
Recessive: Trait expressed only if two alleles are present (lowercase letter).
Homozygous dominant: Two dominant alleles (AA).
Heterozygous: One dominant, one recessive allele (Aa).
Homozygous recessive: Two recessive alleles (aa).
Genotype: Genetic makeup (e.g., Aa).
Phenotype: Observable trait (e.g., tall or short).

Inheritance Patterns

Monohybrid cross: Cross between individuals heterozygous for one gene.
Autosomal dominant/recessive: Trait located on non-sex chromosome.
X-linked recessive: Trait located on X chromosome; more common in males.

Blood Type Inheritance

Determined by multiple alleles (A, B, O) and codominance.

Pedigree Analysis

Used to determine inheritance pattern (autosomal dominant, autosomal recessive, X-linked recessive).

Chapter 16: The Molecular Basis of Inheritance

DNA Replication

Semi-conservative: Each new DNA molecule has one old and one new strand.
Complementary base pairing: A pairs with T, C pairs with G.
Purpose: To accurately copy genetic information for cell division.

Chapter 17: Gene Expression: From Gene to Protein

Genes and Genome

Gene: Sequence of DNA coding for a protein or RNA.
Genome: Complete set of genetic material in an organism.

Gene Expression Steps

1. Transcription: DNA to RNA
2. Translation: RNA to protein

Codon Redundancy

Multiple codons can code for the same amino acid.

Transcription

Starts: DNA template
Ends: mRNA
Main components: RNA polymerase, DNA template, nucleotides

Translation

Starts: mRNA
Ends: Polypeptide (protein)
Main components: Ribosome, tRNA, amino acids

Mutations

Changes in DNA sequence can alter protein structure and function.
Transcription and translation of mutated DNA can result in different amino acids in the protein.