B2.1

• Passive Transport

  Passive transport involves the movement of material along a concentration gradient (high concentration ⇒ low concentration)

  • Because materials are moving down a concentration gradient, it does not require the expenditure of energy (ATP hydrolysis)
• what are the three main types of passive transport:

  • Simple diffusion – movement of small or lipophilic molecules that can freely cross the bilayer
  • Osmosis – movement of water molecules across the bilayer (dependent on solute concentrations)
  • Facilitated diffusion – movement of large or charged molecules via transmembrane proteins
• Active Transport

  Active transport involves the movement of materials against a concentration gradient (low concentration ⇒ high concentration)

  • Because materials are moving against the gradient, it does require the expenditure of energy (ATP hydrolysis)
• what are two main types of active transport:

  • Primary active transport – A molecule is moved against its gradient using energy from the hydrolysis of ATP
  • Secondary active transport – A molecule is moved against its gradient coupled to another molecule moving  down an electrochemical gradient (cotransport)
• The rate of diffusion can be influenced by a number of factors, including:

  • Temperature (affects kinetic energy of particles in solution)
  • Molecular size (larger particles are subjected to greater resistance within a fluid medium)
  • Steepness of gradient (rate of diffusion will be greater with a higher concentration gradient)
• what is this 


  the generalized structure of an amino acid.

  
• Define Protiens


  complex macromolecules composed of one or more chains of amino acids.
• Proteins play an important role in many biological processes including, ..

  • structural support, catalysis and signalling pathways.
• Define Amino acids


  the monomers that are used to make proteins.
• How many type of amino acids are there

  20
• Amino acids join together through a condensation reaction. 

  • A peptide bond is formed when the carboxyl group (-COOH) of one amino acid reacts with the amino group (-NH2) of another amino acid to form a dipeptide.
  • A water (H2O) molecule is released as a by product. 
  • The peptide bond formed is a type of covalent bond and therefore is very stable. 
• The structure of an amino acid contains

  • Amine Group (NH2)
  • Carboxyl group (COOH) 
  • Alpha Carbon (c)
  • R Group
• Amino acid structure - Amine Group (NH2):

  • the -NH2 group attached to the alpha carbon 
• amino acid structure - Carboxyl group (COOH)

  • The -COOH group attached to the alpha carbon 
• Amino acid structure - Alpha Carbon (c)

  •  the central carbon to which the amine group, carboxyl group, hydrogen atom and R groups are attached. 
• amino acid structure - R Group:

  • the side chain that varies between different amino acids. 
• what makes every type of amino acid different

  The R group
• Amine Group


  NH2
• Carboxyl group


  COOH
• alpha carbon 


  C
• R group

  R
• Condensation reaction between two amino acids. Once the water is removed, ...


  the C bonds to the N in a peptide bond.
• Dipeptide


  a molecule consisting of two amino acids joined by a single peptide bond. 
• Oligopeptide

  a molecule composed of a few (typically 2-20) amino acids. 
• Polypeptide


  a longer chain of amino acids, typically longer than 20 residues, but not yet a fullt functional protein
• Longer polypeptide chains

  Formed by adding amino acids through peptide bonds
• 1. terminal (amino-terminal) end


  Refers to the free amino group not involved in the peptide bond
• 1. terminal (carboxyl-terminal) end


  Refers to the unbound carboxyl group
• Formation of longer polypeptide chains

  1. Add amino acids to dipeptide

  2. Form new peptide bond

  3. Repeat process multiple times
• Each time an amino acid joins the growing polypeptide strand


  A new peptide bond is formed and a water molecule is released
• More amino acids can be added to the dipeptide by forming a new peptide bond between an incoming amino acid and the C-terminal of the dipeptide
• This process can be repeated multiple times to form longer chains of amino acids, called polypeptides
• Location of polypeptide formation 

  • Polypeptide formation occurs in the ribosome of a cell, which can be found in the cytoplasm or on the rough endoplasmic reticulum.
• Source of amino acids:

  • Plant cells 
  • Animal cells
• Amino acids can be essential or non-essential

  • Essential amino acids = are the amino acids that your body cannot produce and therefore you must obtain them from the food that you eat. 
  • Necessary for proper growth, maintenance and repair of the body’s tissues and organs
  • non-essential amino acids = can be produced by the body from other amino acids or by the breakdown of proteins. 
  • It is important to have but not required
• Source of amino acids:

  • Plant cells: produce amino acids through photosynthesis and other metabolic processes
  • Animal cells: obtain amino acids through the consumption of food