Human Biochemistry Option B

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Human Biochemistry Option B
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B.1 energy

• Calculate the energy value of a food from
  enthalpy of combustion data
• Energy is made available by cellular respiration
• Glucose oxygen ?
• CO2 H2O

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• Other sources of energy
• Glycogen in the cells
• Starch
• Fats and oils
• proteins

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• Women need 9,200 KJ per day
• Men 12,600 KJ
• If we take in too much we get fat

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Bomb calorimeter

• Heat mass x 4.18 J g-1K-1 x ? T
• Energy absorbed by water energy released

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• A 0.78 g sample of a food substance was combusted
  in a bomb calorimeter and raised the temperature
  of 105.10 g of water from 15.4 oC to 30.6 oC.
  Calculate the energy value of the food in kJ g-1
• 8.56 kJ g-1

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• Animation
• Do question 1

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B.2 Proteins

• Functions
• Stucture- hair, nails, connective tissue, muscles
  examples keratin, collagen, myosin
• Enzymes example lactase
• Protective example antibodies
• Transport example haemoglobin
• Storage

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structure

• Polymer of the monomer amino acid
• NH2CHRCOOH
• Called 2-amino acids because the carbon of the
  acid is 1 carbon
• The difference in amino acids is the R group
• Look in your data booklet table 19 for the common
  human amino acids

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• Abbreviate amino acids with the first 3 letters
• Alanine
• Ala
• Glycine
• Gly
• What are the R groups?

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• Do questions 2 and 3

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properties

• Crystalline solids
• Mp above 200 oC
• More soluble than non-polar compounds
• Typical of ionic compounds
• Dipolar ions zwitterions
• Amphoteric both acid (COOH) and base(NH3) H
  can move from acid to base

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More properties

• Buffers
• Maintains pH in the body cells
• Must be about 7.4
• lt6.9 can be deadly
• Each one has an isoelectric point where it is
  neutral
• Lower pH ion H on the NH3ltisoelectric
  pointlthigher pH ion lose H off the COOH

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Isoelectric point

• Gly 6.0
• Ala 6.0
• Lysine 9.7
• Aspartic acid 2.8
• Does the R group contain and acid or base?

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Condensation reactions form peptide bonds

• Show how the tripeptide Cys-Val-Asn forms
• OH comes off the acid H off the amine
• What other tripeptides can form from this? They
  are different because of the sequence. This is
  the primary structure

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• 20 amino acids can form 8000 tripeptides 20 x 20
  x 20
• Proteins are at least 50 amino acids 2050 types
• Change one and the function changes ie sickle
  cell anaemia 146 amino acids
• Made by DNA, RNA in the ribosomes

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Secondary structure

• Folding of the chain due to the H bonding on the
  peptide groups
• Influenced by R groups
• ?-helix 4 amino acids apart
• Like a spiral staircase
• Flexible and elastic like hair,skin, nails
  (keratin)

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• ß-pleated sheet
• Side by side inter-chain H bonds
• Inelastic ie silk, claws, beaks
• Tough, insoluble in water

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Tertiary structure

• Overall shape due to the R groups
• Conformation
• Intra-molecular forces disulfide bridge, ionic
  bond, H bonds, van der Waals forces

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Globular proteins

• enzymes and hormones
• Water soluble polar R groups on outside
• Insoluble on the inside
• Forces Hydrophobic interactions, H bonding,
  Ionic bonding, Disulfide bridges

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Perming

• Break disulfide bridges in cysteine use a
  reducing agent
• Reoxidize around rollers form new disulfide
  bridges

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Denature

• Messing with the tertiary structure
• With temperature and pH
• Eggs
• Make them biologically active

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Quaternary structure

• More than one polypeptide chain
• Association between chains
• Collagen in skin and tendons is a triple helix
  with rope like structure
• animation

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Hemoglobin

• 4 polypeptides
• 2 alpha 2 beta

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• Do question 4

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Analysis

• What is its amino acids composition?
• Reverse the condensation reaction with acid and
  water to break apart the chain

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chromatography

• Lab activity

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electrophoresis

• Animation
• Lab activity
• Do question 1 page 496 and 2-4 page 497

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B.3 Carbohydrates

• C compounds with H2O 121 rate
• Simple sugars (monosaccharides)
• polysaccharides

