Biochemistry - Macromolecules Carbohydrates, Lipids, Proteins and Nucleic Acids 12/9/2018

Carbohydrates Body’s most important source of energy Plants are our source of carbohydrates Three basics groups of carbohydrates: mono saccharides, disaccharides and polysaccharides 12/9/2018

Monosaccharides Simple sugar molecules made up of chains or rings of carbon, hydrogen and oxygen in the ratio of 1:2:1 12/9/2018

Disaccharides Sugars made up of two mono saccharides formed by dehydration synthesis (or condensation reaction) (sucrose is a combination of glucose and fructose 12/9/2018

Complex Carbohydrates : Poly saccharides Large carbohydrate molecules that are polymers of mono saccharides Examples: starch glycogen, cellulose and chitin Structure may be straight, twisted or branching chains 12/9/2018

Lipids include fats, phospholipids, waxes and steroids fats serve as long-term energy storage molecules phospholipids forms cell membranes steroids include cholesterol and certain sex hormones 12/9/2018

FATS Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemically, fats are generally triesters of glycerol and fatty acids Fats may be either solid or liquid at normal room temperature, depending on their structure and composition. 12/9/2018

Structure of Fats Are made up mainly of two types of molecules: fatty acids and glycerol Fatty acids are long carbon-hydrogen chains with a carboxyl (COOH) group at one end 12/9/2018

Triglycerides Are long-term energy storage molecules found in fat cells of adipose tissue Composed of a glycerol molecule and three fatty acids 12/9/2018

Trans Fats In cis-bonds, the two pieces of the carbon chain on either side of the double bond are either both “up” or both “down In trans-bonds, the two pieces of the molecule are on opposite sides of the double bond, that is, one “up” and one “down” across from each other fatty acids with trans bonds are carcinogenic, or cancer-causing. 12/9/2018

Phospholipids Consist of a hydrophilic phosphate molecule and two hydrophobic fatty acid tails Are and important part of cell membranes 12/9/2018

Steroids Consist of four linked carbon rings Side chains attached to the rings make individual steroids unique Include cholesterol, cortisone and the sex hormones estrogen and testosterone 12/9/2018

Proteins Direct and control the chemical reactions in life processes Make up part of the cell membrane Provide support and shape to cells Function as hormones (chemical messengers) Function as enzymes to speed up chemical reactions Make up about ½ the body’s dry weight 12/9/2018

Amino Acids Proteins are polymers of amino acids AA contain C, H and O like carbohydrates and lipids but also contain N All AA’s have same basic structure Each AA varies only in the structure of the R group There are 20 different AA’s, eight of which are essential 12/9/2018

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Protein Structure Proteins can contain more than 1000 AA monomers and are known as a polypeptide They are formed by dehydration synthesis forming peptide bonds between C and N atoms 12/9/2018

Proper function of proteins is determined by shape There are four different levels of protein structure: primary, secondary, tertiary and quaternary 12/9/2018

Primary Protein structure Is simply the order of AA’s in the polypeptide 12/9/2018

Secondary Protein Structures Primary structure folds upon itself to form a-helix or b-pleated sheet patterns due to hydrogen bonding 12/9/2018

Tertiary Protein Structures Are formed when the secondary structures fold over upon themselves and are held by covalent, ionic, hydrogen and non-polar bonds The covalent bonds are disulfide bridges between Sulphur-containing AA’s 12/9/2018

Tertiary Protein Structure 12/9/2018

Quaternary Protein Structure Occurs when two or more polypeptide chains combine to form the protein 12/9/2018

Protein Denaturation Exposing a protein to heat, radiation or change in pH will alter its shape Physical or chemical factors that disrupt the bonds between the amino acids changing the shape of the protein is called denaturing Sometimes removing the factor allows the protein to assume is original shape When the change is permanent coagulation has occurred 12/9/2018

Nucleic Acids Form the hereditary molecule DNA and RNA Are polymers formed from monomer molecules called nucleotides Nucleotides are made up of three subunits: a nitrogen-containing base, a five-carbon pentose sugar molecule and a phosphate group 12/9/2018

Nitrogenous bases There are five nitrogenous bases, adenine, guanine (the purines), cytosine, thymine and uracil (the pyrimidines) Thymine is present only in DNA and uracil is present only in RNA 12/9/2018

Nucleotide Bases 12/9/2018

DNA Structure The DNA molecule is made up with the outer backbone of the sugar and phosphate group while the bases point inward 12/9/2018

Double and triple hydrogen bonds link the bases of the two chains 12/9/2018

Adenosine Triphosphate (ATP) Is an important nucleotide found in the cell Is a monomer Consisting of three phosphate groups attached to the ribose ATP is the energy providing molecule of the cell and when the third phosphate group is split off by hydrolysis a net release of energy results 12/9/2018

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