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53 Cards in this Set
- Front
- Back
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What is the first stage of catabolism? |
Digestion |
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Digestion |
- physical grinding, softening, and mixing of food, as well as the enzyme-catalyzed hydrolysis of carbohydrates, proteins, and fats |
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Nutrient absorption happens through... |
millions of villi - provide surface area as big as a football field |
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Glucose is the preferred fuel for |
the brain, muscle cells, and red blood cells |
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When glucose enters the cell it is converted to... |
glucose 6-phosphate - phosphorylated molecules cannot cross the cell membrane, so glucose is then trapped inside the cell |
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When energy is needed, glucose 6-phosphate |
proceeds through glycolysis to pyruvate and then to acetyl-coenzyme A - which enters the citric acid cycle |
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When cells are well-supplied with glucose, excess glucose is... |
converted to glycogen by the glycogenesis pathway or to fatty acids |
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Pentose Phosphate Pathway |
- glucose-6-phosphate can enter and it yields NADPH and ribose 5-phosphate - which is necessary for the synthesis of nucleic acids |
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Glycolysis has how many catalyzed reactions |
10-enzyme catalyzed reactions |
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Overall results of glycolysis |
- conversion of glucose to 2 pyruvate molecules - net production of 2 ATP - production of 2 molecules of reduced coenzyme NADH from NAD+ |
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How is fructose converted to glycolysis intermediates? In muscle: In the liver: |
In muscle: it is phosphorylated to fructose 6-phosphate (substrate for step 3) In the liver: it is converted to glyceraldehyde 3-phosphate (substrate for step 6) |
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Galactose is converted to... |
glucose-6-phosphate by a 5-step pathway |
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Mannose |
product of the hydrolysis of plant polysaccharides other than starch |
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Mannose is converted to... |
fructose 6-phosphate (substrate of step 3) by hexokinase and a multistep, enzyme-catalyzed rearrangement |
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Under Aerobic conditions, pyruvate is converted to |
Acetyl-CoA |
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Under anaerobic conditions, pyruvate is instead... |
reduced to lactate |
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Yeast converts pyruvate to... |
ethanol under anaerobic conditions |
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How is pyruvate moved into the inner mitochondrial matrix to become acetyl-CoA |
pyruvate is moved across the outer mitochondrial membrane, then must be carried by a transporter protein across the inner mitochondrial membrane |
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What converts pyruvate to acetyl-CoA once in the matrix? |
pyruvate dehydrogenase complex |
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Pyruvate Dehydrogenase Complex |
a large multienzyme complex that catalyzes the conversion of pyruvate to acetyl-CoA |
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Under Aerobic conditions, NADH is... |
continually reoxidized during electron transport |
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If electron transport slows down because of insufficient oxygen, NADH concentration... |
increases and glycolysis cannot continue |
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in reduction of pyruvate to lactate, NADH serves as the... |
reducing agent and is reoxidized to NAD+ |
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How much ATP are produced per glucose molecule between glycolysis and citric acid cycle? |
4 ATP |
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The complete catabolism of one molecule of glucose produces... |
38 ATP (mostly only prokaryotes) 30-32 (humans max) |
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NADH and FADH2 ATP per molecule |
NADH - 3 ATP FADH2 - 2 ATP |
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Normal blood glucose concentration |
65-100mg/dL |
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Hypoglycemia Symptoms |
causes weakness, sweating, and rapid heartbeat, and in severe cases, low glucose in brain cells causes mental confusion, convulsions, coma, and eventually death |
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Hyperglycemia Symptoms |
causes increased urine flow as the normal osmolarity balance of fluids within the kidney is disrupted - prolonged hyperglycemia can cause low blood pressure, coma, and death |
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Insulin - secreted by - released when - role |
secreted by pancreatic B cells - released when blood glucose concentration rises - role is to accelerate the uptake of glucose by cells |
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Glucagon - secreted by - released when - stimulates |
secreted by pancreatic alpha cells - released when blood glucose concentration drops - glucagon stimulates the breakdown of glycogen in the liver and release of glucose |
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In starvation, a gradual decline in blood glucose concentration is accompanied by |
an increased release of glucose from glycogen |
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When there's no more glucose or glycogen, turn to |
breakdown of proteins - then lipids |
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When citric acid cycle is overloaded, Acetyl-CoA is converted to |
ketone bodies |
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The brain and other tissues are able to switch over to producing 50% of ATP from the... |
catabolism of ketone bodies instead of glucose |
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Diabetes Mellitus |
- one of the most common metabolic diseases - honey - type 1 and 2, and metabolic syndrome (pre-diabetic condition) |
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Type 1 Diabetes |
- juvenile-onset diabetes (autoimmune disease) - caused by failure of pancreatic cells to produce enough insulin - excessive thirst and frequent urination - abnormally high glucose concentration in urine and blood - wasting of body despite good diet - subject to cataracts, blood vessel lesions, and gangrene in legs |
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Type 2 Diabetes |
- adult-onset diabetes - insulin is in good supply but fails to promote the passage of glucose across cell membranes - cell membrane receptors fail to recognize insulin (insulin resistance) |
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Why is type 1 diabetes classified as an autoimmune disease? |
- because the immune system identifies pancreatic beta cells as foreign, develops antibodies to them and destroys them |
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Type 1 diabetes treatment |
- missing insulin supplied by injection |
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Type 2 diabetes treatments |
- drugs that increase insulin or insulin receptor levels - diet modification and exercise |
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Metabolic Syndrome |
- elevated fasting blood glucose levels and impaired glucose response - abdominal obesity, elevated blood pressure, impaired glucose metabolism - treatments involve changes in diet and exercise |
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Ketoacidoses |
results from build up of acidic ketones in the late stages of uncontrolled diabetes - can lead to coma and diminished brain function, can be reversed by timely insulin administration |
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Glycogenesis |
Glycogen synthesis - occurs when glucose concentrations are high - begins with glucose 6-phosphate - isomerized to glucose 1-phoshpate. glucose residue is then attached to uridine triphosphate (UTP) which is hydrolyzed yielding two hydrogen phosphate ions and the resulting glucose-UDP transfers glucose to a growing glycogen chain in an exergonic reaction. |
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glucose 6-phosphate isomerization to glucose 1-phosphate - enzyme |
phosphoglucomutase |
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Enzyme that catalyzes the transfer glucose by glucose-UDP to growing glycogen chain |
glycogen synthase |
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Glycogenolysis |
break down glycogen to glucose-6-phosphate 2 steps: 1 - glucose 1-phosphate is formed by the action of glycogen phosphorylase on a terminal glucose residue in glycogen 2 - glucose 1-phosphate is then converted to glucose 6-phosphate by phosphoglucomutase |
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where and how does glucose 6-phosphate free glucose so it can travel to other cells |
liver cells contain glucose 6-phosphatase, an enzyme that hydrolyzes glucose-6 phosphate |
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In muscle cells, glycogenolysis occurs when... |
...there is an immediate need for energy |
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The Cori Cycle |
as a product of anaerobic respiration, lactate is a product of glycolysis in red blood cells(no mitochondria) and in muscle cells during vigorous muscle activity - lactate absorbed from the blood is converted to pyruvate - the new glucose synthesized in the liver is then returned to the muscles for storage |
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Gluconeogenesis |
conversion of noncarbohydrates to glucose |
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where does gluconeogenesis begin? |
begins in mitochondria with conversion of pyruvate to phosphoenolpyruvate |
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Pyruvate formed from lactate is transported from the... |
cytosol into the mitochondria or is produced there from amino acids |
