Lesson 3 Biochem 1 Flashcards
(106 cards)
1
Q
What is an isotopes?
A
It’s atoms of the same element which have a different numbers of neutrons in the nucleus. This doesn’t affect chemical activity but it does change the mass. Ie C12 and C14
2
Q
What is chemistry?
A
The science that deals with the composition and properties of substances and various elementary forms of matter
3
Q
What is matter?
A
Matter is everything around us that has mass and occupies space. Atoms are small particles that make up matter
4
Q
What is an element?
A
An element is a substance made up of just one type of atom so it cannot be split into simpler substances
5
Q
4 major elements in the human body are
A
Carbon oxygen nitrogen and hydrogen
6
Q
What is electron?
A
Negatively charged particles that ‘buzz’ around the outside of the nucleus with no mass
7
Q
What is electron?
A
Negatively charged particles that ‘buzz’ around the outside of the nucleus with no mass
8
Q
Proton is
A
A subatomic particle in the nucleus that has a positive barge and a mass of 1 atomic unit
9
Q
Neutron is
A
A subatomic particle that has neutral charge and mass of 1 atomic unit
10
Q
Describe electrons
A
Particles with negative charge and virtually no mass at all. They move in groups-‘electron shells’, they pair up within their shells. Atom becomes reactive if its outer shell isn’t full or if it loses and electron. This happens in ‘free radicals’, where electron becomes unpaired
11
Q
What defines chemical properties of an atom?
A
All chemical properties of an atom are down to its number of protons and electrons. Neutrons only add weight to the atom, they don’t significantly change how it chemically reacts
12
Q
Periodic table
A
Is a list of all of the currently known elements, arranged in rows and columns that show which elements share similar reactivity and physical properties
13
Q
What are halogens
A
Atoms in column no 7. Fluorine, chlorine, bromine, iodine. Top of the column is more reactive than the bottom. Relevant in thyroid health when F or Cl can enter the thyroid gland, preventing the formation of thyroid hormones ( which contain I), as F or Cl ‘elbows’ I out of the way preventing thyroid to properly uptake iodine. Hinder body from absorbing and utilising I effectively
14
Q
What is the cause of radioactivity
A
It’s caused by unstable isotopes which need to get rid of extra energy to become stable. This is due to an imbalance between the protons and neutrons in the atom. Ie. PET scan. Imaging technique where radioactive isotopes are introduced to the body.
15
Q
Radiotherapy
A
Uses gamma radiation, a high energy electromagnetic wavelengths that damage rapidly dividing cells. It is also highly damaging to tissues that contain rapidly dividing cells ie. Blood.
16
Q
H.pylori breath test
A
Urea labelled with either radioactive C14 or non radioactive C13 is given to the patient. In 10-30mins, isotope-labelled CO2 is exhaled indicating that urea split. Therefore, Enzyme urease (that H.pylori uses to split urea) is present in stomach and hence H.pylori is also present
17
Q
Inert
A
Atoms that have outer shells filled with a perfect number of electrons and don’t really react with other atoms
18
Q
Two main types of bonding between atoms
A
Ionic- atoms transfer electrons (1gives and 1 takes)
Covalent-atoms share electrons
19
Q
Ionic bonding. Describe:
A
One atom donated some of its electrons to another.
Usually when there are 1,2 or occasionally 3 e- to give.
Moving more isn’t energetically viable.
Ie. NaCl: Na gives e- away (Na+) and Cl gains e- and becomes Cl- then they attract each other creating a lattice crystal. They are magnetically attracted
20
Q
Ion
A
An atom is an electrically charged atom. It’s an atom that has either given up or gained one or more e-
Ions are written in their corresponding - or + charge
21
Q
Ionisation is
A
The process of giving or gaining electrons
22
Q
Covalent bonds occur
A
When two elements share electrons so that they both have full outer shell.
Happens when two atoms are similar or when there are lot of spaces to be filled to reach a full outer shell. (C&C, C&H), H2O
23
Q
Polar covalent bonds form
A
where electrons are shared unequally. This happens because some atoms have a lot of electron pulling power.
