Carbohydrates and Fats Energy and Builder Molecules

Carbohydrates  Carbohydrate come in a great variety of shape and sizes.  All Carbohydrates:  Composed of three elements: carbon, hydrogen and oxygen.  The ratio of hydrogen atoms to oxygen atoms is almost always exactly 2:1, as it is in water.  This ratio made early scientists think that these molecules were hydrates of carbon.

Carbohydrates  The simplest carbohydrates are called monosaccharides - meaning “one sugar”.  Monosaccharides usually contain five or six carbons.  Glucose is a simple sugar, a monosaccharide.  It can be either a ring or a chain form.  Is easily converted to smaller molecules. Structural formulas for glucose. It is found primarily in ring form.

Carbohydrates  Linking very large numbers (usually between ) monosaccharides creates polysaccharides.  Starch is a major component of grains and many vegetables.

Carbohydrates  Cellulose – fibrous or woody material of plants and trees.  Cellulose is indigestible by humans – usually called fiber – we do not have the cellubiase enzyme needed.

Examples of Common Carbohydrates

Carbohydrates  Carbohydrates and fats are the primary high-energy substances in the human diet.  One gram of carbohydrates = 4 Cal of food energy.  Should be 45-65% of dietary Calories.  Carbohydrates are obtained by eating grains (rice, corn, tortillas, bread, pasta), beans, fruits, milk, yogurt and meat (glycogen).  Average US citizen consumes more than 65 kg (145 lbs) of sugar annually.

Fats  Fats are a category of biomolecules that come from meat, fish, poultry, oils, dairy, nuts and grains.  Fats contain 9 Calories per gram.  Excess energy that is not used is stored in the body as fat.  Fats are composed of the same elements as carbohydrates (C,H and O) but with fewer oxygen atoms.  Fats are generally nonpolar and only slightly dissolve in water.  Fats act much like hydrocarbons.

Fats  Fats are triesters of glycerol and different fatty acids.  This process is called esterification. Glycerol + 3 fatty acids → A fat A typical saturated fatty acid

Fats

 Fats are solid triglycerides, while oils are liquid triglycerides – the only difference is their structures.  Determined by:  The length or number of carbons in their side chains  The number of carbon-carbon double bonds known as the degree of unsaturation  Saturated fats (fatty acids) contain only single bonds between carbons while unsaturated fats (fatty acids) contain at least one double bond.

Fats  Saturated Fats contain all single C-C bonds.  Unsaturated Fats contain at least one double C=C bond.  Polyunsaturated Fats contain multiple double C=C bonds.

Fats  Fats from animals are primarily saturated fats (solids).  Fats from plants are commonly polyunsaturated or monounsaturated (liquids).  Unsaturated fats are much more reactive and are more easily broken apart in the body.  Saturated fats are associated with the formation of arterial plaque, resulting in atherosclerosis or “the hardening of the arteries”.  Leading to the brain = stroke; to the heart = heart attack.

Atherosclerosis

Proteins  Protein – comes from the Greek word proteios, meaning “of prime importance”.  Proteins are the major structural components of living tissue.  This includes: skin, hair, eyeballs, nails, bones, cartilage, tendons, ligaments and all enzyme molecules that help control chemical reactions in the cell.  Proteins are necessary for new growth and for maintaining existing tissues.  Red blood cells are replaced every month, intestinal cells are replaced weekly and skin cells are washed away everytime you bathe.

Proteins In The Body TypeFunctionExamples Structural Proteins MuscleContraction, movementMyosin Connective tissueSupport, protectionCollagen, keratin MembranesControl of influx and outflowPore proteins, receptors Transport ProteinsCarries of gases and other substancesHemoglobin Regulatory Proteins EnzymesControl of metabolismProteases HormonesRegulation of body functionsInsulin Protective ProteinsAntibodiesGamma globulin

Proteins  The body contains tens of thousands of different proteins.  Proteins are polymers built from amino acids.  Amino acids are molecules made from carbon, hydrogen, oxygen and nitrogen. Some, like cysteine, may contain sulfur.  20 different amino acids serve as building blocks for all the proteins found in the human body.  All amino acids have two functional groups: the amino group (- NH2) and the carboxylic acid group (-COOH).

Proteins  The amino acids are determined by unique side groups, highlighted in green.

Proteins  Combining two amino acids occurs as a condensation reaction.  The bond that links the amino acids is called a peptide bond.

Enzymes  Enzymes are biomolecules, typically proteins, that are able to speed up reactions without undergoing any significant change.  A substrate is the reactant molecule that fits into an enzyme at the active site, the place on the enzyme where the substrate and enzyme connect.  Every enzyme acts as a catalyst, a substance that accelerates a reaction without being consumed.

DNA