Biochemistry Summaries Flashcards
What is an element?
How many are there in the human body?
A substance made up of just one type of atom so it cannot be split up into simpler substances.
There are 26 different elements; the major 4 are C, H, O, N = 96% of the human body.
What is an isotope?
Are atoms of the same element but with different number of neutrons in the nucleus. This does not affect the chemical activity but changes the mass.
Describe what happens and types of radio active decay
Some isotopes have such an imbalance of protons and neutrons that is can cause the atom to become unstable leading to radioactivity.
I.e. the unstable atom needs to get rid of energy to become stable again and does this by:
- alpha decay - ejecting protons and neutrons from the nucleus
- beta decay - splitting neutrons into protons and electrons that can be ejected
- gamma decay - emitting energy as gamma rays
Describe uses of radiation in medicine
Radiotherapy uses gamma rays to target rapidly dividing cancer cells
Radioactive glucose uptake to evaluate cancer treatment
Breath test for H Pylori - the detection isotope labelled carbon dioxide in exhaled breath indicates that the urea was split and that urease is present in the stomach.
Name the four most electronegative elements?
Fluorine, Chlorine, Oxygen and Nitrogen
CL, F, O, N
What is an electrolyte and what do they do?
An ionic compound i.e. salt when dissolved in water is an electrolyte
- conduct electricity essential for nerve and muscle function
- exert osmotic pressure important for water balance allowing fluid to travel inside and outside of the cell (sodium potassium pump)
- play an important role in the acid-base balance
Main ones: Na+, Cl-, K+ (pace maker of the heart) and Mg+
Difference between an acid and a base
An acid is a substance that releases a high amount of H+ when dissolved in water, whereas a base binds hydrogen ions in solutions increasing lots of OH- (hydroxide)
What is the energy of activation?
Minimum energy that is required for a chemical reaction to occur. Can be lowered by catalysts or stopped by an inhibitor.
(Example of inhibitors are Botox or antibiotics)
What is a chemical reaction and what is is reliant on?
It’s the breaking or formation of chemical bonds. for this to occur there needs to be an opportunity for two molecules to collide.
Starting materials are reactants, end molecules are products.
Written in a formula that must balance balance in electrons on both sides i.e. A + B = AB.
Reliant on: the correct temperature, high enough concentration of reactants;
Increasing pressure can speed up reactions.
Difference between endothermic and exothermic reactions and examples
Endothermic take in heat and tend to be anabolic i.e. body building or freezing water
Exothermic release heat or energy - catabolic i.e. fire, melting ice
What’s a buffer system ? Give an example and how does it work?
Substances that maintain the H+ (pH) concentration in the body within normal limits. The most important one in the blood stream is the bicarbonate buffer.
COs (from cellular respiration) reacts with H2O in the blood = carbonic acid (H2CO3) = bicarbonate ion (HCO3-) and H+.
These reactions are reversible.Lungs and kidneys key players.
What’s a free radical?
Molecules or compounds that have an unpaired electron in its outer shell. They become destructive and steal electrons = oxidation, causing a chain reaction.
Results from normal aerobic respiration, metabolism and information; from within the body or from environment (pollution, sunlights, strenuous exercise, X-rays, smoking, alcohol.
What are antioxidants?
Group of vitamins, minerals, photo chemicals and enzymes that donate electrons without becoming unstable themselves.
ACE, Glutathione (naturally produced in our body)
Work best as a collection, so they can recycle each other.
Functional Groups
Attached to carbon skeleton contributing to structure and function
Hydroxyl: R-O-H (polar and hydrophilic)
Sulfhydryl: R-S-H (polar and hydrophilic; in some proteins)
Carboxyl: R-COOH (hydrophilic, weak acid, found in amino acids)
Esters: R-OOR’ (predominant in triglycerides)
Phosphates: C-POOOO (in ATP, very hydrophilic)
Amine: -NH2 (weak base found in amino acids)
Metabolism of fat for energy production is stimulated or inhibited by what hormones?
