Carbohydrates Flashcards
What do carbohydrates supply to animals?
Energy
What is the basic formula of a carbohydrate?
-Ch2O
-water with a carbon
-a hydrated carbon
What is the basic progression of a carbohydrate?
-feeds supply carbohydrates
-digestion and absorption make them available for metabolism
What is the simplest carbohydrate?
Monosaccharides: a single sugar molecule
What are the most carbon monosaccharides?
6 carbons (Hexose)
What is a disaccharide?
Monosaccharides joined together
glucose x glucose =
Maltose
-digestion from starch
galactose x glucose =
Lactose
-for young animals
glucose x fructose =
Sucrose
-Not usually food in animals
What is an oligosaccharide?
3-15 monosaccharides
What is a polysaccharide?
many monosaccharides
What polymers will we focus on this class?
Starch and cellulose.
What do starch and cellulose have in common?
Both polymers of glucose
What are the types of starches we will be focusing on?
Amylose and Amylopectin
What is amylose?
Straight chain with alpha 1,4 glycosidic bonds
What is amylopectin?
Has branches, alpha 1,4 glycosidic bonds and alpha 1,6 glycosidic bonds.
What is cellulose?
-Glucose monomers joined by beta 1,4 glycosidic bonds
-Animals don’t have enzymes to digest cellulose an can’t break beta bonds
-ridged form
Where is glycogen found?
In the muscles and the liver
-not from the diet
What are the properties of starch?
-if they are water soluble or not
-physical structures and compactness influences digestibility impact
-starch exists as granules and the size and shape affect properties like water absorption capacity and swelling
Is amylose water soluble?
Yes
Is amylopectin water soluble?
Not really, less so because branches limit water access
Cellulose Digestibility
-Animals lack the enzymes to hydrolyze cellulose into glucose subunits
-Animals rely on resident bacteria for cellulose enzymes needed to break down cellulose
-followed by fermentation
Who derives more fiber: ruminants or non-ruminants? and how do they do it?
Ruminants derive more fiber by using fermentation upfront in their digestion tract.
What is the only saccharide that circulates in animals?
Monosaccharides
Which is structed: starch or cellulose?
Cellulose
-Keeps plants upright
Do carbohydrates rely on enzymes for digestion?
Yes
What’s an enzyme?
-made from protein
-catalyze
-turn one thing into another
-reusable
-reduce the energy to make a change
-special helper, do work
What is the enzyme used initial hydrolysis in starch digestion?
alpha amylase
-salivary
-pancreatic
What is the enzyme used to further hydrolysis in starch digestion?
disaccharides
Which is easier to digest: starch or cellulose?
Starch
-get more energy from starch than cellulose
How is starch digested?
By fermentation
Are amylase always found in the same place?
No, location of amylase differs between animals (animalvariation)
Where is starch broken down most of the time?
Small intestine
What breaks branch points alpha 1,6 bonds in amylopectin?
isomaltose
What breaks alpha 1,4 bonds?
alpha amylase
Can isomaltose also break alpha 1,4 bonds?
Yes
What are the two types of Hexose transports?
-Facilitated glucose transporters
-Sodium-glucose transports
Facilitated glucose transport
Allowing things to move the way they want through Glut-5
Sodium-glucose transporters
-SGLT1 is used by Na+ ad glucose to transport
What does Glut-2 do?
Takes the glucose, fructose, ect. transported by Glut-5 and SGLT1 and transports them into the body (submucosa)
What hydrolyze diaccharides?
-Maltose
-Lactose
-Sucrase
Where are disaccharides located?
The brush border
Where and what is the brush border?
-Located on the surface of the small intestine facing the lumen
-In the form of microvilli
-increase surface area for absorption
-enzymes in plasma membrane of enterocyte
-has many types of enzymes that break down molecules
-transport into enterocyte and then into blood
What do ruminants lack?
Sucrase
What enzyme do lactose intolerant people not produce?
Lactase
Ruminant Interaction with Carbohydrates
-The use of fermentation allows herbivores to derive nutrition from fibrous plant material like hay and corn silage
-bacteria in rumen gets first pass on feed before the small intestine
Since the bacteria in the rumen gets first pass on feed what happens to carbohydrates?
Carbohydrates are fermented and the glucose is converted to short-chain (volatile) fatty acids that the animal utilizes through metabolism
-this is through anaerobic conditions (no oxygen)
Is alpha amylase important for ruminants?
Not really, since bacteria get first pass at feed alpha amylase is not really needed
What happens if ruminants are fed to much starch?
Whole starch can pass the bacteria and go further into the stomach
What happens to glucose after it enters the blood stream?
“Glucose Turnover”
-continuous utilization and synthesis in the body
What is glycogen synthesis used for?
Storage for later metabolization and use
What is glycolysis used for?
