human biochemistry
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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