B4 & B5 test (5th Dec) Flashcards
What are the three main biological molecules?
Carbohydrates, Lipids and Proteins
What are monomers
Monomers are small, simple molecules that can join together to form larger molecules called polymers through chemical bonds.
What are polymers
Polymers are large molecules made by joining many monomers together in a chain through chemical reactions.
What are carbohydrates
Molecules consisting of Carbon, Hydrogen & Oxygen. (2 hydrogens for every 1 carbon and 1 oxygen)
What are carbohydrate monomers
monosaccharides
What are carbohydrate polymers
polysaccharides
What is an example of a monossacharide
glucose
What is a disaccharide
A disaccharide is a type of sugar made when two monosaccharides (simple sugars) join together.
What are examples of polysaccharides
starch, glycogen and cellulose (long chains of glucose molecules)
What are example of a disaccharide
Lactose, sucrose
What is a monosaccharide
A monosaccharide is a simple sugar that consists of only one sugar unit.
What are proteins made of
amino acid monomers that have a variety of forms and functions.
What do amino acids consist of
molecules comprised of carbon, hydrogen, oxygen and nitrogen atoms
What are polypeptides
Polypeptides are long chains of amino acids joined together by peptide bonds
How do our bodies process proteins
They disintegrate these amino acid chains to make their own proteins out of the monomers. These go to each of our cells
What do enzymes do in the body?
They catalyse chemical reactions
e.g Amylase breaking down carbohydrates
What do transport proteins do in the body
Movement of materials
e.g Haemoglobin carrying oxygen to cells
What do motor proteins do in the body
Causes movement
e.g actin and myosin in muscle cells
What do defense proteins do in the body
protect against infections
e.g antibodies of the immune system
What are lipids
macromolecules that consist of glycerol and fatty acids
What are lipids characterised by
hydrocarbon chains consisting of carbon, hydrogen and oxygen
What are lipids soluble in
organic solvents such as ethanol
insoluble in water
How do you test for reducing sugars and what would results be
Add Benedict’s solution to the sample.
Heat the mixture in a water bath at ~80°C
Results:
Positive: The solution changes from blue to green, yellow, orange, or brick-red, depending on the amount of reducing sugar.
Negative: The solution stays blue (no reducing sugar present).
How do you test for starch and what would the results be
Add a few drops of iodine solution to the sample.
Results:
Positive: The solution turns blue-black (starch is present).
Negative: The solution stays orange-brown (no starch present).
How do you test for Proteins and what would the results be
Add Biuret solution (a mixture of sodium hydroxide and copper(II) sulfate) to the sample.
Gently shake the mixture.
Results:
Positive: The solution turns purple (protein is present).
Negative: The solution stays blue (no protein present).
How do you test for lipids and what would results be
Add ethanol to the sample and shake to dissolve any lipids.
Then add water and shake again.
Results:
Positive: A milky white emulsion forms (lipids are present).
Negative: The solution remains clear (no lipids present).
What are enzymes
An enzyme is a protein and a biological catalyst that speeds up chemical reactions without being used up in the process
what does each type of enzyme have
a unique active site which a specific substrate can bind
what is a substrate
a substance on which the enzyme can act
what is the shape of the active site in relation to the substrate
it is complementary to the substrate
what does the enzyme and substrate form when binded
an enzyme-substrate complex
What is the active site
The active site is the region of the enzyme where the substrate binds and the reaction occurs.
What is meant by the lock and key model of enzyme action?
the enzyme’s active site has a specific shape that fits only one type of substrate, like a key fitting into a lock.
What happens after the product (different to the original substrate) is formed
the enzyme remains unchanged and is recycled
What is the enzyme for lipids?
lipase- break down fats into fatty acids and glycerol
What is the enzyme for starch
amylase- breaks down larger carbohydrates into smaller monomers: e.g glucose
What is the enzyme for proteins
Protease (e.g Pepsin)- breaks down proteins into amino acids.
enzyme for lactose
lactase- breaks down lactose into glucose and galactose sugars
What is enzyme denaturation?
Denaturation occurs through the breaking of bonds between enzyme particles when an enzyme’s structure changes due to factors like high temperature or extreme pH, causing it to lose its ability to bind with the substrate.
Enzymes not only ______ substances apart but also ______ them __________
break
bind
together
How does temperature affect enzyme activity?
As temperature increase, molecules have more kinetic energy, this increases the rate of reactions
Rate of enzyme-catalysed reactions is greatest at a specific optimum temperature.
Temperatures greater than the optimum temperature results in denaturation of the enzyme.
Rate of reaction decreases as the active site of the enzyme is no longer a complimentary shape to the substrate. Enzyme-substrate complexes can no longer form.
How does PH effect enzyme activity
Enzymes have an optimum pH at which the rate of enzyme catalysed reactions is highest.
A change of pH on either side of the optimum (lower or higher pH) results in a change in shape of the enzyme’s active site.
This causes denaturation of the enzyme as the active site is no longer a complimentary shape to the substrate. Enzyme-substrate complexes can no longer form.
Is optimum PH the same for every enzyme?
no, depending on the enzyme, some types can have higher or lower optimum PH’s and temperature
e.g Pepsin works best in acidic conditions as they are located in the stomach.
What is substrate concentration and how does it affect enzyme activity?
Increasing substrate concentration increases enzyme activity, but only up to a point where the enzyme becomes saturated, and the rate of reaction levels off.
difference between the structure of a protein and a carbohydrate
Proteins: Made of amino acids linked by peptide bonds, forming polypeptide chains with complex folding.
Carbohydrates: Made of sugar molecules (monosaccharides) linked by glycosidic bonds, forming chains or rings.
explain the effect of temperature on enzyme activity at temperatures below optimum
the rate of reaction decreases, but the enzyme remains functional as long as the temperature is not too low to cause denaturation.
what is a polysaccharides
A polysaccharide is a complex carbohydrate made up of many monosaccharides linked together in long chains.
whats the pH to maximise reaction rate for amylase
alkaline: pH 8- 10
Whats the pH to maximise reaction rate for pepsin
acidic: pH2-4
Whats the pH to maximise reaction rate for lipase
alkaline: pH8
how would you answer to ‘write a conclusion based on the results from this investigation’ - the effect of temperature on the rate of enzyme activity (amylase)
Something like: as temperature increases the time taken for the amylase to digest the starch decreases; the starch is digested most quickly at approx. 37C; above 45C the time taken for the starch to be digested starts to increase.
predict what would be observed if the investigation was carried out at 65C
the time taken for the starch to be digested would be greater than/the same as 55C
draw a labeled diagram of an enzyme substrate complex
single clear line
drawing at lease 4cm square
shape of active site complementary to shape of substrate/ substrate fits exactly into active site
explain the significance of the following statement: enzyme behaviour and function depend on the unique shape and structure of the enzyme
shape of active site is unique and specific to a particular substrate.
