Most Common Elements in Living Things

Most Common Elements in Living Things • Carbon - C • Hydrogen - H • Oxygen - O • Nitrogen - N • Make up 95% of your body weight • Organic Compounds – Have carbon in them

Bonding – What holds the molecules together • Covalent – strong, hard to break • Carbon can make 4 covalent bonds • Oxygen can make 2 covalent bonds • Hydrogen can make 1 covalent bond • Ionic – opposites attract • Gives water special properties • Hydrogen – weak, easy to break • Nucleic Acids

Macromolecules • Lipids – cell membranes • Carbohydrates – energy storage, support • Proteins – hormones, enzymes • Nucleic Acids – genetic information All are made of smaller subunits

Lipids • Made up of carbon and hydrogen • Fats, oils, waxes • Storage • Saturated – Only single bonds between carbons • Unsaturated – double bonds between carbons • Phospholipid – found in cell membranes.

Carboxylic Acid Fatty Acid 3 Fatty acids glycerol Triglyceride

Carbohydrates • Made of atoms of carbon, hydrogen and oxygen • Energy storage • Ratio of 1 carbon atom, 2 hydrogen atoms, and 1 oxygen atom. • Made of subunits called monosaccharides • Glucose: C6H12O6

Polysaccharides • When two monosaccharides are linked it is called a disaccharide • When three or more monosaccharides the molecule is called a polysaccharide • Starch – primary source of calories • Cellulose – plant cell walls • Both are polysaccharides of glucose

Proteins • Made of chains of amino acids • Amino acids are made of C, H, N and O • There are 20 amino acids • The sequence of amino acids determines the shape of the protein

Nucleic Acids • DNA - Deoxyribonucleic Acid • RNA - Ribonucleic Acid • Made of two chains nucleotides • The nucleotide chains are twisted into a double helix shape • DNA – nucleotides A, T, G and C • RNA – nucleotides A, U, G and C

Lipids • Sudan stain • Sudan stain is attracted to lipids • If lipids are present they will stain red

Carbohydrate – Monosaccharides and Disaccharides • Benedict's Reagent – starts blue • If sugars are present changes from blue • to green (some sugar) to orange (lots of sugar) • HEAT is needed to do this test

Carbohydrate - Polysaccharides • Starch • Iodine • If starch is present, the iodine will turn blackish-blue

Protein • Biuret reagent – blue to start • If protein is present – turns purple

Enzymes • Protein • Responsible for most cell functions • Functions – to build or break apart • Translate DNA • Breakdown food • Put together macromolecules • Very specific – one enzyme for one function • Ends with -ase • Name reflects function • lactasebreaks apart lactose

Enzyme Action • Enzymes have a specific binding site called the active site • The molecule or molecules that bind to the active site are called a substrates • Some enzymes put two substrates together • A + B AB • Some enzymes break one substrate apart • AB A + B

Active Site • Enzymes do not get used up • Reaction stops when there is no more substrate for the enzyme to use Enzyme substrate complex substrate

Enzymes are Catalysts • Catalyst – a substance that lowers the activation energy of a chemical reaction • Reactions involving enzymes will happen with or without the enzyme. • Enzymes make the reaction use less energy

Common Enzymes • Digestion • Muscle contraction • Photosynthesis and Respiration • Bacterial enzymes Factors that Affect Enzymes • Temperature • Too hot • Too cold • pH • Acidic conditions

Most Common Elements in Living Things