2.2 Biological molecules Flashcards
What are hydrogen bonds?
Hydrogen bonds form between the positive and negatively charged regions of adjacent water molecules
What is water?
Water is the medium in which all metabolic reactions take place in cells
What are the properties of water?
- Important solvent in water
- A transport medium
in animals it is the blood (glucose) & in plants it is the xylem (water) and the phloem (dissloved sugars) - A coolant
sweat can evaporate and take away the heat on your skin surface by kinetic energy transfer therefore take away the heat and cool you down - Provides habitats
What are the water properties that hydrogen bonds contribute for?
- An excellent solvent
- A relatively high specifc heat capacity
- A relatively high latent heat of vaporisation
- Water is less dense when a solid
- Water has high surface tension and cohesion
- It acts as a reagent
What is a polar molecule?
When a molecule has one end that is negatively charged and one end that is positvely charged.
For example water
Why is the sharing of electrons uneven in water when it is electrically neutral as a whole?
The oxygen atom attracts the electrons more strongly than the hydrogen atoms. This results in a weak negatively charged region on the oxygen atom and a weak positively charged region on the hydrogen atoms
What is a dipole?
The seperation of charge due to the electrons in the covalent bonds being unevenly shared
What are the elements in each biological molecule?
Carbohydrates: C,H and O
Lipids: C,H and O
Proteins: C, H, O, N and P
Nucleic acids: C, H, O, N and P
What monosaccharides join up to make the 3 disaccharides?
Maltose - alpha glucose 2x
Sucrose - alpha glucose and fructose
Lactose - galactose and beta glucose
What are the three monosaccharides?
monomers
Glucose, Fructose and galactose
What are disaccharides?
They are made from two monosaccharides. They are joined together by a glycosidic bond and are formed via a condensation reaction
What are the three disaccharides?
dimers
Sucrose, maltose and lactose
What are the three polysaccharides?
polymers
Starch, cellulose and glycogen
What is the structure of starch?
It is made from 2 polymer.
It has amylose (an unbranched helix)
It has amylopectin (a branched molecule)
What is the structure of cellulose?
Polymer forms long straight chains. Chains are held parallel by many hydrogen bonds to form fibrils.
Macrofibrils combine to form a cellulose fibre
What are the functions of cellulose and how does the structure allow that?
Provides collective strength due to having many hydrogen bonds.
Won’t affect water potential because it is insoluble