Chapter 15 - Chromosomal Basis of Inheritance Flashcards Preview

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Flashcards in Chapter 15 - Chromosomal Basis of Inheritance Deck (23):

Who is Thomas Hunt Morgan?

scientist who tested Mendel's results
- he used Drosophila melanogaster (a fruit fly that only has 4 chromosomes)
- Felt like he wasted 2 years because he did not observe differences
- finally found a fly with white eyes instead of the normal red.


What is wild type phenotypes?

A wildtype is the phenotype that will usually show up in nature. It is normal.


What is a Mutant phenotype?

A mutant phenotype is the phenotypes that are different than the wild type (white eyes in fruit flies).


How are the traits labeled for a mutant phenotype and a wildtype?

Use the letter from the mutant to represent the mutant allele (white eyes = w) and the same letter with a + to indicate a wildtype (w+)


What are sex-linked genes?

traits that are found on a sex chromosome (X or Y) are considered sex-linked genes.
- The Y chromosome has few genes and is normally passed from father to son intact
- The X chromosome has ~ 1,100 genes
- An X-linked gene refers to a trait that is caused by the chromosomes on the X chromosome.


What are some examples of an X-linked trait?

Color blindness, Duchenne Muscular Dystrophy, Hemophilia


Why are X-linked trait more common in males than Females?

Males only have one X chromosome so they will most likely receive the trait and its phenotype.


What is a Linked Gene?

Linked genes are two or more genes on the same chromosome that tend to be inherited together.
- When genes are linked there will be a higher proportion of the combination of traits to look like the P generation.


What are the Parental Types?

They are offspring that inherit a phenotype that matches one of the parental phenotype.


What are Recombinant types or Recombinants?

They are offspring that have new combinations of phenotypes.


How do you figure out the recombination frequency?

Total Number of recombinants / Total number of offspring x 100


Why does recombination happen?

Because of crossing over in the genes.


How can there be a lower rate of recombination?

The closer the two genes are on the chromosomes the lower the rate of recombination.


What does crossing over have to do recombinants?

It causes the genes to have separate genes compared to the parents. This causes recombinant type genes to appear and will see different phenotypes than the parent generations.


What is aneuploidy?

Abnormal chromosome number is known as aneuploidy.


What is a monosomic chromosome?

The zygote has only one chromosome (missing a chromosome)


What is a Trisomic chromosome?

The zygote has three chromosomes (has an extra chromosome.


What is a Polyploidy?

Some organisms will have more than one set of chromosomes in all somatic cells.


What are the different types of alterations of chromosome structure?

Deletion, Duplication, Inversions, and Translocations.


What does deletion do?

A deletion will remove a segment of a chromosome.


What does duplication do?

A duplication will repeat a certain segment of a chromosome.


What does inversion do?

An inversion will reverse a segment within a chromosome.


What does Translocation do?

A translocation will move a segment from one chromosome to a nonhomologous (not the same chromosome.) chromosome.