-Energy and
-to produce substrates for fatty acid synthesis (longer term energy storage)
Ruminants and Glucose
-fermentation modifies glucose into fatty acids
-limited amylase production
-no sucrase
What are carbohydrates fermented to in ruminants?
Short-chain (volatile) fatty acids including
-glucose from starch is converted
-and glucose from cellulose is converted
Where do ruminants get their glucose if starch and cellulose are fermented and basically no glucose is absorbed from the intestine?
From short-chain fatty acids and gluconeosynthesis
If ruminants are deriving glucose from another process, how much glycolysis occurs in ruminants?
Not very much, because the energy needed to start the process in not efficient.
Do ruminants and non-ruminants get glucose from their diet?
-Non-ruminants: Yes
-Ruminant: No
What is Gluconeogenesis and who is it present in?
-Synthesis of glucose from non-carbohydrate substrates
-present in ruminants and non-ruminants
-take something and make glucose
How do ruminants use gluconeogenesis?
Ruminates depend on it constantly to produce glucose
How do non-ruminants use gluconeogenesis?
-Utilize it more for production of glucose when availability is reduced
-as needed bases
-back up energy
How do horses use gluconeogenesis?
-lower dependance from volatile fatty acids, but do regularly produce glucose from it.
Who makes glycogen?
Everyone
What is glycogen?
Storage form of glucose in tissue; muscle and liver
-glucose linked by alpha 1,4 and alpha 1,6 glycosidic bonds.
What is another name for glycogen synthesis?
Glycogenesis
Where is glycogen being stored?
In cytosol of cells
What enzymes are used in glycogen synthesis?
-Glycogen synthase
-Branching enzymes (making)
-Gycogenin-protein primer and glycogen synthesis
What are glucose and glycogen linked by?
Alpha 1,4 and alpha 1,6 bonds
What do branching enzymes do?
make branches
What is glycogenolysis?
Degradation of glycogen
-liberation of glucose for utilization
What enzymes are use in glycogenolysis?
-Debranching enzymes
-Glycogen phosphorylase: breaks the alpha 1,4 bonds and adds a phosphate group to glucose to make Glucose -1-P
What can Glucose-1-P be converted to?
Glucose-6-P (muscle and liver)
-and on to glucose in the liver and then released into the blood
Liver and muscle storage of glycogen
-Liver storage giving
-Muscle storage greedy
What can Liver glucose-6-P be converted back to?
Glucose
What does insulin increase and what does it reduce?
-increases glycogenesis
-reduces glycogenolysis
What does fasting, epinephrine, and glucagon increase and reduce?
-increase glycogenolysis
-reduces glucogenesis
What is glycolysis?
conversion of glucose to pyruvate
Where does glycolysis take place?
In the cytosol of cells
What does Hexokinase convert?
glucose to glucose-6-P
What does Phosphofructokinase convert?
fructose-6-P to fructose-1,6-biphosphate
What does pyruvate kinase convert?
phosphoenolpyruvate to pyruvate
Can conversions made by Hexokinase, phosphofructokinase, and pyruvate kinase be reversed?
No, they only go one way, no reverse
How much ATP is used to produce Glucose-6-P and fructose-1,6-biphosphate?
-1ATP is used to produce each
-Total of 2 ATP used
What is Hexose Fructose-1,6-biphosphate broken into?
Two 3-carbon molecules
-Two 1,3-Bisphosphoglycerate molecules
-two Phosphoenolpyruvate molecules -
What does phosphoglycerate kinase convert? and how much ATP is yielded?
-converts 1,3-Bisphosphoglycerate to 3-Phosphoglycerate
-Two 1,3-Biphosphoglycerate molecules yields 2 ATP
What does pyruvate kinase convert? and how much ATP is yielded?
-Converts phosphoenolpyruvate to pyruvate
-Two phosphoenolpyruvate molecules yields 2 ATP
What is the net ATP from glycolysis?
2 ATP
What happens in aerobic condition to glycolysis?
-conversion of Glyceraldehyde-3-P to 1,3-Bisphosphoglycerate produces NADH + H+
-Two 1,3-Bisphosphoglycerat produced per glucose = 2 NADH+ H+
How is NADH + H+ e used under aerobic conditions?
-can be used in oxidative phosphorylation in the mitochondria to produce 3 ATP
How much ATP is yielded if glycolysis is occurring under aerobic conditions and oxidative phosphorylation?
Increases from 2 to 8!
What is the condition for lactate synthesis?
Absence of oxygen
-no oxidative phosphorylation
Cells lacking mitochondria
-red blood cells
What is pyruvate converted to by lactate dehydrogenase? and how is it done?
-lactate
-Converts NADH + H+ to NAD+ allowing it to be reused for glycolysis to keep the pathway flowing and generate ATP
What happens to lactate?
-Can be converted back to pyruvate by lactate
-Back to glucose by gluconeogenesis
What does the conversion of NADH to NAD need?
Mitochondria
What else can glucose be stored as?
Fatty acids
