Chemistry and Biochemistry 1 Flashcards
Define chemistry
the science that deals with the composition and properties of substances and various elementary forms of matter
Define Biochemistry
The science concerning the chemical and physicochemical processes and substances that occur within living organisms.
What is matter?
Matter is everything around us that occupies space
What are atoms?
Atoms are small particles that make up matter - the lego bricks that make up everything in our universe.
They’re made up of electrons, protons and neutrons.
What is an element? Give 3 examples
An element is a substance made up of just one type of atom so it cannot be split up into simpler substances.
EG:
Hydrogen
Carbon
Calcium
Magnesium
What are the 4 main elements that are present in the human body? And what percentages do they occupy?
Oxygen - 65%
Carbon - 18%
Hydrogen - 10%
Nitrogen - 3%
(Other elements making up the remaining 4%)
Is there any relation between elements that sit next to each other in the periodic table?
Yes - elements close to each other will be similar in size and reactivity and so can interfere with each others absorption.
EG Floride and Chloride can interfere with Iodine
What are subatomic particles?
The building blocks of an atom - protons, neutrons and electrons.
Compare how are protons, neutrons and electrons positioned, weighted, and charged.
Protons and neutrons are in the centre of the atom whereas electrons move around the outside.
Protons are positively charged and weigh 1 unit
Neutrons have no charge and weigh 1 unit
Electrons are negatively charged and weigh 0 units
Describe the electron shell including the numbers associated with them.
The electron shell describes the rings around that centre of the atom that the electrons move around.
Within the shell, electrons like to be paired up and for the outer shell to be full. They become reactive if this isn’t the case - becoming a free radical.
Inner shell = 2 electrons
Then 8 electrons
Then 8 electrons
Then 18 electrons
Explain what the atomic number, and atomic weight/mass refers to in the periodic table.
Atomic number = how many protons and electrons (each) there are
Atomic mass = total weight so therefore includes the neutrons. NB round decimals up/down
EG
Atomic number = 19
Atomic mass - 39
= 19 protons & 19 electrons
= 20 neutrons (39-19)
What does the elements in column 1 of the periodic table all react with?
Water
NB The lower down in the column, the more reactive.
Name 3 elements that you find within the halogens
Floride
Chloride
Iodine
What are isotopes? And give 1 example.
Atoms of the same element that have a different number of neutrons in the nucleus.
This therefore doesn’t affect their charge, but does affect their mass.
EG Most carbon has a mass of 12, but some weigh 14.
How do isotopes play a role in radioactivity?
Some isotopes have such an imbalance of protons and neutrons in the nucleus that it causes the atom to become unstable and radioactive.
EG radiotherapy uses gamma rays from radioactive isotopes
Describe Hydrogen in relation to its subatomic particles and behaviour.
Hydrogen contains just 1 proton, 1 electron and 0 neutrons.
As the electron isn’t paired, the atom wants to find another atom that is missing an electron so it can give it away.
By giving it away, the hydrogen particle becomes positively charged (H+)
What is meant by an inert element?
Inert elements have a full outer shell and so do not easily react.
What’s the difference between an ionic bond and covalent bond?
Ionic = atoms transfer electrons from 1 to the other.
Covalent bonds = atoms share electrons.
Why does ionic bonding create a bond?
Once an electron has been transferred from one atom to another, they become positively and negatively charged. This difference in charge causes an attraction/bond.
What’s an ion? And give 1 example
It refers to atoms that have either gained or donated an electron therefore becoming either positively or negatively charged.
For, Ca2+ has given away 2 electrons, becoming positively charged.
Does sodium tend to come positively or negatively charged?
Positively charged.
It has only 1 electron on its outer shell, so it’s easier to give one away than try to gain 7. So it becomes Na+
Give an example of a covalent bond
Water - H2O
2 Hydrogens join the oxygen to share the electrons. This means that:
The 2 hydrogen gain an electron each to make up the full 2 electrons of their only shell/
Oxygen gains 2 electrons to complete its 8 electrons in its outer shell.
What are polar covalent bonds?
When electrons are shared unequally due to some atoms having more “pulling power” than others.
Explain 1 of the most important examples of a polar bond.
Oxygen and hydrogen:
Oxygen pulls electrons towards itself resulting in negatively charged areas over the oxygen and positively charged areas over each hydrogen.
The positive hydrogens on one atom attract the negatively charged oxygen of another. These attractions give water properties such as surface tension and the ability to dissolve so many different things.
What are hydrophilic and hydrophobic molecules? Give an example of each.
Hydrophilic = molecules that have polar bonds and dissolve easily in water (water-loving).
E.g. alcohol
Hydrophobic = molecules containing non-polar covalent bonds so they do not dissolve easily in water (water-hating)
E.g. fats
What is the universal solvent?
Water
What’s an electrolyte?
Where an ionic compound (eg salt) dissolves in water.
