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BlackZzzverrR [31]
3 years ago
8

How do scientists determine when an era ends and an era begins

Biology
1 answer:
rodikova [14]3 years ago
4 0
 Geologic Time Scale.Scientists decide when an era begins<span> and </span>ends<span>, due </span>to<span> mass extinction. ...</span>Scientists determine<span> when drastic changes </span>are<span> made by the fossil record, which shows earths past organisms that have become extinct.</span>
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Genetic linkage mapping for a large number of families identifies 4% recombination between the genes for Rh blood type and ellip
Cloud [144]

Answer:

0.2404

Explanation:

The genes R/r and E/e are linked and there is 4% recombination between them.

<u>The possible genotypes and phenotypes are:</u>

  • RR or Rr: Rh+ blood type
  • rr: Rh- blood type
  • EE or Ee: elliptocytosis
  • ee: normal red blood cells

Tom and Terri each have elliptocytosis (they are E_), and each is Rh+ (they are R_).

Tom's mother has elliptocytosis (E_) and is Rh- (rr), so she has the genotype Er/_r. His father is healthy (ee) and has Rh+ (R_), so he has the genotype eR/e_. Tom must have inherited his E allele from his mother and his R allele  from his father, so he has the genotype eR/Er.

Terri's father is Rh+ (R_) and has elliptocytosis (E_), while Terri's mother is Rh- (rr) and is healthy (ee) with the genotype er/er. Terry could only receive the chromosome <em>er </em>from her mother, and because she is heterozygous for both genes the dominant alleles were both received from her father. Terri's genotype is ER/er.

The frequency of recombination is 4%, so 4% of the produced gametes will be recombinant. There are two possible recombinant gametes, so each will appear 2% of the times (a frequency of 0.02).

<u />

<u>Tom will produce the following gametes:</u>

  • eR, parental (0.48)
  • Er, parental (0.48)
  • er, recombinant (0.02)
  • ER (recombinant (0.02)

<u>Terri will produce the following gametes:</u>

  • ER, parental (0.48)
  • er, parental (0.48)
  • Er, recombinant (0.02)
  • eR, recombinant (0.02)

A child Rh- with elliptocytosis has the genotype rrE_. This can happen from the independent combination of the following gametes from Tom and Terri respectively:

  • Er (0.48) × er (0.48) = 0.2304 Er/er
  • Er (0.48) × Er (0.02) = 0.0096 Er/Er
  • er (0.02) × Er (0.02) = 0.0004 er/Er

And the total probability of having a rrE_ child will be 0.2304 + 0.0096 + 0.0004 = 0.2404

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BIO HELP 10 POINTS
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Answer:

carry the genetic code out of the nucleus to the ribosome for translation to occur.

Explanation:

Messenger RNA (mRNA), molecule in cells that carries codes from the DNA in the nucleus to the sites of protein synthesis in the cytoplasm (the ribosomes).

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The nuclear energy cause s catastrophic meltdown .
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