Elements that have lots of protons compared to the no. of electron shells, ie. a strong positive centre. Known as ‘electronegative’ atoms, as they tend to pull shared electrons towards themselves.
The most electronegative elements are F, Cl, O and N.
These lead to uneven distribution of charge.
24
Q
Hydrogen bonding is
A
Polar bonds btw H and O where O pulls electrons towards itself resulting in a -ve charged area over oxygen and +Celt charged area over H.
These interactions are called hydrogen bonds and give water surface tension property and the ability to dissolve many different things anything that has polar bonds or -ve and +ve ions will easily dissolve in water
25
What is the universal solvent and why?
It is H2O. Universal solvent is water’s unique ability to dissolve anything with polar bonds or with ionic compounds-things with +ve and -ve ions.
And it serves as a medium for most chemical reactions in the body.
H2O contains polar bonds and is an ideal medium for dissolving chemicals into their separate ions. In addition, the different electrical charges in water can allow water molecules to become attracted to other molecules (hence dissolves salt).
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Hydrophilic molecules are
Molecules which have polar bonds and dissolve easily in H2O ie. Alcohol
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Hydrophobic molecules are
Molecules that contain non-polar covalent bonds, so they do not dissolve easily in water. Ie. fats. Have lots of C-C and
C-H bonds
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Electrolytes
Are Formed when an ionic compound dissolves in water. Ie salt.
They can conduct electricity.
Main electrolytes in body are K, Na, Cl, Ca, Mg, phosphate and bicarbonate.
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Roles of electrolytes
-Conduction of electricity which is essential for nerve/muscle function
-They excerpt osmotic pressure which is important for water balance(blood pressure)
-some play important role in acid-base balance
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An Acid is
A substance that releases a high amount of H+ ions when dissolved in water
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A base is
A substance which binds to H+ ions in solution. This creates a lot of OH- (as a lot of H is taken out of the water)
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pH is
A Potential of hydrogen.
A scale developed using water as a standard pH=7
Acid pH lower than 7
Base pH higher than 7
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Blood and stomach pH
Blood pH 7.35-7.45
Stomach pH 2-3
34
Explain how fruits and vegetables become alkaline in the body
They contain organic acids and have lower pH before consumption. They are metabolised by the body and intestinal bacteria to become alkaline. They also contain K, Mg and Ca which contribute to their net alkaline effect
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Dairy and meat are acidic in the body because
Dairy: has alkaline Ca and is not very acidic. But it contains high protein containing sulphur amino acids. This sulphur amino acid increase sulphuric acid formation in the body, which then disrupts blood pH drawing more Ca from the bones and increasing Ca loss in urine.
Meat: also high in sulphur content hence have net acid effect both organic and not as have identical amino acids
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Acidic foods are
Dairy, meat, refined sugars and processed foods.
Also stress and being sedentary create acidic environment. All contributing to acidic load in the body which is perfect environment for cancer to thrive.
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Ph testing
Want pH of 8 and above.
Can’t test tissue pH. So we test urine or saliva,
As blood maintains ph at 7.35-7.45 through breathing, the kidneys and buffer systems.
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PH testing methods
Urine-urinate midstream onto the strip on second morning urination
Saliva- wash mouth upon waking. Wait 10mins. Then spit on the pH paper strip.
This gives information about the terrain/environment. Aiming for slightly alkaline or neutral pH.
Cancer and diabetes patients often have pH of 4.5-6.
Note: pH is a close reflection of what the individual has eaten, their stress and activity levels.
More informative to take regular readings rather than one off.
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What is necessary for chemo reaction to occur?
Two molecules must collide with enough energy and velocity for reaction to occur. Minimum E required for reaction is energy of activation. Temperature and pressure increase an speed up molecules
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What are catalysts?
They speed up reactions by lowering the activation energy required. Therefore reaction is faster and can occur at lower temperature.
In the body, enzymes are catalysts. They work by providing a different pathway for a biological reactions so that they can happen at body temperature.
Eg. HMG-CoA reductase in the production of cholesterol and CoQ10.
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What are inhibitors in relation to catalysts?
They stop catalysts from being so effective by making activation energy higher.
Ie. Statins are HMG-CoA reductase inhibitors.
