Biology Help?

If inheritance of a human trait is sex-linked (on the X chromosome) and recessive, any of the following could result except that


a. females could be a mosaic of two cell types


b. the trait could be more common in females than males


c. all females must be homozygous to express the trait


d. the gene for the trait might mutate to a dominant allele


e. expression of the trait might "skip" a generation





A group of F+ bacteria is mixed with a group of F- bacteria. After several days, all of the bacteria are F=.


a. transduction


b. transposition


c. translation


d. transformation


e. conjugation





You conduct a dihybrid cross and then testcross the F1 generation. A ___ ration would make you suspect that the genes are linked.


a. 7:7:1:1


b. 1:1:1:1


c. 3:1


d. 1:2:1


e. 9:3:3:1





Transcription of the DNA sequence AAGTTC will produce RNA with the sequence...


a. TTCAAG


b.AAGUUC


c.AAGTTC


d.UUCAAG


e.TTGUUC

Biology Help?
b.


e.


a. (not e. e is when they are unlinked) when linked there will be mostly parental type and few others which come from cross overs)


a
Reply:1. B. the trait is more common in females.


This is obviously false since males are usually more affected than females in cases of X-linked recessive traits. Remember that a male has only one X chromosome and when mutated would result to the manifestation of the trait. In the case of females the two X chromosome must be mutated for the disease to be manifested which is a lot difficult.





2. E. conjugation


This is the third type of bacterial modification with the use of sex pilus or the conjugation pilus. The first one being transformation-the uptake of naked DNA from the environment(especially in cultures). The second type is transduction-this employs phages for the genetic transfer.





3. B. 1:1:1:1 ratio


This is the common ratio for gene linkage. Option E is for Mendelian dihybrid cross.





4. A. TTCAAG


The mRNA should complement the DNA strand.
Reply:b. (apparently d can actually happen)


e.


e.


d (in RNA U corresponds to A, A to T, C to G, and G to C)
Reply:I think the first question is b, because females would need two copies of the gene to express a recessive trait so it is therefore more common in males.


The last one might be d, because A-%26gt;U in RNA.

survey monkey