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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 # diff. types weight

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

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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 # diff. types weight

Water 70 1 Inorganic ions 1 20

Sugars & precursors 1 ~250 Wow! – howAmino acidscan & precursorswe keep 0.4 ~100 track of allNucleotides of these! & precursors 0.4 ~100 Fatty Acids & precursors 1 ~50

Other small molecules 0.2 ~300 Macromolecules* 26 >3000

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How can we keep track of these? Categories! • Four basic categories: 1. Proteins 2. Nucleic acids (DNA, RNA) 3. 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

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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 (there are 20) has a different set of atoms attached here

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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

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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

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Groove

(b) A space-filling model of lysozyme

Carbohydrates

• This is a • A is formed when a reaction joins two

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Fig. 5-5

1–4 glycosidic linkage

Glucose Glucose Maltose (a) Dehydration reaction in the synthesis of maltose

1–2 • Two glucose monomers hooked togetherglycosidic make a linkage sugar we call Maltose • Linking different monomers makes different

Glucosetypes of disaccharidesFructose Sucrose (b) Dehydration reaction in the synthesis of sucrose

Polysaccharides • , the polymers of sugars, have storage and structural roles – – Glycogen –

• The structure and function of a are determined by its sugar monomers and the organization of linkages

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Polysaccharides

Starch Cellulose Glycogen

• Plant energy • Plant • Animal storage structure energy • Digestible to • Indigestible storage animals to animals

Chloroplast Starch Mitochondria Glycogen granules

0.5 µm

1 µm

Amylose Glycogen

Amylopectin

(a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide

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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 has long carbon chain

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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

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Structural formula of an unsaturated fat molecule

An unsaturated fatty acid has double bonds that make chain “kink”

cis double bond causes (b) Unsaturated fat bending

Phospholipids

Choline

Phosphate

Glycerol

Hydrophilic head Hydrophilic

Fatty acids Hydrophobic tails Hydrophobic

(a) Structural formula (b) Space-filling model

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Lipids • Biological membranes involve lipids – phospholipids make up the two layers of the membrane – cholesterol is embedded within the membrane

Outside of cell chains

Membrane proteins Phospholipid

Inside of cell

Learning Objectives

• Know the difference between intracellular and extracellular • Be able to the digestive processes of , jelly fish, birds, ruminant, and humans • Identify and describe the various organs in a digestive system • Know the variety of adaptations 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.

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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

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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?

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Tubular Digestive Systems

• Most animals have tubular system which specialized structures including a mouth and an anus

Teeth tell a lot about diet

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Triceratops

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But what if you don’t have teeth?

Ruminants ferment their food with the help of microorganisms

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Cellulose Cows can’t digest cellulose – how do they survive?

Bacteria living in the rumen can break down the cellulose!

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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

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Digestive System

Food  Mouth _____ etc. Anus Jejuno-ileum Pyloric sphincter Rectum Cardiac sphincter Ileum Duodendum Mouth Mesentary/Blood vessels Liver

The Digestive System

Cardiac Stomach Mouth Esophagus Sphincter Small Intestines

Pyloric Duodendum Jejuno-ileum Sphincter

Large Mesentery Rectum Intestines

Blood to Blood Liver Rest of Body Vessels

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The Human Digestive Tract Salivary glands: Secrete lubricating fluid and starch-digesting

Pharynx: Shared digestive Oral cavity, tongue, and respiratory passage teeth: mechanical digestion Epiglottis: Directs food down the esophagus Breaks down Esophagus: Transports Stomach: food to the stomach food and begins protein digestion Liver: Secretes bile (also has many non-digestive functions)

Gallbladder: Stores bile from the liver : Pancreas: Secretes pH Food is digested buffers and several and absorbed digestive enzymes Rectum: Stores feces Large intestine: Absorbs vitamins, minerals, and water; houses bacteria; produces feces Fig. 34-12

Stomach • Stores slow release • Churns • Protein breakdown begins • Secretes gastrin

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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 Stomach: Releases the small intestine via acidic chyme into the bile duct the small intestine

duodenum Pancreas: Produces sodium Cells in small intestine bicarbonate and digestive lining: Produce enzymes enzymes, and releases them that complete carbohydrate into the small intestine via Fig. 34-15 and protein digestion the pancreatic duct

The Structure of the Small Intestine

fold of the capillaries intestinal lining microvilli villi

lacteal

arteriole intestinal lymph gland vessel venule

(a) Small intestine (b) A fold of the (c) A villus (d) Cells of a villus intestinal lining

Fig. 34-16

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The Human Digestive Tract Salivary glands: Secrete lubricating fluid and starch-digesting enzymes

Pharynx: Shared digestive Oral cavity, tongue, and respiratory passage teeth: mechanical digestion Epiglottis: Directs food down the esophagus Breaks down Esophagus: Transports Stomach: food to the stomach food and begins protein digestion Liver: Secretes bile (also has many non-digestive functions)

Gallbladder: Stores bile from the liver Small intestine: Pancreas: Secretes pH Food is digested buffers and several and absorbed digestive enzymes Rectum: Stores feces Large intestine: Absorbs vitamins, minerals, and water; houses bacteria; produces feces Fig. 34-12

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