They can conduct electricity.
Name 4 key electrolytes in the body
Sodium
Potassium
Chloride
Calcium
Magnesium
Phosphate
Bicarbonate
List 3 ways electrolytes are important in the body
- Conduction of electricity in nerves and muscles
- They exert osmotic pressure important for water balance
- Some play an important role in acid-base balance
What is an acid and a base?
An acid is a substance that releases a high amount of H+ ions when dissolved in water.
A base is a substance that binds hydrogen ions in a solution. This creates lots of OH-
Describe a couple of examples of how foods acidity can change.
Fruit contain organic acides and so have a low pH before consumption. Yet when metabolised they become alkaline.
Dairy is not very acidic and is high in calcium (an alkaline mineral). Yet when consumed, it’s acidic because of the higher protein/sulfur amino acid content.
How can pH be measured?
Ideally we would want to measure tissue pH but this is very difficult. Instead, urine and saliva are measured to assess the ‘outputs’ of the body which is its attempt to maintain its own pH internally.
NB it should be tested repeatedly over time as pH to get a broader picture.
What are the terms used for the starting materials and end molecules of a chemical reaction
Starting materials = reactants
End molecule = product.
What is the ‘energy of activation’?
The minimal energy needed for a chemical reaction to occur
How can chemical reactions be sped up?
Heat and pressure
What is a catalyst, and give an example?
Catalysts speed up reactions by lowering the activation energy required.
EG enzymes such as HMG CoA reductase
What are inhibitors?
Inhibitors act antagonistically to catalysts, stopping them from being so effective by making the activation energy higher and hence slowing reaction time.
Briefly describe 2 types of chemical reactions
Anabolic reactions are synthesis / building reactions - this occurs when the body is making new substances and building new bonds.
Catabolism describes reactions where ‘breaking down’ occurs.
What is hydrolysis?
When water is the medium that breaks down the molecule into smaller pieces
What is dehydration synthesis?
When water is formed as a waste product of a reaction.
This is normally when larger molecules are being made such as carbohydrates.
What is a reversible reaction and give an example?
Chemical reactions whereby the producrs of the reaction can react together to produce the original reactant.
EG The bicarbonate buffer system which works both ways to ensure the blood pH levels stay as it’s equalibrium.
What does oxidation and reduction refer to?
Oxidation refers to the removal of electrons from an atom. Generally, this occurs by removing electrons with the help of hydrogen.
Reduction refers to an atom gaining electrons, increasing the energy that molecule has.
NB: OIL RIG
Oxidation is Losing
Reduction is Gaining
This is different from ionic bonding. In this instance, the molecule is stealing an electron from an element that doesn’t want to give it up, causing a chain reaction.
What chemical reactions occur with free radicals and why?
Oxidation - they have an unpaired electron so in order to stabilise itself it will try to steal electrons from other stable molecules. This causing a chain reaction of oxidative damage.
NB Free radicals can even steal electrons from DNA causing damage to genes.
What health conditions is oxidative damage linked to? Name 3.
Cancer
Atherosclerosis
Fibromyalgia
Neurodegenerative diseases
Name 3 categories of antioxidants including 1 made within the body.
Glutathione peroxidase (made in the liver)
Beta-carotene
Vitamin C
Vitamin E
Quercetin
What molecule is found in all living things?
Carbon
What are functional groups?
Functional groups are other groups of atoms that are attached to the carbon skeleton in a living thing.
List the 6 main function groups and give an example of each
Hydroxyl group R-O-H - Alcohol
Sulfhydryl group R-S-H - Amino acids
Carboxyl group - Amino acids
Amine group - amino acids
Esters - triglycerides
Phosphates - ATP
What’s the molecular structure of carbohydrates?
All carbohydrates are made up of C-H-O.
Carbon atoms are normally arranged in a ring with oxygen and hydrogen atoms attached.
Name the 3 major carbohydrate groups and give 2 examples within each.
1) Monosaccharides:
Glucose
Fructose
Ribose
2) Disaccharides:
Sucrose
Lactose
Maltose
3) Polysaccharides:
Glycogen
Starch
Cellulose
What’s an Isomer?
Isomers have the same chemical formula but different structure.
Analogy: each atom is a lego brick. You can build different structures using the same combination of bricks.
What’s a disaccharide and what’s the bond between it?
Disaccharide = two sugar
Two monosaccharides join together in a dehydration synthesis - removing water to create a glycosidic bond.
What’s hydrolysis
Once ingested, the process of inserting water back into a glycosidic bond to break apart a disaccharide.
Are polysaccharides soluble or insoluble?
Insoluble
What type of polysaccharide is most common in the body?
Glycogen
Name 3 foods containing starch
Bread
Rice
Pasta
Name the two polysaccharide components found in starch and describe their structure.
Amylose - single chain of glucose units
Amylopectiin - branch like structure of glucose units
Describe the difference in how amylose and amylopectin are broken down in the body.
