3.3 and 3.4 - Carbohydrates Flashcards
(44 cards)
What elements do carbohydrates contain?
Carbohydrates are molecules that contain only the elements carbon, hydrogen and oxygen.
The literal meaning ‘hydrated carbon’.
What are carbohydrates also known as?
Saccharides or sugars.
What is a single sugar unit called?
A monosaccharide.
Give three examples of monosaccharides.
Glucose, fructose and ribose.
How are two monosaccharides that are joined together called?
A disaccharide.
Give two examples of disaccharides.
Lactose and sucrose.
When two or more monosaccharides are joined together, what is that molecule called?
A polysaccharide.
Give three examples of polysaccharides.
Glycogen, cellulose and starch.
What is the chemical formula for glucose?
C6H12O6
What does it mean if a molecule, for example glucose, is called a hexose monosaccharide?
It means that it contains 6 carbon atoms.
What is the difference between alpha glucose and beta glucose?
The difference between the two is the positioning of the hydroxyl - OH - group. It is in opposite positions on carbon 1.
How are the carbons numbered in molecular structure diagrams?
They are numbered in a clockwise direction, with carbon 1 starting from the right, going to the left.
How are the glucose molecules soluble in water and polar?
It is due to the hydrogen bonding between the hydroxyl groups and water molecules.
Why is it important that glucose is soluble in water?
The solubility in water is important as it means that glucose can be dissolved in the cytosol of the cell.
What reaction takes place between two alpha molecules and how?
What is the bonding that takes place called?
A condensation reaction takes place between the two alpha glucose molecules when they are side by side.
The two hydroxyl groups interact, one on carbon 1 and one on carbon 4, and a covalent bond called a glyosidic bond is formed.
When this happens bonds are broken and new bonds are reformed in different places producing new molecules.
As it is a condensation reaction, a water molecule is produced as a result of this interaction.
Two hydrogen molecules are removed along with one oxygen molecule.
Name two pentose monosaccharides.
Ribose in RNA, and deoxyribose in DNA.
How is glucose made in plant cells?
Through photosynthesis.
What kind of energy store is glucose?
Chemical energy store.
What are the two polysaccharides found in starch, and what is the difference in their bonding?
Amylose and amylopectin
Amylose is bonded only by 1,4 glycosidic bonds.
WHEREAS,
Amylopectin is bonded by 1,4 glycosidic bonds, BUT, amylopectin has a branched structure occurring every 25 glucose subunits causing 1,6 glycosidic bonding.
What is the structure and properties relating to the structure of amylose?
Amylose is joined by 1,4 glycosidic bonds, and the angle of the bonding means that this long chain of glucose twists to form a helix.
This makes the polysaccharide more compact and much less soluble than the glucose used to make it.
What is the structure and properties relating to the structure of amylopectin?
Amylopectin also has 1,4 glycosidic bonding, but some glycosidic bonds are formed between carbon 1 and 6.
This occurs approximately every 25 glucose subunits.
This means amylopectin has a branched structure.
What is the functionally equivalent energy storage to starch used in animals and fungi called?
Glycogen
What is the energy store in plants called?
Starch
What is the structure of glycogen and how does it relate to its function?
Glycogen forms more branches than amylopectin, therefore making it more compact and much less space is needed for it to be stored.
The branching also means that there are a lot of free ends where glucose molecules can be added or removed.
