Biochemistry Part 2

• Cell wall

  A rigid but flexible structure made of cellulose. It acts a pressure vessel, preventing over-expansion when water enters the cell. It is found in mainly in plant cells but also in fungi, algae and some bacteria
• Cell membrane

  The entire cell is covered by this and it is mostly composed of phospholipids. It is "selectively permeable" and controls the entry and exit of various chemicals into and out of the cell
• Flagella

  The "tail-like" projection that helps cells move
• Cilia

  Slender protuberances that project from the cell body. They can aid in motion or serve as sensory organelles
• Mitochondria


  This organelle provides the cells with energy by producing ATP through cellular respiration
• Chloroplasts


  This organelle captures light energy and so is involved in photosynthesis. (is generally only found in plant cells)
• Cytoplasm

  This is where most cellular activities occur, such as metabolic pathways including glycolysis, and processes such as cell division. It is also the space that contains the organelles
• Ribosome

  This organelle makes proteins out of amino acids
• Lysosome


  An organelle that breaks down "worn-out" organelles, viruses/bacteria and food particles. It does this with digestive enzymes in an acidic environment
• Centrioles

  A structure critical for cell division and the organization of the spindle fibres in mitosis. Found only in animal cells
• Smooth Endoplasmic Reticulum

  A series of canals that carry materials throughout the cell and help synthesize lipids such as steroids
• Rough Endoplasmic Reticulum

  This organelle is where many ribosomes are attached and thus it helps synthesize proteins
• Vacuole

  A Membrane-surrounded, fluid-filled "storage space containing water, sugar, minerals or enzymes. Their function varies depending on the type of cell
• Golgi Apparatus


  A structure that stores and packages proteins (such as enzymes) and lipids
• Nucleus

  The control center of the cell that contains the DNA. It also has small "pores" all over it allowing materials to enter or exit
• Nucleolus

  A spherical structure of the nucleus that makes ribosomal RNA (rRNA)
• Chromosomes

  The thread-like structures that contain genetic information
• Passive transport


  No Energy (ATP) required, transport through the plasma membrane
• Active transport

  Energy Required (ATP), includes simple diffusion and facilitated diffusion
• Simple diffusion

  Small, non-polar molecules move from high to low concentration
• Facilitated diffusion

  Same as simple diffusion, but uses a protein channel for large or charged molecules moving from high to low concentration
• Transport proteins

  Protein channels that allow molecules to move from low to high concentration
• Endocytosis


  The cell membrane takes in molecules, includes pinocytosis (cell drinking) and phagocytosis (cell eating)
• Receptor-mediated endocytosis

  The cell uses protein receptors to take in specific molecules
• Exocytosis


  The cell membrane kicks out molecules, including very large molecules
• Enzymes

  Protein catalysts that speed up chemical reactions without being consumed
• Activation energy

  The energy that must be overcome for a chemical reaction to occur
• Substrate

  The reactant that an enzyme acts on
• Active site

  The site on an enzyme where catalysis occurs and the substrate binds
• Enzyme-substrate complex

  The substrate fits closely into the active site of the enzyme
• Induced fit

  The adjustment of the enzyme's shape to accommodate the substrate
• Cofactor

  A non-protein substance required for an enzyme to work properly
• Competitive inhibition


  Inhibitors that bind to the active site and compete with the substrate
• Non-competitive inhibition

  Inhibitors that bind to a different site and change the enzyme's shape
• Industrial uses of enzymes

  • Starch processing
  • Cheese making