Units 1-3 vocab for AP Bio

Transport proteins -

Transport proteins are membrane proteins that help move substances across the cell membrane. They include channels, carriers, and pumps, facilitating passive or active transport. These proteins are essential for maintaining ion gradients, nutrient uptake, and overall cellular homeostasis.

Triglyceride -

Triglycerides are lipids made of one glycerol molecule bonded to three fatty acids. They serve as long-term energy storage and provide insulation and cushioning for organs. Triglycerides are broken down during metabolism to release energy for cellular processes.

Unsaturated fat -

Unsaturated fats contain one or more double bonds in their fatty acid chains. These double bonds create kinks, preventing tight packing, so they are usually liquid at room temperature. Unsaturated fats contribute to membrane fluidity and are generally considered healthier than saturated fats.

Uracil -

Uracil is a pyrimidine nitrogenous base found in RNA. It pairs with adenine during RNA base pairing. Uracil replaces thymine, which is found in DNA, and is essential for RNA transcription and protein synthesis.

Water -

Water is a polar molecule critical for life, acting as a solvent, temperature buffer, and participant in chemical reactions. Hydrogen bonding gives it unique properties like cohesion, adhesion, and high specific heat. Water facilitates nutrient transport, metabolic reactions, and maintains cellular structure.

X-ray crystallography -

X-ray crystallography is a technique used to determine the three-dimensional structures of molecules. Crystals of a molecule are exposed to X-rays, producing diffraction patterns that can be analyzed to reveal atomic arrangements. This method is crucial for understanding protein, DNA, and other macromolecule structures.

Bar graph -

A bar graph uses rectangular bars to display data, where the height or length represents values of a variable. It is useful for comparing categories or groups. Bar graphs allow quick visualization of differences in data.

Acid -

An acid is a substance that increases hydrogen ion (H⁺) concentration in a solution. Acids have a pH below 7 and can donate protons in chemical reactions. They are involved in processes like digestion and metabolism.

Active transport -

Active transport moves molecules across a membrane against their concentration gradient using energy, usually ATP. It allows cells to maintain essential concentrations of ions and nutrients. This process is vital for nerve signaling and nutrient uptake.

1st Law of Thermodynamics -

This law states that energy cannot be created or destroyed, only transformed from one form to another. The total energy in a closed system remains constant. It underlies all biological energy transformations, including cellular respiration and photosynthesis.

Biology -

Biology is the study of life and living organisms. It examines their structure, function, growth, evolution, and interactions with the environment. Biology spans molecular to ecological levels of study.

Adenine -

Adenine is a purine nitrogenous base found in DNA and RNA. In DNA, it pairs with thymine; in RNA, it pairs with uracil. Adenine is essential for storing and transmitting genetic information.

Apoptosis -

Apoptosis is programmed cell death that removes damaged or unneeded cells. It is a controlled process that prevents inflammation and maintains tissue health. Apoptosis is critical during development and immune system function.

2nd Law of Thermodynamics -

This law states that energy transfers increase the disorder (entropy) of a system. Some energy becomes unavailable for work during each transformation. Biological systems maintain order by using energy from the environment.

Box & Whisker plot -

A box and whisker plot displays data distribution using quartiles. The box represents the interquartile range, the line inside is the median, and the whiskers extend to minimum and maximum values. It helps visualize spread and identify outliers.

Adhesion -

Adhesion is the attraction between molecules of different substances. Water adhering to plant cell walls allows capillary action. Adhesion is important in biological transport processes.

Aquaporin -

Aquaporins are membrane proteins that facilitate water transport across cell membranes. They allow rapid osmosis and maintain water balance in cells. They are vital in kidney function and plant root water uptake.

Absorption spectrum (light) -

The absorption spectrum shows wavelengths of light absorbed by a pigment. Peaks indicate wavelengths most effective for processes like photosynthesis. It helps scientists understand how organisms capture light energy.

Cell -

A cell is the smallest unit of life capable of independent functions. It contains DNA, cytoplasm, and a plasma membrane. Cells can be prokaryotic or eukaryotic.

Alpha helix -

An alpha helix is a coiled protein secondary structure stabilized by hydrogen bonds. It contributes to protein stability and function. Alpha helices are common in structural and enzymatic proteins.

ATP (adenosine triphosphate) -

ATP is the primary energy carrier in cells. Energy stored in its high-energy phosphate bonds powers cellular activities. ATP is produced during respiration and photosynthesis and regenerated from ADP.

Acetyl CoA -

Acetyl CoA is a key metabolic molecule delivering acetyl groups to the Krebs cycle. It is formed from pyruvate in cellular respiration. Acetyl CoA connects glycolysis, fatty acid metabolism, and energy production.

