32 Questions
What is the defining characteristic of an essential vitamin?
It is only made by microbes
Which type of molecules function as carriers of specific functional groups and participate in catalysis but are not permanently bound to the enzyme?
Coenzymes
What is the role of iron as a cofactor in enzymes?
Involved in redox reactions and oxygen-binding
Why do some fruits have high concentrations of ascorbic acid?
Acts as an antioxidant
In animals, how is ascorbate biosynthesis different from plants?
It is made from UDP-D-glucose
Which vitamins are considered redox vitamins?
Vitamin E and C
What is the last step in the biosynthesis of ascorbic acid (vitamin C)?
L-Galactono-1,4-lactone is dehydrated into L-ascorbic acid
Why does herbivory reduce the evolutionary pressure to maintain ascorbate biosynthesis in plants?
Herbivores eat a lot of plants anyway.
What is the role of vitamin C in collagen synthesis?
It acts as a cofactor for the enzyme that catalyzes hydroxylation of amino acid residues in the collagen protein chains.
What is the cause of scurvy?
The inability to convert proline to hydroxyproline.
Why do some animals always lose the ability to produce vitamin C in their bodies?
The loss always occurs in the GLO gene.
What is the main structural feature of collagen?
Triple helix of similar peptide chains
What role does acetic acid play when there's not enough oxygen?
Causes burns of muscles by acidification.
Why do we evolve antioxidants in response to radical formation?
To counteract the effects of lipid membrane reactions caused by oxygen free radicals.
What process does vitamin C assist in for collagen synthesis?
Hydroxylation
What is the role of ascorbic acid (vitamin C) during times when there is not enough oxygen?
Acts as a terminal oxygen acceptor
Why did the loss of vitamin C biosynthesis occur?
Herbivory reduces evolutionary pressure to maintain ascorbate biosynthesis, since herbivores eat a lot of plants anyway.
Why is the loss of vitamin C biosynthesis always in the GLO gene?
To minimize the number of metabolic intermediates disrupted; mutations in upstream genes may not be tolerated.
Why is the last step in the biosynthesis of ascorbic acid (vitamin C) similar in animals and plants?
The last step is similar to animal biosynthesis of vitamin C.
What is the defining characteristic of an essential vitamin?
Essential vitamins must be obtained from the diet, as the body cannot produce them in sufficient quantities.
What is the role of ascorbic acid (vitamin C) in collagen synthesis?
Vitamin C assists in the hydroxylation of proline and lysine residues in collagen synthesis.
What process does vitamin C assist in for collagen synthesis?
Vitamin C assists in the hydroxylation of proline and lysine residues in collagen synthesis.
What is the quaternary structure of collagen?
Triple helix of similar peptide chains
What is the consequence of vitamin C deficiency in terms of collagen synthesis?
Inefficient collagen synthesis, possibly leading to conditions like scurvy
What is the role of iron ions in collagen synthesis?
Cofactors for the enzyme lysyl hydroxylase involved in hydroxylation of lysine residue
What is the function of flavonoids in the body?
Act as antioxidants and require oxoacid dependent dioxygenase (ODDO) for their synthesis
How does ascorbate function in terms of electron transfers?
It can donate one or two electrons and be oxidized twice, producing dehydroascorbate
What is the role of vitamin E in radical formation?
It can donate a single electron and become a radical
What is the process that results in the acidification of muscles when there is not enough oxygen?
Conversion of pyruvate to lactate
What is the role of hydroxyl free radicals in the body?
They can react with lipid membranes, leading to the need for antioxidants
What is the consequence of a lack of vitamin C in terms of collagen hydroxylation?
Inefficient hydroxylation of proline and lysine amino acid residues in collagen protein chains
What is the relationship between vitamin C and the enzyme prolyl 4-hydroxylase in collagen synthesis?
Vitamin C is involved as a cofactor for the enzyme prolyl 4-hydroxylase that catalyzes the hydroxylation reactions
Test your knowledge on the biosynthesis of ascorbate (vitamin C) in animals and plants. Explore the differences in the biosynthetic pathways and the unique processes involved in the production of vitamin C in these organisms.
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