L.1 - carbs Flashcards
What are carbs composed of?
- carbon, hydrogen, and oxygen in a 1:2:1 ratio
What does carbohydrate mean?
Hydrate (water of) carbon
Name some types of carbs
- sugars
- starches
- cellulose
- glycogen
- chitin
What purpose does sugar, starch, cellulose, and chitin do for the cell?
- sugar and starch = energy source of cell
- cellulose and chitin = structural components of cell
Example of a monosaccharide, disaccharide, and polysaccharide?
- mono: glucose
- disacc: sucrose
- poly: glycogen or starch
What is the most abundant monosaccharide?
Glucose
What disease is a breakdown of the mechanism that have revolved to keep glucose at a constant level in blood?
- diabetes
What bond joins sugars together?
- glucosidic bonds (these bonds can join sugars together and create polymers of di and polysaccharides)
What are the common disaccharides?
- sucrose
- lactose
- maltose
What 2 monosaccharides make up sucrose
- glucose-a(1-2)- fructose
What 2 monosaccharides make up lactose?
- galactose-b(1-4)-glucose
What 2 monosaccharides make up maltose?
- glucose-a(1-4)-glucose
Distinguish between alpha and beta glucose.
- alpha glucose have both ‘OH’ on the bottom whereas beta glucose has one ‘OH’ on the top and one ‘OH’ on the bottom
What is needed to breakdown disaccharides?
- enzymes. If no enzymes, we can’t break down the sugar and we can’t digest it and this can lead to stomach problems
What enzyme hydrolyses/breakdown sucrose?
- invertase (breaks down to glucose & fructose)
What enzyme hydrolyses/breakdown maltose?
- maltase
What enzyme hydrolyses/breakdown lactose?
- lactase (human)
- b-galactosidase (bacteria)
How can you tell you have lactose intolerance?
- nausea pain
- cramps
- diarrhoea
Normal lactose digestion Vs lactose intolerant.
normal: lactose —> lactase —> glucose & galactose
not normal: lactose —> no lactase —> bacterial fermentation —> acid & gas
Irritation caused then
What is the most abundant carb in nature?
Polysaccharides
Examples of polysaccharides?
- starch, glycogen, cellulose, chitin
What are polysaccharides?
- thousands of monosaccharides joined together by glycosidic linages (usually glucose)
What will turn polysaccharide into monosaccharides in your body?
- enzymatic or acid hydrolysis will release monosaccharides
What chains can polysaccharides appear in?
- long single chain
- or branded chain
What is a-amylose?
- a long unbranded chain of glucose units linked by alpha (1-4) bonds and has
Mr ~ 2000 - 500,000 daltons
Is a-amylose soluble?
Not really water soluble but it forms hydrated micelles and in the micelles the polymer forms a helical coil
What is amylopectin?
- highly branded polymer that has a length of 24-30 glucose molecules depending on the species
Backbone linkage = a(1-4)
Branch points = a(1-6)
What are amyloplasts ?
- starch granules
- constantly built and broken down by plants so they can have energy
What enzyme hydrolysis/breaks down starch?
- a-amylase enzyme
Where is a-amylase enzyme found?
- saliva and pancreatic justices and this enzyme is important for digested of starch
What is another hydrolysis of starch other than a-amylase? Where is it found?
- b-amylase enzyme
- found in malt
What degrades a-amylose? What can this thing also degrade?
- a and b-amylase
They can also degrade amylopectin but cannot break down -(1-6) bonds
The products of this breakdown is dextrins (short chains) but the ultimate product is a limit dextrin
A debranching enzyme a(1-6) glucosidase is needed for complete refraction
What makes up 50% of carbon cpds in plants?
Cellulose
What is cellulose?
- a structural carb
Wood = 50% cellulose
Cotton = 90% cellulose
The cell walls of plants are cellulose
What are bonds between the glucose units in cellulose?
Beta 1-4 glycosidic linkages
Do we have the enzymes necessary to break down cellulose?
- NO!!
- cellulose only provides a roughage in the diet (can’t digest but helps w digestion)
What is the structural carb found in animals?
- chitin
What forms the external skeleton of insects, crayfish, and other arthropods?
Chitin
What is the main component in the cell wall of fungi?
- chitin
What are glycoproteins? What does it secrete?
- integral membrane proteins
- it secretes proteins - antibodies
What linkages of glycoprotein?
- contains oligosaccharides in glycosidic linkage to serine, threonine, or asparagine
What occurs as intermediates in energy yielding metabolism?
- phosphorylation sugars
-example: glucose-6-phosphate (glycolysis)
What does phosphorylation do?
- makes sugars an ionic and allows some of them to participate in glucosidic bonding as reactive intermediates
