Carbohydrates Flashcards
What are the uses of carbohydrates?
- Source of energy (releases glucose when hydrolysed)
- Store of glucose
- Structural units
What are monosaccharides?
Monosaccharides are the monomers from which larger carbohydrates are made
Name 3 monosaccharides
- Glucose
- Galactose
- Fructose
What bond do two monosaccharides form?
A 1 - 4 glycosidic bond
How are disaccharides formed?
Disaccharides are formed by the condensation of two monosaccharides
How is maltose (a disaccharide) formed?
Maltose is formed by the condensation of two glucose molecules
Glucose + glucose → maltose + water
How is sucrose (a disaccharide) formed?
Sucrose is formed by the condensation of a glucose molecule and a fructose molecule
Glucose + fructose → sucrose + water
How is lactose (a disaccharide) formed?
Lactose is formed by the condensation of a glucose molecule and a galactose molecule
Glucose + galactose → lactose + water
What is an isomer?
Molecules with the same molecular formula but with the atoms connected in a different way
What are the two isomers of the monosaccharide glucose?
- α-glucose
- β-glucose
What is the difference between α-glucose and β-glucose?
α-glucose has its OH group linked below the ring and β-glucose has its OH group above the ring (on carbon 1)
How are polysaccharides formed?
Polysaccharides are formed by the condensation of many monosaccharides
Name 3 polysaccharides
- Glycogen
- Starch
- Cellulose
How is glycogen and starch formed?
Glycogen and starch are formed by the condensation of α-glucose
How is cellulose formed?
Cellulose is formed by the condensation of β-glucose
Where is starch found and what is its function?
- Found in plant cells (e.g in chloroplasts)
- It is an insoluble store of glucose
Where is cellulose found and what is its function?
- Found in cell walls of plant cells
- Provides structural strength
Where is glycogen found and what is its function?
- Found in animals cells (e.g liver and muscle cells)
- Store of glucose
What are the two types of starch?
- Amylose
- Amylopectin
Structures & features of amylose
coiled / compact
- allowing for a lot of glucose to be stored in a small space
insoluble
- does not dissolve in water + does not affect water potential of the cell
large
- cannot diffuse out of cells
hydrolysis releases α-glucose
- released to be used in respiration
Structures & features of amylopectin
coiled
- compact allowing for a lot of glucose to be stored in a small space
many side branches
- larger SA for enzymes to hydrolyse the glycosidic bonds
insoluble
- does not dissolve in water + does not affect water potential of the cell
large
- cannot diffuse out of cells
hydrolysis releases α-glucose
- released to be used in respiration
Structures & features of glycogen
compact - allows for a lot of glucose to be stored in a small space
highly branched (more than amylopectin) - larger SA for enzymes to hydrolyse the glycosidic bonds
insoluble - does not dissolve in water + does not affect water potential of the cell
large - cannot diffuse out of cells
hydrolysis releases α-glucose - released to be used in respiration
Structures & features of cellulose
chains run parallel to each other held by H bonds - provides collective strength
chains form microfibrils - provide collective strength and rigidity
overall strength - allows cells to develop turgor pressure, making them turgid; this helps plant cells maintain their shape