CER (Claim, Evidence, Reasoning) -

CER is a framework for constructing scientific explanations. The claim states a conclusion, evidence supports it, and reasoning links evidence to the claim. CER is used in labs and AP exam responses.

Amino group -

An amino group (-NH₂) is a functional group in amino acids and proteins. It can act as a base and forms peptide bonds. The amino group is essential for protein structure and function.

Cell membrane (plasma membrane) -

The cell membrane is a selectively permeable barrier surrounding cells. It regulates transport of molecules and contains proteins for signaling and transport. The membrane is a phospholipid bilayer with hydrophilic and hydrophobic regions.

Action spectrum -

An action spectrum shows the efficiency of biological activity at different wavelengths of light. It often mirrors the absorption spectrum of pigments. This is important for understanding photosynthesis efficiency.

Chi-square (X²) -

The chi-square test compares observed and expected data to evaluate statistical significance. It is often used in genetics to test inheritance ratios. A high chi-square value indicates deviation from expected results.

Amino acid -

Amino acids are the building blocks of proteins. Each contains an amino group, carboxyl group, and variable R-group. Amino acids link via peptide bonds to form polypeptides.

Cell wall -

The cell wall is a rigid structure outside the cell membrane in plants, fungi, and bacteria. It provides structural support and protection. Plant cell walls are made primarily of cellulose.

Activation energy -

Activation energy is the minimum energy needed to start a chemical reaction. Enzymes reduce activation energy, speeding up reactions. Without sufficient activation energy, reactions cannot proceed efficiently.

Control group -

The control group is the part of an experiment not exposed to the independent variable. It provides a baseline to compare the experimental results. Controls validate the effects of the independent variable.

Amphipathic -

Amphipathic molecules have both hydrophilic and hydrophobic regions. Phospholipids in membranes are amphipathic. This property allows them to form bilayers that separate cell compartments.

Centrioles -

Centrioles are cylindrical structures that organize microtubules during cell division. They help form the spindle apparatus to separate chromosomes. Centrioles are present in most animal cells.

Active site -

The active site is the part of an enzyme where substrates bind. Its shape is complementary to the substrate. Chemical reactions occur at the active site to form products.

Controlled experiment -

A controlled experiment tests one variable at a time while keeping others constant. This allows scientists to determine cause-and-effect relationships. Replicates increase reliability.

Channel protein -

Channel proteins form pores in membranes for specific molecules to passively diffuse. They allow ions and small molecules to move along concentration gradients. Channels can open or close in response to signals.

ADP -

ADP (adenosine diphosphate) is formed when ATP loses a phosphate group. It can be converted back to ATP by adding a phosphate in respiration or photosynthesis. ADP is central to cellular energy cycles.

Controlled variables/constants -

These are factors kept the same in an experiment to ensure fair testing. Controlling variables allows valid conclusions about the independent variable's effects.

Base -

A base decreases H⁺ concentration and has pH > 7. Bases accept protons and are important in pH regulation. They are involved in biochemical processes like ATP synthesis.

Chloroplast -

Chloroplasts are plant cell organelles where photosynthesis occurs. They contain chlorophyll pigments that capture light energy. Chloroplasts convert CO₂ and water into glucose and oxygen.

Aerobic respiration -

Aerobic respiration uses oxygen to convert glucose into ATP, CO₂, and water. It occurs in mitochondria and produces more ATP than anaerobic processes. This process powers most eukaryotic cells.

Alcoholic fermentation -

Alcoholic fermentation is an anaerobic process where sugars are converted to ethanol and CO₂. Yeast and some bacteria perform this reaction. It regenerates NAD⁺ to allow glycolysis to continue.

Anabolic -

Anabolic pathways build complex molecules from simpler ones, requiring energy. Examples include protein synthesis and photosynthesis. Anabolism is essential for growth and repair.

Anaerobic respiration -

Anaerobic respiration produces ATP without oxygen. It can result in lactic acid (in muscles) or ethanol (in yeast). It yields less ATP than aerobic respiration.

Apoptosis -

the biological process of programmed cell death, a tidy, self-initiated "cellular suicide" where a cell systematically dismantles itself without causing inflammation .

ATP Synthase -

ATP synthase is an enzyme that produces ATP from ADP and Pi during chemiosmosis. It is embedded in the inner mitochondrial or chloroplast membrane. ATP synthase converts proton gradients into chemical energy.

Autotroph -

Autotrophs produce their own organic molecules from inorganic sources. Plants use photosynthesis, while some bacteria use chemosynthesis. Autotrophs are primary producers in ecosystems.

Calvin cycle (light independent rxn) -

The Calvin cycle fixes CO₂ into sugars in the stroma of chloroplasts. It uses ATP and NADPH from light reactions. It is essential for synthesizing glucose in plants.

