Question

answer no need for explanination

The lac operon is an example of dual control. This means that it undergoes regulation through:

:

	both positive and negative control mechanisms.
	both transcriptional and translational control.
	both inducible and repressible regulation.
	both regulatory proteins and attenuation.

The strand of DNA which acts as the template for transcription:

	is read in the 3’→5’ direction
	is read in the 5’→3’ direction
	is always the same along the length of an entire DNA molecule
	is always synthesized as the lagging strand
	is always synthesized as the leading strand

Which form of inheritance is NOT due to the expression of an autosomal gene?

	maternal genetic effect
	sex-limited
	sex-linked
	sex-influenced

Answer 1

1. The lac operon is an example of dual control. This means that it undergoes regulation through:both positive and negative control mechanisms

Explanation: This operon possesed both the systems negative and positive control. Negative control system involves regulation of expression by blocking n active repressor (the lac repressor) causing transcription toshut down. While he lac repressor binds to the operator region and negatively controls (prevents) transcription. While in positive control system the regulation takes place by catabolite gene activating protein that enhances the transcription by binding upstream of this operator region near the promoter.

2. DNA template strand for transcription is read in 3' to 5' direction.

Explanation: The DNA template strand is read by RNA polymerase to synthesise RNA that is complementary to DNA template strand. The synthesis of RNA takes place in 5' to 3' direction.

3. 'Sex linked' form of inheritance is NOT due to the expression of an autosomal gene

Sex linked genes are due to  genetic differences on the sex chromosomes. They may be X linked or Y linked hence only related to gemetes cells and has nothing to do with autosomal genes. While sex limited or sex influenced that are limited to only one sex and they could also be caused by gene on autosomal chromosomes.