BIOL1308 Unit 1 Vocabulary Flashcards

Vocabulary practice flashcards covering Dr. Roshni Jaffery's BIOL1308 Unit 1 Study Guide at the University of Houston.

Biology

The scientific study of living things.

Cell

The smallest building block of living things.

Prokaryotic cell

A unicellular cell type that lacks a nucleus (DNA located in nucleoid) and membrane-bound organelles, and is smaller in size.

Eukaryotic cell

A cell type containing a nucleus and membrane-bound organelles, which is larger in size and can form unicellular or multicellular organisms.

Cell Theory

A core scientific theory stating that all living things are composed of one or more cells, cells are the smallest units of life, and new cells arise from preexisting cells.

Theory of Evolution by Natural Selection

A core scientific theory that explains where organisms come from.

Chromosome Theory of Inheritance

A core scientific theory detailing how hereditary data is transmitted across generations.

Dependent Variable

The output or factor being measured in an experiment to observe changes.

Independent Variable

The single factor changed by the experimenter in an experiment.

Control Group

The experimental condition where the independent variable is not manipulated, establishing a baseline level for the dependent variable.

Experimental Group

The condition in an experiment where the independent variable is manipulated to observe its effect on the dependent variable.

Experimental Constants

All possible variables aside from the independent variable that are kept identical in both the control and experimental groups to prevent affecting the results.

Hypothesis

A testable and tentative statement about the natural world leading to deductions that can be tested.

Theory

A well-substantiated, testable explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.

CHON

The four elements—Carbon, Hydrogen, Oxygen, and Nitrogen—that make up approximately $95\%$ of all living matter.

Valence shell

An atom's outermost electron shell energy level that dictates its reactivity and capacity to bond.

Covalent Bond

A chemical bond formed when atoms share electron pairs to maximize stability.

Electronegativity

An atom's electron-attracting power.

Polar covalent bond

A covalent bond created by the unequal sharing of electrons between atoms of different electronegativities.

Nonpolar covalent bond

A covalent bond created by the equal sharing of electrons between atoms.

Ionic Bond

A chemical bond formed by electrostatic attraction between oppositely charged ions resulting from the complete loss or gain of an electron.

Hydrogen Bond

A weak electrical attraction between a partially positive hydrogen atom in a polar molecule and a highly electronegative atom in another molecule.

Cohesion

The attraction between molecules of the same substance, such as water molecules attracting each other.

Adhesion

The attraction between molecules of different substances, such as water sticking to the walls of a plant's stem.

Surface tension

The tendency of a liquid's surface to resist being stretched or broken due to cohesive forces between molecules.

Aqueous solution

A solution in which water acts as the solvent.

Hydrophilic

Polar or ionic molecules that are water loving and dissolve readily in water.

Hydrophobic

Nonpolar carbon-hydrogen compounds that are insoluble in water.

Amphipathic

Describing molecules possessing both distinct polar (hydrophilic) and nonpolar (hydrophobic) zones.

Buffer

A system composed of weak acid-base pairs that capture or release $H^+$ ions to prevent disruptive pH shifts in living systems.

Enzyme

A protein that speeds up a chemical reaction without being used up.

Phosphate group

A functional group ($-\text{PO}_4^{2-}$) carrying double negative charges that is critical for energy and nucleic structures.

Sulfhydryl group

A functional group ($-\text{SH}$) that forms structural disulfide bridges.

Dehydration (Condensation) Reaction

A macromolecule elongation reaction where an enzyme removes a water molecule ($H$ from one monomer, $OH$ from another) to form a new covalent link.

Hydrolysis Reaction

The breakdown of a polymer chain into constituent monomers by chemically splitting and inserting a water molecule ($H_2O$) back into the broken bond.

Monosaccharide

The single sugar monomer unit of carbohydrates (ends in -ose).

Disaccharide

A carbohydrate made of two monosaccharides joined by a glycosidic bond via dehydration reaction.

Starch

A polysaccharide used by plants for energy storage.

Glycogen

A polysaccharide stored in animal liver and muscle cells for energy storage.

Cellulose

A structural polysaccharide found in plant cell walls.

Chitin

A structural polysaccharide found in fungal cell walls and insect exoskeletons.

Peptidoglycan

A structural polysaccharide found in bacterial cell walls.

Saturated fatty acid

A fatty acid containing single bonds only, forming a straight structure that is solid at room temperature.

Unsaturated fatty acid

A fatty acid containing single and double bonds, creating a kinked shape that remains liquid at room temperature.

Phospholipid

An amphipathic lipid composed of a glycerol backbone, two hydrophobic fatty acid tails, and a charged/polar hydrophilic head; forms cell membrane bilayers.

Steroid

A lipid characterized by four fused carbon rings, such as cholesterol and sex hormones.

Amino Acid

The monomer building block of proteins, consisting of an amino group ($-\text{NH}_2$), carboxyl group ($-\text{COOH}$), central $\alpha$-carbon, and variable R-group.

Peptide bond

The covalent bond formed between amino acids through dehydration reactions.

Primary Structure

The linear sequence of amino acids in a protein, encoded directly by genes (DNA).

Secondary Structure

Protein folding patterns ($\alpha$-helices and $\beta$-pleated sheets) formed by hydrogen bonds between backbone groups.

Tertiary Structure

The overall 3D shape of a single polypeptide produced by interactions among variable R-groups.

Quaternary Structure

The protein structure resulting from the interaction of two or more polypeptide subunits.

Prion

A misfolded protein that can cause neurodegenerative diseases such as Creutzfeldt-Jakob disease and Mad Cow disease.

DNA vs. RNA Comparison

A comparison showing that DNA contains deoxyribose, thymine (T), is double-stranded, and stores genetic information; whereas RNA contains ribose, uracil (U), is usually single-stranded, and helps express genetic information.

Nucleotide

The building block monomer of nucleic acids, consisting of a phosphate group, a five-carbon sugar, and a nitrogenous base.

Phosphodiester bond

The covalent bond formed between nucleotides to construct the sugar-phosphate backbone of nucleic acids.

ATP

An activated nucleotide with three phosphate groups that serves as the cell's main energy currency.

Cytoskeleton

A network of protein fibers (microtubules, intermediate filaments, and actin filaments) that maintains cell shape, provides support, enables movement, and transports materials.

Nucleus

An organelle that stores DNA, controls gene expression, and regulates molecular transport via nuclear pores.

Rough ER

Endoplasmic reticulum studded with ribosomes on its surface, primarily responsible for protein synthesis.

Smooth ER

Endoplasmic reticulum lacking ribosomes, primarily responsible for lipid synthesis.

Golgi Apparatus

An organelle responsible for processing, sorting, and secreting products received from the endoplasmic reticulum to their final destinations.

Lysosome

An organelle containing digestive enzymes to break down proteins, lipids, carbohydrates, and nucleic acids.

Autophagy

The cellular process of breaking down and recycling worn-out organelles.

Endocytosis

The process by which the cell membrane pinches off a vesicle to bring outside material into the cell.

Endosymbiotic Theory

The theory proposing that mitochondria derived from ancient $\alpha$-proteobacteria and chloroplasts derived from cyanobacteria, supported by their own DNA, double membranes, and division by binary fission.