Chapter 2 & Chapter 3

Element

A substance that cannot be broken down to other substances by chemical means

Atomic number

The number of protons in the nucleus

Mass Number

The sum of protons and neutrons in an atoms nucleus

Isotope

Atoms of the same element that have different numbers of neutrons in the nucleus

Radioactive Isotope

An isotope that is structurally unstable, and will spontaneously give off particles and radiation

Carbon (C), Oxygen (O), Hydrogren (H), and Nitrogen (N)

Main ingredients of biological molecules such as proteins, sugars, fats, and nucleic acids

Sulfur (S)

Found in proteins, and provides extra strength and rigidity

Phosphorus (P)

Found in nucleic acids and cell membranes

Calcium (Ca)

Responsible for proper bone and teeth formation, and plays a significant role in intercellular signaling

Potassium (K)

Important in neuron function and the sending of all nervous impulsing

Sodium (Na)

Important in maintaining body fluid balance and neuron function

Chlorine (Cl)

Important in maintaining body and cellular fluid balance

Magnesium (Mn)

Important in nucleic acid synthesis and function

Iron (Fe)

Required component for specific enzymes and for oxygen transport

Atom

Smallest unit of matter that still retains the properties of an element

Proton

Has a single positive electrical charge

Electron

Has a single negative electrical charge

Neuron

Is electrically neutral

Where are protons and neutrons found?

In the atoms nucleus

Where are electrons found?

Orbiting the nucleus

Molecule

Formed when two or more atoms share electrons from their outer shells

Ion

Formed when an atom or molecule gains or loses one or more electron from its electron shell(s)

Compound

A substance consisting of two or more different elements combined in a fixed ratio

Chemical Bonds

When atoms share, donate, or receive electrons.

Ionic Bond

Formed from the attraction between two ion - atoms or molecules with an electrical charge - of opposite charge

Covalent Bond

Formed when two atoms share two or more electrons from their outer shells

Single Covalent Bond

When two atoms share a pair of electrons

Double Covalent Bond

When two atoms share two pairs of electrons

Triple Covalent Bond

When two atoms share three pairs of electrons

Nonpolar Covalent Bond

In molecules of only one elements, the pull toward each atom is equal, because each atom has the same electronegativity

Hydrogen Bond

Formed by the attraction between the positively charged hydrogen atoms of polar molecules and negatively charged atoms

Chemical Reaction

The making and breaking of chemical bonds that leads to changes in the composition of matter

Reactants

Starting material of the reaction

Products

Result of the reaction

Law of Conservation of Energy

Energy within a closed system is constant. Energy cannot be created of destroyed, only transformed

Exergonic Reaction

Chemical reaction that releases energy

Endergonic Reaction

Requires an input of energy and yields products rich in potential energy

Activation Energy

A specific amount of energy for each reaction must be available to break bonds and form new ones

Catalyst

A molecule that helps to drive (speed up) reactions by lowering the energy of activation

Synthesis Reaction

Reactions where two or more atoms, ions, or molecules combine to form larger molecules

Decomposition Reactions

Reactions where a large molecule breaks down into smaller atoms, ions, or molecules

Exchange Reactions

Combinations of synthesis and decomposition reactions

Reversible Reactions

Reactions where the products can revert to the original reactants

Oxidation-reduction Reactions

Reactions where electrons are transferred between atoms and molecules

Acid

A substance that dissociates, or splits into one or more hydrogen ions and one or more anions when added to water (adds more hydrogen ions to an aqueous solution)

Base

Dissociates into one or more hydroxide ions and one or more cations when added to water (removes hydrogen ions from an aqueous solution)

pH Scale

Used to describe how acidic or basic a solution is

Carbonic Acid-Bicarbonate Buffer System

Maintains a constant pH, serves to convert strong acids or bases into weak acids and bases