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Which enzyme is involved in cholesterol + CoQ10 production
HMG-CoA reductase
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What are types of chemical reactions
Anabolic and Catabolic
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Anabolic reactions are
Synthesis (building) reactions
This occurs when body is making new substances or building new bonds.
Ie. Proteins from amino acids
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Catabolic reactions are
When substances are being broken down.
Ie. When breaking down food, releasing E from them.
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Hydrolysis is
When we use H2O to break the bond.
Ie breaking down carbohydrates into simple sugars
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Dehydration synthesis is
When H2O is removed to make a new bond (water is a waste product of the reaction)
Eg. When making carbohydrates
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Reversible reactions are
Chemical reactions whereby the products of the reaction can react together to produce the original reactants (meaning the reaction can go back the other way). Equilibrium is established where there are always some starting materials and some product present.
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How does the body control the direction of reversible reactions?
By using enzymes as well as having processes in place that remove starting materials and products.
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The most important reversible reaction in the body is
The Buffer systems.
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Buffers are
Substances that maintain the H+ concentration in the body within normal limits. They can bind to H+ ions and OH- to ensure blood pH remains between 7.35-745
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What is THE most important buffer system in the body?
It’s bicarbonate (HCO3-) buffer system in blood, which mops up excess acidity.
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Chemical reaction of bicarbonate buffer system
CO2 + H2O —— H2CO3—HCO3- + H+
Catalysed by carbonic anhydrase
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Describe bicarbonate buffer system
Carbon dioxide from cellular respiration reacts with water in blood to form carbonic acid, which rapidly dissociates to form bicarbonate and hydrogen ion.
These reactions are reversible and at any given time there’s a balance of all 5 substances in the blood.
This is absolutely critical for keeping body in homeostasis= blood pH 7.35-7.45
55
What role do kidneys play in the buffer system?
They can produce HCO3- buffer as well as excrete excess H+ ions.
Kidneys are fairly slow in doing this and it’s fairly strenuous upon the organ.
Therefore it’s important to reduce acidic diet as to reduce the stress placed on this system
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Oxidation reactions are
Reactions where there is a loss of energy from losing an electron.
Mostly they happen by removing electrons with the help of hydrogen , so are called DEHYDROGENATION reactions.
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Reduction reactions
Occur when something is reduced and it gains an electron, resulting in the increase of energy in that molecule.
A gain of hydrogen is normally indicative of something being reduced.
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OIL RIG acronym
Oxidation is Losing
Reduction is Gaining e-
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Free radicals are
Molecules or compounds that have an unpaired electron in their outer shell.
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What do free radicals do?
As they want to stabilise their shell, they ‘steal’ electrons from stable molecules, causing Oxidation.
This leaves the Attacked molecule with unpaired electron, so chain reaction of oxidative damage occurs.
Free radicals can take e-s from DNA which result in damaged genes and can ultimately result in cancerous changes.
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Oxidative damage is linked to (diseases)
Cancer, atherosclerosis (endothelial damage), fibromyalgia and neurodegenerative diseases.
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What creates free radicals?
Processes in out body such as aerobic respiration, metabolism and inflammation.
Environment: pollution, sunlight, strenuous exercise, smoking, alcohol, X-rays
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How do we protect clients from free radical damage?
We need to reduce exposure of our clients to excess sources of free radicals and increase their antioxidant status at the same time, in an effort to protect them from free radical damage.
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antioxidants are
Molecules that can donate electrons to the free radicals to convert them to harmless molecules without being damaged themselves.
They are a group of vitamins, phytochemicals and enzymes.
A good antioxidant must be stable once it has given an electron
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Eg of common antioxidants
Beta-carotene (in orange coloured fruits and veg)
Vitamin E (in nuts and seeds and cold pressed oils)
Vitamin C- in fresh fruits and veg
Quercetin- found in red onions and apples
Natural antioxidant enzymes that our body makes-ie. Glutathione peroxidase
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Antioxidant recycling
AO work best as a collection, where they can recycle each other. They do not work in isolation.
Food will always contain ideal combinations of antioxidants hence recommending a rainbow of fruit and vegetables
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What are functional groups?
Any other groups that are attached to the carbon skeleton of the biochemical molecules. They contribute to the structure and function of that molecule.
