Carbohydrates (Section 1) Flashcards
How many kcal/g of CHO?
4
Approximately how much of the human diet comes from CHO?
50-60%
Of all the CHO consumed in the human diet how much is simple carbs & how much is complex?
50% / 50%
What are the 3 monosaccharides?
Glucose
Fructose
Galactose
What are the 3 Disaccharides?
Sucrose
Lactose
Maltose
What are the 3 Polysaccharides?
Starch (amylose, amylopectin)
Cellulose
Glycogen
Sucrose is made of units of?
Fructose & Glucose
Lactose is made of units of?
Galactose & Glucose
Maltose is made of units of?
Glucose & Glucose
(x2 units of glucose)
Ribose is a ___ Carbon chain molecule and is found where?
5Carbon - found in DNA/RNA
What are Oligosaccharides & what are they made up of?
Complex CHO made of combinations of glucose, galactose, and fructose.
What makes Oligosaccharides unique compared to other simple or complex CHO?
Digested by bacteria in the gut (fermentation)
Polysaccharides contain which types of glycosidic bonds how are the structured?
a1-4 - Linear
a1-6 - Branched
b1-4 - Linear
Amylose (starch) makes up approximately how much of the polysaccharides found in the body?
15-20%
What enzyme opens the a1-4 bound found in Amylose?
Amylase
Amylopectin is different from Amylose in through what primary function?
It is manufactured with the intent of conserving storage space.
Amylopectin accounts for roughly how much of the polysaccharides found in the body?
80-85%
Amylopectin contains which two glycosidic bonds and what are the enzymes that open each one?
a1-4 bond (Amylase)
a1-6 bond (Isomaltase)
Glycogen is known as the ______ form of polysaccharides in animals?
Storage
Why does Cellulose (polysaccharide) goes largely unabsorbed?
It’s bonds (b1-4) are resistant to human enzymes and is utilized by bacteria in the fermentation process.
What sugar is the only sugar to get absorbed via “facilitated diffusion”
Fructose
Fructose is absorbed faster or slower than glucose?
Slower
Fructose absorption can be enhanced when combined with?
Glucose and/or Galactose
Glucose enters other cells via facilitated diffusion by the action of what hormone?
Insulin
(skips portal circulation & goes straight to cellular uptake)
Which sugars are taken up by liver cells freely through portal circulation & what form do they enter downstream metabolic pathways?
Galactose & Fructose
> Enter metabolic pathways as a glucose derivative.
What are the 4 major pathways of CHO Metabolism?
Glycogenesis
Glycogenolysis
Glycolysis
Gluconeogenesis
What is the function of Glycogenesis?
Making of Glycogen (from excess glucose)
What is the function of Glycogenolysis?
Breakdown of glycogen
What is the function of Glycolysis?
Oxidation of glucose into Pyruvate
What is the function of Gluconeogenesis?
Production of glucose from noncarbohydrate intermediates
What is the function of Hexose Monophosphate Shunt?
Production of 5-carbon monosaccharides and NADPH
What is the function of the Tricarboxylic Acid Cycle (TCA) cycle?
Oxidation of pyruvate and acetyle CoA
Where does glycogenesis occur?
Liver & Muscle
What is the irreversible step of glycogenesis?
Glucose is phosphorylated by ATP (and other substrates) to produce: G-6-P
What 2 enzymes are used to kickstart glycogenesis and where do the originate from?
Hexokinase (muscle)
Glucokinase (liver)
Glycogenolysis as the reverse pathway of Glycogenesis converts what into what?
Glycogen > Glucose
In Glycogenolysis, G-1-P is isomerized into what?
G-6-P
Glycolysis is the act of converting glucose into what & where does it occur?
Glucose > Pyruvate
(occurs in the cytoplasm)
What is step 1 of Glycolysis?
(Glucose into what?)
Glucose > (enters cell & is phosphorylated) > G-6-P
(requires ATP)
What is step 2 of Glycolysis?
(G-6-P into what?)
G-6-P > (Phosphoglucose Isomerase) > F-6-P
What is step 3 of Glycolysis?
(F-6-P into what?)
F-6-P > (phosphorylated) > F-1,6-Bisphosphatase
Rate Limiting Enzyme: PFK
What is step 4 of Glycolysis?
(F-1,6-Bisphophatase into what?
F-1,6-Bisphphatase > (cleaved: aldolase) > G3-P
What is step 5 of Glycolysis?
(G3-P into what?)
G3-P > (phosphorylated: G3-P Dehydrogenase) > PEP
In the final steps of Glycolysis, ADP is phosphyorylated into what and yields what?
ADP > ATP ; yields Pyruvate
