endocrine/digestive/nutrition Flashcards
Oxidative Phosphorylation
Takes place on the inner membrane of the mitochondria
Yields: 32 ATP NAD+ FAD H2O
Oxidation-reduction
reactions are coupled reactions that involve the transfer of electrons from one molecule to another, resulting in a transfer of energy between molecules (pp. 920–921).
Ex: the electron transfer chain in the mitochondria
ATP synthesis may occur through two mechanisms:
- substrate-level phosphorylation:
in which high-energy phosphate groups are transferred directly from phosphorylated substrates to ADP - oxidative phosphorylation:
in which some energy from food fuels is used to create a proton gradient that is used to attach phosphates to ADP (pp. 921–922; Figs. 24.4–24.5). Ex: ETC
Cellular Respiration:
The first step is the Krebs Cycle in which ATP and strong oxidizers, NADH and FADH2 are formed that are necessary for the next step
The second step is Oxidative Phosphorylation in which oxygen is required to produce more ATP molecules.
Glycolysis
the breakdown of 1 molecule of glucose to 2 molecules of pyruvate.
This yields 2 ATP and NADH.
Occurs in the cytoplasm
Krebs Cycle—
Takes place in the matrix of mitochondria
Pyruvate formed in glycolysis is converted to acetyl-CoA
The acetyl-CoA enters the Krebs cycle
For every 2 molecules of pyruvate that enters the Krebs cycle yields:
2 ATP
8 NADH
2 FADH2
6 CO2released
Oxidative Phosphorylation—
Takes place on the inner membrane of the mitochondria Yields: 32 ATP NAD+ FAD H2O
Carbohydrate Metabolism:
The ETC: Yields
32 ATP
NAD+
FAD
H2O
Glycogenesis
When ATP levels increase, glycolysis is inhibited and glucose molecules are combined in long chains to form glycogen
Glycogenolysis
when blood sugar levels drop, glycogen splitting occurs
Glucogenesis
When too little glucose is available for metabolism, glycerol and amino acids are converted to glucose.
-occurs in the liver
Lipid Metabolism
Catabolism of triglycerides involves the splitting of the molecule into glycerol and fatty acids: the glycerol portion is converted to glyceraldehyde phosphate, which enters into glycolysis, and the fatty acids are converted to acetyl CoA through beta oxidation that takes place In the mitochondria.
lipogenesis
When cellular ATP and glucose levels are high lipogenesis occurs to store the extra sugars.
High levels of acetyl CoA and glyceraldehyde phosphate also stimulated lipogenesis.
Acetyl CoA molecules are condensed to form fatty acid chains. Glyceraldehyde PO4 is converted to glycerol that is further condensed to form triglycerides.
Lipolysis
The breakdown of stored fats to glycerol and fatty acids
3 processes involved in carbohydrate metablism
1) glycolysis
2) Krebs Cycle
3) oxidative phosphorylation
what 2 initial components are lipids catabolized by the action of lipase?
What is each component converted to in order to enter the Krebs cycle?
glycerol/fatty acid
acetyl co-A
what is the goal of amino acid modification?
The goal of amino acid metabolism is to produce molecules that can be oxidized in the Krebs cycle or converted to glucose
complete the following equation and state the enzyme responsible for the reaction: CO2 + H20–>
CO2 + H20–>H2CO3 (carbonic acid)–>HCO3- + H+(bicarbinate)
enzyme= carbonic anhydrase
what is the meaning of double arrows
reaction can go both ways
Before amino acids can be oxidized for energy, they must have the amine group removed this process is called
deamination
Protein Metabolism -
1) Transamination
Transfer of an amino group from an amino acid to
α-ketoglutaric acid. This resulting in formation
of Glutamic acid. The original amino acid is
converted to a keto acid
Protein Metabolism -
2) Oxidative deamination
Occurs in the liver where the amino group (NH3)
of glutamic acid is removed. The NH3 is excreted in urine and the alpha-ketoglutaric acid is regenerated.
Protein Metabolism -
3) Keto Acid Modification
is used to produce molecules that can be oxidized in the Krebs cycle or converted to glucose from keto acids produced through transamination
- Most important metabolites are pyruvate, acetyl CoA, alpha-ketoglutaric acid
- Deaminated amino acids converted to pyruvate can be reconverted to glucose and be part of gluconeogenesis
Insulin
Insulin is a hypoglycemic hormone, i.e. it removes glucose out of the blood into cells and lowers blood glucose levels.
Insulin also inhibits any process that might increase blood glucose levels, such as glucogenesis by the liver
Decreasing blood glucose levels stimulate the alpha islet cells of the pancreas to secrete ____?
Glucagon
*Glucagon is an insulin antagonist (inhibits effects of insulin)
Rising blood glucose levels after a high carb meal acts as a stimulus that stimulates pancreatic beta islet cells to secrete more ____?
insulin
*This stimulates facilitated Diffusion of glucose into tissue cells
Glucagon
Glucagon is a hyperglycemic hormone, i.e. it promotes increase in blood glucose levels.
Glucagon stimulates liver hepatocytes to increase glycogenolysis and gluconeogenesis.
Glucagon also stimulates lipolysis by the adipose cells and release fatty acids and glycerol to the blood.
Thus increasing blood glucose levels.
Metabolic Role of the Liver
Regulation of Blood Cholesterol and Cholesterol Metabolism:
Cholesterol: is a structural component of bile salts, steroid hormones, and Vit D and a major component of the plasma membrane. It is also a major component of a development signaling protein, hedgehog.
15% of blood cholesterol is dietary, 85% is made from acetyl CoA by the liver
Cholesterol Transport
Is bound to small lipid-protein complexes called lipoproteins.
Lipoprotein complexes vary in the percentage of lipid they contain, but all contain triglycerides, phospholipids, and cholesterol, in addition to protein
VLDLs
transport triglycerides from the liver to peripheral tissues, mostly to adipose
Once the triglycerides transferred, the VLDL residues are converted to LDLs
