Digestion and Human Health

Transcription

1 Digestion and Human Health

2 The Molecules of Living Systems There are three main fluid components in your body Cytoplasm in your cells Fluid between your cells Fluid in your blood The also contain many different kinds of molecules and ions Water, phosphates, hydrogen and sodium are examples of these inorganic molecules Organic molecules contain carbon bonded to other atoms such as O, S, and N Larger complex organic molecules are called MACROMOLECULES

3 Types of Macromolecules: CARBOHYDRATES LIPIDS PROTEINS NUCLEIC ACIDS Lets take a closer look at these!

4 How do they form? All four types of molecules are formed and broken apart in the same way:. Dehydration Synthesis the process by which larger molecules are formed by the removal of water from two smaller molecules Hydrolysis the process by which larger molecules are split into smaller molecules by the addition of water

5 CARBOHYDRATES Always contain C, H and O usually in the same proportion C: H: O in a ratio of 1:2:1 Carbohydrates provide energy for organisms Two main types: Simple sugars Polysaccharides

6 Simple and Complex Sugars 1. Monosaccharide single unit sugars Glucose, galactose and fructose 2. Disaccharides sugar composed of pairs of monosaccharides.(maltose) 3. Polysaccharides large molecules composed of chains of monosaccharide.

7 Structural Differences between Polysaccharides

8 Polysaccharide carbohydrates are formed by the union of many monosaccharide subunits Glycogen: Starches: Are human polysaccharides formed from multiple glucose units for long-term storage Are plants polysaccharides formed from multiple glucose units for long-term storage Amylase and Amlopectin Note the more branches in a polysaccharide, the more difficult it is to digest!

9 LIPIDS 1. Important in the storage of energy. Glycogen supplies are limited in most animals; however, once supplies are built up, excess carbohydrates are converted to fat. This explains why eating too many carbohydrates can cause an increase in fat storage. 2. Cushions are delicate organs 3. Components in cell membranes 4. Carriers of vitamins (A, D, E, and K) 5. Hormone synthesis 6. Heat insulation

10 Insoluble in water Store more energy than any other biological molecule Some function as energy storage Butter, lard ( solid at Room temperature) sunflower oil, canola oil ( liquid at room temperature) Three types of Lipids Triglycerides Phospholipids Waxes

11 How do Fat molecules form:

12 Triglycerides Formed from the union of glycerol and three fatty acids. When solid at room temperature they are called fats. When liquid at room temperature they are called oils.

13 PHOSPHOLIPIDS

14 WAXES In waxes, fatty acids are joined in long-chain alcohols or to carbon rings. They are insoluble in water, hence their importance in waterproofing plant leaves or animal feathers and fur.

15 PROTEINS Most structures are comprised of these molecules (hair, nails, ligaments) These are created from smaller subunits. These are amino acids Contain an central C atom, bonded to a H and to a amino group, acid group and R-group The R group distinguishes it to be one of 20 amino acids from one another **Our body can synthesize 11 of these acids, 9 therefore come from our diet we eat!

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18 NUCLEIC ACIDS Help with the growth and development of organisms They determine the cells function and its characteristics Two types: RNA and DNA Genes are copied by RNA then makes a protein These are long chains made up of smaller subunits like our other macronutrients DNA and RNA are made up of 4 nucleotides

19 Vitamins and Minerals These are micronutrients Essential for structure and function of our cells Many help to give energy and decompose compose Vitamins are organic vs Minerals that are inorganic! Small amounts of each are needed for our bodies! Minerals enable certain reactions to occur, build bones and cartilage Mineral absorbed by the blood stream essential in hemoglobin, hormones, enzymes, and vitamins!

20 Enzymes biological catalysts (structures that speed up reactions) made of proteins and have a specific shape they are not changed or used up in reactions they work by lowering the activation energy necessary for a chemical reaction to occur (ie oxidation of glucose: using digestive enzymes vs. lighting on fire)

21 How do enzymes work? enzymes have folded surfaces that help to attract and bring together or break up substrates (molecules on which the enzyme works) Enzyme models Scientists once believed that enzymes worked on a substrate molecule like a lock and key the lock and key model was proposed in the late 1800s by Emil Fischer. It was believed that a specific enzyme had a specific shape only for a specific substrate and it would fit in perfectly. A modified theory called the induced-fit model replaced the former theory in The induced-fit model suggests that the active site of the enzyme is altered slightly when the substrate molecules are trapped, making the fit even tighter. Sometimes enzymes need help in order to bind to substrates: coenzymes organic molecules synthesized from vitamins cofactors inorganic molecules such as Fe, Zn, K, etc.

22 Factors Affecting Enzyme Reactions 1. Temperature a single enzyme can catalyze anywhere up to 30 million reactions every minute - why do some reactions occur faster than others? Enzymes operate at an optimal temperature of approx. 37 C (body temp) when temperatures get higher, enzymes denature (protein coils unravel and the enzyme changes shape therefore ineffective) 2. ph all enzymes have an optimal ph range within which they work best Because the folds in the protein (enzyme) are created by H bonds (between negatively charged acid groups and positively charged amino groups) the addition of more H+ or OH- ions would affect the existing H bonds therefore altering the 3D shape of the protein. 3. Concentration of the substrate Generally speaking, the greater the concentration of the substrate molecules, the more collisions, therefore the greater the rate of the reaction. However, once all of the substrate molecules are occupied by enzymes, no more reactions can take place until an enzyme comes free. Therefore, the extra substrate molecules will not proceed until it can gain access to the active site on an enzyme. What would the graph look like to illustrate the effects of concentration of substrate on reaction rate?