Can someone please let me know if I am correct. Thank you. True/False 1. A condi
ID: 44041 • Letter: C
Question
Can someone please let me know if I am correct. Thank you.
True/False
1. A conditional mutant of gene X is normal (wild type) under permissive conditions. TRUE
2. G0 state is reversible in non-differentiated cells. TRUE
3. Cdk1 dependent activation of the phosphatase that removes the inhibitory phosphate of Cdk1 is an example of negative feedback. FALSE
4. Phosphorylation of lamins leads to their disassembly during early mitosis. TRUE
5. The enzymatic function of anaphase promoting complex (APC) is that it is a kinase. FALSE
6. The enzymatic function of cyclinds is that they are phosphatases. TRUE
Explanation / Answer
1) Conditional Mutant refers to the expression of the mutation under certain particular environmental conditions. If they are to be restrictive in nature then the mutant phenotype is expressed and if the conditions are permissive the expression is that of the less severe phenotype.
Therefore, the first statement is true.
2) G0 or the G zero state also known as the resting stage forms the part the cell cycle wherein the cells are at a rest period. Some cells like liver cells or nerve cells may stay in this stage forever whereas other cells may proceed further for proliferation.
Therefore, the statement 2 is correct.
3) Negative feedback refers to the control of the by product of a reaction by the reactants acting as controllers. For example : If A hormone releases A which in turn escalates the release of B. When sensed the excessive accumulation of B, A will reduce its secretion.
Therefore, in statement 3 one does not notice the dependent removal or reduction in phosphatase and hence the statement is not true.
4) In the cell nucleus, the structural function and the transcriptional regulation is provided by these fibrous proteins. They are also known as nuclear lamins.
The process of addition of phosphate group to proteins or any other organic molecule is known as phosphorylation.
During mitosis, it becomes essential for the nucleus to breakdown, so that it can interact with chromosomes. This disassembly occurs with the help of phosphorylation.
Therefore, the statement is true.
5) APC or Anaphase Promoting Complex is a ubiquitin ligase. A ubiquitin ligase helps in catalysis of transfer of ubiquitin to protein substrate.
Kinase promotes the transfer of phosphate group.
Therefore, APC is not a kinase. So statement is not true.
6) Cyclin Dependent Kinases or CDKs are protein kinases. They play a significant role in cell cycle regulation. They are small proteins and perform phosphorylation across various sites in the organisms.
Therefore the statement is true.