biology semester 1

Independent Variable :: The variable that is deliberately changed by the experimenter

Dependent Variable :: The variable that is measured or observed in an experiment

Controlled Variable (Constant) :: Variables kept the same to ensure a fair test

Experimental Control :: A baseline setup used for comparison in an experiment

Organization :: Living things are composed of one or more cells, the basic unit of life

Metabolism :: All chemical reactions that maintain life and require energy

Homeostasis :: Ability to maintain a stable internal environment despite external changes

Growth and Development :: Organisms grow and develop according to instructions in their DNA

Reproduction :: Ability to produce new organisms, sexually or asexually

Response to Stimuli :: Ability to respond to environmental changes

Evolution :: Change in populations over time through natural selection and adaptation

Spontaneous Generation :: Disproven idea that life arises from nonliving matter

Biogenesis :: Theory stating that all living things come from pre-existing living things

Francesco Redi :: Scientist who disproved spontaneous generation using meat and maggot experiments

Louis Pasteur :: Scientist who disproved spontaneous generation using swan-neck flask experiments

Miller-Urey Experiment :: Simulated early Earth conditions and produced amino acids from inorganic molecules

Abiogenesis :: Hypothesis that life originated from nonliving matter through chemical processes

Macromolecule :: Large biological molecule formed from smaller repeating units called monomers

Monomer :: Small molecule that serves as a building block for polymers

Polymerization :: Process of joining monomers through condensation reactions

Condensation (Dehydration Synthesis) :: Reaction that forms polymers by removing water

Hydrolysis :: Reaction that breaks polymers into monomers by adding water

Four Biological Macromolecules :: Carbohydrates, lipids, proteins, nucleic acids

CHNOPS :: Elements that make up biological macromolecules (carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur)

Carbohydrate Structure :: Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio

Monosaccharide :: Single sugar molecule (e.g., glucose, fructose)

Disaccharide :: Two monosaccharides bonded together (e.g., sucrose, lactose)

Polysaccharide :: Long chain of monosaccharides (e.g., starch, glycogen, cellulose)

Carbohydrate Function :: Primary source of energy and structural support

Plant Energy Storage :: Starch

Animal Energy Storage :: Glycogen

Structural Carbohydrates :: Cellulose (plants), chitin (fungi and insects)

Glycosidic Bond :: Bond that links monosaccharides together

Lipid Structure :: Mostly carbon and hydrogen; hydrophobic

Triglyceride :: Glycerol bonded to three fatty acids

Phospholipid :: Glycerol, two fatty acids, and a phosphate group

Steroid :: Lipid with four fused carbon rings (e.g., cholesterol)

Lipid Function :: Long-term energy storage, insulation, cell membranes, signaling

Saturated Fat :: Fatty acids with no double bonds; solid at room temperature

Unsaturated Fat :: Fatty acids with one or more double bonds; liquid at room temperature

Ester Bond :: Bond linking fatty acids to glycerol

Phospholipid Bilayer :: Structure forming cell membranes

Protein Structure :: Composed of carbon, hydrogen, oxygen, and nitrogen

Amino Acid :: Monomer of proteins

Peptide Bond :: Bond linking amino acids together

Enzyme :: Protein that catalyzes chemical reactions

Structural Protein :: Protein that provides support (e.g., collagen, keratin)

Transport Protein :: Protein that carries substances (e.g., hemoglobin)

Defense Protein :: Protein involved in immune response (e.g., antibodies)

Hormonal Protein :: Protein that regulates body processes (e.g., insulin)

Essential Amino Acids :: Amino acids that must be obtained from diet

Protease :: Enzyme that breaks down proteins

Nucleic Acid Structure :: Composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus

Nucleotide :: Monomer of nucleic acids consisting of sugar, phosphate, and nitrogenous base

DNA :: Double-stranded nucleic acid that stores genetic information

RNA :: Single-stranded nucleic acid involved in protein synthesis

DNA Bases :: Adenine, Thymine, Cytosine, Guanine

RNA Bases :: Adenine, Uracil, Cytosine, Guanine

Phosphodiester Bond :: Bond linking nucleotides together

Genetic Information :: Instructions for protein synthesis and inheritance

Polarity :: Unequal sharing of electrons causing partial charges

Hydrogen Bond :: Weak attraction between polar molecules

Cohesion :: Attraction between water molecules

Adhesion :: Attraction between water and other substances

High Heat Capacity :: Water resists temperature change

Universal Solvent :: Water dissolves many substances

Capillary Action :: Movement of water through narrow spaces

Density of Ice :: Solid water is less dense than liquid water

Unit 4 – Molecular Genetics

Discovery of DNA

Friedrich Miescher :: Discovered DNA (“nuclein”) while studying white blood cells in pus

