TLS Online TPP Program

#Id: 1997

#Unit 3. Fundamental Processes

The polyadenylation reaction passes through two stages. 

First, a rather short oligo(A) sequence (10 residues) is added to the 3’ end. This reaction is absolutely dependent on the AAUAAA sequence and poly(A) polymerase performs it under the direction of the specificity factor. 

In the second phase, the nuclear poly(A) binding protein (PABP II) binds the oligo(A) tail to allow extension of the poly(A) tail to the full 200 residue length.

TLS Online TPP Program

#Id: 988

#Unit 5. Developmental Biology

The transition from specification to determination in Drosophila is mediated by Segmentation genes.

TLS Online TPP Program

#Id: 5888

#Unit 3. Fundamental Processes

Incorrect base pairing leads to dramatically lower rates of nucleotide addition as a result of a catalytically unfavorable alignment of these substrates. This is an example of kinetic proofreading, in which an enzyme favors catalysis using one of several possible substrates by dramatically increasing the rate of bond formation only when the correct substrate is present. 

TLS Online TPP Program

#Id: 5547

#Unit 7. System Physiology – Animal

Positive charge forces cations such as Mg++ and Ca++ to diffuse from the tubular lumen through the paracellular space and into the interstitial fluid

TLS Online TPP Program

#Id: 6624

#Unit 8. Inheritance Biology

Type of Linkage 

Genes located close together on the same chromosome are called linked genes

Incomplete linkage, intermediate between the two extremes of independent assortment and complete linkage. 

ndependent assortment