Chapter 14: Digestion and some Chapter 15: Metabolism Flashcards
Digestion will have no __________.
ATP Production
Mechanical and chemical breakdown; prep stage
- proteins
- -AAs
- polysaccharides
- sugars
- fat
- fatty acids
Digestion
From AAs, sugars, fatty acids
-small amount of ATP production
Acetyl CoA Production
Citric acid cycle and oxidative phosphorylation
ATP Production (90% of energy generated)
Stomach
- pH 1-2, denaturation of proteins
- Pepsin (protease) breaks peptide bonds
- Protein fragments move to small intestine
Pepsin shows optimal activity in the _____, only one of few that can be active in these conditions.
Stomach
Small Intestine
- low pH of food stimulates the release of secretin
- secretin stimulates release of sodium bicarbonate from pancreas to neutralize pH of the food
- Oligopeptides stimulate CCK -CCK causes secretion of digestive enzymes from pancreas and bile salts from gallbladder
Zymogens are…
Proenzymes secreted from pancreas as inactive precursors
Enteropeptidase activates…
Trypsinogen to Trypsin
Enteropeptidase is the only enzyme in the ________.
Small Intestine
Trypsin activates…
Remaining pancreatic zymogens
-only activated in SI and all at the same time
Zymogens start in the _______ form so that they cannot destroy the ______.
Inactive Pancreas
Pancreatic proteases hydrolyze proteins to _______ and small _______ in the intestines.
Animo acids and small oligopeptides (protein fragments)
Oligopeptides are cleaved into AAs and di- and tri- peptides by…
Intestinal peptidases
AAs are released into….
The blood for use by other tissues
Primary source of dietary carbohydrates are…..
Complex carbs (ie. starch - small amounts of glycogen)
Starch is digested by….
a-amylase
a-amylase cleaves
1,4-bonds NOT 1,6
Products of starch…
Maltose, maltotriose and limit dextrin (has a-1,6 bonds)
Maltose converted to glucose by… Maltotriose is digested by… Limit dextrin is digested by
Maltase a-glucosidase a-dextrinase to simple sugars
Disaccharides are…
Sucrose and Lactose
Sucrose
-present in vegetables, is cleaved to glucose and fructose by sucrase
Lactose
-present in milk is degraded by lactase into glucose and galactose
Monosaccharides are transported from intestinal cells into the bloodstream to be used as…
Fuel/generate energy
The major lipids in our diet are…
Triacylglycerols *form lipid droplets in the stomach*
Bile salts secreted by gallbladder insert into…
The lipid droplets, making them more digestible in SI Bile salts considered amphipathic
Lipases secreted by the pancreas, convert triacylglycerols into…
- 2 fatty acids
- monoacylglycerol
Ionized fatty acids made by lipases form…
Micelles
Micelles prevent
exposure to water and are carried to intestinal cells for absorption
In intestinal cells, triacylglycerols are resynthesized and packed into lipoproteins called…
Chylomicrons
Chylomicrons transport triacylglycerols into the….
Lymph system
Cannot directly transport triacylglycerols, so they must be ______ before they can enter the mucosal cell
Degraded
Ability to maintain adequate but not excessive energy stores
Caloric homeostasis
Some health consequences of being obese:
Diabetes Coronary heart disease Cancers Stroke Hypertension (high blood pressure)
Short-term signals are active during
Only a meal
2 Types of Short-term signals
CCK - generate feels of satiety by acting on hypothalamus GLP-1
-acts like CCK on brain but also acts on pancreas too and potentiates insulin action
Long-term signals…
report on the overall energy status of the body
2 Types of Long-term signals
Leptin - secreted by adipocytes and produces feelings of satiety (long-term); reports on status of triacylglycerol or fat stores Insulin - secreted by pancreas - reports on status of blood glucose levels (carb availibility)
When you lack leptin or the leptin receptor, you…
Do not realize that you are full and will continue to eat –> obesity
List of proteins
- Pepsin
- Secretin
- CCK
- Zymogen
- Enteropeptidase
- Trypsin
List of carbs
- a-amylase
- malatase
- a-glucosidase
- a-dextrinase
List of lipids
- Bile salts
- lipases
- chylomicrons
Long-term control of caloric homeostasis is regulated by:
Leptin and insulin
T or F: The gall bladder secretes bile salts to neutralize the low pH of the stomach.
False
T or F: Fats are a more efficient food source than glucose, because fats are more oxidized.
False
T or F: Muscle contains only enough ATP to power contraction for less than a second.
True
T or F: Activated carriers are common in biochemistry and often are derived from vitamins.
True
T or F: NADPH is used primarily for reductive biosynthetic pathways.
True
T or F: Coenzyme A is an activated carrier of two-carbon fragments.
True
Metabolic pathways that involve the oxidation of fuels to generate ATP are called ____________ pathways.
Catabolic
Which compound has the highest phosphoryl-group transfer potential? ATP or Phosphenolpyruvate
Phosphenolpyruvate
What is the relationship between anabolic and catabolic pathways?
Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.
The role of ATP in cellular metabolism
The free energy released by ATP hydrolysis may be coupled to an endergonic process via the formation of a phosphorylated intermediate.
What metabolite is NOT in a high-energy state and therefore cannot release free energy for ATP generation
Glycerol-3-phosphate