Frederick Griffith :: Studied pneumonia-causing bacteria and discovered transformation using rough (R) and smooth (S) strains

Transformation :: Process by which genetic material from one organism is taken up by another

Oswald Avery :: Demonstrated that DNA—not protein or RNA—is the transforming principle

Hershey-Chase Experiment :: Used radioactive labeling to show that DNA carries genetic information in bacteriophages

Chargaff’s Rule :: Amount of adenine equals thymine and amount of cytosine equals guanine

Rosalind Franklin :: Used X-ray crystallography to capture images of DNA structure

Watson and Crick :: Discovered the double-helix structure of DNA

Meselson-Stahl Experiment :: Proved that DNA replication is semiconservative

Structure of Nucleic Acids

Nucleic Acid :: Polymer made of nucleotide monomers

Nucleotide :: Monomer consisting of a sugar, phosphate group, and nitrogenous base

DNA Sugar :: Deoxyribose

RNA Sugar :: Ribose

Sugar-Phosphate Backbone :: Alternating sugars and phosphates joined by phosphodiester bonds

Phosphodiester Bond :: Covalent bond linking nucleotides

Antiparallel Strands :: DNA strands run in opposite 5’ to 3’ directions

Purines :: Double-ring bases (adenine and guanine)

Pyrimidines :: Single-ring bases (cytosine, thymine, uracil)

DNA Bases :: Adenine, Thymine, Cytosine, Guanine

RNA Bases :: Adenine, Uracil, Cytosine, Guanine

Hydrogen Bonds :: Bonds that hold complementary DNA strands together

A-T Base Pair :: Connected by two hydrogen bonds

G-C Base Pair :: Connected by three hydrogen bonds

Cellular Respiration

Cellular Respiration :: Process by which organisms convert glucose into ATP

Overall Respiration Equation :: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Aerobic Respiration :: Requires oxygen; occurs in mitochondria

Anaerobic Respiration :: Does not require oxygen; occurs in cytoplasm

Electron Carriers :: NAD⁺, NADH, FAD, FADH₂ transport electrons

Glycolysis :: Anaerobic breakdown of glucose into two pyruvate molecules

Glycolysis ATP Yield :: Net gain of 2 ATP and 2 NADH

Pyruvate Oxidation :: Converts pyruvate into acetyl-CoA

Krebs Cycle :: Aerobic cycle producing CO₂, NADH, FADH₂, and ATP

Electron Transport Chain :: Uses electron carriers to create a proton gradient for ATP synthesis

ATP Synthase :: Enzyme that produces ATP using proton flow

Oxidative Phosphorylation :: ATP production driven by the electron transport chain

Alcoholic Fermentation :: Anaerobic pathway producing ethanol and CO₂

Lactic Acid Fermentation :: Anaerobic pathway producing lactic acid

Photosynthesis

Photosynthesis :: Process by which plants convert light energy into chemical energy

Overall Photosynthesis Equation :: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Chloroplast :: Organelle where photosynthesis occurs

