Human Biochemistry

Ethan SavageEmily KayeKatie ChanCrystal Do

Section 1- Energy!

Key Terms

metabolism – the sum total of all of the reactions of the body

respiration – a complex series of oxidation reactions

calorimeter – an instrument that measures temperature change

bomb calorimeter – a type of calorimeter used to measure the heat of combustion in a particular reaction

Respiration Respiration Process-

Begins with sugar (or glucose) other energy rich molecules are turned into glucose

through metabolic process these glucose molecules come from our diet

GlucoseGlycogen Starch

CO2 + H2O

Fats & Oils Protein

O2

Reactions of respiration: multi-step process releasing energy

How to get the energy we need Male vs. Female-

moderately active females need about 9200 kJ of energy per day

moderately active males need about 12600 kJ of energy per day

Fat- extra energy (or glucose) we didn’t use at the end

of the day. dieting: we eat less energy than we need, so our body

uses the fat for fuel Food packaging actually tells us the energy it

has in calories, or joules (or kJ)

Bomb Calorimeters Can also find energy value by measuring the change in

temperature of a pure substance using a bomb calorimeter It combusts the food and transfers the energy into water, with

this info we can calculate the energy Using the following equation

Q=mcΔT q= the energy produced m= mass of water c= constant ΔT = change in temperature of water

Some energy is absorbed by the by metal, making a small random uncertainty

Bomb Calorimeter

Section 2- Proteins

Key Terms

zwitterions – amino acids with dipolar ions buffering – the property of amino acids to

maintain virtually the same pH atmospheric – being able to react with acids

and bases isoelectric – the intermediate point in which

the amino acid is electrical neutral peptide bond – a bond made between two

amino acids in a condensation reaction

Key Terms (continue) fibrous – proteins with well defined secondary

structure side chains – R groups conformation – proteins specific compact, 3D

structure globular proteins – all the enzymes and

protein hormones denatured – when a protein loses its specific

tertiary structure from disruptions hydrolysis - a reaction that reverses a

condensation reaction

Key Terms (continued) locating reagent – makes amino acids take on

color origin – the original spot of the amino acid on

chromatography paper solvent front – final position of solvent in

chromatography ninhydrin - a locating reagent Rf – retention factor

= Distance moved by amino acid Distance moved by solvent

General Info

Largely responsible for body structure, as we are mostly made of proteins

Act as “tools” on molecular level Catalysts (enzymes) that speed up metabolic

reactions Transport oxygen in the blood Help fight disease Hormones (messengers) They drive the metabolic process

Specific Functions

Structure of Proteins Proteins are long chain molecules (polymers) of

monomer waits called amino acid Aminos consist of an amino group (-NH2) and a carboxylic

group (-COOH) bonded to a carbon atom R groups

There's a difference between each amino acid, and they define amino acids

About 20 types of naturally occurring amino acids Each has a three letter abbreviation

Amino Acid Properties

Crystalline compounds High melting points (usually about 200oC) Much greater solubility in water than in non-

polar solvents Amino acids can exist as zwitterions

Formation of zwitterion is the result of an internal acid-base reaction that transfers a H+ from COOH to the NH2

Amino Acid Properties Cont...

Amino acids are atmospheric because they are both acidic and basic

In an aqueous solution they will accept and donate H+ according to changes in pH of the medium as shown in the next slide

Amino Acid Properties Cont...

pH is a measure of H+ concentration in something (adding H+ or OH- can change pH)

Amino acids have the buffering property, they don’t easily change pH

Isoelectric Point

pH determines net charge the amino acid carriesLow pH = positiveHigh pH = negativeNeutral = isoelectric point

Amino Acids and Condensation Reactions

In a condensation reaction, two amino acids can form a peptide bond, which makes the amino acids dipeptide

Peptide Bonds

Can be dipeptide, tripeptide or polypeptide Because of this, there can be an infinite number of

types of proteins R groups make different types of amino acids

Many types of amino acids can make polypeptide chains to create lots of kinds of proteins

Primary Protein Structure

Peptide bonds / amino acid sequence The amino acid sequence creates primary

structure of proteins It’s the covalent backbone of the molecule

Dictates the entire structure & function of protein Changing one amino acid atom, can completely

change the function of the molecule Ex) DNA is a protein (polypeptide), changing one

atom can even change our physical appearance

Secondary Protein Structure The secondary structure is

dependent on hydrogen bonds in the protein molecule R groups can also make this

differ Two main types of

secondary structure α-helix is a coiled

configuration

Secondary Structure Cont…

-pleated sheet is “side-by-side” configuration

Tertiary Protein Structure Further coiling/twisting as a result of R group

interactions (called side chains) is the tertiary structure

Conformation – specific 3D structure of the protein Conformation is very important in globular proteins

