Carbohydrates Flashcards
For the glucose oxidase method what substances can falsely decrease glucose deduced (inferred measurement) if their levels are high (increased)?
Uric acid, bilirubin and ascorbic acid.
What is the greek word for “sugar”?
Saccharides
What is our main source of energy in our diet? What % is it?
Carbs, 80% of our body’s energy comes from carbohydrates.
What particular organs in particular need carbs?
Carbs are the primary energy source for the brain, erythrocytes and retinal cells.
Nervous system totally depends on it as it cannot store carbs and so needs a steady supply to function properly.
Where are carbohydrates stored in the body?
Liver and muscle.
What other sources of energy that are in the body that can be used by our cells for energy?
Amino acids and lipids.
What elements are carbohydrates composed of?
C, H, and O.
What molecular functional groups are contained within carbohydrates?
Contains C = O (carbonyl) and -OH (hydroxyl) functional groups.
What are two carbohydrate utilization diseases?
Hypoglycemia and
Hyperglycemia.
What are carbohydrates classification based on?
- Size of base carbon chain - 3C, 4C, etc.
- Location of the CO (i.e. C=O) functional group.
- Number of sugar units - number of monosaccharides.
- Stereochemistry of the compound.
What are 3, 4, 5 and 6 carbon chains called?
Triose (3 C atoms)
Tetrose (4 C atoms)
Pentose (5 C atoms)
Hexose (6 C atoms)
How many sugar units does a disaccharide, a oligosaccharide, and a polysaccharide have?
Disaccharide - Two monosaccharides.
Oligosaccharide - 2 - 10 sugar units
Polysaccharide - > 10 monosaccharides.
What is the definition of a monosaccharide and name some examples?
- Monosaccharides are simple sugars that cannot be hydrolyzed to a simpler form.
- E.g. Glucose, fructose, and galactose.
What is a disaccharide? Name some examples.
- Two monosaccharides joined by a glyosidic bond.
2. E.g. Sucrose, lactose, maltose.
What does the hydrolysis of a disaccharide make? What is the purpose?
- Hydrolysis of a disaccharide makes 2 monosaccharides.
2. Allows for absorption.
How many sugar units does an oligosaccharide have?
Oligosaccharide has 2 - 10 sugar units.
What are some examples of Polysaccharides?
Glycogen and starch.
What does hydrolysis and condensation reactions (aka dehydration synthesis) mean?
Hydrolysis - means a more complex sugar comes a part, water is broken down and consumed in the reaction.
Condensation (dehydration synthesis) - means two more simpler sugars come together, i.e. two monosaccharides come together and form a disaccaride + H2O.
What are two forms of carbohydrates?
Aldose and Ketose.
What is the difference between aldose and ketose?
Aldose - has the carbonyl group, O=C, at the end of its molecular structure.
Ketose - has the carbonyl group in the middle.
What are stereoisomers? Name some examples.
Stereoisomers are molecules with the same order and types of bond (same molecular formula) but different spatial arrangement and different properties.
Examples: Glucose and galactose, both C6H12O6 but are arranged differently in space.
What is an enantiomer?
Stereoisomers that are non-superimposable mirror images of each other such as D and L glucose.
C=O at the end of the chain such as galactose
Aldose sugar
A sugar in which the anomeric C is not involved in a glycosidic bond and can therefore undergo oxidation such as glucose
Reducing sugar
A simple sugar with a backbone containing 6 carbon atoms such as glucose
Hexose
The major form of stored carbohydrate in animals
Glycogen
A simple sugar with a backbone containing 3 carbon atoms such as glyceraldehyde
Triose
A method for representing molecules to show the configuration of groups around chiral centres
Fischer Projection
C=O usually positioned at the C2 (second carbon) and not at the end of the chain such as fructose
Ketose sugar
Electrons are lost
Oxidation
What type of sugar is it if the hydroxyl projection is to the right? left?
Hydroxyl group to the right: D
Hydroxyl group to the left: L
These are referred to as enantiomers as they cannot be overlapped and are non-superimposable. Mirror images.
What does our body need to do to carbohydrates?
Our body needs to break down carbohydrates into monosaccharides.
Describe the digestion process at the start of carbohydrates? middle/end?
- Starts in mouth with amylase, which starts to break down starch and glycogen.
- In duodenum disaccharides are further broken down by enzymes into monosaccharides.
- From gut to bloodstream to liver –> monosaccharides are absorbed, used, and/or stored in the liver as glycogen.
What pancreatic juices (or enzymes) break down disaccharides: maltose, lactose, and sucrose?
- Maltose is broken down by maltase to be 2 glucoses.
- Lactose is broken down by lactase to be glucose and galactose.
- Sucrose is broken down by sucrase to glucose and fructose.
What happens if you have deficiencies in pancreatic juices (enzymes) for breaking down disaccharides? Name an condition given as an example.
Results in malabsorption, nausea, vomiting, and abdominal cramping.
Example: Lactose intolerance.
What is the first step in the metabolism of glucose?
The first step of all pathways requires glucose to be catalyzed by hexokinase into glucose-6-phosphate using ATP.
What is the result of glycolysis?
Glycolysis (Embden-Meyerof Pathway) in the cytoplasm of the cell.
- 10 steps that result in the production of 2 ATP and 2 NADH = ENERGY!!
- Can occur aerobically or anaerobically
What happens in aerobic glycolysis?
Aerobic = Glucose to Pyruvate to Acetyl-CoA.
What happens in anaerobic glycolysis? Why is this important?
Anaerobic = Glucose to Pyruvate to Lactic Acid
- Energy via lactic acid fermentation
- Important for muscles (energy without oxygen)
- Lactate converted back to glucose
What happen in the tricarboxylic acid (TCA) cycle?
2 Pyruvate molecules from glycolysis will undergo pyruvate oxidation to yield Acetyl-CoA and 2 NADH
Acetyl-CoA enters the Tricarboxylic Acid (TCA) Cycle
Occurs in the inner space of mitochondria
What is the result of the tricarboxylic acid cycle (TCA) (aka Krebs)?
Results in 2 ATP, 6 NADH, 2 FADH2
NADH and FADH2 products continue into Electron Transport Chain,
What is the electron transport chain?
It is an electrochemical gradient along the mitochondrial cell membrane.
(Remember this membrane is folded into cristae that increase its surface area).
What are the inputs in terms of NADH and FADH into the electron transport chain?
2 NADH from glycolysis + 2 NADH from pyruvate oxidation + 6 NADH from TCA = 10 NADH into the ETC
2 FADH2 from TCA into the ETC
10 NADH and 2 FADH2 are oxidized