Carbohydrates
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What are all carbohydrates composed of?
Consists of single units called monosaccharides containing only carbon, hydrogen and oxygen.
Differentiate between the different types of saccharides.
Monosaccharide=single sugar unit Disaccharide=2 sugar units Polysaccharides=3 or more sugar units
What is the general formula for monosaccharides?
(CH2O)n
Name 2 isomers of glucose.
Alpha and beta glucose
Name the monosaccharides in lactose.
B glucose and galactose
What is the source of lactose?
Main carb in milk
Name the monosaccharides of maltose
Glucose and glucose
Where might hydrolysis take place?
During digestion in the gut and in muscle and liver cells when carbs are broken down during respiration
What are the 3 main types of polysaccharides?
Starch, glycogen and cellulose
What is starch used for?
Energy storage in plants
What compounds of A glucose make up starch?
Amylose and amylopectin
Describe the structure of amylose.
Long, unbranched chains of α-glucose Angles of glycosidic bonds makes it a coiled structure, this makes it compact and good for storage. Amylose is insoluble so does not effect water potential, contain 1-4 glycosidic bonds
Describe the structure of amylopectin?
Long, branched chains of α-glucose. Has side branches which allows enzyme to hydrolyse bonds more easily so glucose is released quickly, amylopectin is insoluble so does not effect water potential inside a cell, contain 1-4 glyosidic bonds and branches with 1-6 glycosidic bonds
What are the roles of amylose and amylopectin in starch?
Amylose releases glucose slowly over a longer period of time keeping you going longer. Amylopectin releases glucose rapidly for cellular respiration
What is glycogen used for?
Only carbohydrate energy store in animals
How does glycogen differ from starch?
Glycogen molecule has more 1,6 glycosidic bonds giving it many more side branches, meaning it can be broken down more rapidly
Why is glycogen branched?
The branched structure means that it can be used as a source of glucose for active tissues with a constantly high rate of cellular respiration such as muscle and liver tissue
What is cellulose made of?
Long unbranched chains of B glucose
Why can humans not digest cellulose?
We lack the enzyme needed to break the 1,4 glycosidic bonds between B glucose
How does Beta glucose differ from Alpha glucose?
One of the -OH swaps with the H.
The internal conditions within the body are maintained by homeostatic mechanisms. The regulation of blood glucose involves homeostatic mechanisms. (i) Describe how glucose moves into cells by facilitated diffusion
• Carrier protein in cell surface membrane • Glucose moves from high to low conc • Glucose binds to carrier protein and protein changes shape
Explain how the structure of glycogen allows it to be an energy store
• Glycogen is a polymer of glucose • Provides glucose for respiration • Contains 1,6 glycosidic bonds for rapid hydrolysis
Describe the reaction that joins two α-glucose molecules to form a disaccharide
• Condensation reaction involving -OH groups on either side
Carbohydrates are used as a source of energy. Excess carbohydrate can be stored as glycogen in animal cells. (a) Give two reasons why glycogen is used as a storage molecule.
• Compact and insoluble