Stimulated by Adrenalin/epinephrine
Inhibited by insulin
What are two types of complementary bases that form nucleotides?
Purines and pyrimidines
What is the structure of an amino acid?
Formed from elements C, H, O and N (some have Sulphur)
There are 20 AAs in humans;
Everyone has a carboxyl (-COOH) and an amino (-NH2) group with different R- side chain
What are the essential amino acids? (9)
Histidine. Valine
Isoleucine. Phenylalanine
Leucine. Threonine
Lysine. Tryptophan
Methionine
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What are non-essential amino acids? (5)
Alanine Aspartic Acid Glutamic acid Serine Asparagine
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What are conditionally essential amino acids? (6)
Arginine Cysteine (depends on Methionine) Glutamine Glycine Proline Tyrosine
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Give an example of a di-peptide?
Aspartame is made up of aspartic acid and phenylalanine
Give an example of a tri-peptide
The body’s own glutathione is made up of L-cysteine, L-glutamate and glycine.
Different protein structures
Primary structure - linear sequence held by peptide bonds
Secondary - nearby side chains interacts to cause twists and folds - alpha helix or beta pleated sheet
Tertiary - further interactions to create 3D structure via hydrogen bonds, salt bridges, disulphide bonds or non-polar hydrophobic interactions
Quaternary - larger structures made up of individual protein chains
What is an example of a quaternary structure?
Haemoglobin which is made up of 4 x protein chains.
Why are disulphide bonds in tertiary protein structures important?
A disulphide bond is the only proper covalent bond in tertiary protein structure so very important for stabilisation
What is desaturation? And what can it caused by? (6)
Shape = function; denaturation is the unfolding of protein chains (breaking interactions) leading to inability to function.
Denaturing agents include heat (fried egg), solvents, mechanical mixing, strong acids or bases, detergents and ions of heavy metals like lead or mercury.
Function of Proteins (12)
Structure of body tissues i.e. collagen Movement i.e. actin and myosin fibres Carrier molecules i.e. haemoglobin Storage molecule i.e. ferritin Fluid balance in the blood i.e. albumin Enzymes Hormones i.e. insulin Immune function i.e. antibodies Clotting mechanism Alternative energy source (not ideal) Control of gene expression Cell membrane receptors
What is hydrolysis and what is the opposite?
Hydrolysis is when water is the medium that breaks down the molecule into smaller pieces.
when water is formed as a waste produce, it’s dehydration synthesis or condensation reaction.
What are isomers?
Molecules that have the same chemical formula but different structures like fructose, glucose, galactose and mannose.
How are disaccharides formed?
glycosidic bond via dehydration synthesis (condensation reaction)
Structure of carbs
Monosacs - fructose, glucose, galactose, ribose and deoxyribose
Disaccs - sucrose, lactose, maltose
polysaccs - glycogen (made and stored in liver and muscles)
starch - 25% Amylose (resistant starch) and 75% amylopectin (branched)
Cellulose - flat ribbon,lacking enzyme, fibre
Function of carbs (3)
Fuel for energy production
stored energy (glycogen)
Fibre
Function of fibre and how much is needed? (6)
needed for proper bowel function protects against CV disease (14g per 1000 kcal) protects against diabetes (15g per day) increase satiety (14 - 24g per day) aids weight loss (14g per day) protects against colorectal cancer
current intake 3 - 5g per day; optimal 30g
Functions of glucose in particular (4)
ATP production
glycogen synthesis
triglycerides synthesis
amino acid synthesis
Functions of triglycerides (4)
energy source (but less efficient than carbs)
storage of excess calorific intake
insulation
protection of body parts (kidneys)
What are essential fatty acids?
polyunsaturated acids that the body cannot made and therefore must be supplied by the diet i.e. Omega 3 and Omega 6’s.
examples of Omega 3’s (anti-inflam)
ALA - alpha linolenic acid (green leafy veg, flaxseed, walnuts, brazil nuts
EPA - Eicosapentaenoic acid (fish oil)
DHA - docosahexaenoic acid (fish oil)