Complete question:
Imagine that a newly discovered, recessively inherited disease is expressed only in individuals with type O blood, although the disease and blood group are independently inherited.
A normal man with type A blood and a normal woman with type B blood have already had one child with the disease. The woman is now pregnant for a second time.
Assuming that both parents are heterozygous for the gene that causes the disease, what is the probability that the second child will also have the disease? Express your answer as a fraction using the slash symbol and no spaces (for example, 1/2).
Answer:
The probability that the second child will also have the disease is 1/16.
Explanation:
<u>Available data:</u>
- Two genes independently inherited: one for blood type, the other for disease
- Man with type A blood x Woman with type B blood
- Both parents are heterozygous for the gene that causes the disease; Dd
If the man has A blood, and the woman has B blood, and they already have an affected child, this means that they must be heterozygous for blood type too.
Cross:
Parentals) AiDd x BiDd
Gametes) AD Ad iD id BD Bd iD id
Punnett square) AD Ad iD id
BD ABDD ABDd BiDD BiDd
Bd ABDd ABdd BiDd Bidd
iD AiDD AiDd iiDD iiDd
id AiDd Aidd iiDd iidd
F1) <u>Genotype</u>:
1/16 ABDD
2/16 ABDd
1/16 ABdd
1/16 AiDD
1/16 BiDD
2/16 AiDd
2/16 BiDd
1/16 Aidd
1/16 Bidd
1/16 iiDD
2/16 iiDd
1/16 iidd
<u>Phenotype:</u>
3/16 A/B normal
4/16 A normal
4/16 B normal
3/16 0 normal
1/16 0 affected by the disease.
They no longer will be able to produce adequate amounts of ATP.
Answer:
Dominant allele does not completely conceal recessive allele.
Snapdragon with genotype Rr (R being red and r being white), would have a phenotype of pink flowers.
Explanation:
Incomplete dominance is where a dominant allele is not able to completely conceal a recessive allele, usually leading to a phenotype which appears to be a combination of the two.
For example, in snapdragons:
The allele for red flowers (R) is dominant over the allele for white flowers (r). Let's say a snapdragon flower had the genotype Rr, one allele for red flowers and one for white. In the case of 'normal' dominance the dominant red flower allele (R) would mask the effects of the recessive white flower allele (r), resulting in the phenotype (outward observable characteristics) of having red flowers.
However here in the case of incomplete dominance, the dominant allele would not be able to fully cover up the effects of the white flower allele, meaning that both colors (red and white) are expressed in the phenotype, resulting in pink flowers.
Hope this helped!
Answer:
The correct answer is: C. third nucleotide position.
Explanation:
- Genes located on the chromosomes encodes for proteins.
- A Gene is made up of a Deoxyribonucleotide (DNA) sequence which is transcribed into the messenger Ribonucleotide (mRNA) sequence by the help of RNA polymerase.
- This mRNA sequence is further translated into the amino acid sequence, that folds to form the functional protein, by the help of the Ribosome.
- The Ribosome reads the mRNA sequence in the form of triplets (three nucleotide together) and each such triplet nucleotide codes for an amino acid.
- Each such triplet nucleotide is known as a Codon.
- The Genetic Code is a table which represents the amino acid encoded by each codon.
- However, the Genetic Code is degenerate in nature. This means that one amino acid can be coded by more than one codon.
- This is because, among the the three nucleotide positions in a codon only the first two determine the specificity of the amino acid while the third nucleotide, also called the wobble nucleotide, is not specific. Presence of any nucleotide in the third position of the codon will not alter the amino acid encoded by the codon.
- In the given question, organisms producing homologous protein have similar amino acid sequence but they vary in the corresponding nucleotide sequence of the gene which codes for the homologous protein.
- This is because at the nucleotide level the variation lies in the wobble nucleotide position that occupies the third position in the codon.
