Biology Unit 3 - AOS 1

• Active site


  The region of an enzyme molecule that provides the site for attachment of molecules of substrate.

  
  

  The place on the surface of an enzyme molecule where substrate molecules attach.
• Active transport


  The transport of molecules across the cell membrane against a concentration gradient. Active transport occurs through the protein molecules and requires the cell to expend energy in the form of ATP.
• Amino acid


  A small molecule that is the building block of protein. All amino acids contain an amino group (NH2) and a carboxylic acid group (COOH).
• Anabolic reaction


  An energy-releasing cellular reaction that does not require oxygen. It occurs in the cytosol of cells.

  
• ATP (adenosine triphosphate)


  A portable energy source that moves about the cell to wherever energy is required. At sites in the cell where anergy is required. ATP breaks down to from ADP (adenosine diphosphate) and inorganic phosphate (Pi), and releases energy.

  
  

  A high energy compound composed of adenine and ribose with a chain of three phosphate groups attached. Releases energy for cellular reaction when its last phosphate group is removed and converted into ADP.

  
• Adhesion proteins

  proteins on the surface of cells that are involved in binding with other cells or to an extracellular matrix in a process called cell adhesion.
• Alpha helix


  A type of secondary protein structure in which the polypeptide chain folds into a tight coil.
• Anticodon


  The three nucleotides in tRNA that bind to mRNA following bas-pairing rules.
• Activation energy

  The energy required to initiate a reaction.
• ADP (adenosine diphosphate)

  A low-energy compound composed of adenine and ribose with two phosphate groups attached; it is converted to ATP for energy storage when it gains a phosphate group.
• Aerobic cellular respiratio


  A metabolic reaction that requires oxygen to produce energy for the cell.
• Anabolic reaction


  A reaction that builds up complex molecules from more simple ones.
• ATP synthesis


  An enzyme that provides energy for the cell through synthesis of ATP.
• Biomacromolecule


  A large biological molecule
• Biochemical pathway

  In biochemistry, a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites, which are modified by a sequence of chemical reactions catalysed by enzymes.
• Base pair


  A pair of complementary nitrogen bases linked by hydrogen bonding.

  
• Bulk transport


  The transport of large quantities of material into or out of the cytoplasm all at one time.
• Catabolic reaction


  A reaction in which there is a net grain or release of energy.
• Catalyst


  Any chemical that increases the rate of a chemical reaction without itself being used up in the reaction.
• Coenzyme


  An organic molecule that acts as a cofactor. Most coenzymes are carrier molecules that transfer electrons or ions from one reaction to another in a biological reaction.
• Competitive inhibiotor


  A molecule that compete with the substrate by binding temporarily to an enzyme's active site.
• Condensation reaction


  The formation of polymers, such as peptides and carbohydrates, by a reaction that involves the release of water molecules; also known as condensation polymerisation.
• Covalent bond


  Chemical bond in which atoms share electrons.
• Cytoplasm

  The cell membrane, organelles and cytosol together; all the cell except the nucleus.
• Cytosol


  The semi-fluid matrix in which cellular organelles are suspended.
• Chromosome

  A threaded structure made up of nucleic acids and protein that encode genetic information.
• Codon


  A group of three nucleotides in mRNA that specifies an amino acid.
• Chlorophyll


  The green pigment found in chloroplasts; it is able to absorb light energy, making it available for photosynthesis.
• Cytochrome


  A membrane-bound protein that carries our electron transport; cytochromes are located in the mitochondrial inner membrane and in chloroplasts.
• Degenerate (triplet code)


  A genetic code in which one amnio acid may be coded for by more than one codon; also known as redundant triplet code.
• Denature


  To destroy the secondary structure and or/ tertiary structure of a protein, rendering the protein functional.
• Diffusion


  The tendency of particles of gases, liquids and solutes to disperse randomly and fill the space.
• DNA


  The information molecule;e that is the basis of an organism's genetic material.
• Disulfide bridge


  A strong bond formed between two sulfur atoms within a protein.
• Differentially permeable


  Describes a membrane that allows some substances but not others to pass across it.
• Enzyme

  A biological catalyst. Enzymes are protein molecules, manufactured by cells in the ribosomes. Most reactions in cells are catalysed by enzymes.
• Enzyme-substrate complex


  A complex formed when an enzyme combines with a substrate (reactant) during a reaction.
• Exons


  Parts of a gene that contain the base sequence that code for the amino acids needed to build a peptide chain.
• Electron transport chain


  The process involving the stepwise transport of electrons to a final electron acceptor; such as oxygen (in aerobic cellular respiration); ultimately, it creates an electrochemical gradient across membranes to drive the phosphorylation of ADP to yield ATP.
• Endocytosis


  The movement of solids or liquids into a cell from the environment via vesicle formation.