(which are water soluble) Polar - hydrophilic Non-polar – hydrophobic

Tertiary Protein Structure Cont… Interactions that stabilize this conformation are:

Hydrophobic interactions – between non-polar side chains Hydrogen bonding – between polar side chains Ionic bond – between side chains carrying a charge Disulfide bridges – between the sulfur atoms in the amino

acid cysteine These are covalent bonds and hence the strongest of these

interactions Protein that has lost its conformation due to pH,

temp, or other changes are said to be denatured

Quaternary Protein Structure

The interactions between multiple polypeptide chains is the quaternary structure

Analysis of Proteins Start analysis by determining amino acid

composition (not primary structure) To do this, use hydrolysis (reverse condensation) to

break polypeptide bonds Separating the amino acid mixture

Chromatograph Put dot of amino acid on bottom of chromatography paper Put paper in solvent Solvent will rise up paper, separating as it goes Now find Rf value (refer to equations) Compare with charts to find out what the amino acid is

Analysis of Proteins Cont... Electrophoresis

Uses movement of charged amino acids in an electric field

Gel electrophoresis puts amino acid in wells in center of gel and electric field is applied

Amino acids move positive or negative depending on charge/pH

When separation is complete, they can be detected by a stain/use UV light to see and identified from their position using data tables

Section 3 – Carbohydrates☻

Key Terms monosaccharides – one of the two main types of

carbs; simple sugars; usually readily soluble in water polysaccharides – other type of carbohydrates;

condensation polymers; usually insoluble glucose – a readily soluble monosaccharides fructose – a readily soluble monosaccharides glycogen – an insoluble polysaccharide cellulose – another polysaccharide

Key Terms-continue

glycosidic link – a bond between monosaccharides

starch grains – starch compactly stored in plant cells

microfibrils – cellulose cablescellulose – an enzyme required to break down

glycosidic links in cellulosedietary fiber- substances like cellulose which

the body can’t digest

General Carb info

Carbs are made of Carbon, oxygen, and HydrogenRatio of H to O is always 2:1, like water General Carb FormulaCX(H2O)Y

Functions of Carbohydrates

Monosaccharides are a main substrate for respiration, releasing energy for all cell processes

Precursors in metabolic reactionsCan lead to the synthesis of fats, nucleic acids &

amino acidsPolysaccharides are a storage form of

carbohydrates

Structure of Carbohydrates Monosaccharaides are classified by the # of carbon

atoms they contain These sugar molecules have two or more alcohol

groups (-OH) and carbonyl group(-C=O)The large # of polar hydroxyl groups is why they’re so

water soluble Monosaccharide empirical formula is CH2O

but the there can be many isomers representing different molecules

Ex. C6H12O6 is both glucose and frutose In an aqueous solution, they make a ring structure

instead of a straight chain structure

Disaccharides

Two simple sugars linked together Gyclosidic link – bond made between H and OH,

which make water Disaccharides are soluble Can be hydrolysed into two monosaccharides by

acid hydrolysis or by enzyme-catalysed reactionCombining different monosaccharides will produce

different disaccharides

Polysaccharides Long chains of monosaccharide units held together

with glycosidic bonds Three types of polysaccharides

Starch – a polymer of α-glucose storage carb in plants, which is why flour, rice and potatoes are

starchesGlycogen – animal starchCellulose- polymer of β-glucose

structural material in plant cell walls forms cables called microfibrilsparallel chains that give it its rigid structure

Digestion of Polysaccharides

Polysaccharides don’t break down easily, as they are insoluble

The enzyme cellulase can break them down, but our body doesn’t make cellulase

Dietary Fiber – substances (like cellulose) that can’t be broken down in our bodiesHowever, it still benefits our bodies

Section 4 - Lipids

Key Terms۞ lipids – range of biological molecules which are

hydrophobic or insoluble in water۞ adipose tissue – fat stores; serves as storage of energy۞ phospholipids – major component of membranes that

binds cells۞ atherosclerosis – a condition that causes deposits in the

walls of the main blood vessels and restricts blood flow۞ obesity- a health issue caused by a rich diet of lipids and

causes someone to be overweight

Key Terms Cont...

