D3.2 Inheritance Flashcards
State whether a person with sickle-cell trait is homozygous or heterozygous for sickle-cell haemoglobin
Heterozygous.
Construct a table to explain the relationship between Mendel’s Law of Segregation and meisosis
Hint: Mendel’s Law of Segregation states that during the formation of gametes (egg and sperm), the two alleles for a gene separate, so that each gamete receives only one allele. This means that offspring inherit one allele for each gene from each parent.
What is phenotypic plasticity?
Phenotypic plasticity is the capacity to develop traits suited to the environment experienced by an organism, by varying patterns of gene expression
For example, the change in the shape of leaves in plants based on the amount of sunlight they receive
Name a disease caused by dominant alleles
Huntington’s disease, resulting in progressive metal deterioration and involuntary muscle movement.
Name a disease caused by recessive alleles (HINT: PKU) TESTED QN
Phenyleketonuria (PKU), a recessive genetic condition caused by a mutation in an autosomal gene that codes for enzyme that is needed to convert phenylalanine to tyrosine. Causing seizures and involuntary tremors.
Distinguish between codominance and incomplete dominance, referencing their different phenotypic ratios
In codominance, both alleles are expressed in a phenotype. E.g. AB blood group. However, in incomplete dominance, a dominant allele does not completely mask the effects pf the recessive allele, resulting in a heterozygote having an intermediate phenotype The phenotypic ratios are 3:1 and 1:2:1 respectively.
Incomplete dominance . Include four o’clock
flower or marvel of Peru (Mirabilis jalapa) as an example.
Haemophilia results from a sex linked gene. The disease is more common in male, but the haemophilia allele is on the X chromosone. Explain the apparent anomaly.
The genes controlling production f blood proteins are located on the X chromosome and haemophilia is caused by a recessive allele. As a result, hameophilia is largely a dosease of the male- since a single X chromosome carrying the defective allele X^h Y will result in the disease. For a female to have the dosease, she must be homozygous for the recessive gene (X^h X^h) but this is usually fatal in utero.
ALLELES CARRIED ON THE X as SUPERSCRIPT***
Genetically speaking. why is there prohibition of marriage between close relatives in
many societies?
In inbreedng, there is a reduction in variation due to meiosis because of the smaller number of near ancestors. Overall gene pool is therefore smaller than in overall society. If two siblings produce offspeing, the offspring has increased risk of inhereting two copies of a harmful recessive alleles as opposed to only one, having harmful health effects.
TLDR: Invreeding increases the chance of homozygous recessive offspring for autosomal genetic disorders.
Deductive vs inductive reasoning
Deductive reasoning- general statement, ends up being able to apply to all scenarios through a general rule
Inductive reasoning- start with specific case and end up being a probable conclusion
What is polygenic inherutance and give an example.
Polygenic inheritance is ineritance of pgenotypic characters such as height and eye colour in humans, that are determined by the collective efforts of several different genes.