Ie. Amino group and carboxyl group in amino acids
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Hydroxyl group
R-O-H
Polar and hydrophilic.
Dissolve easily in water.
Polar group (similar to H2O molecule.
Found in alcohols.
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Sulfhydryl group
R-S-H
Polar and hydrophilic
Found in the sulphur-containing amino acids such as cysteine
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Carboxyl Group
R-COOH
Found on the end of amino acids and on the end of fatty acids.
Hydrophilic (two polar O atoms-lots of H pulling capabilities, lots of polarity, hydrophilic) and can interact as a weak acid or as negative particle
Responsible for why they’re called a. ACIDS
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Amine group
R-NH2
Nitrogen based group (also quite electronegative, pulling e-‘s towards itself, also a polar group)
Can act as a base as it has a spare pair of electrons and is useful at mopping up extra H+(acid). Therefore can act as a weak base if necessary.
Found in amino acids.
It’s found at the opposite end to the carboxyl grp in the aa and gives name AMINO acid.
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Ester group
R-COOR’
Predominantly found in triglycerides-fats
Could be polar (O) but as it’s found in between two big carbon chains, it gets buried in between and doesn’t have much effect on water solubility
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Phosphates
R-O-PO3H2 (H3PO4 phosphoric acid)
Found in ATP.
It’s v,very hydrophilic and they can form double negative charge.
Bond btw OandP is a very high energy- a way of trapping E in ATP molecule
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Carbohydrates include
Starches, cellulose and sugars
As a group, they’re all made of C-H-O
C atoms are normally arranged in a ring with O And H atoms attached
Have many hydroxyl -OH groups so that they can form hydrogen bonds. Meaning that smaller CH’s such as sugars can easily dissolve in water.
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Grouped into… depending on their size
Monosaccharides.
Disaccharides
Polysaccharides
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Monosaccharides
Single sugar units.
3-7 carbon atoms
Glucose (banana)
Fructose (apple)
Galactose (milk)
Deoxyribose (DNA)
Ribose
Names end in -ose.
Fructose is the sweetest (apples)
Glucose (tropical fruits)
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Disaccharides
2 monosaccharides joined together by dehydration reaction
Sucrose=glucose+fructose-table sugar
Lactose=glucose+galactose- 5% of cows milk + 7% human
Maltose=glucose + glucose
-Joined together in a dehydration synthesis - formed during the hydrolysis of starch
Broken by hydrolysis during digestion into simple monosaccharides
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Polysaccharides
Glycogen- most common type in the body
Starch- bread, pasta, potatoes
Cellulose - in plants
10-100s of monosaccharides in glycosidic bonds. Insoluble in water and don’t taste sweet.
Digestion begins in mouth by amylase.
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Isomers
Have same chemical formula but different structures
C6H12O6 for fructose, glucose and galactose
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Starch
A major dietary source of carbohydrate. Bread, rice and pasta.
Made up of 2 polysaccharides:
-Amylose 20-25%- single chain of glucose units- long, curly
-Amylopectin 75-80% - branched with many ends so faster to digest (start digestion at each end)
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Amylopectin
-Highly branched polysaccharide, therefore more surface for digestion
- broken down quickly causing large spike in blood glucose and subsequently a high rise in insulin
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Amylose
Straight chain, hence limited the amount of surface area for digestion. Referred to as a resistant starch and digested more slowly.
Some ends up in large intestine where it can act as a food source for bacteria that live there.
When starches cook and cool down, a lot of amylopectin is transformed into amylose
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Glycogen
-A polysaccharide of glucose which functions as the primary short-term E storage.
-around 60,000 glucose molecules even more branched than amylopectin
-made and stored primarily by liver (used to help maintain blood sugar levels) and muscles (only used for that particular muscle in exercise).
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Cellulose
-Found as a structural material in plant walls.
-glucose units in a flat, ribbon-like strand
-Humans haven’t got enzymes to break it so it acts as fibre which assists in the movement of materials through the intestines
-a single most abundant organic compound on earth
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Functions of carbohydrates
-Energy:primary E fuel and for limited storage of energy as glycogen
-Fibre (cellulose):
Needed for proper bowel function. Bulk up.
