Practice Problems (Due Monday March 17th) 1. Below is the sequence of the transc

Question

Practice Problems (Due Monday March 17th) 1. Below is the sequence of the transcribed region of an imaginary eukaryotic gene along with the mRNA it encodes. Assume that the circled thymine undergoes a transition mutation. How would this affect the structure of the protein encoded by this gene? DNA: ACCAGACTAGATCTATGTTCGAGGGTACCATATOGGTCGCTAATGTTTGSC RNA: ACCAGACUAGAUCUAUGUUCGAGGGUACCAUAAUGGGUCGCUAAUGUUUGGC 2. The-10 core promoter of the lac operon gene has the sequence TATGTT. Describe an example of a base substitution mutation which would lead to increase transcription of the gene. Explain whether this mutation would increase or decrease the fitness of the organisms

Explanation / Answer

1. In RNA we need to see the start codon AUG

TRANSITION convers pyrimidine to pyrimidine so in DNA T converted to C. So in RNA we get instead of U we have G.

NORMAL RNA - AUG UUC GAG GGU ACC AUA AUG GGU

mUTATED RNA - AUG UUC GAG GGU ACC AUA AGG GGU

Met converted to Arg. Non polar amino acid converted to polar amino acid so 3-D conformation will change. Hydrophobic interaction will be distrubed.

2. Transition in 4th base pair leads to G to A makes a promoter TATATT box. It is most familiar promoter in the
most of the organisms. It increase the transcription of the gene. This not fitness to the organism because LAc operon has to regulate at specfic point at only glucose starvation it has to operate. This mutation increase the lac operon it unnecessary swith On the lac operon even glucose present in th emedium it
makes unnecessary loss of energy in the cell.

3. RNA polymerase -
Substrate = DNA
Template required = DNA
Role = Undergoes transcription- mRNA synthesis

Primase
Substrate = DNA
Template required = No template required
Role = Primer synthesis

Telomerase
Substrate = DNA
Template required = RNA
Role = TTAGGG repeats added in end of the chromosome

Poly A polymerase
Substrate = RNA
Template required = No template
Role =
poly(A) tail is added to an RNA at the end of transcription.

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