human systyems

• 5 Molecules required for living things

  • Micronutrients (small, simple structures, needed in small quantities) - Vitamins/minerals
  • Macronutrients (Large, complex molecules needed in large proportions) - Carbohydrates, Proteins, Lipids (fats), Nucleic Acids
• Carbohydrates


  • Primary energy source of cells (sugars), broken down to create ATP
  • Structural material of plant cell walls
  • Largest component of our diet
  • Animals cannot make carbs, we rely on plants to create them through photosynthesis then we ingest plants or other animals that have eaten plants
  • If not burned off they are stored as fat
• Carbohydrate Structure


  • Molecules composed of sugar subunits that contain carbon, hydrogen, and oxygen in a 1:2:1 ratio
  • Divided into 3 main types based on structural complexity - monosaccharides, disaccharides, and polysaccharides
  • Several isomers of the molecules categorized in these divisions (same chemical formula, different arrangement of atoms)
• Simple Sugars - Monosaccharides

  • Simplest sugars, have only ONE sugar unit, broken down very easily
  • 3 sugar isomer monosaccharides: Glucose (photosynthetic product), Fructose (sweeter than glucose, used in candy), Galactose (less sweet than glucose)
• Disaccharides


  • Two monosaccharides in combination
  • Sucrose (table sugar) - glucose and fructose
  • Maltose (malt sugar) - glucose and glucose, found in beer
  • Lactose (milk sugar) - glucose and galactose
• Polysaccharides


  • Polymers of monosaccharides (long chains of single units)
  • Starch (Plants) - long chain of glucose (could be amylose or amylopectin, amylose is unbranched, amylopectin is branched)
  • Glycogen - stored glucose in liver of animals, branching structure like amylopectin but bonded differently
  • Cellulose (Plants) - 50% of all organic carbon tied up in cellulose, plant cell walls made of this, does not form coiled structures like starch or glycogen, layers of cellulose are attracted to each other by H-bonds between -OH groups
  • Starch and glycogen use alpha glucose, cellulose uses alpha and beta glucose (C6 is flipped)
• Disassembling and Assembling Macromolecules

  • Assembly (Dehydration Synthesis)
  • Disassembling (Hydrolysis)
• Lipids


  • Also called fats, INSOLUBLE in water, nonpolar
  • Many important functions in the body: Long term energy storage (higher energy potential than carbs), Excess carbs are stored as fats once glycogen stores are built up, Important constituent of PHOSPHOLIPID BILAYERS of cell membranes, Cushioning and insulation of body, Carry vitamins A, D, E, K through the body, Main component of steroid hormones (cholesterols) - estrogens and testosterone
• Lipid Structures (Triglycerides)


  • 3 groups of lipids, 1st group to be discussed will be triglycerides, Triglycerides are what we would think of as traditional lipids (fat on our bodies and in foods), COMPOSED of 1 glycerol molecule and 3 fatty acid tails - fatty acids are attached to glycerol by dehydration synthesis
• Triglycerides


  • Triglycerides that are solid at room temperature are called FATS (Mostly from animals), Triglycerides that are liquid at room temperature are called OILS (mostly from plants)
• Saturated vs. Unsaturated Triglycerides


  • Saturated (mostly animal fats), Unsaturated (mostly plant fats)
• Phospholipids


  • Lipid with a phosphate molecule attached to the glycerol backbone, making it polar, Major component of cell membranes, P head is polar, hydrophilic, Lipid tails are not polar, hydrophobic
• Waxes


  • Long chain fatty acids are attached to carbon rings or alcohols, Long, stable molecules are insoluble in water, Well suited to waterproof plant leaves or animal fur
• Proteins


  • Not primarily energy compounds, unlike fats and carbs - CONTAINS NITROGEN, as well as C, H, O, Form the structural parts of cells, building blocks of living things, structural repair, Also act as antibodies or enzymes, Also called peptides, chemicals called AMINO ACIDS are linked together to create proteins (polypeptides)
• Building Blocks of Proteins - Amino Acids


  • Composed of an amino group - NH2, Carboxyl Group - COOH, R Group - the variant, can be multiple structures, determines the difference between amino acids
• Protein Structure


  • Proteins are polypeptides folded into 3D shapes, the shape determines the function
• Building Blocks of Proteins – Amino Acids


  • Composed of an amino group – NH2
  • Carboxyl Group – COOH
  • R Group – the variant, can be multiple structures, determines the difference between amino acids
• Protein Structure


  • Proteins are polypeptides folded into 3D shapes, the shape determines the function
  • 4 levels of protein organization: Primary structure, Secondary structure, Tertiary structure, Quaternary structure
• Primary Structure


  1. Sequence of amino acids in polypeptide strand

  2. Determines the secondary structure
• Secondary Structure


  1. Folds and coils occur along polypeptide chain due to hydrogen bonding

  2. H bonding creates these folds and coils, the folds are called beta pleated sheets and the coils are alpha helixes
• Tertiary/Quaternary Structure


