B1-Biological molecules Flashcards
What is the test for reducing sugars?
What is the colour change?
Benedicts test
Blue-Red
What is the test for starch?
What is the colour for a positive result?
Iodine test
Blue/black
What is the test for lipids?
What is the positve result?
Emulsion test
White emulsion forms at surface
What is the test for protien?
What is the positive result?
Biuret test
Changes from blue to Purple
What is a carbohydrate made of
Carbon, hydrogen and oxygen
What is a monosaccharide?
It is a monomer of carbohdrate.
The simplest carbohydrate.
What is a disaccharide?
Two monosaccharides bonded together
What is a polysaccharide?
Many monosaccharides bonded together.
Respiration equation
glucose+oxygen > Carbon dioxide+water
Properties of glucose
Very small-making it easy to be transported into cells.
Soluble-makes it easlily transported around organisms.
What is a condensation reaction
A reaction where two molecules are bonded to form one molecule. Water is lost during the reaction.
what is a hydrolysis reaction?
Involves using water to break down larger molecules.
List monosaccharides
Fructose
Glucose
Galactose
list disaccharides
Maltose
Lactose
Sucrose
Glycosidic bond:
A bond formed between two monosaccharides in a condensation reaction.
What are polysaccharide properties
Insoluble
Not sweet tasting
Variety of different forms
large molecule
Easily broken- energy is readily accesible
Were is starch found in a plant
Found in photosynthesising cells in the leaves.
storage cells in the leaves.
Storage organs.
What organelle is starch stored in plants
Amyloplasts
Different structures of starch in plants:
Amylose and amylopectin
What is amylose
Amylose is a long chain A-glucose molecule joined together by a 1,4 glycosidic bond.
How can amylose be broken down to access the a-glucose
The glucoes store amylose can be broken down by the enzyme amylase.
It is a slow process
What is amylopectin
It is a long chain of A-glucose molecules joined together by a 1,4 glycosidic bond.
However it has an occasional 1,6 glycosidic bond.
What is the main polysaccharide energy store found in animals
glycogen
Where is glycogen found
It is found in cells with high metabolic rate
( muscel cells and liver cells)
What is the structure of glycogen?
glycogen has a similar structure to amylopectin. A-glucose molecules joined by 1,4 and 1,6 glycosidic bonds
How is glycogen broken down.
It can be broken down very fast and it has a high ammount of accesible ends making energy easily accesible. It can be easily hydrolysed to access the a-glucose molecules.
Why do animals use glycogen but plants do not.
Becuase animals have higher metabolic requirements than plants. They are much more mobile.
What is celllulose?
It is a polysaccharide and it gives cells its shape and stops plant cells from bursting.
What is the composition of cellulose?
Cellulose is made from many B-glucose molecules joined together by a 1,4 glycosicdic bond.
Bonding in cellulose
Cellulose chains are very straight allowing for many chains to run parallel. Individual hydrogen bonds are weak however many thousands of hydroxyl groups (hydrogen bonds) make cellulose very strong.
What is a microfibril
It it a fine fibre of strand made from cellulose.
How are plant cells strong and rigid.
Microfibrils wrap around plant cells in multiple layers. This provides extra strength to the cell wall.
What enzyme breaks down cellulose
Cellulase.
Most animals lack the enzyme needed to break down cellulose.
Why is cellulose important in the human diet?
It provides fibre in order to keep the digestive system healthy.
What is chitin?
It is a structural poysaccharide that can be found in fungi and insects.
What is chitin function in a fungi?
Strengthens the cell walls
What is chitins function in insects?
Give strength to insects exo skeleton.
Chitin is also waterproof which helps reduce water loss from their body.
What is the molecular structure of chitin?
It is composed of B-glucose molecules joined by a 1,4 glycosidic bond.
What are the two main types of lipids.
Tryglycerides and phospholipids
What is the role of phospholipids?
They are used to build up cell membranes.
What is the role of tryglicerides?
They are a good source of energy (oil, butter and fats )
Lipids ……
Composed of mostly carbon,hydrogen and some oxygen.
They not a polymer but a macromolecule.
They are non polar as they dont dissolve in water.
Molecular structure of triglycerides
One molecule of glycerol and 3 molecules of fatty acids
What is an ester bond
It is a bond formed between the glycerol and a fatty acid via a condensation reaction.
What is molecule is made when 3 ester bonds form
A tryglyceride
What are the main roles of proteins?
Structural roles (bones, tendons, muscels)
metabolic roles (enzymes)
Transport roles (haemaglobin transtports oxygen)
What are amino acids
Amino acids are the monomers of protiens
What is the basic structure of amino acids
They all have a central carbon with a carboxyl group a hydrogen group an amino group and an R group. All amino acids have the same basic structures but have a different R group.
What is a polypeptide?
It is an unbranched chain of amino acids held together by peptide bonds.
What is the primary protein structure?
It is an unbranched chain of amino acids.
What are the secondary protein structures?
Hydrogen bonds causes the chains to twist.
Long polypeptide chains are twisted (alpha helix)
Sheats of polypeptide twited chains called beta pleated sheats.
What is the tertiary protein structure?
The tertiary structure is a 3 dimenstional shape of a protein. It consists of one or more secondary structures.
What is the quaternary protein structure?
They are made of More than one polypeptide chain to form a complex protein molecule.
Globular proteins:
They have a spherical shape caused by folded polypeptide chains. They have hydrophilic R groups on the outside making them soluble in water.
Fibrous proteins:
They are formed by parallel polypeptide chains. Polypeptide chains are wound up which makes fibrous proteins very strong.
Roles of globular proteins:
They have metabolic roles such as:
Enzymes-lipase
Transport proteins-haemoglobin
Hormones-insulin
Antibodies
Importance of haemoglobin:
It has an important role of the transport of oxygen from the lungs to body tissues in red blood cells.
Importance of the globular protein insulin:
Helps maintain blood glucose concentration.
Secreted in the pancreas.
Roles of fibrous proteins:
They have structural roles such as:
Collagen- forms tendons
keratin-hardens finger nails
esalstin-makes tissues strechy.
Collagen:
Collagen forms very strong fibres which is used to provide strenghth for many parts of the body. It is found in artery walls to stop vessels from bursting.
It is also used to make bones.
Keratin:
Used for hard parts of the body such as fingernails and horns.
