L3: Carbohydrates Flashcards
What ratio of elements are found in carbohydrates?
1 carbon : 2 hydrogen : 1 oxygen
How are carbohydrates formed?
Carbon Dioxide + Water
Carbo = carbon; hydrates = water
Where does this process occur in nature?
In plants, carbohydrates are formed through photosynthesis.
Where do plants gets the energy to form the bonds in carbohydrates?
UV energy. It is locked in C-H bonds
How do organisms use carbohydrates?
Energy. Body transports energy in the form of complex carbohydrates and then hydrolyses the molecules to unlock the energy in the bonds.
What are three functions of carbohydrates?
- Rapid energy for cellular reactions
- Molecular structures (e.g. DNA sugar-phosphate backbone)
- Cell surface markers (blood group markers)
What are the simplest carbohydrates called?
Monosaccharides
What is the suffix when naming monosaccharides?
-ose
How many carbon atoms can a monosaccharide have?
3-10
What is pentose?
A monosaccharide with 5 carbon atoms
What would you name a monosaccharide with 4 carbon atoms?
Tetrose
Which functional groups are found in monosaccharides?
Hydroxyl, aldehyde, and ketone
What do you name a monosaccharide that has 5 carbons and an aldehyde group?
Aldopentose
Is glucose an aldose or a ketose?
Aldose
Is fructose an aldose or a ketose?
Ketose
What is a deoxy- monosaccharide?
Where a hydroxyl group is replaced by H. Include the carbon number that has been deoxylated. e.g. 2-deoxy-ribose
In stereoisomerism, which of the following are the same and which are different?
- Chemical formula
- Bond types and orders
- Spatial arrangements
- Biological functions
Same:
- Chemical formula
- Bond types and orders
Different:
- Spatial arrangements
- Biological functions
What is a chiral carbon?
A carbon with 4 different things attached to it
True or false: monosaccharides can exist in cyclic structures
True
How many C-H bonds are found in glucose?
7
How many C-H bonds are found in fructose?
7
After cyclisation of fructose, what type of ring is formed?
Furan - 4 carbons, 1 oxygen. Other carbons are found on branches
What is a disaccharide?
Two monosaccharides linked together
How do you form a disaccharide?
Dehydration synthesis
What biological molecules assist the formation of disaccharides?
Enzymes
What type of bond joins two monosaccharides?
Glycosidic link
What is the primary function of a disaccharide?
Nutritional source of monosaccharides
What are the monosaccharides in Maltose?
Glucose + Glucose
alpha 1,4 glycosidic link
What are the monosaccharides in Lactose?
Glucose + Galactose
beta 1,4 glycosidic link
What are the monosaccharides in Sucrose?
Glucose + Fructose
alpha 1,2 glycosidic link
How are disaccharides broken down?
Hydrolysis with enzyme assistance
Sucrose, maltose, and lactose are examples of what?
Disaccharide
Why are monosaccharides sometimes converted to oligo- and poly-saccharides?
To make them insoluble so they can be stored, be used in structures, or take part in cellular processes
What is a glycoprotein?
A protein that has oligosaccharide chains (glycan) attached covalently
What is a glycolipid?
A lipid that has oligosaccharide chains (glycans) attached covalently
What glycosylated molecules are important in immune recognition?
Glycoproteins in the cell membrane
What are mucins?
Secreted glycoproteins that form either components of mucous or saliva
What are GAGs?
Jokes. Jk, they are glycosaminoglycans. These are long, unbranched chains of repeating disaccharide units.
What are the two base components of glycosaminoglycans?
Amino sugars and uronic acids
True or false: GAGs are hydrophobic.
False. They are hydrophilic (-ve charge)
True or false: GAGs form gels.
True.
True or false: GAGs have a high viscosity and low compressibility.
True.
True or false: GAGs are good lubricants.
True.
True or false: GAGs add structural integrity.
True.
True or false: GAGs that are attached to proteins are known as mucopolysaccharides.
False. Mucopolysaccharides are NOT attached to proteins.
What do you call GAGs that are attached to proteins?
Proteoglycans
Chondroitin is an example of what molecule? What are its functions?
Proteoglycan - cartilage, heart valves and bones
Hyaluronic Acid is an example of what molecule? What are its functions?
Mucopolysaccharide - lubricant and shock absorber in synovial fluid and vitreous humour of the eye
What kind of molecule is usually associated with phospholipids on the outer surface of the cell membrane?
Glycolipids
When associated with phospholipids, what are the common functions of glycolipids?
Recognition signals, attachment factors, membrane stabilisers
Ceramide, sphingomyelin, cerebrosides, and gangliosides are all examples of what type of molecule?
Sphingolipids, which are a subtype of glycolipid
True or false: The most common type of starch is Amylopectin
True. It accounts for 70-80% of starch molecules and is a brush shape (like a T, where the lines are helical)
True or false: Amylose assumes a straight, unbranched shape.
False. It is a helical coil shape, and it accounts for 20-30% of starch molecules
True or false: Starch is the main source of carbohydrate in the diet.
True. It is found in the amyloplasts and chloroplasts of plant cells
True or false: Starch is digested by amylase and lactase.
False. It is digested by amylase and maltase
True or false: Starch is the main storage polymer of animals.
False. It is the main storage polymer of plants.
True or false: Glycogen is the main storage polymer of animals.
True. It is stored in the liver and muscle cells.
True or false: Glycogen branches more frequently than starch.
True. With branch points occurring every 8 to 12 residues.
What is the difference between alpha and beta glucose?
The position of the H and OH on the first carbon determine whether it is alpha or beta. In a-glucose, the H is up top. In b-glucose, the H is down.
