Summary
Summary Topic 4: Biological molecules
- Course
- Institution
- Book
Topic 4: Biological molecules: IGCSE Biology course notes which will help you study for your papers. By studying these notes I achieved a 9 - A* on my Igcse
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
More summaries for
-
IGCSE Biology Topic 1 (Characteristics & Classification of Living Organisms)
-
Class notes biology: Characteristics of living organisms
-
Class and mark scheme notes Biology Cambridge IGCSE with Biology Coursebook with CD-ROM
Seller
Follow
alejandrahuartealfaro
Content preview
TOPIC 4: BIOLOGICAL MOLECULES4.1 CARBOHYDRATES, FATS & PROTEINS
-Most of the molecules in living organisms fall into three categories: →Carbohydrates, Proteins and Lipids.
Most of our body is made of water:
-Metabolic reactions can only take place if the
chemicals which are reacting are dissolved in water.
-Water is an important solvent.
-Water is also needed in blood plasma so substances
can dissolve in it (i.e. glucose).
Carbohydrates
→Long chains of simple sugars
→Glucose is a simple sugar/monosaccharide: can dissolve in water.
→When 2 simple sugars (i.e. glucose) join together a disaccharide is formed (i.e. maltose): can dissolve in water.
→When lots of simple sugars join together a polysaccharide can form (i.e. starch, glycogen or cellulose)
-FUNCTIONS:
-Needed for energy (1g of carbohydrate – 17kJ of
energy) which is then released by respiration.
-The carbohydrate used in respiration is glucose.
-Plant cells transport glucose in the form of sucrose
(change it when use it) and store it as starch
-Animals store carbohydrates in the form of
polysaccharide glycogen.
Fats
→Most fats (lipids) in the body are made up of triglycerides
→Their fat molecule is formed by 1 glycerol molecule chemically bonded to 3 fatty acid chains
→The fatty acids vary in size and structure
→Lipids are divided into fats (solids at room temperature) and oils (liquids at room temperature): both insoluble in
water.
-FUNCTIONS:
-Fats and oils can be used to release energy (1g of fat – 39kJ of
energy)
-Used as energy when carbohydrates have been used.
-Very good stores of energy
-Adipose tissue (layer of cells) helps keep body warmth.
Proteins
→Long chains of amino acids (smaller molecules)
→They all contain the same basic structure but the ‘R’ group is different for each one
→When amino acids are joined together a protein is formed
→The amino acids can be arranged in any order, resulting in hundreds of thousands of different proteins, but the
order of each amino acid is precise.
→Even a small difference in the order of the amino acids results in a different protein being formed.
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 alejandrahuartealfaro. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.35. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
70055 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now