What are you made of????

Transcription

1 What are you made of???? Approximate composition of a bacterial Cell Adapted from Alberts et.al Molecular Biology of the Cell, 3rd edition Molecule class % total weight # diff. types Water 70 1 Inorganic ions 1 20 Sugars & precursors 1 ~250 Amino acids & precursors 0.4 ~100 Nucleotides & precursors 0.4 ~100 Fatty Acids & precursors 1 ~50 Other small molecules 0.2 ~300 Macromolecules* 26 >3000 1

2 What are these molecules doing? Digesting the food you eat they are the food you eat! Storing your genetic information Keeping your cells together Making chemistry happen in your body All of the things living organisms do! Approximate composition of a bacterial Cell Adapted from Alberts et.al Molecular Biology of the Cell, 3rd edition Molecule class % total weight # diff. types Water 70 1 Inorganic ions 1 20 Sugars & precursors 1 ~250 Wow! how can we keep track of all of these! Amino acids & precursors 0.4 ~100 Nucleotides & precursors 0.4 ~100 Fatty Acids & precursors 1 ~50 Other small molecules 0.2 ~300 Macromolecules* 26 >3000 2

3 How can we keep track of these? Categories! Four basic categories: 1. Proteins 2. Nucleic acids (DNA, RNA) 3. Carbohydrates 4. Lipids Macromolecules are usually chains built of smaller Links Smaller molecules called monomers Long chains are called polymers Entire chain = polymer All show similar patter of construction 3

4 Thousands of different Proteins Monomer subunits called Amino Acids 20 different types All organisms use the same 20 a.a. Basic structure of all is the same same functional group Amino acids are bonded together to make proteins Amino Acid Structure Variable region R Every amino acid (there are 20) has a different set of atoms attached here 4

5 Thousands of different Proteins How do they differ? Primary structure Which amino acids are used Their order Secondary structure forms as chains interact The folded structure may resemble coils, helices, or sheets 5

6 Groove (a) A ribbon model of lysozyme Figure 4.7 Tertiary structure the final 3-D shape of the protein The final twists and folds that lead to this shape are the result of polarity differences in regions of the polypeptide 6

7 Groove (b) A space-filling model of lysozyme Carbohydrates Glucose This is a monosaccharide A disaccharide is formed when a reaction joins two monosaccharides 7

8 Fig glycosidic linkage Glucose Glucose (a) Dehydration reaction in the synthesis of maltose Glucose Fructose Sucrose (b) Dehydration reaction in the synthesis of sucrose Maltose 1 2 Two glucose monomers hooked together make a glycosidic linkage sugar we call Maltose Linking different monomers makes different types of disaccharides Polysaccharides Polysaccharides, the polymers of sugars, have storage and structural roles Starch Glycogen Cellulose The structure and function of a polysaccharide are determined by its sugar monomers and the organization of linkages 8

9 Polysaccharides Starch Plant energy storage Digestible to animals Cellulose Plant structure Indigestible to animals Glycogen Animal energy storage Chloroplast Starch Mitochondria Glycogen granules 0.5 µm 1 µm Amylose Glycogen Amylopectin (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide 9

10 Cell walls Cellulose microfibrils in a plant cell wall Microfibril 10 µm 0.5 µm Cellulose molecules Glucose monomer Lipids: Fats Fats are constructed from two types of smaller molecules: Glycerol fatty acids A fatty acid has long carbon chain 10

11 Fats Fats are constructed from two types of smaller molecules: glycerol and fatty acids A fatty acid has long carbon chain May be: Saturated Unsaturated Depends on if they are completely covered by hydrogen atoms Structural formula of a saturated fat molecule A saturated fatty acid has no double bonds (a) Saturated fat 11

12 Structural formula of an unsaturated fat molecule An unsaturated fatty acid has double bonds that make chain kink (b) Unsaturated fat cis double bond causes bending Phospholipids Hydrophobic tails Hydrophilic head Choline Phosphate Glycerol Fatty acids (a) Structural formula (b) Space-filling model 12