Carbohydrate -

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen. They serve as energy sources (glucose) and structural components (cellulose). Carbohydrates include monosaccharides, disaccharides, and polysaccharides.

Catabolic -

Catabolic pathways break down complex molecules into simpler ones, releasing energy. Examples include glycolysis and the Krebs cycle. Catabolism provides energy and building blocks for anabolism.

Catalyst -

A catalyst speeds up a chemical reaction without being consumed. Enzymes are biological catalysts that lower activation energy. Catalysts are essential for maintaining reaction rates in cells.

Cellular respiration -

Cellular respiration converts glucose and oxygen into ATP, CO₂, and water. It involves glycolysis, Krebs cycle, and electron transport chain. This process provides energy for cellular functions.

Chlorophyll -

Chlorophyll is the green pigment in chloroplasts that absorbs light for photosynthesis. It primarily absorbs blue and red wavelengths. Chlorophyll is critical for energy capture and conversion.

Cholesterol -

Cholesterol is a lipid in cell membranes that stabilizes fluidity. It prevents membranes from becoming too rigid or too fluid. Cholesterol is also a precursor for steroid hormones.

Cytoplasm -

Cytoplasm is the jelly-like substance in cells surrounding organelles. It provides a medium for chemical reactions and intracellular transport. Cytoplasm includes cytosol and organelles.

Cytosol -

Cytosol is the fluid portion of the cytoplasm where metabolic reactions occur. It suspends organelles and provides a site for enzymatic activities.

Cytoskeleton -

The cytoskeleton is a network of protein fibers providing structure, shape, and intracellular transport. It includes microtubules, actin filaments, and intermediate filaments.

Density of water -

Water has a density of ~1 g/mL at 4°C. Its density affects buoyancy, transport in plants, and aquatic life. Ice is less dense than liquid water due to hydrogen bonding.

Dehydration synthesis -

Dehydration synthesis joins monomers by removing water. It forms macromolecules like proteins, polysaccharides, and lipids. This reaction is essential for building cellular structures.

Denaturation -

Denaturation is the loss of protein or nucleic acid structure due to heat, pH changes, or chemicals. It disrupts function but does not break peptide bonds. Denatured enzymes lose catalytic activity.

Diffusion -

Diffusion is the passive movement of molecules from high to low concentration. It does not require energy. Diffusion is essential for gas exchange and nutrient transport.

Endocytosis -

Endocytosis is the process by which cells engulf materials into vesicles. It allows intake of large particles or fluids. Phagocytosis and pinocytosis are types of endocytosis.

Endergonic reaction -

Endergonic reactions absorb energy from the surroundings. Photosynthesis is an example. They are usually coupled with exergonic reactions to proceed.

Endoplasmic reticulum (ER) -

The ER is a membrane network involved in protein and lipid synthesis. Rough ER has ribosomes for protein synthesis; smooth ER synthesizes lipids and detoxifies chemicals.

Endosymbiosis / Endosymbiotic theory -

The theory states that mitochondria and chloroplasts originated from free-living prokaryotes engulfed by ancestral eukaryotes. These organelles retain their own DNA and double membranes. Endosymbiosis explains eukaryotic organelle evolution.

Electron -

An electron is a negatively charged subatomic particle. Electrons are involved in chemical bonding and energy transfer. Electron movement powers processes like the electron transport chain.

Electron acceptor -

An electron acceptor is a molecule that receives electrons during redox reactions. Oxygen is the final acceptor in aerobic respiration. Acceptors are essential for energy transfer in metabolism.

Electron carrier molecule -

Electron carriers like NAD⁺, NADP⁺, and FAD transport electrons between reactions. They play critical roles in cellular respiration and photosynthesis. They help generate ATP.

Electron transport chain (ETC) -

The ETC is a series of proteins that transfer electrons, creating a proton gradient. This gradient powers ATP synthase to produce ATP. ETC occurs in the inner mitochondrial membrane or thylakoid membrane.

Exocytosis -

Exocytosis is the process of vesicles fusing with the plasma membrane to release contents outside the cell. It is important for secretion of hormones, neurotransmitters, and waste.

Facilitated diffusion -

Facilitated diffusion is passive transport using membrane proteins to move molecules along a concentration gradient. It does not require energy. Glucose and ions often use facilitated diffusion.

Fatty acid -

Fatty acids are long hydrocarbon chains with a carboxyl group. They are building blocks of lipids and energy storage molecules. Saturated fatty acids have no double bonds; unsaturated have one or more.

Fermentation (anaerobic) -

Fermentation produces ATP without oxygen. Lactic acid fermentation occurs in muscles, while alcoholic fermentation occurs in yeast. It regenerates NAD⁺ for glycolysis.

