Other
Biological Molecules
- Course
- Institution
This is a document that consists of notes for the topic, Biological Molecules, as part of the AS/A level OCR Biology A course
[Show more]
Seller
Follow
DS13990609
Content preview
Molecule of water = 1 atom of Oxygen joined to 2 atoms of Hydrogen by shared electrons1. Because shared negative hydrogen electrons are pulled towards the oxygen atom,
the other side of each hydrogen atom is left with a slight positive charge
2. The unshared negative electrons on the oxygen atom give it a slight negative
charge - makes water a polar molecule (has 𝛿− charge on one side and 𝛿+ on
the other)
3. Slightly negatively-charged oxygen atoms attract the slightly positively-charged
hydrogen atoms of other water molecules
4. This is Hydrogen Bonding (weak intermolecular bonds)
Structure related to its properties and functions:
● Hydrogen bonds give water a high specific heat capacity (energy required to
raise the temp of 1 gram of a substance by 1°C)
○ Hydrogen bonds absorb a lot of energy - so high SHC
○ So water doesn’t experience rapid temp changes - good habitat
● Hydrogen bonds give water a high latent heat of evaporation
○ A lot of energy needed to break hydrogen bonds between H2O molecules
○ Useful for living organisms - water’s good for cooling things (sweat
when too hot - cools surface of skin)
● Water’s polarity makes it very cohesive (attraction between molecules of same
type)
○ Very cohesive because they’re polar
○ Helps water to flow (good for transporting substances)
● Water’s polarity makes it a good solvent
○ Water = polar so slightly positive end will be attracted to negative ion
(and the same for the other one)
○ Ions get surrounded = they dissolve
○ Important ions can dissolve in water in blood and then transported
● Ice = Less dense
○ Water molecules held further apart - each water molecule forms 4
hydrogen bonds to other water molecules, making a lattice shape
○ Forms insulating layer on top of water (fishes don’t freeze/still move
around)
Monomers = individual molecules that make up a polymer
Polymer = molecule made from monomers bonded together
Carbohydrates: First important biological molecule
● Monomers that make this are called monosaccharides
○ Example: Glucose: Monosaccharide with 6 carbon atoms (hexose)
○ 2 forms: alpha and beta
○ It’s structure is related to its function as the main energy source in animals
+ plants - structure makes it soluble - easily transported
, Example: Ribose: Monosaccharide with 5 carbon atoms
(pentose)
All carbohydrates made up of the same 3 chemical
elements: Carbon, Hydrogen, Oxygen
For every carbon atom = 2 hydrogen atoms and 1 oxygen
atom
Monosaccharides are joined together by glycosidic bonds
During synthesis, a hydrogen atom on one monosaccharide bonds to a hydroxyl (OH)
group on the other, releasing a water molecule = Condensation reaction
Hydrolysis = water molecule reacts with glycosidic bond, breaking it apart
When 2 monosaccharides join together = disaccharide
Example:
● 2 alpha glucose molecules are joined together by a glycosidic bond to form
maltose
● Alpha glucose and fructose joined together = sucrose
● Beta glucose and galactose = lactose
When more than 2 monosaccharides join together = polysaccharides
Example: Lots of alpha glucose molecules are joined together by glycosidic bonds to
form amylose
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller DS13990609. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.79. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
53068 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now