Topic 1 - Molecules AS Biology

What is the role of water in living organisms?

-As a solvent

-Mass transport of sugars in the phloem tissue of plants

-As a component of urine

What does polar mean?

Uneven distribution of charge

Why is water polar?

• The oxygen atoms have a stronger affinity for electrons than the hydrogen atoms

• They pull the electrons of the hydrogen atoms closer to it

• The oxygen is given a negative sign

• Hydrogen is given a positive sign

What bond forms between water molecules?

Hydrogen

Why is water a good solvent?

• The positive sodium atoms are attracted to the negative oxygen in the water molecule

• The negative chlorine is attracted to the positive hydrogen of the water molecule

• The water molecules form hydration shells around the sodium chloride

Why is water a useful solvent?

• Most of a celll’s reactions need an aqueous medium to take place

• Water has an ability to act as a transport medium in living organisms

• It has different effects on molecules that hyrdrophobic or hydrophilic.

What are buffers?

This is something that resists changes in pH when acids are added/prevents flactuations in pH

Why are buffers important?

So that enzymes are operating at their optimum pH → i.e they’re not denatured

What is the role of potasssium in living organisms?

• Maintenance of membrane potential accross neurones

• As a buffer

What is calcium a component of and what is its role?

• Calcium pectate → ‘Glues’ plant cells together as it forms a structure called the middle lamella

• Acts as a buffer in cells

• Involved in muscle contraction and blood clotting

What is magnesium a component of and whats its role?

• Chlorophyll

• Forms chlorophyll found in chloroplats - it absorbs light and allows photosynthesis to occur in plants

What is the component of iron and whats its roles?

• Haemoglobin

• forms the haem component of haemoglobin

• Transports oxygen from the alveoli to respiring cells

• Acts as a buffer for H+ ions in the blood

What is the role of hydrogen carboonate?

• Acts as a buffer in blood plasma

What is nitrate a component of and what are the roles?

• Nucleotides, amino acids, chlorophyll

• Nucleotides are the monomer of nucleic acids - RNA & DNA

What is phosphate a component of and what are the roles?

• Nucleotides, ATP, Phospholipids

• ATP → Energy molecule in cells

• Phospholipids → Makes up the cell membrane found in cells

What do all organic molecules contain?

Carbon

What is a polymer made up of?

Many repeating monomers which are the same or similar in shape chemically joined together inn condensation reactions

How do you form water?

Hydrogen + Hydroxyl = Water

What is a condensation reaction?

Smaller molecules join together to form a larger one and release a molecule of water

What is a hydrolysis reaction?

A larger water moleculea are split into smaller molecules with the addition of water