Which features of Neurospora crassa led to Beadle and Tatum to select Neurospora
ID: 212950 • Letter: W
Question
Which features of Neurospora crassa led to Beadle and Tatum to select Neurospora crassa as a model organism? Check all that apply.
A. Neurospora crassais a single-celled organism.
B. Neurospora crassa is a multicellular organism.
C. Neurospora crassa has simple genetics.
D. Neurospora crassa has complicated genetics.
E. Neurospora crassa has a relatively short doubling time.
F. Neurospora crassa has a long doubling time
In terms of the regulation of pathways, what does it mean that yeast cells do not synthesize certain amino acids when grown on a rich medium?
A. Yeast cells do not have the ability to synthesize amino acids on rich media.
B. On rich media, the yeast cells accumulate mutations in the enzymes of these pathways.
C. Rich media contains glucose, so the yeast cells do not need to make amino acids.
D. The enzymes of the amino acids synthesis pathways are inhibited by glucose.
E. Rich media contains amino acids, and the presence of amino acids inhibit the enzymes of the amino acids synthesis pathways.
To study the biochemical pathway of arginine synthesis using genetics, describe the type of mutants that you would want to find and what information these mutants could give you about the pathway.
You mutagenize haploid, wild type yeast cells. You plate mutagenized cells onto rich medium, and then replica plate onto minimal medium, minimal medium + phenylalanine, minimal medium + leucine, and minimal medium + arginine. See below.
Which colonies are made up of prototrophic cells?
Which colonies would you choose to use to study the arginine synthesis pathway?
After an extensive mutant hunt you isolate 17 colonies whose cells cannot synthesize arginine. One of the mutants has a dominant phenotype, and a complementation test with the remaining 16 mutants allows you to identify 5 different complementation groups. What does this suggest about the number of genes in the arginine synthesis pathway?
A. There are at least 17 different genes in the arginine synthesis pathway.
B. There are at least 16 different genes in the arginine synthesis pathway.
C. There are at least 6 different genes in the arginine synthesis pathway.
D. There are at least 5 different genes in the arginine synthesis pathway.
Given the following pathway, which compound A, B, C, or D would accumulate in a cell that is missing both enzymes 2 and 4?
2 7 4 6 ial Medium Minimal Medium + Phenylalanine Minimal Medium +Leucine Minimal Medium +Arginine Rich MediumExplanation / Answer
ANS1. correct options are B, C, and E
Neurospora. crassa is used as a model organism because it is easy to grow and has a haploid life cycle that makes genetic analysis simple since recessive traits will show up in the offspring.
ANS 2. correct option is C
A minimal medium for yeast can contain glucose as the sole source of carbon; metabolism of glucose to smaller molecules (e.g., CO2, ethanol, or acetic acid) can generate the ATP which is necessary for energy-requiring activities of the cells. The sole nitrogen source in a minimal medium can be ammonium (NH4+), from which the cells can synthesize all the necessary amino acids and other nitrogen-containing metabolites.
ANS 3.
Normally four auxotrophs can only grow on minimal media if it is supplemented with arginine. These arginine auxotrophs carried mutations that blocks arginine biosynthesis. Each mutation mapped to a different linkage group so there are at least four genes required for the biosynthesis of arginine. They named these genes ARG-E, ARG-F, ARGG, and ARG-H.
ANS 4.
a) colonies in the minimal medium+ phenylalanine, minimal medium+ leucine, minimal medium+ arginine are having prototrophic cells. As, prototrophic cells self sufficient producers of required amino acids.
b) Minimal medium + Arginine colonies will be chosen for the arginine biosynthesis pathway. Wild yeast cells employ the arginine biosynthesis pathway ,possess the argJ gene, which encodes the enzyme ornithine acetyltransferase (OAT). OAT catalyzes the transfer of the acetyl group from N--acetyl-ornithine to glutamate, generating ornithine and N-acetyl-glutamate (NAG).
ANS 5:
option B , there are at least 16 different genes in the arginine biosynthesis pathway.
ANS 6:
In the given pathway, B compound will accumulate in the cell because if any of enzyme is missing or defective it will not allow the compounds to function.
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