Biological Molecules (biological molecules, protein structure/types, nucleic acids, DNA replication, protein synthesis, ATP)

Question 1

What are elements?

Answer 1

Elements are different types of atoms and are distinguished by the number of protons in their atomic nuclei

Question 2

What elements are most abundant in biological molecules? (6)

Answer 2

• Carbon (C)
• Hydrogen (H)
• Oxygen (O)
• Nitrogen (N)
• Phosphorus (P)
• Sulfur (S)

Question 3

Which other elements have important roles in biochemistry? (4)

Answer 3

• Sodium (Na)
• Potassium (K)
• Calcium (Ca)
• Iron (Fe)

Question 4

What is bonding?

Answer 4

Atoms connect with each other by forming bonds with other atoms of the same element or atoms of different elements

Question 5

What is a molecule?

Answer 5

A molecule is a complex created when two or more atoms are bonded together

Question 6

What is a covalent bond?

Answer 6

• A covalent bond occurs when two atoms share a pair of electrons
• The electrons used to form bonds are unpaired and present in the outer orbital of the atoms

Question 7

Bonding follows some simple rules, determined by the number of unpaired electrons present in the outer orbitals of different elements: …

Answer 7

• Carbon atoms can form 4 bonds with other atoms
• Nitrogen atoms can form 3 bonds with other atoms
• Oxygen atoms can form 2 bonds with other atoms
• Hydrogen atoms can only form 1 bond with another atom

Question 8

What are ions?

Answer 8

An atom or molecule in which the total number of electrons is not equal to the total number of protons is called an ion

Question 9

What are cations?

Answer 9

If an atom or molecule loses one or more electrons it has a net positive charge and is known as a cation

Question 10

What are anions?

Answer 10

If an atom or molecule gains one or more electrons, it has a net negative charge and is known as an anion

Question 11

What is an ionic bond?

Answer 11

A chemical bond that involves the donating of an electron from one atom to another, forming positive and negative ions held together by the attraction of the opposite charges

Question 12

What are the components of an atom?

Answer 12

Atomic nucleus containing proton/s (positively charged) and neutron/s (no charge), electron shell/s containing orbiting electron/s (negatively charged)

Question 13

What are electrolytes?

Answer 13

Ions in solution (that have an electric charge), these help with normal bodily functions

Question 14

What are some important roles of cations in the body?

Answer 14

• Calcium ions (Ca²⁺) - nerve impulse transmission and muscle contraction
• Sodium ions (Na⁺) - nerve impulse transmission and kidney function
• Potassium ions (K⁺) - nerve impulse transmission and stomatal opening
• Hydrogen ions (H⁺) - catalysis of reactions and pH determination
• Ammonium ions (NH₄⁺) - the production of nitrate ions by bacteria

Question 15

What are some important roles of anions in the body?

Answer 15

• Nitrate ions (NO₃⁻) - nitrogen supply to plants for amino acid and protein formation
• Hydrogen Carbonate ions (HCO₃⁻) - maintenance of blood pH
• Chloride ions (Cl⁻) - balance positive charge of sodium and potassium ions in cells
• Phosphate ions (PO₄³⁻) - cell membrane formation, nucleic acid and ATP formation, and bone formation
• Hydroxide ions (OH⁻) - catalysis of reactions and pH determination

Question 16

What are polymers?

Answer 16

Polymers are long-chain molecules made up by the linking of multiple individual molecules (called monomers) in a repeating pattern

Question 17

What does it mean if a molecule is ‘polar’?

Answer 17

They have regions of negativity and regions of positivity

Question 18

How many hydroxyl (OH) groups does water contain?

Answer 18

2

Question 19

What are hydrogen bonds?

Answer 19

• Polar molecules, including water, interact with each other as the positive and negative regions of the molecule attract each other and form bonds, called hydrogen bonds
• These are relatively weak interactions, which break and reform between the constantly moving water molecules
• They occur in high numbers

Question 20

Characteristics of water

Answer 20

• High boiling point - it takes a lot of energy to increase the temperature of water and cause it to become gaseous (evaporate)
• Liquid at room temperature due to the hydrogen bonding between water molecules
• When it freezes, it turns to ice - this is less dense than water and allows it to float (As water is cooled below 4°C the hydrogen bonds fix the positions of the polar molecules slightly further apart than the average distance in the liquid state. This produces a giant, rigid but open structure with every oxygen atom at the centre of a tetrahedral arrangement of hydrogen atoms, resulting in a solid that is less dense than liquid water)
• It has cohesive properties - it moves as one mass as molecules are attracted to each other, e.g. plants are able to draw water up their roots, drinking water through a straw
• It is also adhesive - water is attracted to other materials, e.g. when washing your hands, the water doesn’t run straight off

Question 21

Because it is a polar molecule, water acts as a solvent. What does this mean?

Answer 21

A solvent is a substance that dissolves a solute, resulting in a solution

Question 22

Ways in which water important for life?

Answer 22

• It is a solvent
• The cytosol of eukaryotes and prokaryotes is mainly water
• It acts as a medium for chemical reactions
• It helps transport dissolved compounds into and out of the cells - cohesion means that when water is transported through the body, molecules will stick together
• It acts as a coolant, helping to buffer temperature changes during chemical reactions in prokaryotic and eukaryotic cells because of the large amounts of energy required to overcome hydrogen bonding
• Many organisms, such as fish, live in water and cannot survive out of it
• It is stable

Question 23

What is capillary action?

Answer 23

This is the process by which water can rise up a narrow tube against the force of gravity

Question 24

How is water stable?

Answer 24

• It does not change temperature or become gas easily, therefore providing a constant environment
• Because ice floats, it forms on the surface of ponds and lakes. This forms an insulating layer above the water below

Question 25

What is surface tension?

Answer 25

• Water molecules are more strongly cohesive to each other than they are to air, this results in water having a ‘skin’ of surface tension
• This creates habitats for organisms, e.g. pond skaters