Biological molecules 04-04-16
Announcements Your lab report 1 is due now Quiz 1 is on Wednesday at the beginning of class, so don t be late
Review Macromolecues are large molecules necessary for life made up of smaller molecules or subunits The small subunits that make up macromolecules are known as monomers When monomers combine together (covalent bonds) they form polymers E.g. glucose monomers make up starch, glycogen, and cellulose
How are polymers formed?
How are polymers broken down?
The four categories of macromolecules
Carbohydrates Made up of carbon, hydrogen, and oxygen Provide energy for the short term Mainly as glucose
Carb subtypes Monosaccharides simple sugar Between 3 and 7 carbons Glucose is essential for cell respiration Plants synthesize glucose
Carb subtypes Disaccharides two monosaccharides together Joined by a glycosidic bond
Carb subtypes Polysaccharides Long chains of monosaccharides Joined by glycosidic bonds Storage polysaccharides Starch Glycogen Structural polysaccharides Chitin Cellulose
Lipids Made up mainly of carbon and hydrogen Provide energy in the long term Functions/major groups: Provide energy They form waterproof coverings on plant and animal bodies They serve as the primary component of cellular membranes Still others are hormones
The fat molecules, the triglyceride, is made up of three fatty acids and one glycerol molecules
Difference between this fatty acid: and this fatty acid?
More facts about lipids Animals store fats in cells known as adipocytes Adipose tissue is found under skin, surrounding internal organs, muscles, etc Plants store unsaturated fats and oils in seeds
Essential Fatty Acids (EFA) Essential for our development Humans cannot synthesize them Omega-3 and omega-6 fatty acids Humans can synthesize omega-9 They are all polyunsaturated Research indicates that they: Reduce the risk of chronic diseases: heart disease, cancer, and arthritis Reduce triglycerides in the blood Lower blood pressure Reduce inflammation
Three categories Oils, fats, and waxes Phospholipids Steroids containing rings of carbon, hydrogen, and oxygen
Fats, oils, and waxes Oils, fats, and waxes are made of one or more fatty acid subunits Fats and oils are made up of fatty acid chains esterified to one glycerol molecule Energy Waxes are made up of long fatty acid chains esterified to long-chain alcohols Insulation
Figure 3-13b Wax Wax
Phospholipids Main component of plasma membrane Made up of Glycerol Two fatty acid chains Phosphate group Glycerol and two fatty acids chains diacylglycerol
Phospholipids are amphipathic
What Are Lipids? Steroids contain four fused carbon rings with various functional groups protruding from them They are structurally different to fats, oils, and waxes But they are hydrophobic
Cholesterol is the most common steroid Synthesized in liver Precursor to testosterone and estrogen Component of the plasma membrane of animal cells Estrogen Cholesterol Testosterone
Proteins Proteins are molecules composed of chains of amino acids Most common Most diverse
Proteins Most diverse Proteins have a variety of functions Enzymes are proteins that promote specific chemical reactions Structural proteins (e.g., elastin) provide support Defense proteins protect us from disease and venoms
Hair Horn Silk
Protein shape related to function They have different shapes and molecular weights Globular vs fibrous Protein shape is critical to its function Shape is maintained by chemical bonds Changes in temperature, ph, and exposure to chemicals may lead to permanent changes in the shape of the protein, leading to loss of function, known as denaturation
hydrogen Proteins are polymers Proteins are molecules composed of chains of amino acids Proteins are polymers of amino acids joined by peptide bonds All amino acids have a similar structure variable group (R) amino group carboxylic acid group
Proteins are polymers Amino acids are joined by dehydration synthesis amino acid dehydration amino acid synthesis peptide water amino group carboxylic acid group amino group peptide bond
Twenty amino acids Grouped according to chemical nature of the side chain or R group
Questions Which categories of amino acid would you expect to find on the surface of a soluble protein, and which would you expect to find in the interior? Polar or nonpolar? What about charged? In membrane proteins, what distribution of amino acids would you expect to find in a protein embedded in a lipid bilayer?
Structure of proteins A protein can have as many as four levels of structure Primary structure Secondary structure Tertiary structure Quaternary structure
The four levels of protein structure can be observed in these illustrations.
The α-helix and β- pleated sheet are secondary structures of proteins that form because of hydrogen bonding between carbonyl and amino groups in the peptide backbone.
The tertiary structure of proteins is determined by a variety of chemical interactions. These include hydrophobic interactions, ionic bonding, hydrogen bonding and disulfide linkages.
Shape and function Precise positioning of amino acid R groups leads to bonds that determine secondary and tertiary structure Disruption of secondary and tertiary bonds leads to denatured proteins and loss of function
Nucleotides make up nucleic acids Nucleotides are the monomers of nucleic acid chains Deoxyribose nucleotides Ribose nucleotides
Nucleotides All nucleotides are made of three parts Phosphate group Five-carbon (pentose) sugar Nitrogenous base
Nucleic acids DNA and RNA, the molecules of heredity, are nucleic acids Nucleic acids are polymers formed by monomers strung together in long chains by dehydration synthesis
Differences DNA and RNA, the molecules of heredity, are nucleic acids There are two types of polymers of nucleic acids DNA (deoxyribonucleic acid) Double-stranded Antiparallel double helix RNA (ribonucleic acid) Single-stranded
Figure 3-25 Deoxyribonucleic acid hydrogen bond
Worksheet for quiz 1