Chapter 4 - Biological Molecules Flashcards
Biological molecules
Why are biological molecules important in organism?
They are needed to build structure and for use in metabolic reactions
What are carbohydrates made up of?
Carbohydrates are made up of sugar molecules containing carbon, hydrogen and oxygen atoms.
When glucose molecules bind together in a chain what can be made?
cellulose, starch and glycogen
What are monosaccharides? Name an example and some characteristics of them.
Monosaccharides are simple sugars such as glucose and taste sweet and are very small
What is the symbol formula of glucose?
C6H12O6
What are polysaccharides? Name an example and some characteristics of them
A chain of many simple sugars such as starch and are mostly insoluble and don’t taste sweet
In what form are excess sugars stored in plants?
Sugars are stored as starch usually in the tissue and seeds.
In what form are excess sugars stored in animals?
Sugars are stored as glycogen in the liver
Functions of carbohydrates:
- Needed for energy released by respiration
- Stored as glycogen in animals in liver
- Stored as starch in plants seeds or tubers
- Used to make cellulose, very strong
What are fats also known as? and what are they made up of?
Fats are also known as lipids and oils and are made up of glycerol and fatty acids
What do fats contain?
Fats contain carbon, hydrogen and oxygen
Functions of fats:
- Can be used to release energy
- Extra energy from fat makes it useful for storing energy
- Insulates body heat
- Plants store it in oils
What do proteins contain?
Nitrogen, carbon, hydrogen, oxygen and sulphur. They make up amino acids which bind in a chain and different arrangements make different proteins and shapes.
Functions of proteins:
- Your hair and nails are made up of a protein called keratin
- Proteins in food used for making new cells
- Cell membranes and cytoplasm contain alot of protein
- Needed for antibodies
- For enzymes
What does DNA stand for?
Deoxyribonucleic acid
What is the structure of DNA?
It is composed of two strands coiled around each other to form a double helix. Each strand made of a sugar backbone with bases attached. These bases bind to bases on the other strand to form cross links
Which bases bind to each other?
C-G and A-T
Why is water important?
- It acts as a solvent in which chemical reactions occur
- Helps to maintain a constant temperature
- Needed for digestion as a medium for enzymes and to allow free passage of digestive product
- Allows soluble molecules in digestion to be transported around and through cell membranes
- Transports waste products such as urea
Chemical test for starch and the method:
Iodine test, add iodine solution to sample a colour change from yellow-brown to blue - black indicates presence of starch
Chemical test for reducing sugars and method:
Benedicts test, add sample to benedicts solution and heat to 80 C. Colour change from blue to brick red indicates presence of glucose and other reducing sugars
Chemical test for proteins and method:
Biuret test, sample solution added to tube with equal amount of sodium/potassium hydroxide and add a few drops of copper sulphate solution. Colour change from blue to purple
Chemical test for fats and oils and method:
Emulsion test, add sample to tube and add ethanol, Shake tube and then add water and shake gently. Colour change from clear to cloudy white
Chemical test for Vitamin C and method:
DCPIP test, add DPIP to tube then sample and shake gently, colour change from blue to colourless.
