AP Bio Units 1-4

Active site

Site substrate attaches to on an enzyme

Allosteric site

Other location on an enzyme that an inhibitor can bind to

Catalyst

Speeds up chemical reactions without being consumed (or changed) by the reaction

Polypeptide

Polymer (chain) of amino acids

Primary structure

Sequence of amino acids; determined by genes

Secondary structure

Coils and folds in the polypeptide chain resulting from hydrogen bonds between amino group of one amino acid and the carboxyl group of another; alpha helices and beta-pleated sheets

Tertiary structure

Interactions among various R groups of a polypeptide

Quaternary structure

Interactions between multiple (key word) polypeptide chains

Monomer

Smaller, simpler molecules that are linked together to form larger, more complex molecules

Polymer

A large complex molecule formed from simpler molecules (monomers)

Dehydration synthesis reaction

A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule

Hydrolysis

Breaking down complex molecules by the chemical addition of water

Denature

Unfold a protein's structure; occurs in extreme temperatures & pH ranges

Synthesis

To make or to build

Substrate

The molecule that is changed by the enzyme

Optimal/ optimum

Best or most favorable

Control treatment

Lacks (or does not receive) the specific factor being tested in an experiment

Dependent variable

Factor that is measured, which may change in response to the independent variable; always the y-axis on a graph

Independent variable

Factor that is purposely changed; this is what is being investigated

Hydrogen bond

A weak chemical bond between a hydrogen on one molecule and an electronegative atom on another molecule

Hydrophilic

"water loving"; substance can interact with water and is able to form hydrogen bonds; POLAR

Hydrophobic

"water fearing"; substance cannot interact with water and is unable to form hydrogen bonds; NON-POLAR

Phospholipid diagram

Polar covalent bond

One atom is more electronegative, and the atoms do not share the electron equally; Unequal sharing of electrons causes a partial positive or negative charge for each atom or molecule

Nonpolar covalent bond

The atoms share the electron equally

Example: oxygen molecule, carbon dioxide

Ion

Electrically charged particle that forms when an atom gains or loses one or more electrons

Example: H+, Na+, K+

Ionic bond

Attraction between oppositely charged atoms, or ions due to transfer of electron from one atom to another

Acid

Any substance that increases the H+ concentration of a solution; acidic solutions have pH values less than 7

The more H+ = more acidic = the lower the pH

Base

Any substance that reduces the H+ concentration of a solution; basic solutions have pH values greater than 7

The lower H+ = more basic= the higher the pH

Concentration

A measure of the amount of dissolved substance contained per unit of volume

Carboxyl group

"Acid" in amino acids

Phosphate group

Chemical group consisting of a phosphorus atom bonded to four oxygen atoms

Amino group

"Amino" in amino acids

Fatty acid

A carboxyl (carboxylic acid) group attached to a long carbon skeleton (hydrophobic)

Competitive inhibitor

Substance that reduces the activity of an enzyme by binding to the active site

Monosaccharide

"One sugar"; the monomer used to build larger carbohydrates; molecular formula=C6 H12 O6

Examples: glucose, galactose, fructose

Noncompetitive inhibitor

Substance that reduces the activity of an enzyme by binding to an allosteric site, changing the enzyme's shape so that the active site no longer effectively catalyzes the conversion of substrate to product

Disaccharide

Two monosaccharides joined from a dehydration reaction

Examples: sucrose, lactose, maltose

Amino acid

Compound with an amino group on one end and a carboxyl group on the other end; building block of proteins

Polysaccharide

Polymers of sugars; have storage and structural roles; ratio of atoms= 1 carbon: 2 hydrogen: 1 oxygen

Ribose

Sugar in RNA

Lipid

Organic compound; common feature= HYDROPHOBIC

Consist mostly of hydrocarbon regions= nonpolar

Examples= fats, phospholipids, and cholesterol

R group

A functional group that defines a particular amino acid and gives it special properties

Deoxyribose

Sugar in DNA

Nucleotide

Monomer of nucleic acids; contains: nitrogen containing base, sugar, & phosphate group

Cohesion

Attraction between molecules of the same substance

Example: water to water

Adhesion

Attraction between molecules of different substances

Example: water to penny

Surface tension

The attractive intermolecular forces at the surface of a liquid

Saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton

Unsaturated fatty acid

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail

Prokaryote

Cells that do NOT contain a nucleus or other membrane bound organelles; bacteria

Eukaryote

Cells that contain a nucleus and other membrane bound organelles (ER, GA, lysosome, vacuole, mitochondria, etc)

Fluid mosaic model

Model that describes the plasma membrane as a mosaic (mixture) of protein molecules bobbing in a fluid (moves) bilayer of phospholipids