Protects from CVD, diabetes, colorectal cancer
Increase satiety and aids in weight loss
-Glucose as an individual sugar is critical for E production- ATP production, glycogen synthesis, triglyceride synthesis (if excess in quantity) and amino acid synthesis.
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Carbohydrate digestion
-Salivary amylase in mouth and chewing. Works well in the mouth at fairly neutral pH, but get deactivated by stomach acid.
-In the small intestine, pancreatic amylase continues digestion into disaccharide units.
- Brush border enzymes in the small intestine (lactase, makes and sucrase).
Nb. In coeliac disease the brush border is damaged leading to poor carbohydrate digestion
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Lipids
They also have C,H and O like CH’s but a lot less -OH groups, so they’re hydrophobic.
Bonded to proteins= Lipoproteins, to make them more soluble and to move around the body.
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Triglycerides
The main source of dietary fat. Formed from a glycerol back bone and three fatty acid chains (which can be saturated or unsaturated) by hydrolysis. Contain ester COOC group.
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Functions of triglycerides
-source of energy. 1g of fat= 9 cal
- a convenient form to store excess calorific intake (extra glucose turned into triglycerides)
-insulation
-protection of body parts and organs, ie around kidneys. Keeps them in place and protected
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Saturated fats
Contain single covalent bonds between each of the carbon atoms of the fatty acids.
Each carbons atom is saturated with hydrogen atoms.
They are very straight allowing them to line up close to each other making them solid.
Generally solider room temperature.
Eg. Coconut oil.
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MONOUNSATURATED fats
Contain fatty acids with ONE double covalent bond between two carbons.
Giving molecule bent configuration.
Generally liquids at room temperature.
Eg. Olive oil.
Somewhat chemically unstable, can turn rancid when exposed to air, heat and light.
Associated with heart healthy Mediterranean diet when used in balance with other nutrients.
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POLYUNSATURATED fats
Contain more than one double bond in the carbon chain.
Molecules with kinks.
Liquid at room temperature.
Eg. Sunflower oil, vegetable oils, rapeseed oil.
Very easily damaged by oxygen and heat.
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Naming Fatty Acids
Named according to the closest bond to the end of the chain (the end without oxygens).
Ie. Omega-3 (=bond is 3 carbons up from the end)
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Cis and Trans Configuration
-CIS- when H atoms are on the same side of the double bond
-TRANS- when H atoms are on the opposite side of the =bond, hence straighter and more rigid.
In nature nearly all fats have cis structure.
Cis and trans fats behave differently when incorporated in the cell membrane.
Cis fatty acids are bent, make cell membranes more flexible, and can be turned into trans by heating.
Trans fats stiffen cell membranes and are prone to oxidative damage making cell membranes leaky. They are formed during hydrogenation reactions used to make margarine and processed foods.
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ESSENTIAL FATTY ACIDS (EFAs)
They are polyunsaturated fatty acids they cannot be made in the body from other components and therefore must be obtained from the diet.
Omega-3 and Omega-6 family.
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***OMEGA-3 fatty acids***
-Alpha-linoleic acid (ALA)- essential in the diet
-Eicopentaenoic acid (EPA)
-Docosahexaenoic acid (DHA)
ALA- walnuts, flax seeds, green leafy vegetables
EPA&DHA- oily fish
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***OMEGA-6 Fatty Acids***
-Linoleic acid (LA).
-Gamma linoleic acid (GLA).
-Arachidonic acid (AA).
LA-sunflower seeds, vegetable oils, most nuts/seeds
GLA-starflower oil, evening primrose oil, borage oil
AA-meat, dairy and eggs
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Omega-3 family conversion
ALA ➡️ EPA ➡️ DHA
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The CONVERSION OF essential fatty acids
Conversion involves adding double bonds with involvement of DESATURASE enzymes.
The conversion of ALA to EPA and DHA is only about 10% efficient and even lower for LA to GLA and AA.
Conversion favours more abundant essential fatty acid- often Omega-6.
Most western diets are particularly rich in Omega-6 especially AA which is PRO-INFLAMMATORY.
