The precursor RNA for the siRNA pathway is a longer dsRNA. As a consequence of this different initial substrate, Drosha is not needed for the generation of siRNAs. Cleavage by Dicer is still required, however, and again generates a suitable 21- to 22-nucleotide RNA for incorporation into RISC.

TLS Online TPP Program

#Id: 3111

#Unit 3. Fundamental Processes

The replicated region appears as a replication bubble within the nonreplicated DNA. 

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#Id: 1176

#Unit 7. System Physiology – Animal

Inputs from eye to CNS: 

• Input from the rods 

• Input from the cones

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#Id: 6909

#Unit 8. Inheritance Biology

Duplication- is a mutation in which part of the chromosome has been doubled.

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#Id: 7748

#Unit 1. Molecules and their Interaction Relevant to Biology

Zeff=Z –S

Chlorine would have a Z value of 17 (the atomic number of Chlorine). Continuing to use Chlorine as an example, the 10 inner electrons (S) would screen out the positive charge of ten protons. Therefore there would be and effective nuclear charge of 17-10 or +7.

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#Id: 3429

#Unit 6. System Physiology – Plant

In molecules, two types of excited states can exist;
a) The singlet state is relatively short‐lived and contains electrons with opposite (antiparallel) spins.
b) The more long‐lived triplet state has electron spins that are aligned (parallel).