Any Bio majors?? give me a hand

[StUck686]

1. Which of the following are theoretically possible? Indicate your answer with a Yes or No beside each question.

a) A piece of double-stranded DNA in which 45% of the nucleotides are adenine.
b) A piece of single-stranded DNA consisting entirely of cytosine.
c) A piece of double-stranded DNA consisting entirely of cytosine and guanine.
d) A piece of double-stranded DNA in which 25% of the nucleotides are cytosine and 35% are thymine.
e) A piece of RNA consisting entirely of adenine and thymine.

2. In eggplant, a dominant allele A at a locus on chromosome 1 is needed for the expression of color in both flowers and stems. Individuals homozygous for the recessive allele a have white flowers and green stems. At the flower color locus on chromosome 2, the dominant R allele codes for red flowers, the recessive r allele codes for white flowers. At the stem color locus on chromosome 3, the dominant T allele encodes for purple stems, the recessive t allele codes for green stems.

What is the expected phenotypic ratio in the offspring if two eggplants with the following genotypes are crossed: Aarrtt x AaRrTt?

[Ravage7]

Originally Posted by StUck686

1. Which of the following are theoretically possible? Indicate your answer with a Yes or No beside each question.

a) A piece of double-stranded DNA in which 45% of the nucleotides are adenine. should be possible
b) A piece of single-stranded DNA consisting entirely of cytosine. should be possible
c) A piece of double-stranded DNA consisting entirely of cytosine and guanine.
should be possible
d) A piece of double-stranded DNA in which 25% of the nucleotides are cytosine and 35% are thymine.
don't think this is possible. in double stranded dna every nucleotide has its opposite, that means that for 25% cytosine there would have to be another 25% guanine, and for 35% thymine there would have to be another 35% adenine, and those percentages exceed 100
e) A piece of RNA consisting entirely of adenine and thymine.
not possible, RNA has uracil instead of thymine

2. In eggplant, a dominant allele A at a locus on chromosome 1 is needed for the expression of color in both flowers and stems. Individuals homozygous for the recessive allele a have white flowers and green stems. At the flower color locus on chromosome 2, the dominant R allele codes for red flowers, the recessive r allele codes for white flowers. At the stem color locus on chromosome 3, the dominant T allele encodes for purple stems, the recessive t allele codes for green stems.

What is the expected phenotypic ratio in the offspring if two eggplants with the following genotypes are crossed: Aarrtt x AaRrTt?
don't feel like doing this, you basically have to set up a large table and cross all the alleles. keeping in mind phenotypic refers to the physical appearance of the offspring, you could disregard certain cases, and you get your ratio by counting all the possible physical appearances up

Did what I could/felt like.

[klue85]

Im too lazy so here is some of the asnwers:

a) A piece of double-stranded DNA in which 45% of the nucleotides are adenine.
b) A piece of single-stranded DNA consisting entirely of cytosine.
c) A piece of double-stranded DNA consisting entirely of cytosine and guanine.
d) A piece of double-stranded DNA in which 25% of the nucleotides are cytosine and 35% are thymine.
e) A piece of RNA consisting entirely of adenine and thymine.

my answers:
a. yes. 45 A 45 T, leave 5 C and 5% G
b. yes. can be only C since ss.
c. yes. C and G can bond so possible.
d. no. because 25 C means 25 G, thats 50% there. then 35 T = 35 A, thats too much.
e. yes. RNA ss im guessing. so it can work. but RNA uses U.

[5PercentFat]

Originally Posted by klue85

Im too lazy so here is some of the asnwers:

a) A piece of double-stranded DNA in which 45% of the nucleotides are adenine.
b) A piece of single-stranded DNA consisting entirely of cytosine.
c) A piece of double-stranded DNA consisting entirely of cytosine and guanine.
d) A piece of double-stranded DNA in which 25% of the nucleotides are cytosine and 35% are thymine.
e) A piece of RNA consisting entirely of adenine and thymine.

my answers:
a. yes. 45 A 45 T, leave 5 C and 5% G
b. yes. can be only C since ss.
c. yes. C and G can bond so possible.
d. no. because 25 C means 25 G, thats 50% there. then 35 T = 35 A, thats too much.
e. yes. RNA ss im guessing. so it can work. but RNA uses U.

e is NO

thymine is replaced by uracil in RNA....so no, thymine does not exist in RNA

otherwise, I concur