BY1- Biological Molecules

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  • Created by: bsiobhan
  • Created on: 28-03-16 14:42
What is carbohydrate's monomer?
alpha glucose and beta glucose
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What bonds are used between two carbohydrates?
Glycosidic bonds
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Name 4 carbohydrates
Starch, Cellulose, Glycogen and Chitin
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What is the function of Starch?
Storage molecule in plant cells
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What is the function of Cellulose?
Used in plant cell walls
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What is the function of Glycogen?
Storage molecule in animal cells
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What is the function of Chitin?
Used as an exoskeleton in some insects
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How does the properties of Starch make it suitable for its function?
Not soluble in water - allows energy to be stored in the cell without altering the water potential of the cell. Also arranged in chains allowing glucose molecules to easily 'break off' releasing energy
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How does the properties of Cellulose make it suitible for its function?
Cellulose consists of long parallel chains of beta glucose, cross linked by hydrogen bonds, providing structural strength
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How does the properties of Glycogen make it suitable for its function?
Not soluble in water - allows energy to be stored in the cell without altering the water potential of the cell. Also arranged in chains allowing glucose molecules to easily 'break off' releasing energy
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How does the properties of Chitin relate to its function?
Strong, waterproof and lightweight - required for exoskeleton of insects that fly
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How would you test for a reducing sugar?
Benedicts Test- Add benedicts test to the solution being tested and heat strongly
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What results should be visible from carrying out the Benedicts Test on a reducing sugar?
Solution should change colour from blue to green, yellow and finally brick red- depending on the concentration of reducing sugar
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How would you test for a non reducing sugar?
Heat with hydrochloric acid and neutralise by adding alkali slowly until any fizzing stops. Then add Benedict's reagent and heat as before. Observe results.
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Name one example of a non-reducing sugar
Sucrose
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How would you improve the reliability of the observed results of the Benedicts test?
Use a colorimeter to create quantitative results rather than qualitative results achieved by observing the colour change by eye
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Describe the structure of Starch
Starch is a storage polysaccharide which consists of two polymers- amylose and amylopectin. Amylose is linear and coils into a helix. Amylopectin is branched and fits inside the amylose
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How do you test for starch?
Add orange/brown iodine to the solution. A blue/black colour can be observed in the presence of starch
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Describe the structure of Cellulose
Cellulose is a structural polysaccharide which consists of many parallel chains of beta glucose cross linked by hydrogen bonds. Adjacent beta glucose are rotated by 180 degrees.
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What are microfibrils and what is their role in plant cell walls?
Microfibrils consist of 60-70 cellulose molecules which become tightly cross linked. Cell walls have multiple of these fibres running in different directions to increase strength. Still freely permeable.
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How do fatty acids join to glycerol and what bond is formed?
Fatty acids join glycerol by a condensation reaction (3 H2O molecules formed) and an ester bond (oxygen bond) is formed
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What is the difference between a saturated and unsaturated fat?
Saturated fats have no carbon-carbon double bonds, unsaturated fats have one or more of these double bonds
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1 Property of lipids
Unsoluble in water but dissolve in organic solvents such as alcohols and acetone
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5 Roles of Lipids
Excellent energy reserves, Acts as an insulator when stored under skin, Provides protection to vital organs such as kidneys when stored around them, Triglycerides produce a lot of metabolic water when oxidised - desert animals, Waterproofing
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Describe the structure and role of a phospholipid
A phospholipid has a similar structure to a triglyceride but instead of 3 fatty acids, they're made up of 2 fatty acids and a phosphate group. This creates a hydrophilic head and 2 hydrophobic tails. Used in the phospholipid bilayer
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What elements are Carbohydrates made up of?
Carbon, Hydrogen and Oxygen
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What elements are lipids made up of?
Carbon, Hydrogen and less oxygen in comparison to Carbon and Hydrogen
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What elements are Proteins made up of?
Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulphur
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What elements are Nucleic Acids made up of?
Carbon, Hydrogen, Oxygen, Nitrogen, Sulphur and Phosphate
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What is the monomer of proteins?
Amino acids
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What bonds are formed between molecules in primary structure proteins?
Peptide bonds
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What bonds are formed between molecules in secondary and tertiary structure proteins?
Peptide and Hydrogen bonds
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What forms can the secondary structure take?
alpha helix and beta pleated sheet
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What bonds are formed between molecules in quaternary structure proteins?
Peptide, Hydrogen, Sulphur and ionic
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Describe the structure of globular proteins and their functions
Compact and folded as spherical molecules. Soluble in water. Used as enzymes, antibodies, plasma proteins and hormones
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Describe the structure of fibrous proteins and their functions
Polypeptides in parallel chains or sheets with cross linkages to form long fibres. Insoluble in water, strong and tough. Keratin and Collagen
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How would you test for protein?
Add a few drops of Biuret reagent. Solution turns from blue to purple in presence of proteins
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Why is water a good solvent?
It is a polar molecule - attracts other charged particles
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What does 'high specific heat' mean?
A lot of energy is required to raise the temperature of water due to hydrogen bonds between molecules which restricts their movement
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What does 'high latent heat' mean?
A lot of energy is required to change it from liquid to vapour state
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5 properties of water
high specific heat, high latent heat, cohesive, high surface tension, transparent
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Other cards in this set

Card 2

Front

What bonds are used between two carbohydrates?

Back

Glycosidic bonds

Card 3

Front

Name 4 carbohydrates

Back

Preview of the front of card 3

Card 4

Front

What is the function of Starch?

Back

Preview of the front of card 4

Card 5

Front

What is the function of Cellulose?

Back

Preview of the front of card 5
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