biology of animals test 1 tau

Heritable variation

A trait that can be inherited and therefore can be selected.

Compound

A substance containing two or more elements in a fixed ratio.

Molecule

A group of atoms joined together; molecules make up compounds.

Organic molecule

A molecule that contains carbon.

Proton

A positively charged subatomic particle found in the nucleus.

Neutron

An electrically neutral subatomic particle found in the nucleus.

Electron

A negatively charged subatomic particle that occupies orbitals around the nucleus and is directly involved in chemical reactions.

Orbital

A region or path around the nucleus associated with an electron.

Mass number

The total number of protons and neutrons in an atom's nucleus.

Isotope

An atom of the same element with the same number of protons but a different number of neutrons.

Radioactive isotope

An isotope whose nucleus decays spontaneously.

Chemical reaction

A process in which atoms rearrange as chemical bonds break or form; matter is not created or destroyed.

Chemical bond

An attraction that holds atoms close together after electrons are transferred or shared.

Covalent bond

A strong bond formed when two atoms share one or more pairs of electrons.

Nonpolar covalent bond

A covalent bond in which electrons are distributed equally.

Polar covalent bond

A covalent bond in which electrons are distributed unequally.

Hydrogen bond

A weak electrical attraction between partial charges, such as the attraction between neighboring water molecules.

Ion

An atom or molecule with a net electrical charge because it gained or lost electrons.

Ionic bond

A bond formed between oppositely charged ions after electrons are transferred.

Ionic compound

A compound, such as table salt, held together by ionic bonds.

Hydrophilic

Able to interact with and dissolve readily in water.

Pseudoscience

A field of study falsely presented as having a scientific basis.

Anecdotal evidence

An assertion based on a single or a few examples that do not support a generalized conclusion.

Tissue

A group of similar cells performing a specific function.

Cell

The smallest unit that can display all the characteristics of life.

Organelle

A functional component inside a cell, such as the nucleus.

Cohesion

The tendency of molecules of the same kind to stick together; water has strong cohesion because of hydrogen bonding.

Surface tension

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

Evaporative cooling

Cooling that occurs when a substance evaporates and the liquid left behind becomes cooler.

Aqueous solution

A solution in which water is the solvent.

Acid

A chemical compound that releases hydrogen ions (H+) into a solution.

Base

A compound that accepts hydrogen ions (H+) and removes them from solution.

pH

A scale used to describe acidity by measuring hydrogen ion concentration in a solution.

Buffer

A substance or system that minimizes changes in pH.

Radiometric dating

A method of estimating age by measuring radioactive isotopes and the number of half-life reductions that have occurred.

Half-life

The time associated with a radioactive isotope decreasing to half of its previous amount or radioactivity.

Fossil record

The ordered sequence of fossils used to document the history of life.

Macromolecule

A very large biological molecule; many macromolecules are built from smaller molecular building blocks.

Monomer

A small molecular building block that can be joined to other similar units.

Polymer

A large molecule made by stringing together many monomers.

Dehydration reaction

A reaction that links monomers together while removing a molecule of water.

Hydrolysis

The breakdown of a polymer by adding water; essentially the reverse of a dehydration reaction.

Carbohydrate

A class of organic molecules that includes sugars and polymers of sugars and is used for energy and structure.

Monosaccharide

A carbohydrate monomer that cannot be broken down into smaller sugars.

Polysaccharide

A carbohydrate polymer made from many monosaccharides.

Glucose

A monosaccharide that is a major fuel for cellular work and a monomer of several important polysaccharides.

Fructose

A monosaccharide found in fruit; it has the same molecular formula as glucose but a different structure.

Isomer

A molecule that has the same molecular formula as another molecule but a different structure.

Starch

A polysaccharide made from glucose and used as a carbohydrate form discussed in the slides.

Glycogen

A polysaccharide made from glucose that can be stored in the liver and muscles.

Cellulose

A glucose-based polysaccharide that humans cannot digest.

Lipid

A diverse group of hydrophobic molecules that do not readily mix with water.

Fatty acid

A molecular building block used in fats and phospholipids.

Glycerol

The molecule joined to three fatty acids to form a typical triglyceride.

Triglyceride

A typical fat consisting of one glycerol molecule joined to three fatty acid molecules.

Saturated fatty acid

A fatty acid with the maximum number of hydrogens and no carbon-carbon double-bond kink.

