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- polypeptides
- a polymer chain of amino acids linked together by peptide bonds
- 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
- feedback inhibition
- A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
- deoxyribose
- the carbohydrate (sugar) component of DNA. it is a pentose (5 carbon sugar) that contains one less hydroxyl group than ribose (RNA)
- cofactors
- Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis
- scanning electron microscope (SEM)
- a microscope that uses an electron beam to scan the surface of a sample to study details of its topography
- electron microscope
- a microscope that focuses on an electron beam through a specimen, resulting in resolving power a thousandfold greater than that of a light microscope
- organelles
- One of several bodies with a specialized function that is suspended in the cytosol of the cell
- tertiary structure
- Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.
- gene
- A distinct unit of hereditary material found in chromosomes; a sequence of nucleotides in DNA that codes for a particular tRNA, rRNA, or polypeptide.
- transmission electron microscope (TEM)
- a microscope that passes an electron beam through very thin sections, primarily used to study the internal ultrastructure of cells
- light microscope
- an optical instrument with lenses that refract visible light to magnify images of specimens
- exergonic reaction
- A spontaneous chemical reaction in which there is a net release of free energy.
- anabolic pathways
- a metabolic pathway that synthesizes a complex molecule from simpler compounds
- chromosomes
- A threadlike linear strand of DNA and associated proteins in the nucleus of eukaryotic cells that carries the genes and functions in the transmission of hereditary information.
- secondary structure
- The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between peptide linkages.
- alpha helix
- A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure.
- coenzymes
- organic molecule serving as a cofactor (required for the proper functioning of an enzyme). Vitamins function as coenzymes in metabolic reactions
- prokaryotic cell
- a type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; bacteria and archaea
- plasma membranes
- The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition
- cytoplasm
- watery environment containing other organelles, where many biochemical activties occur
- kinetic energy
- The energy of motion, which is directly related to the speed of that motion. Moving matter does work by imparting motion to other matter
- ribosomes
- a cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules , which make up two subunits
- nucleus
- The chromosome-containing organelle of a eukaryotic cell
- nucleic acid
- A polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities. The types are DNA and RNA.
- resolving power
- a measure of the clarity of an image; the min distance that two points can be separated and still be distinguished as two separate points
- pleated sheet
- One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, or where two regions of the chain lie parallel to each other and are held together by hydrogen bonds.
- enzymes
- A protein serving as a catalyst, a chemical agent that changes the rate of a reaction without being consumed by the reaction.
- deoxyribonucleic acid
- A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins.
- nucleotides
- building blocks of nucleic acids, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group
- energy
- The capacity to do work or to produce heat
- ribose
- the sugar component of RNA
- endergonic reaction
- A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings.
- hydrophobic interaction
- A type of weak chemical bond formed when molecules that do not mix with water coalesce to exclude the water.
- nucleolus
- A specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes.
- disulfide bridges
- Strong covalent bonds formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer
- allosteric site
- A specific receptor site on some part of an enzyme molecule remote from the active site.
- ribonucleic acid
- 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.
- substrate
- the reactant on which an enzyme works
- active site
- The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds.
- second law of thermodynamics
- The principle whereby every energy transfer or transformation increases the entropy of the universe. Ordered forms of energy are at least partly converted to heat, and in spontaneous reactions, the free energy of the system also decreases
- primary structure
- The level of protein structure referring to the specific sequence of amino acids.
- entropy
- A quantitative measure of disorder or randomness, symbolized by S
- double helix
- The form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape.
- polynucleotide
- a polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular activities: DNA and RNA
- nucleoid
- A dense region of DNA in Prokaryotic cells
- free energy of activation
- the initial investment of energy necessary to start a chemical reaction also called activation energy
- quaternary structure
- The particular shape of a complex, aggregate protein, defined by the characteristc three-dimensional arrangement of its constituent subunits, each a polypeptide.
- noncompetitive inhibitors
- A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate.
- peptide bond
- the covalent bond formed between two amino acid units, formed by dehydration reaction
- competitive inhibitors
- A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics
- denaturation
- For proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. For DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme conditions of pH, salt concentration, and temperature.
- activation energy
- The amount of energy that reactants must absorb before a chemical reaction will start.
- catalyst
- A chemical agent that changes the rate of a reaction without being consumed by the reaction
- catabolic pathways
- a metabolic pathway that releases energy by breaking down complex molecules to simpler compounds
- adenosine triphophate (ATP)
- An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells
- first law of thermodynamics
- The principle of conservation of energy. Energy can be transferred and transformed, but it cannot be created or destroyed
- potential energy
- energy stored due to an object's position or arrangement
- purine
- One of two types of nitrogenous bases found in nucleotides. Adenine (A) and guanine (G) are purines.
- cytosol
- The semifluid portion of the cytoplasm
- energy coupling
- In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction
- pyrimidine
- One of two families of nitrogenous bases found in nucleotides. Cytosine (C), thymine (T), and uracil (U) are pyrimidines.
- chromatin
- the complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope.