3.1.2 Carbohydrates (C1) Flashcards
Name a structural polysaccharide
Cellulose (plant cell walls)
Which elements make up carbohydrates?
Carbon
Hydrogen
Oxygen
When 2 monosaccharides join together, they form a…
Disaccharide
What happens during a condensation reaction?
A water molecule is released from the reacting molecules
How many covalent bonds does carbon make?
4
Which type of reaction takes place when two monosaccharides join together?
Condensation Reaction
Polysaccharides are large. This means that they…
are insoluble (will not dissolve)
Cannot escape from the cell
Identify the monosaccharide
α-Glucose
What happens during hydrolysis
A water molecule reacts with a polymer to break it down.
Name the bond that forms between two monosaccharides
Glycosidic bond
What is the difference between 1,4 and 1,6 glyosidic bonds
The numbers refer to which carbon in the molecule the bond is joined to
Which type of reaction takes place when a disaccharide or polysaccharide is broken down?
Hydrolysis
Name 3 common disaccharides
Maltose (alpha glucose + alpha glucose)
Sucrose (alpha glucose + fructose)
Lactose (alpha glucose + galactose)
What is an isomer?
Molecules that have the same chemical formula but whose atoms are arranged differently.
A 6 carbon sugar is called a…
hexose sugar
A 5 carbon sugar is called a…
pentose sugar
Glucose + Fructose
Sucrose
Glucose + Glucose
Maltose
Glucose + Galactose
Lactose
A 3 carbon sugar is called a…
triose
The general chemical formula of a monosaccharide is…
(CH2O)n where n is the number of carbon atoms.
Identify the monosaccharide
β-Glucose
When many monosaccharides join together, they form a…
polysaccharide
An individual sugar molecule is called a…
monosaccharide
Name 4 common hexose monomers
α-Glucose
β-Glucose
Galactose
Fructose
Name 2 common storage polysaccharides
Glycogen
Starch
Name the two molecules that make up starch
Amylose and Amylopectin
What are polysaccharides used for?
Storage (energy)
Structure (cell walls)
Name the monomer that makes up maltose
2 x alpha glucose
sucrose hydrolysis produces..
fructose and
alpha glucose
Describe the structure of starch
Alpha glucose monomers
Polysaccharide
Has 1-4 glycosidic bonds
Amylose is helical
Amylopectin is branched and has additional 1-6 glycosidic bonds
How is the structure of starch related to the function?
Insoluble so doesn’t effect water potential
Compact so doesn’t take up much space
Branched so accessible for respiration
Describe the structure of glycogen
Alpha glucose monomers
Polysaccharide
Has 1-4 glycosidic bonds
Is branched and has many additional 1-6 glycosidic bonds
How is the structure of glycogen related to the function?
Highly branched so accessible for respiration
Describe the structure of cellulose
Beta-glucose monomers
Polysaccharide
Has 1-4 glycosidic bonds with alternating molecules being rotated by 180 degrees
Straight, unbranched chains
How is the structure of cellulose related to its function?
Straight chains ideal for cell wall, have crosslinks for stability
Long, straight/unbranched chains of β glucose;
Joined by hydrogen bonding;
To form (micro/macro)fibrils;
Provides rigidity/strength;
Give 2 differences between the structure of cellulose and glycogen
celluose molecules straight chains;glycogen branched
cellulose beta glucose;glycogen alpha glucose
celluose molecules straight chains; glycogen coiled
celluose has only 1, 4 glycosidic bonds; glycogen has 1,4 and 1,6 bonds
Desccribe and explain 2 features of starch that makes it a good storage molecule
coiled/helical making it compact
insoluble so does not affect the water potential of cells
Large so can’t cross the cell membrane
Branched so more ends for enzyme action
Name the chemical which tests for starch?
iodine,it turns blue/black in the presence of starch
Describe how lactose is formed
alpha glucose and galactose
join by condensation reaction
through a glycosidic bond
What is the test for reducing sugars?
Add Benedict’s reagent
Boil in a waterbath
Brick red colour indicates a reducing sugar
What is the test for non-reducing sugars?
Carry out benedict’s test and see a negative result
Boil in a water bath with hydrochloric acid
Neutralise the acid with sodium hydrogen carbonate
Carry out Benedict’s test – a brick red result indicates a reducing sugar.
E.g. sucrose (this is the only one you need to remember)
What do we mean when we say that the Benedict’s Test for Reducing Sugars is ‘semi-quantitative’?
That the colour of the result can be used to estimate the approximate amount of reducing sugar in a sample
Name a disaccharide that is a non-reducing sugar
Sucrose
Which two reducing sugars are released when sucrose is hydrolysed?
Glucose and Fructose
How could you improve the validity of a Benedicts test?
Use a colourimeter to removed subjectivity
Unbranched starch (amylose) coils into a…
compact helix structure
What form does starch take within plant cells?
Starch grains
Which type of bond forms between branching α-glucose molecules in glycogen?
α 1-6 glycosidic bonds
Which type of bond forms between unbranched starch (amylose) molecules?
α 1-4 glycosidic bonds
How is glycogen different to starch?
Glycogen has many more branches
Which type of organism contains starch?
Plants
What form does glycogen take in cells?
granules within muscle and liver cells
Which monosaccharide is cellulose made from?
β-Glucose
What type of reaction occurs when monosaccharides join?
Condensation reaction
How does the structure of glycogen make it suited to its function?
It is insoluble so does not cause water to move into the cell via osmosis
It is large so does not diffuse out of animal cells
It is compact
It forms α-Glucose when hydrolysed for respiration
Many more branches than starch allow α-Glucose to be released faster from glycogen
What is the function of glycogen?
an energy store for animal and bacterial cells
What is the function of cellulose?
Cellulose is a major component of plant cell walls and provides rigidity to plant cells
Stops plant cells bursting when water enters
How are parallel chains of cellulose held together?
hydrogen bonds (crosslinks)
What structure does cellulose take?
Long unbranched chains that run parallel to each other
Which type of monosaccharide is starch made from?
α-Glucose
Which type of bond forms between branched starch (amylopectin) molecules?
α 1-6 glycosidic bonds
Which type of bonds join β-Glucose molecules when they form cellulose?
β 1-4 glycosidic bonds
Cellulose chains are arranged in parallel groups called….
microfibrils
Why does glycogen require more branches than starch?
Animal cells require more energy to function
How does the structure of starch make it suited to its function?
It is insoluble so does not cause water to move into the cell via osmosis
It is large so does not diffuse out of plant cells
It is compact
It forms α-Glucose when hydrolysed for respiration
Many branches allow α-Glucose to be released fast
Describe the structure of glycogen
POLYMER of alpha glucose
joined by glycosidic bonds
branched structure
How does glycogen act as a source of energy?
branched chains are HYDROLYSED
into glucose
used in respiration
Which type of monosaccharide is glycogen made from?
α-Glucose