1.2 - Biological Molecules 1 Flashcards
What are monosaccharides?
a single sugar molecule
What are disaccharides?
a sugar made up of two monosaccharides units joined by a glycosidic bond, formed in a condensation reaction
What are polysaccharides?
is a polymer made up of long chains of monosaccharide units joined by glycosidic bonds
What is glucose?
it is a monosaccharide
is the main substrate for respiration
what are the structure of the two isomers of glucose?
ALPHA GLUCOSE:
has H on top
BETA GLUCOSE
has H on the bottom
Give other examples of monosaccharides
- fructose
- galactose
- ribose: has five carbon atoms, is a pentose sugar, is a component of RNA
(need to know the structure)
How is maltose formed?
Maltose (disaccharide) formed by condensation of two glucose molecules forming glycosidic bonds
found in barley
How is sucrose formed?
Sucrose (disaccharide) formed by condensation reaction of glucose and fructose forming glycosidic bonds
found in sugar cane
How is lactose formed?
Lactose (disaccharide) formed by condensation reaction of glucose and galactose forming glycosidic bonds
found in milk
Through what reaction do maltose, lactose, sucrose split in?
Hydrolysis reactions
Give an example of carbohydrates as energy stores
STARCH (important energy stores in plants)
- formed from a mixture fo two compounds:
1. AMYLOSE - unbranched polymer of a-glucose joined by 1,4 glycosidic bonds - this makes them coiled so very compact meaning it can store a lot of energy
- AMYLOPECTIN - made up of glucose molecules joined by 1,4 glycosidic bonds + few 1,6 glycosidic bonds, making them branched
- the presence of side branches is rapidly digested by enzymes so energy is released quickly
Give another example of a carbohydrate as an energy store
GLYCOGEN (only carbohydrate energy store found in animals)
- made up of many a-glucose molecules
-very compact - has 1,4 glycosidic bonds but it has more 1,6 glycosidic bonds than starch so has many side branches
- these side branches means glycogen can be broken down quickly
What is cellulose and how does its structure relate to its function?
- a component in cell walls in plants and is composed of long unbranched chains of beta glucose monomers joined by 1,4 glycosidic bonds
- microfibres and microfibrils are strong threads which are made of long cellulose chains joined together by hydrogen bonds and they provide structural support in plant cells
What are the properties of lipids?
- they contain C, H, O
- they are insoluble in water
- soluble in organic solvents like alcohol
How are triglycerides synthesised?
they are formed in the condensation reactions between glycerol and three fatty acids forming ester bonds
How can fatty acids vary?
- length of hydrocarbon chain
- the fatty acid chain may be saturated or unsaturated
What are unsaturated fatty acids?
- they have double bonds
- either mono (1) or poly (>1)
- they are bent in structure and have kinks which hinder the tight packing and lead to a lower melting point
- liquid at room temperature
- eg. vegetable oil
What are saturated fatty acids?
- they have no double bonds
- usually solid at room temperature
- are in a linear structure at room temperature
- animal fats
How does the structure of lipids relate to their role in energy storage?
- lipid in the form of triglycerides consist of one glycerol and three fatty acid chains
- these fatty acid chains are long chains that are rich in C-H bonds
- C-H bonds store large amounts of chemical energy making lipids highly efficient energy store
How does the structure of lipids relate to their role in waterproofing?
- lipids are hydrophobic due to their longs non-polar fatty acid chains
- this property makes lipids ideal for waterproofing
How does the structure of lipids relate to their role in insulation?
- lipids are poor conductors of heat, meaning they do not transfer heat well
- this means they can retain heat well and are good thermal insulators
What are the structure of phospholipids?
phosphate head - contains a phosphate group which is hydrophilic
fatty acids tail - consists of two fatty acids chains which are hydrophobic
functions of phospholipids
Selective permeability: The hydrophobic interior of the bilayer prevents water-soluble (polar) molecules and ions from passing through easily, but allows small, nonpolar molecules like oxygen and carbon dioxide to diffuse freely. This selective barrier helps regulate what enters and leaves the cell.
Fluidity: The tails of phospholipids can be either saturated (straight) or unsaturated (kinked due to double bonds). More unsaturated tails increase membrane fluidity, which is important for the flexibility and functioning of the membrane.
Membrane proteins: The bilayer provides a matrix into which proteins can embed. These proteins serve various roles such as
transport, signaling, and cell recognition.
Self-healing: If the membrane is disrupted, the phospholipids can spontaneously rearrange to seal small gaps, maintaining the integrity of the cell.
what is the arrangement of phospholipids in the cell membrane?
In water, phospholipids spontaneously arrange themselves into a bilayer. The hydrophilic heads face outward towards the aqueous environment (inside and outside the cell), while the hydrophobic tails face inward, shielded from water. This forms the basic structure of the phospholipid bilayer that makes up cell membranes.