Amylose has a smaller surface area and is therefore digested slowly. Some ends up in the large intestine and act as a food source for bacteria there.
Amylopectin’s branch-like structure gives it a larger surface area and is broken down quickly. This can cause a high in blood sugar and insulin.
Describe the structure and location of glycogen in the body.
Glycogen is make up of approx 60,000 glucose molecules and has a branch-like structure.
It is made and stored in the liver and muscles.
Glycogen in the liver helps maintain blood sugar levels.
What is cellulose and how is it digested?
Structural materials of plants - found in the plant cell walls.
Humans lack the enzyme to break it down, so it cannot be digested. Instead, it acts as fiber, helping the movement of materials through the intestines.
What’s the main function of carbohydrates?
Energy - primary fuel for energy production and a limited storage form of energy.
List 3 functions of fibre (cellulose)
- Needed for proper bowel movements
- Protect again cardiovascular disease
- Protect again diabetes
- Increase satiety and aids weight loss
- Protects against colorectal cancer
Describe the process of digesting carbohydrates
Salivary amylase in the mouth starts to break down glucose chains.
This is deactivated in the stomach acid.
The pancreas releases pancreatic amylase breaks down further.
Brush border enzymes in small intestines do the final stage of breakdown.
Describe the structure of lipids
Contain carbon, hydrogen and oxygen.
Have fewer polar -OH groups, so they are hydrophobic
How do lipids move around the body?
Bond to a protein to make them more soluble - they are then called lipoproteins
What is our main form of dietary fat called, and describe its structure?
Triglycerides
Contain a single glycerol molecule and 3 fatty acid chains.
Fatty acids are attached by a dehydration synthesis reaction, and the bond formed is called an ester.
Name 4 functions of fats
- Source of energy (less efficient than carbs though)
- Store excess calorific intake
- Insulation
- Protection of body parts and organs
Describe the structure of saturated fats. Give 1 example.
(Saturated = full: Each carbon bond is saturated with hydrogen atoms.)
Contain single covalent bonds between each of the fatty acid carbon atoms.
Its structure is very straight meaning they line up close to each other and hence likely to be solid at room temp.
Eg. Coconut oil
Describe the structure of monounsaturated fats. Give 1 example.
Contain fatty acids with one double covalent bond between two carbons.
Generally liquid at room temp as the kink in its structure means they can’t stack closely together.
E.g. Olive oil
Describe the structure of polyunsaturated fats. Give 1 example.
Contain more than one double bond in the carbon change.
Kinked structure = liquid at room temp.
Eg. sunflower oil, rapeseed oil, vegetable oils
How can you distinguish between omega 3 and omega 6 when looking at their molecular structure?
Omega 3 - the double bond is 3 carbons from the end
Omega 6 - the double bond is 6 carbons away from the end.
What are cis and trans configurations? Where might we find them?
cis fats and trans fats are unsaturated fats so have a double bond in them.
Cis is when the Hatoms are on the same side of the double bond.
Trans is when the H atoms are on separate/opposite sides of the double bond.
In nature, nearly all fats have a cis structure.
When creating fats in a lab/industry, trans fats are created.
What are essential fatty acids?
Polyunsaturated fats that cannot be constructed within the body and therefore must be obtained from the diet.
Omega 3 and Omega 6
Name the different types of omega 3 and 6 and give a food example of each.
Omega 3:
ALA = flax seeds, walnuts
EPA = oily fish
DHA = oily fish
Omega 6:
LA = vegetable oi, most nuts/seeds
GLA = evening primrose oil
AA = meat, dairy, eggs
List 4 functions of EFAs (essential fatty acids)
- Fluidity and structure of cell membranes
- Synthesis of prostaglandin
- Help form haemoglobin
- Support production of digestive enzymes
- Lubricate joints
- Help generate electric current
What oils should be cooked with to prevent oxidative damage?
Cook with unsaturated fats - eg organic coconut oil for high heats.
Extra virgin olive oil can be cooked with potentially due to it’s high antioxidant content.
Oils such as flax seed oil should only be used for salads, etc.
Name three types of lipoproteins and their function
Very Low Density Lipoproteins (VLDL) carry newly synthesized triglycerides from the liver to adipose tissue
Low Density Lipoproteins (LDL) carry cholesterol from the liver to cells
High Density Lipoproteins (HDL) collect cholesterol from the body tissues and bring it back to the liver.
It’s important to have a balance between LDLs and HDLs.
Describe the structure of phospholipids
Contain a glycerol part and two fatty acid chains.
Phosphate head contains lots of -OH molecules making it hydrophilic.
Fatty acid tails are non-polar, contain saturated and unsaturated fats, and are hydrophobic.
What are steroids? Describe their structure.
Lipids formed from cholesterol.
Structurally they form 4 rings of carbon atoms.
They’re used to create hormones.
