26. Which of the following statements is true? a) dominant alleles are always ex

Question

26. Which of the following statements is true? a) dominant alleles are always expressed b) haploinsufficient alleles are always recessive c) a genetic map will match the physical map d) all mutations produce changes to the genotype e) alleles on the same chromosome are always inherited togetheir 27. You make a cross between rotifers of the following genotypes: A/A; B/b; d/d; e/e; F/f and A/a; B/B; d/d; E/E; F/F. How many different phenotypes will be present in the offspring? a) one b) two c) eight d) sixteen e) there's not enough information to tell 28. Consider the following exon sequence belonging to a gene that codes for a protein: AAT GGC TGT CCA GCG TTC AAG Now imagine that the sequence is changed to the following: AAT GGT GTC CAG CGT TCA AG This is most likely to result in a) a silent mutation b) a missense mutation c) a nonsense mutation d) a frameshift mutation e) all of the above are possible outcomes

Explanation / Answer

25. a) dominant alleles will always be expressed.

when one copy of allele is enough to show a phenotype its called dominant allele. Dominant allele will mask the expression of other allele. On the other hand, if a recessive phenotype need to expreesed , it will need two copies of the gene.

b) haploinsufficient alleles are always recessive.

Haploinsufficiency is happened when an organism lost one copy of a functional gene. The second copy of the gene can not express the particular phenotype alone.

d) all mutation produce changes to the genotype

Mutation is the change in nucleotide sequence. This change is parmanent.

27.

A/A, B/b, d/d, e/e, f/f      X    A/a,B/B/,d/d,E/E,F/F

Lets divided them

AA X Aa   Bb X BB        dd X dd    ee X EE    ff X FF

A

A

A

AA

AA

a

Aa

Aa

B

b

B

BB

Bb

B

BB

Bb

d

d

d

dd

dd

d

dd

dd

e

e

E

Ee

Ee

E

Ee

Ee

f

f

F

Ff

Ff

F

Ff

Ff

two types of genotype arrangement can happened

AABBddEeFf    ,     AaBbddEeFf

All the gamets are arranged in homozygous or heterozygous manner. Only one phenotype expression will be there.

d) frameshift mutation

if we look at the sequences, the mutation occurs due to deletion of the base C at position 6. This mutation changes the reading frame of the protein.

AATGGCTGTCCAGCGTTCAAG

AATGG   TGTCCAGCGTTCAAG

A

A

A

AA

AA

a

Aa

Aa

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