  1. Tertiary - Polypeptides fold in on each other due to H bond interaction between R groups

  2. Quaternary – clustering of two or more polypeptides
• Denaturation/Coagulation


  1. Denaturation – bonds of a protein are disrupted, causing a temporary change in structure in function (due to heat, radiation, pH, etc)

  2. Coagulation – bonds of a protein molecule are permanently disrupted, causing a permanent change in shape and structure
• There are 20 different amino acids that create all the different kinds of proteins that exist amongst all species
• Protein diversity is determined by DNA, the diversity of proteins show us evolutionary relationships between species
• Essential vs. Non-essential Amino Acids

  • 9 amino acids that are considered ESSENTIAL, we cannot synthesize in our body and we need them from our diet – the lack of these proteins lead to deficiency and disease
  • The other 11 are NONESSENTIAL and our body synthesizes them on its own
• Nucleic Acids


  • DNA and RNA
  • Long chains of repeating subunits called nucleotides
  • Contain genetic information, direct growth and development of all organisms using a chemical code
• Enzymes


  • Proteins that catalyze chemical reactions involving metabolism
  • Speed up reactions and allow them to occur at lower temperatures
  • A catalyst is chemical that increases the rate of chemical reactions without altering the products or being altered itself
  • Enzymes act on a substrate, the substrate is changed during the reaction to create new products
• Enzymes identified by the suffix

  • -ase (carbohydrases, proteases, lipases, alcohol dehydrogenase etc.)
• Enzyme Lock and Key Model

  1. Each enzyme has a specifically shaped ACTIVE SITE, which acts as a “docking bay” for substrate molecules. The enzyme temporarily joins with the substrate

  2. Lock and Key model was upgraded when it was noticed that the actual shape of the ACTIVE SITE changes when in contact with substrate molecules, makes the fit between enzyme-substrate even tighter – INDUCED FIT is currently the most accepted form of the lock and key model
• Cofactors and Coenzymes


  • Help enzymes bind to substrate molecules
  • Cofactors are inorganic ions (Fe, Zn, K, Cu)
  • Coenzymes are organic molecules synthesized from vitamins
• Factors that Affect Rate of Enzyme Reactions

  1. pH

  2. Concentration

  3. Temperature

  4. Competitive Inhibition
• pH


  1. Certain enzymes function within certain pH’s

  2. Enzymes are proteins and their folding is created by H bonds

  3. 3D structure of protein is altered by addition of H and/or OH ions, affecting reaction rate
• Substrate Concentration


  1. Greater substrate concentration = greater particle collisions = faster reaction rate

  2. However, reaction rate is dependent on enzyme available, the amount of enzyme available places a limit on the speed of reactions
• Temperature


  1. Similar to substrate concentration, reaction rates increase with increased temperature and energy, particles move faster, more collisions occur

  2. However in humans, our optimum body temperature is 37 C, enzymes denature if body temperature increases much past that and reaction rates reach an upper limit
• Competitive Inhibition


  1. Molecules that have very similar shapes to substrate molecules

  2. Compete with substrate for active sites on enzymes

  3. Substrates cannot bond to active sites

  4. Ex. CO and O2 in blood, many psychoactive drugs
• Negative Feedback Regulation of Enzymes

  Most chemicals in the body are
• Competitive Inhibition


  1. Molecules that have very similar shapes to substrate molecules compete with substrate for active sites on enzymes

  2. Substrates cannot bond to active sites

  3. Example: CO and O2 in blood, many psychoactive drugs
• Negative Feedback Regulation of Enzymes

  1. Most chemicals in the body are regulated by negative feedback to control concentrations of chemicals along the entire reaction pathway

  2. With negative feedback, also called feedback inhibition, the excretion of an enzyme is reduced by the final product of the reaction pathway

  3. Final product attaches to a regulatory site on an enzyme, changes its shape so substrate can no longer bind
• Regulatory Sites on enzymes

  • They inhibit enzyme activity and increase enzyme activity if substrates bond to them
  • Precursor activity occurs when substrates bond to the regulatory site, activate the last enzyme in a pathway, and speeds up formation of final products
  • The binding of molecules to enzymes causing changes in their functions is called ALLOSTERIC ACTIVITY
• Digestive System


  1. Ingestion – taking in nutrients

  2. Digestion – breakdown of complex organic molecules into smaller components by enzymes

  3. Absorption – transport of digested nutrients to cells of the body

  4. Egestion – removal of food waste from the body

  5. The digestive tract is 6.5-9.0m in humans

  6. Two types of digestion – physical and chemical – physical digestion breaks down large pieces of food into smaller portions, chemical digestion breaks down small pieces of food and converts them into raw materials for use by the body