Lectures 1-9 (Exam 1 Material)

Electron shells

An energy level of electrons at a characteristic average distance from the nucleus of an atom

Eukaryotic cell

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Examples of organisms with these cells are protists, plants, fungi, and animals

Prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea

Gene

A segment of DNA on a chromosome that codes for a specific trait

Gene expression

The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs

Genome

All the genetic information in an organism; all of an organism's chromosomes

Essential elements

Elements that an organism needs to live a healthy life and reproduce

Isotope

Atoms of the same element that have different numbers of neutrons

Radioactive isotope

An isotope whose nucleus decays spontaneously, giving off particles and energy

Energy

The ability to do work or cause change

Potential energy

Energy that is stored and held in readiness

Valence electrons

Electrons on the outermost energy level of an atom

Polar covalent bond

A covalent bond in which electrons are not shared equally

Ion

A charged atom

Anion

A negatively charged ion

Ionic compounds

A compound resulting from the formation of an ionic bond; salts

Chemical equilibrium

The point at which the reactions offset one another exactly

Cohesion

An attraction between molecules of the same substance, often by hydrogen bonds

Temperature

A measure in degrees of the average kinetic energy (thermal energy) of the atoms and molecules in a body of matter

Heat

Thermal energy in transfer from one body of matter to another

Kilocalorie

1,000 calories; the amount of heat energy required to raise the temperature of 1kg of water by 1 degree C

Solution

A homogeneous mixture of two or more substances

Hydrophilic

Having an affinity for water

Acid

A substance that increases the hydrogen ion concentration of a solution

Ocean acidification

Decreasing pH of ocean waters due to the formation of carbonic acid due to the absorption of excess atmospheric CO2

Organic compound

A compound that contains carbon

Macromolecule

A giant molecule formed by the joining of smaller molecules, usually by a condensation reaction; polysaccharides, proteins, and nucleic acids

Enzymes

Proteins that speed up chemical reactions

Fatty acid

A carboxylic acid with a hydrocarbon chain

Trans fat

An unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds

Steroid

A type of lipid characterized by a carbon skeleton consisting of four rings with various functional groups attached

Cholesterol

A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids

Catalysts

Chemical agents that selectively speed up chemical reactions without being consumed by the reaction

Amino acid

An organic molecule containing a carboxyl group and an amino group; serves as the monomer of polypeptides

Primary structure of protein

The amino acid sequence of the polypeptide chain

Tertiary structure of a protein

The overall shape of a polypeptide due to interactions of amino acid side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges

Hydrophobic interaction

A type of weak chemical bond formed when molecules that do not mix with water coalesce to exclude the water

Deoxyribose

A five-carbon sugar that is a component of DNA nucleotides

Cytoplasm

The contents of the cell enclosed by the plasma membrane

Plasma membrane

The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition

Nucleus

The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes

Nuclear lamina

A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes

Endoplasmic Reticulum (ER)

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions

Golgi apparatus

An organelle consisting of stacks of membranous sacs that modifies, sorts, and packages proteins from the endoplasmic reticulum

Chloroplast

Organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds

Thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy

Stroma

The fluid of the chloroplast surrounding the thylakoid membrane

Peroxisome

Organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide

Actin

A globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other contractile elements in cells

Primary cell wall

A relatively thin and flexible layer that surrounds the plasma membrane of a young plant cell

Secondary cell wall

A strong and durable matrix that is often deposited in several laminated layers around the plasma membrane and provides protection and support in plant cells

Plasmodesmata

An open channel in the cell wall of plants through which strands of cytosol connect from adjacent cells

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration

Passive transport

The diffusion of a substance across a biological membrane without the use of energy

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water

Hypotonic

A solution that will cause a cell to gain water

Turgid

Swollen as from a fluid; bloated

Ion channel

A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient

Gated channel

Transmembrane protein channel that opens or closes in response to a particular stimulus

Sodium-potassium pump

A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

Endocytosis

Cellular uptake of biological molecules and particulate matter via formation of new vesicles from the plasma membrane

Response

The change in a specific cellular activity brought about by a transduced signal from outside the cell

Protein kinase

An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein

Phosphorylation cascade

A series of chemical reactions during cell signaling mediated by kinases where each kinase phosphorylates and activates another, ultimately leading to phosphorylation of many proteins

Element

A substance that cannot be broken down into simpler substances

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds

Trace elements

Elements required by an organism in only minute quantities

Atom

The smallest unit of matter that still retains the properties of an element

Atomic nucleus

An atom's dense central core, containing protons and neutrons

Mass number

The total number of protons and neutrons in the nucleus of an atom

Valence shell

Outermost electron shell

Chemical bonds

An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells

Covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

Molecule

Two or more atoms held together by covalent bonds

Valence

The bonding capacity of an atom; number of covalent bonds an atom can form

Electronegativity

The attraction of a given atom for the electrons of a covalent bond

Nonpolar covalent bond

A covalent bond in which the electrons are shared equally by the two atoms

Cation

A positively charged ion

Ionic bond

A chemical bond resulting from the attraction between oppositely charged ions

Hydrogen bond

A weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule

Van der Waals interactions

Weak attractions between molecules or parts of molecules that result from transient local partial charges

Polar molecule

A molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end

Adhesion

The clinging of one substance to another

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid

Kinetic energy

Energy of motion

Thermal energy

Kinetic energy due to the random motion of atoms and molecules; energy in its most random form

Calorie

Amount of energy needed to raise temperature 1 gram of water 1 degree C

Specific heat

The amount of heat that must be absorbed or lost for 1g of a substance to change its temperature by 1 degree C

Heat of vaporization

The quantity of heat a liquid must absorb for 1 g of it to be converted from the liquid to the gaseous state

Solvent

The dissolving agent of a solution

Solute

The substance that is dissolved in a solution

Aqueous solution

A solution in which water is the solvent

Hydrophobic

Having an aversion to water

Molecular mass

The sum of the masses of all the atoms in a molecule

Mole

The number of grams of a substance that equals its molecular weight in daltons

Hydrogen ion (H+)

A positively charged ion formed from a hydrogen atom that has lost its electron

Hydroxide ion (OH-)

A negatively charged ion made of oxygen and hydrogen

Hydronium ion (H3O+)

The ion that forms when a water molecule gains a hydrogen ion

Base

A substance that decreases the hydrogen ion concentration in a solution