Biological Molecules & Water Flashcards
What are the main elements that are key to biochemistry?
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
- Phosphorus
- Sulfur
Where is phosphorus evident in biochemistry?
DNA, ATP
How many bonds can carbon, hydrogen, oxygen and nitrogen form
- Carbon = 4
- Hydrogen = 1
- Oxygen = 2
- Nitrogen = 3
Which key elements are present in carbohydrates?
Carbon, hydrogen, oxygen
Which key elements are present in lipids?
Carbon, hydrogen, oxygen
Which key elements are present in proteins?
Carbon, hydrogen, oxygen, nitrogen, sulfur
Which key elements are present in nucleic acids?
Carbon, hydrogen, oxygen, nitrogen, phosphorus
What is a cation?
An ion that is positively charged due to the loss of electrons from an atom.
What are the main cations needed in the body?
- Calcium ions (Ca2+)
- Sodium ions (Na+)
- Potassium ions (K+)
- Hydrogen ions (H+)
- Ammonium ions (NH4+)
What is an anion?
An ion which is negatively charged due to the gain of electrons from an atom.
What are the main anions needed in the body?
- Nitrate ions (NO3-)
- Hydrogen carbonate ions (HCO3-)
- Chloride ions (Cl-)
- Phosphate ions (PO4 3-)*
- Hydroxide ions (OH-)
*the 3- is the charge
What are polymers?
Long chain molecules made up by the linking of individual molecules known as monomers in a repeating pattern.
The monomers in carbohydrates are sugars (saccharides) and amino acids in proteins.
What is the difference between organic and inorganic substances?
Organic substances contain carbon bonded to hydrogen (C-H) but inorganic substances do not.
What are the biological functions of water?
- Reactant in many chemical reactions (e.g. hydrolysis)
- Transports substances (e.g. glucose, mineral ions)
- Solvent -most biological reactions take place in a solution such as cytoplasm
- Involved in temperature control - high specific heat capacity, high latent heat of evaporation
- Habitat - nutrients can be dissolved in water. Water contains oxygen, allowing organisms to survive and reproduce.
What is meant by a “polar molecule”?
When water is formed, the shared negative hydrogen electrons are pulled towards the oxygen atom, leaving the other side of each hydrogen atom with a slight positive charge.
The unshared negative electrons on the oxygen atom give it a slight positive charge. This means water is a “polar “ molecule, as it has a partial negative charge on one side and a partial positive charge on the other.
What is hydrogen bonding?
The slightly negatively charged oxygen atoms attract the slightly positively charged hydrogen atoms of other water molecules.
This force of attraction is known as hydrogen bonding, and it is a relatively weak force.
What are the 5 key properties of water?
- High specific heat capacity
- High latent heat of evaporation
- Cohesive
- Good solvent
- Less dense as a solid
How do hydrogen bonds give water a high specific heat capacity?
Hydrogen bonds between water molecules can absorb a lot of energy - meaning water has a high SHC as it takes a lot of energy to heat up.
As a result of this, water does not experience rapid temperature changes, making it a good habitat. Temperature underwater is more stable than in water on land.
How do hydrogen bonds give water a high latent heat of evaporation?
A lot of energy is needed to break the hydrogen bonds between water molecules, meaning water has a high latent heat of evaporation as a lot of energy is used up when water evaporates.
Water is useful for cooling things - mammals sweat in the heat and when sweat evaporates, it cools the skin’s surface.
What is meant by cohesion?
Attraction between molecules of the same type.
Why is cohesiveness of water useful?
It allows it to flow, making it great for transporting substances. It also helps water move up plant stems in a transpiration stream.
How does water’s polarity make it a good solvent?
The strength of polar attraction and hydrogen bonds mean ions are totally surrounded by water molecules, meaning they will dissolve. This makes water a useful solvent (e.g. ions can dissolve in the water in the blood).
Why is water less dense as a solid?
Water molecules are held further apart in ice, and they form 4 hydrogen bonds to form a lattice shape. This makes ice less dense than liquid, hence why it floats.
This is useful for organisms as ice forms an insulating layer on top of water - the water below the ice doesn’t freeze.