13 Lipids Biological membranes involve lipids phospholipids make up the two layers of the membrane cholesterol is embedded within the membrane Outside of cell Carbohydrate chains Cell membrane Membrane proteins Phospholipid Inside of cell Learning Objectives Know the difference between intracellular and extracellular digestion Be able to the digestive processes of sponges, jelly fish, birds, ruminant, and humans Identify and describe the various organs in a vertebrate digestive system Know the variety of adaptations vertebrates have to accommodate various eating strategies Outline the steps in human digestion: The path food takes, the purpose of each organ/gland in the process and where vitamins and nutrients are absorbed. 13

14 Tasks of the Digestive System Ingestion Mechanical Digestion Chemical Digestion Absorption Elimination Each task is performed by a different component in complex systems Intracellular Digestion Simplest system, only found in sponges 14

15 Gastrovascular Digestion Simple system involving a sac-like chamber Chamber contains in opening where ingestion and excretion occur Cniderians: Jelly fish, hydra, coral, sea anemones Discuss with a partner: Why do you think saclike digestive systems are unsuitable for animals that eat frequently? 15

16 Tubular Digestive Systems Most animals have tubular system which specialized structures including a mouth and an anus Teeth tell a lot about diet 16

17 Triceratops 17

18 But what if you don t have teeth? Ruminants ferment their food with the help of microorganisms 18

19 Cellulose Cows can t digest cellulose how do they survive? Bacteria living in the rumen can break down the cellulose! 19

20 Cell walls Cellulose microfibrils in a plant cell wall Microfibril 10 µm 0.5 µm Cellulose molecules Glucose monomer Human Digestion: Activity Activity: 1. Working alone, put the following words in order according to how food moves through the body of a mammal. 2. Check your answers/fill in any blanks with a partner. ~2 minutes 20

21 Digestive System Food Mouth etc. Anus Jejuno-ileum Esophagus Pyloric sphincter Large intestine Stomach Rectum Cardiac sphincter Ileum Duodendum Mouth Mesentary/Blood vessels Liver The Digestive System Mouth Esophagus Cardiac Sphincter Stomach Small Intestines Pyloric Sphincter Duodendum Jejuno-ileum Large Intestines Rectum Mesentery Blood to Rest of Body Liver Blood Vessels 21

22 The Human Digestive Tract Salivary glands: Secrete lubricating fluid and starch-digesting enzymes Pharynx: Shared digestive and respiratory passage Epiglottis: Directs food down the esophagus Esophagus: Transports food to the stomach Liver: Secretes bile (also has many non-digestive functions) Gallbladder: Stores bile from the liver Pancreas: Secretes ph buffers and several digestive enzymes Large intestine: Absorbs vitamins, minerals, and water; houses bacteria; produces feces Oral cavity, tongue, teeth: mechanical digestion Stomach: Breaks down food and begins protein digestion Small intestine: Food is digested and absorbed Rectum: Stores feces Fig Stomach Stores slow release Churns Protein breakdown begins Secretes gastrin 22

23 Small intestine is where the magic happens! Liver: Produces bile, which is stored in the gallbladder bile duct pancreatic duct Gallbladder: Stores and releases bile into the small intestine via the bile duct duodenum Cells in small intestine lining: Produce enzymes that complete carbohydrate and protein digestion Stomach: Releases acidic chyme into the small intestine Pancreas: Produces sodium bicarbonate and digestive enzymes, and releases them into the small intestine via the pancreatic duct Fig The Structure of the Small Intestine fold of the intestinal lining villi capillaries microvilli lacteal intestinal gland arteriole lymph vessel venule (a) Small intestine (b) A fold of the intestinal lining (c) A villus (d) Cells of a villus Fig

24 The Human Digestive Tract Salivary glands: Secrete lubricating fluid and starch-digesting enzymes Pharynx: Shared digestive and respiratory passage Epiglottis: Directs food down the esophagus Esophagus: Transports food to the stomach Liver: Secretes bile (also has many non-digestive functions) Gallbladder: Stores bile from the liver Pancreas: Secretes ph buffers and several digestive enzymes Large intestine: Absorbs vitamins, minerals, and water; houses bacteria; produces feces Oral cavity, tongue, teeth: mechanical digestion Stomach: Breaks down food and begins protein digestion Small intestine: Food is digested and absorbed Rectum: Stores feces Fig