Fluid mosaic model -

The fluid mosaic model describes membranes as a flexible bilayer of phospholipids with embedded proteins. Proteins serve as channels, receptors, and enzymes. The membrane's fluidity allows cell movement and transport.

Glycerol -

Glycerol is a three-carbon alcohol that forms the backbone of triglycerides. Each glycerol molecule binds to three fatty acids in lipid synthesis. Glycerol is also involved in carbohydrate and lipid metabolism.

Glycolipid -

Glycolipids are lipids with carbohydrate chains attached. They are found in cell membranes and help with cell recognition and signaling. Glycolipids contribute to tissue formation and immune responses.

Glycoprotein -

Glycoproteins are proteins with carbohydrate chains attached. They are important for cell recognition, signaling, and adhesion. Many membrane proteins are glycoproteins.

Glycolysis -

Glycolysis is the breakdown of glucose into two pyruvate molecules, producing ATP and NADH. It occurs in the cytoplasm and does not require oxygen. Glycolysis is the first step of cellular respiration.

Granum -

A granum is a stack of thylakoids in chloroplasts. Light-dependent reactions occur here. Grana maximize surface area for capturing light energy.

Guanine -

Guanine is a purine nitrogenous base in DNA and RNA. It pairs with cytosine via three hydrogen bonds. Guanine is essential for genetic information storage.

Heterotroph -

Heterotrophs obtain energy and organic molecules by consuming other organisms. Animals and fungi are heterotrophs. They rely on autotrophs for food and energy.

Homeostasis -

Homeostasis is the maintenance of stable internal conditions despite environmental changes. It involves regulation of temperature, pH, and water balance. Homeostasis is essential for survival.

Hydrophilic -

Hydrophilic molecules interact with water and dissolve easily. Polar molecules and ions are typically hydrophilic. They participate in chemical reactions in aqueous environments.

Hydrophobic -

Hydrophobic molecules repel water and do not dissolve in it. Non-polar molecules like lipids are hydrophobic. This property helps form membranes and protein folding.

Hypothesis / Alternative hypothesis -

A hypothesis is a testable prediction, while an alternative hypothesis predicts a difference or effect exists. Experiments test these hypotheses to support or reject them. Hypotheses are the basis of scientific inquiry.

Independent variable -

The independent variable is the factor manipulated in an experiment. Its effect is measured on the dependent variable. Controlling other variables ensures a valid test.

Inner membrane -

The inner mitochondrial membrane or chloroplast membrane contains proteins for the electron transport chain and ATP synthase. It creates compartments for chemiosmosis. Inner membranes increase surface area for energy production.

Ion -

An ion is an atom or molecule with a net electric charge. Ions are important in nerve signaling, muscle contraction, and osmoregulation.

Ion pump -

Ion pumps actively transport ions across membranes using energy. Examples include the sodium-potassium pump. They maintain concentration gradients necessary for cellular function.

Isotonic -

An isotonic solution has the same solute concentration as the cell. Water moves equally in and out, maintaining cell size. Isotonic solutions prevent cell swelling or shrinking.

Krebs cycle (Citric Acid Cycle) -

The Krebs cycle is a series of reactions in mitochondria that oxidize acetyl-CoA to CO₂. It produces NADH, FADH₂, and ATP for cellular energy. It is a central metabolic pathway in aerobic respiration.

Lactic acid fermentation -

Lactic acid fermentation converts pyruvate to lactate without oxygen. It regenerates NAD⁺ for glycolysis. This occurs in muscle cells during strenuous activity.

Law -

A law describes consistent observations or patterns in nature, often mathematically. Laws summarize phenomena without explaining underlying mechanisms. Examples include Mendel's law of segregation.

Light reactions (light dependent rxn) -

Light reactions occur in the thylakoid membranes of chloroplasts. They convert light energy into chemical energy in ATP and NADPH. Oxygen is released as a byproduct.

Line graph -

A line graph uses points connected by lines to show changes over continuous data. It is useful for trends over time. Line graphs allow easy visualization of relationships between variables.

Line of best fit -

The line of best fit approximates the trend in a scatter plot. It helps predict values and analyze relationships. It minimizes the distance between the line and data points.

Macromolecule -

Macromolecules are large molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids. They are built from smaller monomers. Macromolecules perform structural, informational, and metabolic roles.

Mean -

The mean is the average of a dataset, calculated by summing all values and dividing by the number of values. It is a measure of central tendency. The mean can be influenced by outliers.

Metabolism -

Metabolism includes all chemical reactions in cells, including catabolic and anabolic pathways. It manages energy and material transformations. Metabolism sustains growth, repair, and homeostasis.

Microscope -

Microscopes magnify small objects for observation. Light microscopes use lenses and visible light, while electron microscopes use electrons for higher resolution. Microscopy is essential for studying cell structure.