Chapter 13 - Modern Understanding Of Inheritance Flashcards
What type of genes disrupted mendels model?
Linked genes (genes in the same chromosome) especially if they are close together
How does recombination frequency work?
Genes that linked perfectly (very close together on the chromosome) have a recombination frequency of 0, while those that are perfectly unlinked (far apart in the chromosome or on different chromosomes) had a recombination frequency of 100
What disorders occur when chromosomes behave abnormally? What are the two types called?
Congenital disorders
1- structural rearrangements
2- abnormalities in chromosome number
What is a karyotype and karyogram?
A procedure to see the arrangements and characteristics of all 23 of your chromosomes which is shown in the karyogram
What is the size arrangement of autosomes?
1-22 is largest to smallest, except 21 is shorter than 22
What are the long and short arms called in a chromosome?
Long arms are q and short arms are p
How does nondisjunction occur?
It occurs during meiosis when homologous chromosomes or sister chromatids fail to separate due to misalignment or incomplete synapsis or spindle apparatus dysfunction
Individuals with the proper number of chromosomes for that species are called…; while those with an error in chromosome number are called what?
Correct is euploid, incorrect is aneuploid
What is monosomy?
Losing one chromosome, happens if the zygote is missing an autosome or development fails
What is trisomy?
Gaining an extra chromosome, these zygotes may develop offsprings that can live a long time. But excess gene dosage results in many functional and developmental difficulties due to excess gene products
What is the most common trisomy?
Trisomy 21
What is polyploidy? Where is it seen?
Individuals with more than the correct number of chromosome sets
Common in plants, but rare in animals
What does triploid zygotes result from?
An abnormal diploid sperm fertilizing a normal haploid egg
Sex chromosome nondisjunction in humans is relatively mild due to what?
X inactivation in female embryos where one X chromosome condenses into a quiescent structure called a Barr body, females can compensate for this loss of an X chromosome via dosage compensation, that is the remaining X chromosome is hyperactive and the Barr body can express a few genes usually involved in ovary and brain development
What do individuals carrying abnormal numbers of X chromosomes do?
Inactivate all but one X chromosome in each cell