Thylakoid :: Membrane sacs where light-dependent reactions occur

Stroma :: Fluid-filled space where Calvin cycle occurs

Light-Dependent Reactions :: Use light to produce ATP and NADPH

Photosystem II :: Absorbs light and splits water molecules

Photolysis :: Splitting of water into oxygen, protons, and electrons

Photosystem I :: Re-energizes electrons to produce NADPH

Calvin Cycle :: Light-independent reactions that produce sugar

Carbon Fixation :: CO₂ binds to RuBP via Rubisco

Reduction Phase :: 3-PGA converted to G3P using ATP and NADPH

Regeneration :: RuBP is regenerated to continue the Calvin cycle

G3P :: Three-carbon sugar used to make glucose

Unit 3 – Energy Flow

Molecular Energy

Metabolism :: Sum of all chemical reactions in an organism

Anabolic Reactions :: Build complex molecules and require energy

Catabolic Reactions :: Break down molecules and release energy

Hydrolysis :: Catabolic reaction that breaks bonds using water

Condensation Reaction :: Anabolic reaction that forms bonds by removing water

ATP :: Primary energy molecule of cells

ATP to ADP :: Releases energy by breaking a phosphate bond

High-Energy Phosphate Bond :: Bond between the 2nd and 3rd phosphate groups

Enzyme Structure

Enzyme :: Protein that catalyzes biochemical reactions

Activation Energy :: Energy required to start a reaction

Substrate :: Reactant that binds to an enzyme

Active Site :: Region where substrate binds

Competitive Inhibition :: Inhibitor competes with substrate for active site

Noncompetitive Inhibition :: Inhibitor binds elsewhere and changes enzyme shape

Enzyme Models

Lock and Key Model :: Enzyme has a rigid active site specific to substrate shape

Induced Fit Model :: Enzyme changes shape upon substrate binding

Enzyme Activity

Optimal Conditions :: Conditions under which enzymes work best

Vmax :: Maximum reaction rate when enzymes are saturated

Temperature Effect :: Reaction rate increases until enzyme denatures

pH Effect :: Enzymes denature outside optimal pH

Substrate Concentration :: Increases rate until enzymes are saturated

Enzyme Concentration :: Increasing enzymes increases reaction rate

Unit 2 – Cells

Membrane Structure

Davson-Danielli Model :: Early membrane model with protein layers

Fluid Mosaic Model :: Current model of membrane structure

Phospholipid :: Amphipathic molecule with hydrophilic head and hydrophobic tail

Phospholipid Bilayer :: Double layer forming the cell membrane

Diffusion & Transport

Diffusion :: Movement of molecules from high to low concentration

Simple Diffusion :: Occurs directly through lipid bilayer

Facilitated Diffusion :: Uses membrane proteins, no energy required

Active Transport :: Movement against gradient using ATP

Osmosis

Osmosis :: Diffusion of water across a selectively permeable membrane

Hypertonic Solution :: Higher solute concentration outside the cell

Hypotonic Solution :: Lower solute concentration outside the cell

Isotonic Solution :: Equal solute concentration inside and outside cell

Osmolality

Osmolality :: Measure of solute concentration

Medical Isotonic Solutions :: Prevent cell damage during procedures

Endocytosis & Exocytosis

Endocytosis :: Cell engulfs material into vesicles

Exocytosis :: Cell releases material via vesicles

Vesicle :: Membrane-bound transport sac

Endosymbiosis

Endosymbiotic Theory :: Mitochondria and chloroplasts originated from prokaryotes

Double Membrane Evidence :: Supports endosymbiosis

Circular DNA :: Found in mitochondria and chloroplasts

70S Ribosomes :: Prokaryotic ribosomes found in organelles

Binary Fission :: Division method of mitochondria and chloroplasts

Microscopes

Light Microscope :: Uses light; magnifies up to 1000x

Electron Microscope :: Uses electrons; much higher resolution

Calculating Magnification :: Ocular lens × objective lens

Cell Theory

Cell Theory :: All living things are made of cells

Cells as Basic Unit :: Cells are the fundamental unit of life

Cells from Cells :: All cells arise from pre-existing cells

Surface Area to Volume Ratio :: Limits cell size

Cell Types

Eukaryotic Cells :: Show nucleus and membrane-bound organelles

Prokaryotic Cells :: Lack nucleus and membrane-bound organelles

Organelles

Nucleus :: Contains DNA and controls cell activities

Mitochondria :: Site of cellular respiration

Chloroplast :: Site of photosynthesis

Ribosome :: Site of protein synthesis

Rough ER :: Protein synthesis

Smooth ER :: Lipid synthesis

Golgi Apparatus :: Modifies and packages proteins

Lysosome :: Digests waste

Vacuole :: Storage organelle

Cell Membrane :: Regulates entry and exit

Cell Wall :: Structural support in plants

Stem Cells

Stem Cell :: Undifferentiated cell capable of specialization

Differentiation :: Process by which cells become specialized

Totipotent :: Can form all cell types

Pluripotent :: Can form many cell types

Induced Pluripotent Stem Cells :: Reprogrammed adult cells