Vesicle

Membrane surrounded container used to ship or store materials for the cell

Endomembrane system

System of organelles that are continuous or connected through the transfer of vesicles; example: ER --> GA --> plasma membrane

Nucleus

Contains most of the DNA in a eukaryotic cell

Asexual reproduction

The generation of offspring from a single parent, without the fusion of reproductive cells

Plasma membrane

The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell's chemical composition; a phospholipid bilayer with embedded proteins

Selectively permeable

Allows only some substances to cross

Free ribosomes

Uses mRNA to build proteins that remain in cytosol (such as cytoskeleton or motor proteins); NOT attached to ER

Bound ribosomes

Attached to endoplasmic reticulum; builds proteins that need to enter the endomembrane system (such as excreted from the cell, integrated into the plasma membrane, found inside an organelle)

Smooth ER

Organelle that synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions; no ribosomes

Rough ER

Has attached ribosomes that make proteins found in membrane & secreted proteins, distributes transport vesicles, and is a membrane factory for the cell

Golgi apparatus (GA)/ Golgi complex

Modifies certain products of the ER;

Manufactures certain macromolecules;

Sorts and packages materials into transport vesicles, adds molecular "ID tags" for proper delivery

Lysosome

Vesicle containing hydrolytic enzymes that can digest macromolecules

Vacuole

Organelle that store molecules, mainly water

Mitochondria

Organelle that uses sugar & oxygen to generate ATP (process called cellular respiration)

Contains circular DNA, ribosomes, double phospholipid membrane, cristae (folds)

Chloroplast

Organelle that uses light energy to generate oxygen & sugars (process called photosynthesis)

Contains circular DNA, ribosomes, double phospholipid membrane, thylakoids, stroma

Endosymbiosis theory

The theory that mitochondria and chloroplast originated as prokaryotic cells engulfed by host cells

Evidence includes that they both contain:

Phospholipid membrane

Free-floating circular DNA

Ribosomes

Similar size (1-10 mm)

Similar reproduction

Diffusion

The tendency for molecules to spread out evenly into the available space

A substance will move from where it is MORE concentrated to where it is LESS concentrated

Osmosis

Diffusion of water

Lysis

To break; the disintegration of a cell by rupture of the cell wall or membrane; example: when an animal cell is placed in a hypotonic solution

Salinity

Measure of all the salts dissolved in water

Hypertonic solution

Solute concentration is greater than that of the other solution; cell placed in a hypertonic solution will shrink

Hypotonic solution

Solute concentration is less than that of the other solution; cell placed in a hypotonic solution will expand

Isotonic solution

Solute concentration is the same as inside the cell; no net water movement across the plasma membrane

Osmoregulation

The control of solute concentrations and water balance; example: paramecium in freshwater (hypo) have contractile vacuoles to pump incoming water back out

Facilitated diffusion

Movement of specific molecules across cell membranes through protein channels; passive transport process (no energy required); example includes aquaporins

Water potential

Tendency of water to diffuse from one area to another;

= Water's potential energy;

Always moves from regions of higher water potential to regions of lower water potential

Exocytosis

transport vesicles migrate to the membrane, fuse with it, and release their contents

EXO= EXIT

Endocytosis

Cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane

ENDO= ENTER

Phagocytosis

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell

ATP

Adenosine triphosphate; Main energy source that cells use for most of their work

An organic molecule called adenosine attached to a string of three phosphate groups

Active transport

Moves substances against their concentration gradients

Requires energy, usually in the form of ATP

Sodium-potassium pump

A carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell

Result= Higher Na+ concentration outside cell; positive charge outside, negative inside cell

Solute

A substance that is dissolved in a solution.

Osmolarity

Total concentration of all solute particles in a solution

Homeostasis

Process by which organisms maintain a relatively stable internal environment

Proton pump

An active transport protein in a cell membrane that uses ATP to transport hydrogen ions against their concentration gradient, generating a membrane potential in the process.

Metabolism

Sum total of an organism's chemical reactions

Metabolic pathway

A series of chemical reactions that are catalyzed by enzymes; two major pathways are cellular respiration and photosynthesis

1st law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed

2nd law of thermodynamics

During every energy transfer or transformation, some energy is unusable and is often lost as heat

Exergonic reaction

Breaks molecules apart and releases energy; is spontaneous (no energy input)

Endergonic reaction

Builds molecules and requires energy input; is not spontaneous

Activation energy

Initial energy needed to start a chemical reaction

Activation energy diagram

Feedback inhibition

The end product of a metabolic pathway shuts down the pathway

Adenosine triphosphate (ATP)

An organic molecule called adenosine attached to a string of three phosphate groups; primary energy-transferring molecule in the cell

Phosphorylation

Removing phosphate group from ATP and adding it to another molecule to activate it