Intro to Metabolism Flashcards
What is the difference between catabolism and anabolism?
catabolism: utilization of compounds for the generation of energy
anabolism: utilization of energy to produce compounds
What do fats, polysaccharides, and proteins get broken down into during energy production?
fats: fatty acids and glycerol
polysaccharides: glucose and other sugars
proteins: AAs
____ is an important intermediate in several pathways
acetyl-CoA
Define glycogenesis and glycogenolysis.
glycogenesis: synthesis of glycogen
glycogenolysis: breakdown of glycogen
The pentose phosphate pathway generates what?
NADPH and 5 carbon sugars (ribose) for nucleotides
What are the starting and ending products of glycolysis
glucose -> pyruvate
What are some important side products from glycolysis in some tissues?
glycerol-3-phosphate
2,3-bisphophoglycerate
What is gluconeogensis and where does it take place?
synthesis of glucose from pyruvate; restricted to liver and kidney
____ is also the source for carbohydrates in glycoproteins and proteoglycans
glucose
Acetyl-CoA from carbohydrate and/or protein can be utilized to make ___
fat
Acetyl-CoA is a substrate for what? (4)
- TCA cycle
- lipogenesis
- cholesterol synthesis
- ketone bodies
____ ____ are also required for complex lipids, components of membranes
fatty acids
Some AAs can produce acetyl-CoA, some AAs can produce carbohydrate intermediates. In both cases, what happens to the AA?
- AA is eliminated as urea
2. AA is re-utilized to form another AA
AAs are the source of nearly all the ___ in compounds making up an organism
nitrogen
More than one pathway may be required for some special compounds. Describe what Phospholipids and Nucleotides require.
Phospholipids: require contribution from lipids, carbohydrates, and AAs
Nucleotides: require contribution form AAs and carbohydrates
Gluconeogeneis only occurs where?
liver and part of kidney
Red blood cells contain no ____, and cannot utilize ___ ___ metabolism
mitochondria; aerobic carbohydrate
Organs participate in specialized pathways associated with their function. ___ hormones are produced in endocrine glands
steroid
Some storage forms of molecules are restricted to certain organs. Where are glycogen and triacylglycerols stored?
glycogen: only in muscle and liver
triacylglycerols: only in adipose tissue
Pathways may be found only in certain sub cellular locations. Fatty acid oxidation and fatty acid synthesis both occur where?
liver
Fatty acid oxidation occurs only inside _____, while fatty acid synthesis occurs only in ____
mitochondria; cytosol
note: this arrangement prevents “futile cycling”
Control of a pathway is through control of ___ activity
enzyme
A key regulated enzyme of glycolysis is affected ____ by a product of the pathway. This is an example of what?
allosterically; example of feedback inhibition
True or false? an enzyme responds the same way to the same hormone in different tissues
false; responds differently
For each of the following components, give their associated amount of calories/gram: carbohydrate protein ethanol fat
carbohydrate: 4
protein: 4
ethanol: 7
fat: 9
There are no essential carbohydrates since there are biochemical mechanisms to synthesize required carbohydrates from non-carbohydrate molecules
true
The “typical” western diet consists of about half the calories from _____
carbohydrates
In regards to fiber, cellulose and himicelluloses ____ stool bulk and ____ transit time
increase; decrease
In regards to fiber, lignins ____ stool bulk and bind what two things
increase; bind cholesterol and carcinogens
In regards to fiber, pectin and gums decrease rate what 3 things?
decrease rate of gastric emptying
decrease rate of carbohydrate absorption
decrease serum cholesterol
What does the glycemic index show?
the effect of a standard amount of carbohydrate on blood glucose concentration compared to the effect of a standard amount of glucose
A higher glycemic index would be expected to ____ blood glucose faster and lead to a greater release of ____
raise; insulin
What is the recommended protein intake?
0.8 g/kg body wt/day
Protein intake needs to be increased during growth and illness. True or false?
true
What are the essential AAs?
Threonine, Tryptophan, Valine, Arginine, Histidine, Lysine, Phenylalanine, Leucine, Isoleucine, Methionine
mnemonic: These Ten Valuable Amino-acids Have Long Preserved Life In Man
____ is sometimes considered essential for growing children
arginine
Positive nitrogen balance: more nitrogen ingested than excreted occurs during what two periods?
growth; convalescence
Negative nitrogen balance: more nitrogen is excreted than ingested occurs when?
starvation; diseases; severe burns
Fats require essential fatty acids. What are these two essential fatty acids?
Linoleic acid (18:2), Linolenic acid (18:3)
What is the recommended intake of fat in a balanced diet? give in percentage of total calories
20-35%
In regards to under-nutrition, describe Marasmus.
- Occurs in both adults and children
- extreme emanation from prolonged negative energy balance
- loss of protein from muscle, heart, liver, and kidneys
In regards to under-nutrition, describe kwasiorkor
- affects undernourished children primarily in the developing world
- thought to be due to a diet adequate in calories but sufficient in protein
- poor growth, low plasma protein and AA levels, muscle wasting, edema, fatty liver, diarrhea, increased susceptibility to infection
