Carbohydrates Flashcards
What are carbohydrates made of ?
Carbon , Hydrogen and Oxygen
What is the main purpose of carbohydrates in plants and animals ?
Store energy
What are monosaccharides ?
Simple sugars that cannot be broken down into other sugars.
A single sugar unti
Sweet and soluble
Give examples of monosaccharides
Glucose
Fructose
Galactose
What are disaccharides?
Two monosaccharides bonded together.
Give examples of disaccharides and what 2 monosaccharides they are made up of.
Maltose ( 2x glucose)
Sucrose ( Fructose and glucose)
Lactose ( Glucose and Galatose)
What are polysaccharides?
Chain of many monosaccharides bonded together.
Give examples of polysaccharides
Cellulose , starch and glycogen
What is the general formula of monosaccharides?
(CH2O)n
How many carbons does glucose have and therefore what type of sugar is it ?
6 therefore is is a Hexose.
How many carbons does Ribose have and therefore what type of sugar is it ?
5 - Pentose
Write down what type of sugar a molecule is depending on it quantity of carbons.
Mono -1 Di -2 Tri -3 Tetra -4 Pent-5 Hex-6 Poly- Many
Which way are the carbons numbered ?
Clockwise
What’s an isomer ?
The hydroxyl group is below the carbon 1 in alpha glucose and above carbon 1 in beta glucose.
Deadcjbe how maltose ( a disaccharide) can be formed ?
Two alpha glucose molecules (C1 and C4) meet.
Oh hydroxyl group from 1 glucose and H from the other glucose react.
Water is expelled as this is a condensation reaction.
It is called a a-1,4 glycosidic bond
What is the final bond in maltose called ?
a-1,4 glycosidic bond
How can a disaccharide become a monosaccharide again ?
Reversed bonding by hydrolysis
What is Benedictus test and describe how this was done.
The test for a reducing sugar.
2cmcubed of a food sample into a test tube and grind if not in liquid form.
Add equal volume of Benedictus solution and place in boiling water bath for 5 minutes.
An orange or brown colour indicates a presence of reducing sugar.
What happens if the colour does not change after Benedictus test and how is this tested ?
If the solution remains blue then sugar is not present.
Add another 2cm cubes of a food sample and hydrochloride acid into a test tube and place in boiling water bath for 5 minutes. The acid will hydrolyse any disaccharide present into monosaccharides.
Retest the solution using the Benedictus method.
If non- reducing sugar was present in the original sample you will not see an orange or brown colour. This is because reducing sugars were produced from the hydrolysis of the non-reducing sugar.
Which monomers make up starch ?
Alpha-glucose
Which monomers make up cellulose ?
Beta- glucose
Why is sucrose classifies as a carbohydrate ?
Carbon and hydrogen are in a 2:1 ration which is the same as water.
Explain why sucrose will prodcuee a positive result with Benedictus test only after it has been boiled with dilute acid.
Once the glycosidic bond has been hydrolysed, reducing sugars in the form of glucose and fructose monosaccharides will be formed.
Explain how proteins are suited to their roles as receptor molecules. Thanks
Many different types of proteins have different primary structures due to their different sequence of amino acids. This gives a tertiary structure and allows the formation of a receptor binding site in which the substrate can fit.
Explain why glucose and maltose both taste sweet but starch does not.
Glucose and maltose are soluble but starch is insoluble.
Describe a chemical test to identify starch.
Add iodine solution.
If it turns black or deep blue, starch is present.
What is the molecular formula for sucrose ?
C12H22O11
Explain what a positive biuret test shows and what this means.
A lilac/ purple solution would be shown as the sample is most likely a protein with enzymes which have peptide bonds.
What are the main uses of carbohydrates ?
They store energy in plants and animals.
Plant cell all’s depend on the structural roles of some carbohydrates.
What is a monosaccharide and give examples.
Simple sugars which can’t be broken down into other sugars.
Glucose , galactose and fructose.
What are disaccharides ? Give example.
Two monosaccharides bonded together by a glycosidic bond.
Sucrose - fructose + glucose
Lactose - glucose + galactose
Maltose - 2x alpha glucose
What two monosaccharides is sucrose made of ?
Fructose and glucose
What two monosaccharides is lactose made of ?
Glucose and galactose
What two monosaccharides is maltose made of ?
