Chapter 4- Proteins, Enzymes, and Nucleic Acids

side chain (R group)

the distinguishing group of atoms of a particular amino acid

Denaturation

A process in which a protein unravels, losing its specific structure and hence function; can be caused by changes in pH or salt concentration or by high temperature.

Chaperones

a type of protein that assists in the folding of other molecules

peptide bond

covalent bond formed between amino acids

Amino acid

monomer of protein

dehydration synthesis

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

Hydrolysis

the chemical breakdown of a compound due to reaction with water.

polypeptide chain

A chain of amino acids linked together by peptide bonds.

deoxyribonucleic acid (DNA)

A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins.

ribonucleic acid (RNA)

A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses.

Nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

nitrogenous base

is a carbon ring structure that contains one or more atoms of nitrogen. In DNA, Adenine, Thymine, Cytosine, Guanine.

phosphodiester linkage

covalent bonds that join adjacent nucleotides between the -OH group of the 3' carbon of one nucleotide and the phosphate on the 5' carbon of the next

Double helix

two strands of nucleotides wound about each other; structure of DNA

Complementary Base Pairs

the standard arrangement of bases in nucleotides in relation to their opposite pairing, such as cytosine paired with guanine and adenine with thymine (or uracil in RNA).

antiparallel strands

Two DNA strands parallel to each other going in opposite directions (3'-5' and 5'-3')

Gene

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

ATP

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

Enzyme

A type of protein that speeds up a chemical reaction in a living thing

Catalyst

substance that speeds up the rate of a chemical reaction

Induced Fit

The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate.

Activation energy

the minimum amount of energy required to start a chemical reaction

Substrate

A specific reactant acted upon by an enzyme

Active site

the region on the enzyme where the substrate binds

competitive inhibition

substance that resembles the normal substrate competes with the substrate for the active site

Allosteric inhibitor

substrate binds to allosteric site and stabilizes the enzyme shape so that the active sites are closed

Feedback inhibition

A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.