Topic 1- Carbohydrates Flashcards
What elements do all carbohydrates contain?
Carbon, hydrogen and oxygen
What ratio are Hydrogen and oxygen always in?
2:1
What are the 3 types of carbohydrates
monosaccharides, disaccharides and polysaccharides
Define monosaccharide
Single sugar monomer
Define disaccharide
a sugar formed from 2 monosaccharides joined by a glyosidic bond in a condensation reaction
Define polysaccharide
a polymer formed by many monosaccharides joined by glyosidic bonds in a condensation reaction
Give 2 examples of monosaccharides
-Ribose (5c)
-Glucose (6c)
Give 3 examples of disacharides
-Lactose (a glucose+ b galactose)
-Sucrose (a glucose + fructose)
-Maltose (a glucose + a glucose)
Give 3 examples of polysacharides
-Cellulose (b glucose)
-Starch (a glucose in the form of amylose and amylopectin)
What are the functions of monosaccharides?
-Source of energy in respiration
-Building blocks of polymers
What are the functions of disaccharides?
-Sugar found in germinating seeds ( maltose)
-Mammal milk sugar (lactose)
-Sugar stored in sugar cane (sucrose)
What are the functions of polysaccharides?
-Energy storage (plants- starch) (animals-glycogen)
-Structural- cell wall
How are sugars classified a reducing or non reducing?
Whether they can donate electrons or not
Which sugar can donate electrons?
-Reducing sugar
-the carbonyl group becomes oxidised
Give some examples of reducing sugars
glucose, fructose and galactose
Different 1._____ = Different properties
1.Structural formula
OILRIG
Oxidation is loss, reduction is gain
What is the molecular formula for glucose?
C6H12O6
Why is glucose known as an isomer?
Glucose exists in two structurally different forms – alpha (α) glucose and beta (β) glucose
ABBA
-Alpha is below (OH)
-Beta is above (OH)
Do starch and glucose only contain alpha glucose?
Yes
Does cellulose just contain beta glucose?
yes
why are monosaccharides bonded to form disaccharides and polysaccharides?
to make them more suitable for transport, storage and to have less influence on a cell’s osmolarity
Which reactions are glyosidic bonds formed by?
Condensation reaction
On which part of the molecule do the glyosidic bonds form on?
On the hydroxyl group (-OH)
Types of glyosidic bonds for Maltose,Sucrose,cellulose,amylose
and Amylopectin
-Maltose a 1-4
-Sucrose a 1-2
-cellulose b 1-4
-amylose a 1-4
-Amylopectin a 1-4 and 1-6
When is the glyosidic bond broken?
During a hydrolysis reaction
Why are starch and glycogen good storage molecules?
-Compact (so large quantities can be stored)
-Insoluble (so will have no osmotic effect, unlike glucose which would lower the water potential of a cell causing water to move into cells, plant cells would then have to have thicker cell walls, and animal cells would burst under the increased pressure
Give some features of amolysose
-Unbranched helix-shaped chain with 1,4 glyosidic bonds between α-glucose molecules
-The helix shape enables it to be more compact and thus it is more resistant to digestion
Give some features of amylopectin
-1,4 glyosidic bonds between α-glucose molecules but also 1,6 glyosidic bonds form between glucose molecules creating a branched molecule
-The branches result in many terminal glucose molecules that can be easily hydrolysed for use during cellular respiration or added to for storage
What is glycogen
-A storage molecule in animals and fungi
Where is glycogen most commonly found?
Muscles and the liver
Is glycogen more or less branched than amylopectin?
More branched so more compact which helps animals store more
Is cellulose a polysaccharide?
Yes
Give some features of polysaccharides
Branched or unbranched
Folded (making the molecule compact which is ideal for storage, eg. starch and glycogen)
Straight (making the molecules suitable to construct cellular structures, eg. cellulose) or coiled
Polysaccharides are insoluble in water
What is the structure of cellulose?
-Is a polymer consisting of long chains of β-glucose joined together by 1,4 glycosidic bonds?
-Due to the inversion (because it is an isomer (same molecular formula but different structure) of a glucose) of the β-glucose molecules many hydrogen bonds form between the long chains giving cellulose its strength
What is the function of cellulose
-main structural component of cell walls due to its strength which is a result of the many hydrogen bonds found between the parallel chains of microfibrils
-The high tensile strength of cellulose allows it to be stretched without breaking which makes it possible for cell walls to withstand turgor pressure
-The cellulose fibres and other molecules (eg. lignin) found in the cell wall form a matrix which increases the strength of the cell walls
-The strengthened cell walls provide support to the plant
-Cellulose fibres are freely permeable which allows water and solutes to leave or reach the cell surface membrane
-As few organisms have the enzyme (cellulase) to hydrolyse cellulose it is a source of fibre
