Biology: Unit 2 (Cell Chemistry, Structure, and Transport)

Element

A pure substance made of only one kind of atom

Atom

The smallest part of a substance that cannot be broken down chemically

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge

Atomic Number

the number of protons in the nucleus of an atom

Isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

Electron Shells

Regions surrounding the atomic nucleus containing a specific number of electrons

Chemical bonds

The attractive force that holds atoms or ions together

Ionic bonds

Attractions between oppositely charged atoms or groups of atoms where electrons are donated and accepted.

Covalent bonds

A chemical link between atoms where electron pairs are shared

Electronegativity

The tendency of an atom to attract electrons in a molecule

Nonpolar covalent bonds

A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.

Polar covalent bond

A covalent bond in which electrons are not shared equally

Ion

An atom or group of atoms that has an electric charge

Hydrogen bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom.

Cohesion

Attraction between molecules of the same substance

Adhesion

An attraction between molecules of different substances

Surface tension

The property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules

Solvent

The material that is able to dissolve the solute to make a solution

Acid

Any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance

Base

A substance that can accept protons or donate a pair of valence electrons

Buffer

Organic substances that maintain a constant pH over a given range by neutralizing the effects of hydrogen ions

Hydrophilic

Water loving, molecules that can interact with water

Hydrophobic

Water fearing, a property of molecules that do not mix with water

Macromolecules

A very large molecule important to biological processes, ex. protein

Carbohydrates

Broken down to glucose to provide energy.

Monosaccharide

The simplest forms of sugar and the most basic units (monomers) from which all carbohydrates are built

Glucose

The main type of sugar in the blood and is the major source of energy for the body's cells

Disaccharide

A double sugar molecule made of two monosaccharides bonded together through dehydration synthesis

Polysaccharide

Carbohydrates that are made up of more than two monosaccharides

Starch

A polysaccharide or complex carbohydrate that is made up of a chain of glucose molecules joined together in covalent bonds

Glycogen

A polysaccharide of glucose that serves as a form of energy storage in fungi and animals

Cellulose

A molecule, consisting of hundreds - and sometimes even thousands - of carbon, hydrogen and oxygen atoms, main substance in walls of plants

Lipids

Fatty, waxy, or oily compounds that are soluble in organic solvents and insoluble in polar solvents such as water

Fat

A large lipid molecule made from an alcohol called glycerol and three fatty acids; a triglyceride. Most fats function as energy-storage molecules.

Phospholipids

Compound lipids, consisting of phosphoric acids, nitrogen base, alcohol and fatty acids

Steroid

Any of a group of lipids (fats) that have a certain chemical structure

Saturated fatty acids

Fatty acids without double bonds in their hydrocarbon chain

Unsaturated fatty acids

A fat or fatty acid in which there is at least one double bond within the fatty acid chain

Trans fatty acid

unsaturated fats with trans double bonds instead of cis bonds

Protein

A three dimensional polymer made of monomers of amino acids.

Amino acid

Building blocks of protein

Polypeptide

A continuous, unbranched chain of amino acids joined by peptide bonds

DNA

The molecule that carries genetic information for the development and functioning of an organism

RNA

A single-stranded nucleic acid that passes along genetic messages

Nucleotide

A molecule that is the basic building block of the nucleic acids DNA and RNA

Prokaryotic

An organism whose cells do not have an enclosed nucleus, such as bacteria.

Eukaryotic

Cell with a nucleus (surrounded by its own membrane) and other internal organelles.

Ribosomes

Tiny spherical organelles that make proteins by joining amino acids together

Cytoplasm

The gelatinous liquid that fills the inside of a cell

Organelles

A tiny cell structure that carries out a specific function within the cell

Nucleus

The structure in a cell that contains the chromosomes

Nuclear envelope

A double membrane that surrounds the nucleus in the cell

Rough Endoplasmic Reticulum

An endomembrane system covered with ribosomes where many proteins for transport are assembled.

Smooth Endoplasmic Reticulum

An endomembrane system where lipids are synthesized, calcium levels are regulated, and toxic substances are broken down.

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell

Lysosome

An organelle containing digestive enzymes

Vacuole

Storage areas for cells and important cell parts

Peroxisomes

Small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions, including several aspects of energy metabolism

Mitochondria

Powerhouse of the cell, organelle that is the site of ATP (energy) production

Chloroplast

Organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Centrosomes

An organelle near the nucleus of a cell that contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division.

Cilia

Small, slender, hair-like structures present on the surface of all mammalian cells

Flagella

Whiplike tails found in one-celled organisms to aid in movement

Cell wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

Selective permeability

Condition or quality of allowing some, but not all, materials to cross a barrier or membrane

Concentration gradient

A difference in the concentration of a substance across a distance.

Passive transport

The process of transporting molecules from one side of the membrane to the other without any energy requirements

Diffusion

The net movement of molecules from an area of greater concentration to an area of lesser concentration

Osmosis

Movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules

Isotonic

Describes a solution whose solute concentration is equal to the solute concentration inside a cell

Hypertonic

Any external solution that has a high solute concentration and low water concentration compared to body fluids

Hypotonic

A solution that has a lower concentration of solute compared to the cell

Facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

Active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

Endocytosis

The process by which cells take in substances from outside of the cell by engulfing them in a vesicle

Pinocytosis

A process by which the cell takes in the fluids along with dissolved small molecules

Phagcytosis

Process by which certain living cells called phagocytes ingest or engulf other cells or particles

Receptor-mediated endocytosis

A form of endocytosis in which receptor proteins on the cell surface are used to capture a specific target molecule

Exocytosis

A process that occurs when a cell moves large materials from inside the cell to the outside of the cell using small spheres of membrane called vesicles