2 alpha glucose
What is a polysaccharide and give examples.
Chain of many monosaccarides.
Cellulose, starch and glycogen.
What type of sugar is glucose and why ?
Hexose sugar because it has 6 carbons.
What are the main uses of glucose.
Aerobic respiration
Makes other substances such as sucrose, starch, cellulose and glycogen.
What type of sugar is ribose and why ?
Pentose sugar because it has 5 carbons.
Where is ribose found.
In ATP and DNA.
When is the general formula for all monosaccharides?
C6 H12 06
What is the general formula for all disaccharides?
C6 H10 05
Loss of one H20 water molecule by a condensation reaction.
What type of reaction allows a monosaccharide to become a disaccharide ?
Condensation where a water molecule is replaced by a glycosidic bond.
In which direction are carbons numbered after the oxygen in carbohydrates ?
Clockwise.
What type of bond allows two monosaccharides to be bonded.
Glycosidic bond.
What are the 3 main polysaccharides and what are they all made of ?
Starch , glycogen, cellulose
All made from glucose
Which polysaccharide is often called animal starch and why ?
Glycogen because it is a major carbohydrate storage product in animals ?
In what type of organisms is glycogen found ?
Only in animals and bacteria. Never in plants
What is the structure of glycogen and what does this help ?
Explore the functions of glycogen.
Short chains which are highly branches. This means that each branch end can be acted on by an enzyme. This therefore helps it be rapidly broken into glucose monomers and creates a rapid metabolic rate in animals. Helps respiration.
It is stored in the muscles and liver of animals in granules of small mass.
It is insoluble so ensures a constant water potential and can’t diffuse out of the cell.
Is compact so many can be stored in a small area.
What two types of starch polysaccharide are there ?
Amylose and amylopectin
Describe the structure and fiction of amylose !
Alpha glucose in a helix structure.
Bonded by glycosidic bonds.
Describe he functions and structure of amylopectin.
Alpha glucose in a branched chain bonded by glycosidic bonds.
Acts as an energy store at is large and insoluble.
What polysaccharide is alpha glucose in branches chains ?
Amylopectin
What polysaccharide is alpha glucose in a helix structure.
Amylose.
Describe the structure of cellulose polysaccharide.
Beta glucose monomer in straight , unbranched, parallel chains.
Cross links are formed by hydrogen bonds.
Group to form microfibrils. Microfibrils then group to form fibres which are very strong.
What are the main functions of cellulose polysaccharide.
Give plant cell wall rigidity
Prevent osmotic lysis by creating an inward pressure which stops water coming in.
Makes cells turgid so they have a maximum surface area for photosynthesis.
Which polysaccharide is made of beta glucose bonded by glycosidic bonds ?
Cellulose
Explain in detail how cellulose’ structure is adapted for its fictions.
Cellulose is a polysaccharide made of only glucose monosaccharides. It has rows of beta glucose bonded by glycosidic bonds which are formed by a condensation reaction where water is expelled. The monosaccharides also have hydrogen cross links which create a strong cell wall which helps to prevent osmotic lysis in cells as cellulose exerts inward pressure- stopping more water entering the cell.
Each beta glucose is rotated 180 degrees to allow the glycosidic bonds.
1:4 glycosidic bonds.
Explain the different in the structure of starch molecules and cellulose molecules.
Starch is made from alpha glucose bonded by glycosidic bonds. Whilst cellulose is made of beta glucose, of which every other glucose molecule is inverted 180 degrees
Explain a way starch molecules are adapted for their functions in plant cells.
They are insoluble and therefore don’t affect water potential.
Explain how cellulose molecules are adapted for their functions in plant cells.
Cellulose molecules are aligned in parallel lines with strong hydrogen cross links called fibrils. This means that they allow cell walls to maintain rigidity and be very strong.
Explain why triglycerides are not considered polymers
They are not made of monomers
What is the formula for lactose ?
C12 H22 O11
Why is sucrose a carbohydrate ?
Sucrose has the same ratio of carbon:hydroxyl bonds as water.
What is indicated by a positive biuret test ?
Enzymes are present and have peptide bonds.
What is the test for starch ?
Add drops of iodine solution to sample. Black / brown colour change indicated the presence of starch.
How does the starch test with iodine Work ?
During the formation of iodine , starch forms a complex intense dark colour.
