Heredity B/Designer Genes C Question Marathon

[billyhoho]

I have a question! What unwinds the DNA strand? What is a Replication Fork? And, what is an Okazaki Fragment?

I believe Brett was supposed to get a question...assuming it was right >.> Though for

1. DNA Helicase?

2. Where DNA (2 strands) splits into 2 1-strands...

3. DNA Fragments.. I'm too lazy to explain any further ^_^

[PacificGoldenPlover]

To finish billyhoho's answer: Okazaki fragments are made on the lagging strand of replicating DNA. This is because DNA polymerase, which adds new nucleotides, only works in the 5'-3' direction. On the lagging strand, since it is antiparallel to the leading strand, it would have to go backwards to go in the 5'-3' direction. So polymerase solves this by creating short fragments of replicated DNA as the DNA unwinds. These fragments are the Okazaki fragments, and are afterwards tied together with ligase.

[jjetpack]

Define an operon
Name the structural genes of the lac operon
What does the lacI (<-- uppercase i) gene do?

An operon is a group of genes or a segment of DNA that functions in a coordinated matter consisting of an operator, promotor, and structural genes.

The structural genes of the lac operon are Lac Z (beta-galactosidase enzyme), Lac Y (permease enzyme), and Lac A (acetylase enzyme).

The lacI is the regulatory gene. It produces mRNA which in turn produces a repressor protein, which can then bind the the operator of the lac.

Correct. I would have also mentioned that in an operon the structural genes are all transcribed together into single mRNA (which may be spliced apart later). Your turn

[brettt]

Correct. I would have also mentioned that in an operon the structural genes are all transcribed together into single mRNA (which may be spliced apart later). Your turn

A certain condition is recessive. If the disease is present in 4% of the population, what is the frequency of the dominant allele?

[billyhoho]

Correct. I would have also mentioned that in an operon the structural genes are all transcribed together into single mRNA (which may be spliced apart later). Your turn

A certain condition is recessive. If the disease is present in 4% of the population, what is the frequency of the dominant allele?

AGH! HARDY WEINBERG! ...If it is in equilibrium... of course. .8

[brettt]

AGH! HARDY WEINBERG! ...If it is in equilibrium... of course. .8

Correct; your turn

[billyhoho]

1. What is pangenesis and who proposed it?

2. Is it proven incorrect or correct?

3. What is epistasis?

[Gemma W]

Pangenesis is Darwin's theory of heredity, which included some Lamarkian principles of passing on acquired traits as well as some other funky things. It was therefore disproved, replaced with Mendelian genetics.

Epistasis is when one gene's expression is modified by the presence of another gene.

[rtunnel97]

its been awhile so i thought i would post, what is the difference between co dominance and incomplete dominance?

[Gemma W]

Codominance is when both phenotypes manifest together, such as with the black and white chickens or AB blood type, whereas incomplete dominance is when the two alleles modify each other causing a new phenotype, as with pink four-o-clock flowers.