Heredity Phenotype ratio possible gametes of a dihybrid with a genotype of AaBb
ID: 205927 • Letter: H
Question
Heredity Phenotype ratio possible gametes of a dihybrid with a genotype of AaBb List the positle gametes h progeny tall n dwart. dihybrid corm plants were crossed, each with a genotype of TIiGg, what is the expected phenoype com C If two tall-green green, g albino)? Recall ast a and gees aee dominan Phenotype ratio all-green tall-albino trays of com sogrty of a cros betwoen tll grom dityrids Each y i phenotypes in alil these trays. Determine the observed phenotpe raio by diviling 4 In the lab, thore are several labeled tray 3. Count and record the the number of each phenotype by the number of dwarf-albino Phenotype ratio plants and rounding to the ncarest whole number tall-green dwarf-green tall-albino dwarf-albino Explain any difference between the expected and observed phenotype ratios. 6. LINKED GENES a A dihybrid was crossed with a homozygous recessive for each trait, and the cross produced only two classes of progeny. How do you explain this? & Why are more males color-blind than females? Determine the expected phenotype ratio of children from these matings. 1. Normal female (XX) x color-blind male (XCy) 2. Carrier female (XXC) x normal male (XY) 7. PEDIGREE ANALYSIS Examine the podigrees shown here, and determine whether the inherited trait or ) is dominant, recessive, or X-limked rocessive: o male; o -female. 133Explanation / Answer
Part a missing
b) possible gametes are AB , Ab ,aB ,ab
It's done by simply combining all alleles of one Gene , with all alleles of given genes.
c) the phenotypic ratio shall be 12 Tall green , 3 Tall albino , 3 dwarf green and 1 dwarf albino
This is so because , 'at least ' one dominant allele of each Gene is present in 12 of 16 possible combination , hence giving both dominant traits.
In 3 each ,' both alleles ' of one Gene are recessive , while at least one is dominant for the other Gene , hence giving one dominant trait and one recessive trait for the 3 , and again 3 but vice versa for type of traits.
In one out of 16 combinations , all alleles are recessive , giving both the recessive traits.
Draw the punnet square to see the combinations yourself
d) A typical case of dihybrid cross , with the same phenotypic ratio as mentioned in part c .
Any different between the expected and observed ratios are either due to chance event of some gametes , carrying certainly alleles , fertilizing more/ less successfully than others , or due to better germination of some seeds than others.
Please note that the expected ratios are based upon presumption that all alleles have equal chance to enter a gamete and all gametes have equal chance of fertilizing successfully , and then equal chance of germinating . In large enough sample size , the deviation from expected is very small usually.