۞ cholesterol – a lipid molecule found in animal fat that is synthesized in the body

۞ essential fatty acids – can’t be manufactured by the body, and comes only from our diet

۞ glycerol – molecule of three carbon atoms, each have an alcohol group

۞ three fatty acids – a fatty acid is a carboxylic acid chain۞ saturated – fatty acids with no double bonds۞ mono-unsaturated – fatty acids with one double bond۞ polyunsaturated – fatty acids w/ several double bonds

Key Terms Cont...

۞ fats – triglycerides with relatively high melting points that are solids at room temperature

۞ oils – triglycerides with weaker intermolecular forces and lower melting points that are liquids at room temperature

۞ Iodine number – the number of grams that reacts w/ 100 grams of fat

۞ addition reactions – reactions in which the unsaturated fatty acids break the double bonds and add incoming groups

۞ trans fats – resulting fats from the cis position on the bond to the trans position

Key Terms Cont...

۞ lipases – a kind of enzymes that involves hydrolysis reactions

۞ lecithin – most common phospholipid۞ phospholipid bilayer – maximizes the interactions

between the polar groups and water۞ steroids – lipids with a structure of four fused rings

Lipids

۞ lipids are soluble in non-polar solvents۞ they contain carbon, oxygen and hydrogen۞ are less oxidized than carbohydrates۞ common lipids: fats, oils, steroids, phospholipids

Functions of Lipids

۞ essential molecules in a variety of roles in the body۞ contain stored energy which can be released when

respiration of cells occurs۞ lipids are less oxidized so they can easily undergo

more oxidation and release more energy per unit than carbs ۞ great to use as a respiratory substrate۞ energy in lipids is not readily available as more reactions

are involved in their breakdown

Functions Cont...

۞ adipose tissues help to protect body organs and a layer of fat under the skin to insulate the body

۞ sex hormones (testosterone & estrogen) are made from lipids in the form of steroids

۞ lipids help absorb some vitamins (A, D, E and K)۞ bile acids aid digestion of fat in the intestine۞ phospholipids help determine the transport of

metabolites across cell boundaries

Negative Effects of Lipids

۞ also associated with various health problems caused by excess intake of lipids

۞ too many can create deposits in blood vessels that can block blood (atherosclerosis) which can lead to a heart attack

۞ also, diet with too many lipids can lead to obesity ۞ lipids are also associated w/ cholesterol, which is a

main culprit in some circulatory conditions

Structure of Lipids: Triglycerides

۞ triglycerides are major constituents of fats & oils۞ esters formed by glycerol and three fatty acids۞ Esterification takes place between an acid -

COOH group and each –OH group in glycerol forming the ester links

۞ triglyceride are formed by one glycerol bond with three fatty acids

Structure of Lipids: Triglycerides Cont…۞ Fatty acids differs from each other which specifies

properties of different fats and oils:۞ Length of hydrocarbon chains are usually between 14-22

carbons long۞ The number and position of carbons can create double

bonds, classifying the fatty acids as: ۞ saturated, mono-unsaturated, polysaturated

۞ The nature of the fatty acids can change the melting point of the triglyceride

۞ Melting point makes the triglyceride a fat or an oil۞ Fats have high melting point; oils have lower mp۞ Saturated fats (single C-C bond) have higher mp۞ Unsaturated fatty acids contain one or more double C-C bond

Structure of Lipids: Triglycerides Cont…

۞ Addition reactions to unsaturated fats are used in the food industry۞ Partially hydrogenated fat & oils that have been chemically

modified in an addition reaction which makes it easier to store

۞However, this process can create trans fats; not good۞ The digestion of fats are broken down in a hydrolysis

reaction in the body, can’t be digested otherwise۞ Reaction is controlled by lipases

Structure of Lipids: Triglycerides

Structure of Lipids: Phospholipids

۞ Similar to triglycerides, made of three fatty acids and glycerol۞However, they now have an additional phosphate group

Hydrophilic head (phosphate)

Hydrophobic tails (hydrocarbon chains)

Structure of Lipids: Phospholipids Cont…

۞ Phosphate have a polar or hydrophilic head۞ Hydrocarbon chains are two non-polar hydrophobic tails۞ Because they have these, they form a phospholipid

bilayer, which maximizes interactions between polar groups and water while creating non-polar insides

The Structures of Steroids

۞One of the most important steroids is cholesterol

۞Cholesterol is the steroid used in the body in the synthesis of many other steroids, including the sex hormones

