Genetic Testing

What is a monohybrid cross?

A cross involving one trait, typically represented by a 2x2 Punnett square, showing a 3:1 phenotype ratio.

What is a dihybrid cross?

A cross involving two traits, represented by a 16-box Punnett square, showing a typical phenotype ratio of 9:3:3:1.

What do circles and squares represent in a pedigree chart?

Circles represent females, and squares represent males.

How does a dominant trait appear in pedigrees?

A dominant trait appears in every generation.

How can you tell if a trait is recessive in a pedigree?

A recessive trait can skip generations.

What is the importance of karyotypes?

Karyotypes visually represent chromosomes, allowing the detection of disorders and the identification of sex chromosomes (XX or XY).

What are sex-linked traits?

Traits located on sex chromosomes, with X-linked traits affecting more males due to their XY chromosome structure.

What is non-disjunction?

The failure of chromosomes to separate during meiosis, leading to gametes with extra or missing chromosomes.

What is the main difference between meiosis and mitosis?

Meiosis produces 4 unique haploid gametes, while mitosis produces 2 identical diploid cells.

What are polygenic traits?

Traits controlled by many genes that result in a wide range of phenotypes, typically represented by a bell curve.

What are multiple alleles?

More than two allele options exist for a gene, such as the A, B, and O blood types.

What are the genotypes for blood types A, B, AB, and O?

Type A: IAIA or IAi; Type B: IBIB or IBi; Type AB: IAIB; Type O: ii.

What does the term 'heterozygous advantage' mean?

The condition where carriers of a recessive allele have a survival benefit, such as sickle cell trait providing malaria resistance.

What is Tay-Sachs disease?

An autosomal recessive disorder where carriers are unaffected but can pass it to offspring, persisting in populations due to potential heterozygous advantages.

What is the typical phenotype ratio for a dihybrid cross?

9:3:3:1.

What does crossing over do during meiosis?

It increases genetic diversity by exchanging genetic material between homologous chromosomes.

What is the role of a Punnett square?

To predict the probabilities of offspring genotypes and phenotypes from given parental genotypes.

What happens during non-disjunction?

Gametes may end up with too many or too few chromosomes, leading to genetic disorders.

What is indicated by a karyotype showing XXX?

It indicates a female with an extra X chromosome, which could lead to disorders.

What is an example of a genetic disorder detected by a karyotype?

Down syndrome, resulting from trisomy 21.

What inheritance pattern do blood types follow?

Codominance and multiple alleles, where IA and IB are dominant over i.

What can be determined from a pedigree analysis?

Inheritance patterns, whether traits are dominant/recessive, and if they are autosomal/sex-linked.