Hydroxyl

A hydrogren atom bonded to an oxygen atom

Sulfhydryl

A hydrogen atoms bonded to a sulfur atom

Carbonyl

A carbon atom double bonded to an oxygen atom

Carboxyl

A carbon atom double bonded to an oxygen atom and also bonded to a hydroxyl group

Ester

A carboxyl group where the hydrogen is replaced with a connection to another carbon

Phosphate

A phosphorus atom double bonded to one oxygen atom and bonded to three other oxygen atoms

Amino Group

A nitrogen atom bonded to two hydrogen atoms

Macromolecules

Very large molecules, cabrohydrates, lipids, nucleic acids, and proteins

Polymers

Made from similar or identical building blocks strung together

Monomers

Building blocks to polymers

Isomers

Molecules with the same molecular formula but different structures

Carbohydrates

Class of organic compounds made of carbon, hydrogen, and oxygen

Monosaccharides

Carbohydrate monomers

Disaccharide

Formed from two monosaccharides connected by a dehydration reaction

Lipids

Hydrophobic compounds that are important in energy storage

Primary Protein Structure

The amino acid sequence

Secondary Protein Structure

Folding the polypeptide into local patterns through formation of hydrogen bonds

Tertiary

The overall three-dimensional shape of the polypeptide

Quaternary

The assembly of multiple polypeptides

Nucleic Acids

Organic molecules first found in cell nuclei

Nucleus

Contains most of the cell’s DNA, which contains the instructions for most aspects of cellular structure and function

Cytoplasm

Contains all of the cellular contents between the nucleus and the plasma membrane, and includes the cytosol and other organelles

Plasma Membrane

Forms the barrier separating the interior of the cell from the outside environment, commonly described using a fluid mosaic model

Fluid

The proteins can drift about in the phospholipids

Mosaic

Because of the protein embedded in the phospholipids

Selective Permeability

Plasma membranes allow certain substances to pass more easily through than others

Concentration Gradient

A difference in the concentration of a chemical between two separate areas

Electrical Gradient

A difference in the electrical charges between two separate areas

Simple Diffusion

The diffusion of particles across a plasma membrane

Facilitated Diffusion

A passive process by which polar or charged solutes are able to move through a plasma membrane

Osmosis

The process by which water moves across membranes in response to solute concentration inside and outside the cell

Active Transport

The process by which a cell transports molecules against their concentration gradient through the expenditure of energy

Tonicity

Describes the ability of a solution to cause a cell to gain or lose water

Isotonic

Concentration of a solute is the same inside and outside the cell

Hypertonic

Concentration of solute is higher outside the cell

Hypotonic

Concentration of solute is higher inside the cell

Exocytosis

Used to export bulky molecules, such as proteins or polysaccharides

Endocytosis

Used to import substances useful to the livelihood of the cell

Transcytosis

Combination of exocytosis and endocytosis to move substances through a cell

Phagocytosis

Non-specific engulfment of a particle by forming a vacuole around it, using plasma membrane

Pinocytosis

Non-specific uptake of fluids into the cell through the use of small vesicles

Receptor-Mediated Endocytosis

Highly specific uptake of a particular molecule where receptors interact with and bind those molecules, initiating formation of a vesicle

Microfilaments

Support the cells shape and are involved in motility

Intermediate Filaments

Reinforce cell shape and anchor organelles

Microtubules

Shape the cell and act as tracks for motor protein

Centrosomes

Responsible for the formation of the mitotic spindle during cell division

Cilia

Small hair-like extensions of the cell, primarily responsible for the steady movement of fluid along the cells surface

Flagella

Long tail-like extensions of the cell used for cellular propulsion

Lysosomes

Vesicles containing digestive enzymes that are able to break down many organic molecules

Peroxisomes

Contain enzymes to break down toxic substance, by-products of oxidation, and various lipids for metabolic purposes

Proteasomes

Tiny cellular structures made of proteins that contain proteases - enzymes that break down proteins into small peptides

Ribosomes

Involved in the cells protein synthesis