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Functions of EFA
-Fluidity and structure of cell membranes.
-Synthesis of prostaglandins.
-Help to form haemoglobin.
-Regulate oxygen use, electron transportation and energy production.
-Support production of digestive enzymes.
-Help make lubricants for joints.
-Help transport cholesterol in the blood.
-Help generate electric currents and keep the heart rate regular.
-Needed by the tissues of the brain, retina, adrenal glands and testes.
-Help balance the immune system and prevent allergies.
-Ensure proper nerve transmission, especially in the brain.
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Oxidation of fatty acids
Polyunsaturated fats, such as EFAs are very prone to becoming free radicals.
When fats are heated, electrons can be lost (oxidation), forming free radicals. This then further reacts with O in the air making it even more damaging.
The CH2 groups btw the double bonds are especially voulnerable to this as free radicals formed here are very stable.
Formed damaged fats are incorporated into cell membranes or continue causing havoc in the body by causing further oxidation.
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Oxidation of fatty acids cont.
Radical formation is accelerated by
LIGHT, OXYGEN and HEAT
-eat nuts and seeds in its most natural form
-can use polyunsaturated fats if cold pressed, kept in dark glass bottles in the fridge-used just for dressings or consumed as such, sprinkled on top of salads, never use for cooking. Ie. Flaxseed oil
-cook with saturated fats for higher temperatures (ie.coconut oil). Or animal fats such as duck fat, ghee or lard but used in small quantities.
-olive oil can be used for cooking at lower temperatures, such as stew, roasting veg in the oven or olive oil cake (only one double bond, hence a bit more stable than vegetable oils)
-extra virgin olive oil remains stable when cooked at higher temperatures(ie stir-fry or frying steak). This is due to its higher antioxidant content. Must be of very high quality, cold pressed by mechanical means and used sparingly.
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LIPOPROTEINS (fat molecule joined with a protein)
A fat molecule joined with a protein molecule, enabling the lipid to move around the bloodstream.
Lipoproteins are the way that we transport fats around bloodstream.
Contain triglycerides and cholesterol internally. Hydrophobic.
Phospholipids and proteins on the outside. Hydrophilic.
Synthesised by the liver and there’s different types of
A type of lipoproteins, chylomicrons carry triglycerides from the intestines (absorbed through the food intake) to the liver, skeletal muscle and adipose tissue.
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Types of lipoproteins
-VLDL- Very Low Density Lipoproteins
Carry newly synthesised triglycerides from the liver to adipose tissue (if high-a sign of overeating and of a metabolic imbalance like diabetes)
-LDL- Low Density Lipoproteins
Carry cholesterol from the liver to cells of the body. Needed to repair cells, support cell membranes and synthesise sex and adrenal hormones, vitamin D precursor in the skin.
-HDL-High Density Lipoproteins
Collect cholesterol from body’s tissues, bringing it back to the liver.
The balance btw LDL and HDL is ultimately important. Want to have enough high HDL to bring excess cholesterol back.
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PHOSPHOLIPIDS
Contain one glycerol part and two fatty acid chains.
Phosphate head contains lots of -OH molecules making it hydrophilic and is therefore polar and water soluble.
The fatty acids tails are non-polar and interact only with other lipids. They are hydrophobic and fat-soluble. These tails can contain saturated and unsaturated fats(ie.mono/poly). Cells should contain a balance of these to support a healthy cell membrane structure that is neither excessively rigid nor fluid. Hence making cell membrane strong, but also flexible.
AMPHIPATHIC- soluble on one side and insoluble on the other.
In cell membrane arranged tail to tail-heads facing outside and inwards towards water cytoplasm, with fat layer on the inside giving the actual membrane to a cell. Cell membrane = Double phospholipid layer.
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STEROIDS and Sterols
Lipids formed from cholesterol.
Formed from four rings of carbon atoms joined together at their base.
(STEROLS-steroid bases that contain an -OH group. Commonly found in plants).
Steroids used to create hormones-sex hormones and stress hormones- oestrogen, testosterone, cortisol etc…
-Liver produce cholesterol (using enzyme HMGCoA reductase), and we also get it from diet. In healthy body liver adjust the production according to the amount ingested via diet.
