Lecture 13- Non-Mendelian & Chromosomal Genetics

Flashcards covering Non-Mendelian genetics, including sex-linked traits, linked genes, autosomal disorders, chromosomal aberrations like aneuploidy and nondisjunction, and prenatal testing methods.

Who was the researcher at Columbia University in 1908 who discovered the link between specific traits and sex chromosomes using the fruit fly (Drosophila melanogaster)?

Thomas Morgan

What is the definition of a reciprocal cross in genetics?

An experiment to test the role of sex on the inheritance of a trait.

What are genetic disorders caused by genes found on the X chromosome called?

X-linked disorders

How does the transcript define a recessive disorder?

A genetic disorder that does not exist in the presence of a functioning allele, where a defective gene on one allele results in the expression of the functional allele on the other chromosome.

Why do females have a "back-up" for X-linked recessive disorders like color blindness that males do not?

Females have two X chromosomes, whereas males only have one.

What are linked traits?

Genes that are located on the same chromosome and have a tendency to be inherited together.

Which genetic principle do linked traits violate?

The principle of independent assortment.

What is an example of linked traits provided in the lecture?

Red hair and freckles

What are recombinant chromosomes and how are they produced?

Chromosomes with a combination of alleles different from the parent chromosomes, produced due to crossing over.

What is the difference between autosomal recessive and autosomal dominant disorders?

Autosomal recessive disorders occur when both chromosomes in a pair contain a defective gene; autosomal dominant disorders occur when an offspring receives just one defective allele from a parent.

According to the provided table, what are the effects of Hemophilia?

Faulty blood clotting

What genetic condition results from a defective hemoglobin protein causing a specific cell shape?

Sickle-cell anemia

If one parent has a single Huntington allele (autosomal dominant), what is the probability that a son or daughter will inherit the condition?

$$50\%$$

What term refers to a person who carries an allele for a recessive disorder but does not suffer from it?

Carrier

What is a pedigree?

A family history used to track genetic conditions.

What is a common observation about X-linked inherited traits in a royal pedigree?

They tend to "skip" a generation.

Define Polyploidy.

A condition in which one or more numbers of chromosomes have been added to the genome of a diploid organism.

What is Aneuploidy, and what percentage of miscarriages is it possibly responsible for?

A condition where an organism has an incorrect number of chromosomes; it is possibly responsible for $30\%$ of miscarriages.

What is Nondisjunction?

The failure in the separation of homologous chromosomes (Meiosis I) or sister chromatids (Meiosis II) during cell division.

What is the chromosomal configuration of Turner Syndrome and what is its frequency in human females?

A female with a single X chromosome ($X0$); it occurs in $1$ of $2,500$ human females.

What are the characteristics of Klinefelter's Syndrome?

An extra X-chromosome in males ($XXY$), underdeveloped testes, development of some female features, long limbs, and being taller than average.

What specifically causes Cri-du-chat Syndrome?

A deletion of chromosome $5$.

What is Pre-implantation Genetic Diagnostics (PGD)?

The screening of the genotype of potential embryos prior to in-vitro fertilization ($IVF$).

At what stage of development is a cell removed for PGD screening?

The $8$-cell stage.

Compare the timing of Amniocentesis and Chorionic villus sampling (CVS).

Amniocentesis is performed at $14-18$ weeks of fetal development, while CVS is performed at $8-10$ weeks.