Question 1

-How many different types of offspring (genotypes) are possible as a result of this cross, according to the Punnett square in the diagram?

Accepted Answer

The answer of 
-How many different types of offspring (genotypes)...

Question 2

What does a typical recessive allele code for?

Accepted Answer

A recessive allele typically codes for a nonfunctional protein, meaning that the trait it codes for will only be expressed if the individual has two copies of the recessive allele.

Question 3

If you're interested in studying one gene within a human, and each gene has two alleles, then how many boxes would be used in the Punnett square to predict the inheritance of the alleles?

Accepted Answer

A Punnett square for one gene with two alleles requires four boxes. Each parent contributes one allele, so there are four possible combinations of alleles in the offspring.

Question 4

Which genotype would have an advantage if a recessive allele changed cellular proteins that led to circulatory problems and premature death?

Accepted Answer

In this scenario, the recessive allele is causing problems, so individuals with two copies of this allele (homozygous recessive) will have the greatest disadvantage. Heterozygous individuals will have one functional copy of the gene, which may be enough to prevent or delay the onset of the circulatory problems associated with the recessive allele. Homozygous dominant individuals will have no copies of the recessive allele, but having two copies of the dominant allele may not provide any advantage in this scenario. Therefore, heterozygous individuals (choice D) will have the advantage over homozygous recessive individuals.

Question 5

What may result if a mutation occurs in a gene?

Accepted Answer

The answer of What may result if a mutation occurs...

Question 6

How did Gregor Mendel's research affect the science of his time?

Accepted Answer

Mendel's work was largely unrecognized by the scientific community during his lifetime. It wasn't until decades later that the significance of his research was acknowledged, marking the foundation of modern genetics.

Question 7

When a recessive allele is associated with a genetic disease in humans, what would heterozygotes be considered?

Accepted Answer

Heterozygotes are carriers of the recessive allele associated with the genetic disease. They may not exhibit symptoms of the disease themselves but can pass the allele on to their offspring.

Question 8

If DNA is like an instruction manual, what would be similar to the typographical errors that may result when the DNA manual is transcribed?

Accepted Answer

Mutations are similar to typographical errors in that they are mistakes or changes that occur during the copying process of the DNA instruction manual. Just as a typo can alter the meaning of a sentence, a mutation in the DNA can alter the function of a protein or even lead to disease. Dominant and recessive alleles are variations of genes that are inherited from parents, while homologous chromosomes are pairs of chromosomes that carry the same genes. These concepts are not directly related to errors in the transcription of DNA.

Question 9

When does a dominant genetic disorder occur?

Accepted Answer

A dominant genetic disorder occurs when either one or both alleles of the gene are mutant.

Question 10

What are homologous chromosomes?

Accepted Answer

Homologous chromosomes are two chromosomes (one inherited from each parent) that have the same genes at the same loci, but not necessarily the same alleles. They are similar in size and shape, and pair up during meiosis.

Question 11

Which structure would be expected in normal eye cells but not in normal heart cells?

Accepted Answer

Rhodopsin is a light-sensitive receptor protein found in the photoreceptor cells of the retina in the eye, not in heart cells.

Question 12

What is CFTR/CFTR-DF508?

Accepted Answer

The answer of What is CFTR/CFTR-DF508?
...

Question 13

What percentage of alleles will be shared by certain siblings due to the law of independent assortment?

Accepted Answer

Two typical siblings will have about 50% of their alleles in common due to the law of independent assortment, which states that each allele segregates independently during gamete formation. This means that each sibling has a 50% chance of receiving a certain allele from each parent, resulting in about 50% of their alleles being the same. Monozygotic twins come from the same fertilized egg and share 100% of their alleles, while dizygotic twins come from two different fertilized eggs and share about 50% of their alleles like typical siblings.

Question 14

A heterozygous organism

Accepted Answer

A heterozygous organism has two different alleles of a gene, one dominant and one recessive. This allows for different possible combinations of gametes to be produced during meiosis.

Question 15

Which situation most likely describes a recessive genetic disorder?

Accepted Answer

Recessive genetic disorders typically occur when the mutant allele produces a nonfunctional protein, requiring two copies of the mutant allele (one from each parent) for the disorder to manifest. This is because one functional allele can often compensate for the loss of function in the other allele, preventing the disorder from appearing in heterozygous individuals.

Question 16

In a certain plant species, thick-shelled seeds are caused by the dominant allele T. Thin-shelled seeds are caused by the recessive allele t. What is the genotype of an individual with thin-shelled seeds?

Accepted Answer

An individual with thin-shelled seeds must have two copies of the recessive allele, so their genotype can only be tt. The other options (TT and Tt) would result in thick-shelled seeds. The answer could also be written as D (tt or Tt), but B is the most specific and accurate answer.

Question 17

What other term describes fraternal twins?

Accepted Answer

Fraternal twins are also called dizygotic twins as they are formed when two different eggs are fertilized by two different sperms.

Question 18

How many genetically different children could your parents have produced with their combinations of gametes?

Accepted Answer

The combination of 23 pairs of chromosomes in humans allows for a maximum of 2^23 (or 8,388,608) different possible gamete combinations for each parent. Therefore, the total number of genetically different children that could be produced with these combinations is 2^23 x 2^23 or 2^46 (or approximately 64 trillion).

Question 19

Cystic fibrosis is caused by the allele f, which is completely recessive to the normal dominant allele F. Consider a couple who both have the genotype Ff. What is the chance that their first child will develop cystic fibrosis?

Accepted Answer

Both parents carry one copy of the recessive allele f but do not have cystic fibrosis. Therefore, there is a 25% chance that their offspring will inherit two copies of the recessive allele (f) and develop cystic fibrosis. The possible genotypes for their offspring are FF, Ff, and ff with a 25% chance of each genotype.

Question 20

Cystic fibrosis is caused by the allele f, which is completely recessive to the normal dominant allele F. Consider a couple who both have the genotype Ff. What is the chance that their second child will develop cystic fibrosis?

Accepted Answer

The chance that their second child will develop cystic fibrosis is 25% because each child has a 1 in 4 chance of inheriting two recessive alleles (ff) when both parents are carriers (Ff). The outcome for each child is independent of the outcomes for their siblings.

Quiz 7: Are You Only As Smart As Your Genes Mendelian and Quantitative Genetics