Topic 1 BIO MOLECULES- carbohydrates Flashcards
What is sugar?
A soluble carbohydrate (usually a monosaccharide or disaccharide)
What is a monosaccharide?
Single (mono) sugar (saccharide) units
glucose+fructose
sucrose+water
glucose+galactose
lactose+water
What is the food test for starch
iodine solution/potassium iodide solution
What results do you get from the test for starch
positive- blue/black
negative- stays yellow/brown
What is the food test for sugar?
- benedict’s
What are the results for a non reducing sugar?
stays blue
What are the results for a reducing sugar
sample forms a green or yellow or orange or brick red precipitate (the higher the concentration of reducing sugar the further the colour changes)
name 3 monosaccharides
glucose
fructose
galactose
name 3 disaccarides
sucrose
maltose
lactose
name 3 polysaccharides
startch
glycogen
cellulose
is starch soluble or insoluble
insoluble
What is the function of starch?
stores energy for plants
Where is starch found and in what form
plants in the form of grains
What is a starch made up of
alpha glucose molecules linked together by glyosidic bonds
How are unbranched chains adapted for there function
coiled so can be stored in small cells
What forms a glucose which is used in respiration
hydrolose
How are branched chains adapted for their function
has many ends so can be broken off to form monomers more easily
Where is glycogen found
animal and bacterial cells
What are the differences between glycogen and starch
-Glycogen is more highly branched than starch (amylopectin)
-Glycogen branches every 10-15 glucose, amylopectin has branching every 25 glucose molecules
Is glycogen a major carbohydrate store in animals
yes
Where is glycogen stored
small granules in muscles and liver
Describe the structure and the function of cellulose?
-Betaglucose-inverted and normal glucose molecules form alternating glycosidic bonds to form straight, unbranched chains
-Hydrogen bonding- H bonds form between parallel strands, creating strong and stable molecules of cellulose
-Microfubrilis- parallel chains group to form microfibrils
-Fibrils- microfibrils group into fibrils that provide greater strength
What is starch is made up of ?
Two polysacharides:
-amylose
-amylopectin
What is amylose
unbranched chain of glucose molecules joined by 1’4 glycosidic bonds which as a result is coiled and stores a lot of energy compactly
What is amylopectin
branched glucose molecules joined by 1,4 and 1,6 glycosidic bonds
What happens at the end of the branches of amylopectin?
hydrolysis of the glycosidic bonds and they can be acted upon by enzymes and release energy
What happens when starch is hydrolysed
A glucose can be transported easily
What is a carbohydrate
molecules which consist of only carbon oxygen and hydrogen and they are long chains of sugar units called saccharides
how is a glyosidic bond formed
a condensation reaction between two monosaccharides
how are disaccharides formed
the condensation of two monosaccharides
How is maltose formed
condensation of two glucose molecules
how is sucrose formed
condensation of a glucose molecule and a fructose molecule
how is lactose formed
condensation of a glucose molecule and a galactose molecule
hoiw are polysaccarides formed
the condensation of many glucose units
how is cellulose formed?
condensation of b glucose
What is the unique bond?
-Glycosidic
What do the 3 monosaccharides have in common?
-They are isomers of each other (they have the same chemical formula but the atoms are arranged differently)
What is the difference between alpha glucose and beta glucose?
-Alpha glucose- OH is on the bottom right
-Beta glucose- H is on the bottom right
What is the structure of starch?
-Compact, coiled structure- a lot of glucose can be stored in a small space
-Large insoluble- does not diffuse out of cells so does not affect osmotic pressure within the cell
-Easily hydrolysed to glucose- valuable for respiration
-Amylopectin branching- more sites for hydrolytic enzymes to work, therefore glucose can be released faster
What is glycogen?
-Polysaccharide
-Made up of repeating alpha glucose units
-Only found in animal cells
Why is cellulose different to the other 2 polysaccharides?
-Made up of glucose molecules rather than alpha-glucose
What is a reducing sugar?
-A sugar that will donate electrons to another chemical therefore reducing the other substance
What is oxidation
-The gain of oxygen
-The loss of electrons
-The loss of hydrogen
What is reduction
-The loss of oxygen
-The gain of electrons
-The gain of hydrogen
OIL RIG
What is Benedict’s solution made up of?
-Alkaline solution of copper (II) sulfate
What is the method for Benedict’s test for reducing sugars
-Add a sample in liquid form to a test tube
-Add an equal volume of benedicts reagent
-Heat in a boiling (100c) water bath for 5 mins
What colour will the precipitate be if reducing sugars are present? Why?
-Red
-Because the copper II sulfate has been reduced to copper I oxide which is an insoluble red precipitate
What is the method to test for non-reducing sugars?
-Carry out benedicts test ]
-Add dilute HCL and boil gently
-Add Na HCO3
-Retest the sample with benedicts solution
How does the hydrochloric acid show results for a non-reducing sugar
-It hydrolyses any disaccharides into their monosaccharides, therefore showing a positive result in the second test
-The sodium hydrogen carbonate neutralises the hydrochloric acid
What colour does the solution turn if there is a positive result for starch?
blue/black