Unsaturated fatty acid

A fatty acid with fewer than the maximum number of hydrogens because it contains one or more double bonds.

Saturated fat

A fat whose three fatty acids are saturated; these fats can stack and tend to be solid at room temperature.

Unsaturated fat

A fat rich in unsaturated fatty acids; these fats tend to remain liquid at room temperature.

Hydrogenation

The addition of hydrogen that converts unsaturated fats toward saturated fats and can make liquid fats solid.

Trans fat

A type of unsaturated fat created by hydrogenation and described in the slides as particularly unhealthy.

Phospholipid

A lipid with two fatty acid tails and a phosphate-containing head; the head is hydrophilic and the tails are hydrophobic.

Phospholipid bilayer

A two-layer sheet of phospholipids with hydrophilic heads facing water and hydrophobic tails tucked inside; it forms cell membranes.

Steroid

A lipid with a carbon skeleton of four fused rings; many steroids function as hormones.

Cholesterol

A steroid that is a key component of cell membranes and the base steroid used to make other steroids such as estrogen and testosterone.

Anabolic steroid

A synthetic variant of testosterone that mimics some testosterone effects and can promote muscle growth.

Protein

A functional molecule made from one or more polypeptide chains folded into a specific shape.

Amino acid

A protein monomer with a central carbon bonded to an amino group, carboxyl group, hydrogen, and a variable side chain.

Amino group

The nitrogen-containing group found in every amino acid.

Carboxyl group

The acidic carbon-and-oxygen-containing group found in every amino acid.

R group

The variable side chain of an amino acid that gives each amino acid its special chemical properties.

Peptide bond

The bond formed between amino acids when cells link them together by dehydration reactions.

Primary structure

The sequence of amino acids in a polypeptide chain.

Secondary structure

Local folding patterns in a protein, including alpha helices, beta-pleated sheets, and random coils.

Alpha helix

A spiral-staircase-like type of protein secondary structure stabilized by hydrogen bonds.

Beta-pleated sheet

A zigzag type of protein secondary structure stabilized by hydrogen bonds.

Random coil

A flexible, less regular type of protein secondary structure.

Tertiary structure

The overall three-dimensional folding of a single polypeptide, influenced by hydrophobic and hydrophilic amino acids.

Quaternary structure

A protein structure formed when two or more polypeptide chains come together.

Globular protein

A protein folded into a compact, ball-like shape.

Fibrous protein

A protein that remains relatively straight and can form fibers or rope-like bundles.

Nucleic acid

A macromolecule that stores information and provides instructions for building proteins.

DNA

Deoxyribonucleic acid; the inherited genetic material stored in chromosomes.

RNA

Ribonucleic acid; one of the two major types of nucleic acid.

Chromosome

A long DNA fiber in the cell that contains inherited genetic information.

Gene

A unit of inheritance encoded in a specific stretch of DNA that programs the amino acid sequence of a polypeptide.

Nucleotide

A nucleic-acid monomer made of a five-carbon sugar, a phosphate group, and a nitrogen-containing base.

Cell theory

The central idea that all living things are composed of cells, the cell is the basic unit of life, and cells come from pre-existing cells.

Plasma membrane

The membrane surrounding the cell; it separates the living cell from its nonliving surroundings and is mainly a phospholipid bilayer with proteins.

Prokaryotic cell

A small cell type shown with a cell wall, plasma membrane, cytoplasm, ribosomes, chromosome, and sometimes plasmids.

Eukaryotic cell

A larger cell type containing a nucleus and membrane-bound organelles.

Cytoplasm

The fluid-filled interior of the cell outside the nucleus where many cell structures are located.

Plasmid

A small coil of DNA shown in prokaryotic cells in addition to the main chromosome.

Nuclear envelope

The double membrane surrounding the nucleus.

Nuclear pore

An opening through the nuclear envelope that allows selected materials to move into or out of the nucleus.

Nucleolus

A structure inside the nucleus involved in ribosome subunit assembly and RNA production.

Ribosome

A non-membrane-bound complex of RNA and proteins where protein synthesis occurs.

Rough endoplasmic reticulum

A membrane network studded with ribosomes that functions in protein synthesis and processing.

Smooth endoplasmic reticulum

A membrane network without ribosomes that functions in lipid synthesis and processing.

Golgi apparatus

A stack of flattened membrane sacs that processes, sorts, and ships proteins, lipids, and carbohydrates.