Section 5 – Micronutrients and Macronutrients

Key Terms ξ recommended daily intake – amounts of nutrients

needed on a daily basisξ micronutrients – nutrients needed in very small

amounts; includes vitamins and trace mineralsξ macronutrients – nutrients needed in large amountsξ malnutrition – occurs when balance of nutrients

needed in the diet are not obtainedξ Iodine – needed for production of hormone

thyroxide

Key Terms Cont…ξ goitre – a condition created by the lack of iodine in the

diet; causes swelling in thyroid gland in the neckξ Vitamin A (retinol) – needed in diet for healthy skin, good

eyesight and protection against toxinsξ xerophthalmia – a condition characterized by dry eyes

and night blindnessξ anemia – deficiency of iron, which also decreases the

transportation of oxygen in the red blood cellsξ Marasmus – condition resulting from protein deficiency,

mostly found in infantsξ Kwashiorkor – condition that affects young children

whose diet is high in starch and low protein

General

ξ nutrients-molecules required in the diet for absorption in the body

ξ Should meet the recommended daily intake

Micronutrients Macronutrients

Used in the body for hormones, enzymes, ect

Used to provide energy, build/maintain structure

Vitamins-organic compounds Carbohydrates, proteins, lipids

Trace minerals- ex: Fe, Cu, Zn, ect Minerals- ex: Na, Mg, K P, S, Cl

Vitaminsξ Organic compounds needed for metabolism and

growth ξ Vitamin A: helps eyesight and skinξ Vitamin C: enzymes, disease resistanceξ Vitamin D: Bones and Teeth

ξ Vary in whether they are soluble in water or fatξ Differences in structure determine solubilityξ Water soluble vitamins (vitamin c) have polar bonds and

ability to form hydrogen bonds with waterξ Fat soluble vitamins (vitamins A & D) are mostly non-polar

molecules with long hydrocarbon chains/rings

Malnutrition

ξ Deficiencies in micronutrientξ Iodine Deficiency can lead to goitreξ Vitamin A deficiency can lead to xerophthalmia and other

eye/skin related conditionξ Iron deficiency can lead to anaemia

ξ Deficiencies in micronutrientξ Protein deficiency can cause Marasmusξ Protein deficiency and starch over efficiency can cause

Kwashiokor

Hormones

General InfoHormones are chemical messengersMany chemical structures

Ex. proteins, steroids, modified amino acids or fatty acids

Endocrine system creates hormonesSecretes the hormone directly in the blood, where it will circulate throughout the bodypituitary gland, thyroid gland, pancreas, adrenal glands, ovaries/testes

Target Cells – cells that receives hormones via receptors

Particular cell is a target for a hormone if it contains functional receptors for that hormone, and cells which do not have such a receptor cannot be influenced directly by that hormone

Important hormonesGland Name/Structure Type Target Cells Functions

Pituitary Anti-diuretic hormone (ADH) Short peptide

Kidney tubules Increase water uptake, increase concentration of urine

Thyroid Thyroxine; modified amino acid w/ iodine

All cells Regulate metabolic rate, growth and development

Adrenal cortex Aldosterone; steroid Kidney tubules Increase uptake of sodium by kidneys, Control Na:K ratio, raise blood pressure

Adrenal medulla Adrenaline; modified amino acid

Muscles, brain, etc. Heartbeat, blood supply, glucose increase

Pancreas Insulin; protein All cells, esp. liver Decrease blood glucose level, increase glucose to glycogen conversion

Ovary Estrogen/progesterone; steroid

Many, uterus during pregnancy

Female; control menstrual cycle, secondary characteristics, growth of placenta & fetus

Testes Testosterone; steroid Many Male; secondary sexual characteristics develop

Steroid-based hormone structure

Sex hormone structure is similar to steroid cholesterolEstrogen Progesterone Testosterone

Female progesterone only differs slightly from maleProgesterone has a ketone group in place of alcohol groupEstrogen/estradiol contains 2 amino acids

Oral Contraceptives

Pills can replicate hormonesBirth ControlAlso used in medications prescribed to women at menopause to alleviate some of the unpleasant symptoms (HRT – hormone replacement therapy)

Uses and Abuses of Steroids

Androgen – male steroid hormonesTestosterone are important

Testosterone can be used in medical treatment of disorders in testes and breast cancerMedical hormones = anabolic steroidsModified anabolic have been used by athletes to help build muscles. There are many dangers in this and it is usually banned in sports