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Functions

• Source of energy
• Precursors to other molecules
• Storage
• Cellulose in plants

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monosaccharides

• Trioses, pentoses, hexoses
• Very soluble
• 2 or more hydroxyl and a carbonyl group
• Form rings when dissolved in water

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aldoses

• Carbonyl on the end of the dry crystal
• Glucose
• Know straight and ring

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ring

• In water O breaks and attaches to the 5 carbon
• draw

???
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ketoses

• Ketone on the 2nd carbon
• in the ring O and attaches to the 5 carbon

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Alpha and beta forms

• Alpha OH below the plane on carbon 1
• Beta OH above the plane

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Disaccharides

• Maltose 2 alpha glucose
• Lactose ß-glucose and ß-galactose found in milk
• Sucrose a-glucose and ß-fructose (table sugar)
• Attaches from the 1 and 4 carbon

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polysaccharides

• Starch polymer of alpha glucose 1-4 linkage
• Plant storage energy molecule
• 2 forms amylose straight chain

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• Amylopectin side group off every other glucose
  6-1 linkage
• Both are a compact spiral structure

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glycogen

• Animal starch
• Stored in the liver and muscles
• Polymer of alpha glucose
• Like amylopectin but more side linkages

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cellulose

• Plant structure
• Polymer of ß-glucose
• Uncoiled allowing H bonding
• Forms microfibrils with parallel chains
• Woody type structure

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Dietary fiber

• Doesnt digest
• Abrade the digestive tract lining making it
  produce mucous
• Whole grains

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• Do question 5 and 6
• Question 5 page 501

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B.3 Lipids

• Insoluble in water
• Oily nonpolar molecules
• Less oxidized molecules
• Oils, steroids, fats, phospholipids

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functions

• Variety of roles
• Storage of energy- they release more energy
  because they can be oxidized more
• 2x per gram of carbohydrate

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• Hormones
• Cell membranes
• insulation

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problems

• Obesity
• Atherosclerosis fats, cholesterol

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Cholesterol

• LDL Low density lipoprotein (bad?)
• Lots of this means it gets deposited on the walls
  of arteries
• Sources are saturated and trans fats

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• HDL high density lipoprotein (good?)
• Seem to protect against heart disease
• Tends to carry LDL away from arteries

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Diet

• Decrease saturated and trans fats (tend to be
  solid)
• Increase polyunsaturated (fish, nuts, corn oil)
• Essential fatty acids (cannot be manufactured by
  body) omega-3-polyunsaturated fatty acid

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Structure of triglycerides

• Glycerol and 3 fatty acids

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Essential fatty acids

• Linoleic acid (omega-6-fatty acid)
  CH3(CH2)4(CHCHCH2)2(CH2)6COOH
• Linolenic acid (omega-3-fatty acid)
  CH3CH2(CHCHCH2)3(CH2)6COOH
• Number refers to position of the first double
  bond omega distance from the first C
• Cannot be made in the human body

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• Involved in lowering blood pressure by
  synthesizing postaglandins
• Lower LDL cholesterol

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Determining unsaturation

• I2 breaks the double bond
• Iodine number grams of Iodine that reacts with
  100 g of fat
• Linoleic acid has the formula C18H32O2 Determine
  the iodine number of linoleic acid.

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• 2 CC bonds
• Mm Linoleic acid 280 g mol-1 mm I2 254
• 280 g reacts with 508 g I2
• Iodine number is 181

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Partially hydrogenated fat

• Oils more solid by adding H2 to CC
• More convenient packing
• Break down less
• Remaining CC go to trans forms (trans fat)
• Trans fat decreased HDL increased LDL

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Digestion of fats

• Lipases
• Slow to digest

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phospholipids

• Glycerol and 2 fatty acids with a phosphate
• Differ in fatty acids and what is attached to the
  phosphate
• Hydrophilic head and hydrophobic interior

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steroids

• Four fused rings
• Pg 509 in your textbook
• LDL transports cholesterol

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• Do questions 7 and 8
• Do question 6 page 509
• Web quiz