Biology Study Guide: Life, Cells, and Genetics

A vocabulary set covering the fundamental biological concepts from the study of life to ecology, based on the provided Keystone Biology Keystone Review notes.

Biotic

An environmental factor associated with the activities of a living organism.

Abiotic

An environmental factor that is NOT associated with the activities of a living organism.

Homeostasis

To maintain stable levels of internal conditions even though the environment is changing.

Metabolism

The sum of all chemical reactions that take in and transform energy and materials from the environment.

Covalent Bond

A bond formed when atoms share two valence electrons (electrons in the outermost energy level).

Polar

A molecule (like water) that is charged because it has a partial negative region and a partial positive region.

Hydrogen Bonding

A force that occurs between the hydrogen in one molecule and the negatively charged region in another molecule.

Cohesion

An attractive force that holds molecules of a single substance together.

Adhesion

The attractive force between two different substances.

Capillarity

The attraction between molecules that results in the rise of the surface of a liquid when in contact with a solid.

Solution

Mixture in which one or more substances is uniformly distributed in another substance.

Solute

Substance dissolved in the solvent.

Solvent

Substance which the solute is dissolved.

Aqueous Solution

Solution where water is the solvent.

Dissociation

Part of a reaction where one water molecule pulls apart another water molecule into two ions: $H_2O \rightleftharpoons H^+ + OH^-$.

Hydroxide Ion

The $OH^-$ ion which signifies a base.

Hydronium Ion

The $H_3O^+$ ion created when a free $H^+$ ion reacts with another water molecule ($H^+ + H_2O \rightleftharpoons H_3O^+$).

Acid

A solution where the number of hydronium ions is $>$ the number of hydroxide ions.

Base

A solution where the number of hydronium ions is $<$ the number of hydroxide ions.

Buffers

Chemical substances that are added to neutralize small amounts of acids or bases.

Organic Compounds

Compounds that are made primarily of Carbon atoms.

Monomers

Smaller units that can be bonded together to form polymers.

Polymers

Large particles formed from the bonding of smaller monomers.

Dehydration Synthesis Reactions

A reaction where each time a monomer is added to a polymer, a water is released.

Hydrolysis

A process where a polymer is broken down and water is added.

ATP (Adenosine Tri-phosphate)

The energy currency of the cell that stores energy for cells to use.

Glucose

A monosaccharide that is the main source of energy for cells.

Glycogen

Hundreds of glucose molecules in a highly branched chain stored in the liver and muscles for quick energy.

Amino Acids

The monomers of proteins.

Peptide Bond

A covalent bond formed when two or more amino acids join together.

Enzymes

RNA or protein molecules that help reactions take place with a lower amount of activation energy.

Substrate

The reactant in a chemical reaction that fits into the active site of an enzyme.

Lipids

Large, nonpolar molecules that store energy, such as phospholipids, steroids, waxes, and pigments.

Saturated Carbon Chains

Carbon chains with all single bonds between the carbons, typically solid at room temperature.

Unsaturated Carbon Chains

Carbon chains with some double bonds between the carbons, typically liquid at room temperature.

Nucleic Acids

Large, complex molecules that store important information, composed of nucleotides.

Nucleotides

Monomers of nucleic acids containing a phosphate group, a five-carbon sugar, and a ring-shaped nitrogen base.

Cell Theory

1. All living organisms are composed of one or more cells; 2. Cells are the basic units of life; 3. Cells come only from the reproduction of existing cells.

Prokaryotic Cells

Organisms that lack a nucleus and membrane bound organelles.

Eukaryotic Cells

Organisms that possess a nucleus and membrane bound organelles.

Mitochondria

Organelle that produces energy in the form of ATP; the power plant of the cell.

Plasma Membrane

Membrane consisting of a phospholipid bilayer with embedded proteins that regulates the entrance and exit of molecules.

Ribosome

Small particle that functions as the site of protein synthesis.

Passive Transport

Substances crossing the cell membrane without any input of energy.

Diffusion

The movement of molecules from an area of higher concentration to lower concentration.

Osmosis

The diffusion of water molecules from an area of higher concentration to lower concentration.

Hypertonic

A solution where the concentration outside of the cell is higher, causing water to diffuse out of the cell.

Hypotonic

A solution where the concentration outside of the cell is lower, causing water to diffuse into the cell.

Active Transport

The movement of materials from an area of lower concentration to higher concentration, requiring energy.

Endocytosis

Process where cells bring in extra fluid, macromolecules, and large particles by enclosing them in a portion of the cell membrane.

Phagocytosis

A type of endocytosis that transports large particles or whole cells.

Exocytosis

Process where substances are released from the cell through a vesicle.

Photosynthesis Equation

$$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$$

Chromosomes

Rod shaped structures made of DNA and proteins coiled around histones.

Chromatids

Two identical parts of a chromosome attached at a centromere.

Haploid

Cells that contain only one set of chromosomes, such as sperm and egg cells.

Diploid

Cells that have two sets of chromosomes, referred to as somatic cells.

Binary Fission

The process used for cell reproduction in prokaryotic cells.

Meiosis

A process that reduces the number of chromosomes in new cells to half the original cell's number.

Heredity

The transmission of genetic characteristics from generation to generation.

Alleles

A variation of a gene's nucleotide sequence.

Genotype

The genetic composition of an organism for one specific trait.

Phenotype

The observable expression of a specific trait.

Incomplete Dominance

When the phenotype is intermediate between the phenotypes of the two parents.

Codominance

When the phenotypes for both alleles are present in the offspring.

Helicases

Enzymes that separate DNA strands by breaking the hydrogen bonds between nitrogen base pairs.

DNA Polymerases

Enzymes that add complementary nucleotides to the DNA strands during replication.

Transcription

The process where genetic instructions are re-written into an RNA molecule.

Translation

The process occurring on a ribosome where mRNA is decoded into a polypeptide chain.

Codons

Groups of three letters in mRNA that code for a specific amino acid.

Pedigree

A diagram showing how a trait is inherited over several generations in a family.

Evolution

A change in the allele frequencies of a population from generation to generation causing new species to develop.

Natural Selection

Occurs when organisms possessing certain inherited traits have a better likelihood of survival and reproduction.

Homologous Structures

Characteristics in different organisms that are similar because they were inherited from a common ancestor.

Vestigial Structures

Characteristics in an organism that have lost original function as the species has changed over time.

Biosphere

The zone of life on Earth or the sum of all ecosystems on Earth.

Ecosystem

A system of living organisms (biotic) and nonliving components (abiotic) living in an environment.