Biochemistry 1

Question 1

What is matter

What is an atom

What is an element

Answer 1

Matter is everything around us that has mass/occupies space
An atom is a small particle of matter made up of electrons, protons and neutrons
All matter is made up of limited building blocks of nature called chemical elements -an element is a substance made up of just ONE type of atom so it cannot be split up into simpler substances

Question 2

How many elements are there in the human body and what are the major 4

Answer 2

There are 26 elements in the human body

Main ones are C, H O2 and N - accounting for 96% of the human body

Question 3

Every element is made up of atoms but what are atoms themselves made up from

Answer 3

Atoms are made up from protons, neutrons and electons
Protons and neutrons = the nucleus
Protons have a + charge and a mass of 1
Neutrons have no charge and a mass of 1

Question 4

Are electrons + or -v and what is their function

Answer 4

Electrons are -ve charged particles that buzz around the outside of the nucleus (electron shells) creating an electron cloud - virtually no mass at all.

Question 5

Define a stable element

Answer 5

A stable element will have the same number of protons as it does electrons = overall neutral charge

Question 6

What does the atomic number of an element correspond to

Answer 6

The number given to an element corresponds to the number of protons and electrons

Question 7

How do you work out the number of neutrons in an element

Answer 7

The number of neutrons is the mass number - the atomic number

Question 8

Define isotope

Answer 8

An isotope are atoms of the same element with a different number of neutrons in the nucleus.
This does not affect the electrical activity as neutrons have no charge but it does change the mass

Question 9

Electrons ‘hang out’ in set numbers. What is their preferred arrangement

Answer 9

2, 8, 8 and 8 - the basic amount required for stability

Question 10

The bonding properties of an element are dependant on which of the electron shells

Answer 10

The bonding property of a element is dependent on the number of electrons in THE OUTER SHELL. Electrons like to fill these outer shells up so they are full.

Question 11

How many shells does H have in its outer shell

Answer 11

H has only 1 electron is its outer shell and can be referred to as the valence electron - it will go looking for other atoms that need one electron to fill their outer shell. That means that H easily reacts with other atoms

Question 12

Define ‘inert atom’

Answer 12

Some elements have exactly the right amount of electrons in their outer shell, meaning they are rarely involved in chemical reactions. These elements are inert.

Question 13

When an atom gives up or gains an electron to stablise its outer shell that atom becomes an ……

Answer 13

ION
Therefore, ionisation is the process of giving or gaining electrons.
Ions are either written with - or + charge

Question 14

What is the process called when electrons are removed from an atom

Answer 14

This is called oxidation
Oxidation decreases the potential energy of a compound
Generally most oxidation occurs with the removal of H from a molecule

Question 15

When H is lost, we call this a…….

Answer 15

dehydrogenation reaction

Question 16

What is the term describing simultaneous oxidation and reduction

Answer 16

This is called a REDOX reaction

NB - O I L R I G

Question 17

What is a free radical and what do they do?

Answer 17

free radicals are molecules or compounds that have unpaired electrons in their outer shell
Because they want to stabalise their outer shell, they become destructive and ‘steal’ electrons from other stable molecules - OXIDATION

This leaves the attacked molecule with an unpaired electron causing a chain reaction of oxidative damage

Question 18

How do free radicals develop in the body

Answer 18

Free radicals develop from processes within our bodies such as normal aerobic respiration, metabolism and inflammation

They can also come from the environment - pollution, sunlight, strenuous exercise, smoking and alcohol

Question 19

What is an antioxidant and what is its job

Answer 19

Antioxidants consist of a group of vitamins, minerals and phytochemicals and enzymes that work to neutralise free radicals before harm occurs

Question 20

How do antioxidants work

Answer 20

They work by donating electrons to the free radicals to convert them to harmless molecules.

The key to a good antioxidant is that it must be stable once it has given away an electron

Question 21

Define a molecule

Answer 21

A molecule is a discrete group of atoms bonded together is a specific arrangement ie water H2O

Question 22

Define a compound

Answer 22

A compound is an electrically neutral substance containing 2 or more elements in a defined ratio, ie NaCl (table salt)

Question 23

There are two types of bonding processes.

What are these processes called

Answer 23

When ions are trying to become stable they bond with other ions so that they can get just the right number of electrons in their outer shell.

These processes are known as:

Electrovalence bonding (ionic bonding). Ionic bonds occur when one element donates some of its electrons to another

Covalent bonding - occurs when two elements share electrons so they both have the magic number of electrons on their outer shells.

Question 24

What is electonegativity

Answer 24

Some elements have a lot of electron ‘pulling power’ this is their electronegativity

Question 25

What is a polar bond

Answer 25

Very elecronegative atoms are able to pull the electrons in a bond closer towards them, causing an uneven distribution of electrons, and therefore charge where one part of the molecule is slightly +ve and the other slightly -ve

Question 26

Name the 4 most electronegative elements

Answer 26

Flouride, Chlorine, Oxygen and Nitrogen

Question 27

What is hydrogen bonding

Answer 27

When hydrogen is bonded to a more electronegative atom a partial +ve charge develops on the hydrogen due to the unequal sharing of electrons. This +ve charge on the H atom will be attracted to atoms with a
-ve charge
This attraction is called a H bond and occurs in water

Question 28

Water is termed the universal solvent, why is this

Answer 28

Water serves as the medium for most chemical reactions in the body.

Water contains polar bonds it is the ideal solvent for dissolving chemicals in to their separate ions

HYDROPHILIC molecules are molecules which have polar bonds. They dissolve easily in water (eg alcohol)

HYDROPHOBIC molecules contain non-polar covalent bonds so do not dissociate easily in water (eg fats)

Question 29

What is an electrolyte

Why are electrolytes important

Answer 29

An ionic compound, eg salt, when dissolved in a solution is called an electrolyte

They are important for nerve and muscle function
They exert osmotic pressure important for water balance
Some play a role in acid-base balance acting as buffers

Question 30

What is an acid?

Answer 30

An acid is a substance that RELEASES high amounts of H+ions when dissolved in water
Lots of H+ = low pH (acidic)

Question 31

What is a base?

Answer 31

A base is a substance that BINDS H+ ions in a solution thus creating a lot of OH-
Lots of OH- = high pH (alkaline)

Question 32

How is H ion concentration measured?

Why is pH important

Answer 32

The number of H ions in a solution is a measure of acidity

H concentration is measured using the pH scale (% H)

The body has to maintain optimal pH concentrations for certain reactions to take place

Question 33

When acids and bases react chemically what do they form

Answer 33

Acids and bases react chemically to form a salt + a H20

Question 34

What is a buffer

Answer 34

Buffers are substances that maintain H+ concentration in the body within normal limits