3. CHEMISTRY & BIOCHEMISTRY 1 Flashcards
This module covers: • Key concepts in chemistry and biochemistry, including water, pH and buffers. • Structure and functions of carbohydrates. • Structure and functions of lipids.
State THREE functions of triglycerides
- Fats provide a source of energy, but the process of energy released from fats is less efficient than when carbohydrates are used.
- Fats provide a convenient form in which to store excess calorific intake (extra glucose is also turned into triglycerides).
- Insulation.
- Protection of body parts and organs (e.g. kidneys).
What is Chemistry?
The science that deals with the composition and properties of substances and various elementary forms of matter (gas, liquid, solid).
What is Biochemistry?
The science concerned with the chemical and physicochemical processes and substances that occur within living organisms.
What is matter?
Everything around us that has mass and occupies space
What are atoms?
Atoms are small particles that make up matter
What are atoms made up of?
Electrons, protons and neutrons
What is an element?
A element is a substance made up of one type of atom so it cannot be split up into simpler substances
Where are all known elements recorded?
Periodic table
List the chemical symbol for the following:
* Hydrogen
* Carbon
* Calcium
* Magnesium
- H+
- C
- Ca
- Mg
How many elements are there in the human body?
26
Name 4 major elements that make up 96% of the human body?
Carbon, hydrogen, oxygen and nitrogen
Describe:
When a chemical reactions occurs, what happens to the bonds?
Chemical reactions occur when new bonds are formed or old bonds are broken between different molecules.
In which TWO ways does energy transfer change in every chemical reation?
Energy changes from either potential energy (stored) or kinetic energy (heat).
In chemical reactions what are the STARTING and END materials called respectively?
- Reactants
- Products
In what way are chemical reactions written?
Reactions are written in a formula. They must always balance in electrons from one side to the other.
What is needed for a chemical reaction to occur?
Collision. Needs to have the opportunity for two molecules to collide to start with.
What happens when the molecules possess higher energy?
The molecules move faster and they have a greater chance of reacting.
What is the minimum energy that is required for a reaction known as?
It is known as the ENERGY OF ACTIVATION
What do chemical reactions rely on?
They rely on the correct temperature and enough reactants.
What can change the speed of reactions apart from temperature and reactants.
Changes in Pressure: Increasing pressure forces molecules closer together.
What do catalysts do in a chemical reaction?
Catalysts speeds up reactions by lowering the activation energy required. It means that the reaction is faster or can occur at a lower temperature.
What is the name of the catalysts that the body produces and give one example.
Enzymes, HMG-CoA reductase in the production of cholesterol and CoQ10
What do inhibitors do in relationship to catalysts?
They act antagonistically. They stop the catalysts from being so effective by making the activation energy higher and hence slow down the reaction time.
Name the HMG-CoA reductase inhibitor?
STATINS
Define anabolic reactions and give an example?
Anabolic reactions are synthesis (building) reactions. E.g Taking amino acids and building a protein. This requires energy.
Define catabolism and provide an example.
Catabolism describes reactions where ‘breaking down’ occurs. E.g. When breaking down food, releasing energy from them. We trap that energy as ‘ATP’.
Define ‘Hydrolysis reaction’
when water is the medium that breaks down the molecule into smaller pieces, it is known as a hydrolysis reaction.
Explain what is dehydration synthesis and give an example.
When water is formed as the waste product of a reaction. This is normally when larger molecules are being made, e.g. when making carbohydrates.
What are ‘reversible reactions’?
They describe chemical reactions whereby the products of the reaction can react together to produce the original reactants (meaning it can go back the other way). A+B ⇋ AB
How do you control the direction of reversable reactions in the body?
This is done using enzymes and having mechanisms in place that allow us to remove starting materials and products.
What is the function of buffers?
Buffers maintain the H+ concentration in the body within normal limits. They can bind to H+ ions and OH− to ensure the blood pH remains between 7.35 - 7.45.
Name the buffer system that mops up excess acidity.
The most important buffer system in the blood stream is the bicarbonate (HCO3)- buffer system.
What forms when carbon dioxide from cellular respiration reacts with water in the blood?
Carbon dioxide, catalysed by carbonic anhydrase form carbonic acid which rapidly dissociates to form a bicarbonate and hydrogen ion.
Give the formula for carbon dioxide, water, carbonic acid, hydrogen and a buffer in the blood.
CO2+H2O ↔ H2CO3 ↔ HCO3- + H+
Describe the workings of the lungs as a buffer system.
When extra hydrogen ions accumulate in the blood, for example after strenous excercise ( ↑ lactic acid), the reaction is able to adjust to mop up the extra H+ ions, making more carbon dioxide and water.
This then accounted for by increasing the breathing rate and hence the exhalation of carbon dioxide through the lungs.
Describe how the kidneys function as a buffer system.
Kidneys produce HCO3 which acts as a buffer. They can also excrete excess H+ ions. But this is a fairly slow and strenuous process, so it is important to avoid an acidic diet to reduce the strain on this system.
What is meant by ‘oxidation’?
It is the loss of electrons from an atom or a molecule.
How does most oxidation generally occur?
Most oxidation occurs by removing electrons with the help of hydrogen.
What happens to the energy in a compound by oxidation?
Reduction of the potential energy in the compound.
Name the reaction when hydrogen is lost?
It is called a Dehydration reaction
What happens when something is ‘reduced’ in a chemical reaction?
When something is ‘reduced’, it gains electrons, resulting in the increase of energy in that molecule. A gain of hydrogen is normally indicative of something being reduced.
What are ‘free radicals’?
Free radicals are molecules or compounds that have an unpaired electron in their outer shell.
What do free radicals do?
Free radicals want to stabilise their outer shell, so they try and ‘steal’ electrons from other stable molecules. By doing so, they become destructive, causing ‘oxidation’.
What happens in the environment when a molecule is with an unpaired electron?
A chain reaction of oxidative damage occurs. Free radicals can even take electrons from DNA, which can damage genes and can ultimately result in cancerous changes.
Give 4 examples of conditions linked to ‘oxidative damage’?
It is linked to cancer, atherosclerosis (endothelial damage), fibromyalgia and neurodegenerative diseases.
From which processes within our bodies and from the environment can free radical damage occur?
Within our bodies it can result from aerobic respiration, metabolic processes and inflammation.
From the environment e.g. pollution, sunlight, strenuous exercise, X-rays, smoking and alcohol.
How do antioxidants work?
Antioxidants donate electrons to free radicals to convert them to harmless molecules, without being damaged themselves.
What is the key to a good antioxidant?
The key to a good antioxidant is that it must be stable once it has given away its electron(s).
Name 5 antioxidants
Beta carotene
Vitamin C
Vitamin E
Quercetin
Glutathione peroxidase (antioxidant enzyme).
In which way do antioxidants work best?
Antioxidants work best as a collection, where they can recycle each other. They do not work in isolation.
What is a key characteristic of living things?
Living things are characterised by molecules made from carbon.
Characterise functional groups
Any other groups of atoms that are attached to the carbon skeleton are known as ‘functional groups’.
What is the purpose of the functional group in a molecule?
Functional groups contribute to the structure and function of that molecule.
Explain what does ‘R’ group in chemical reaction stand for?
The ‘R’ group is an abbreviation for the unreactive part of the molecule that is just made up of carbon and hydrogen bonds.
What are some characteristics of Sulfhydril groups and where are they found?
They are polar and hydrophilic. They are common in some protein channels. Found in the sulphur-containing amino acid cysteine.
