10.4 Study Guide Flashcards
What is nondisjunction?
When the chromosomes don’t separate properly during meiosis.
What is trisomy?
Diploid cells have 3 copies of one chromosome type (2n+1)
What is monosomy?
Diploid cells have only 1 copy of a chromosome (2n-1)
What are autosomes?
Any chromosome that is not a sex chromosome.
What are sex chromosomes?
Chromosomes that determine the biological sex of an individual. Ex: X and Y
What is a barr body?
An inactive X chromosome found in female cells.
What is deletion?
A gene is deleted from the chromosome.
What is duplication?
A group of genes or a gene on a chromosome are duplicated, creating more of those genes.
What is inversion?
The order of a group of genes on a chromosome is reversed in order.
What is translocation?
A portion of gene(s) on one chromosome swaps with a group of genes on another chromosome.
How does nondisjunction lead to the incorrect number of chromosomes?
When chromosomes fail to separate during meiosis, the resulting daughter cells could end up with two chromosomes, which is one too many, one chromosome like normal, or with no chromosomes at all. When the chromosomes do not separate, they are not divided among the daughter cells, resulting in the incorrect number of chromosomes.
What determines human biological sex at birth?
The chromosomes present in the the cells determine biological sex at birth. Biological sex is mainly determined by the presence or absence of a Y chromosome. Females usually have two X chromosomes and males have one X and one Y chromosome.
What happens to a zygote for each type of chromosomal abnormality (deletion, duplication, inversion, translocation)?
Deletion: One version of gene(s) instead of two, which might not make enough functional protein (missing gene(s).
Duplication: Three versions of gene(s) instead of two, might make too much of a protein (extra gene(s).
Inversion: Might have more trouble pairing chromosomes for meiosis- issues with fertility (same number, maybe neither missing or extra).
Translocation: The zygotes could be normal or could have missing or extra genes (Depends on which chromatids end up in gamete).
Determine the type of reproductive system (male or female) and the number of Barr bodies produced per cell for a given set of sex chromosomes. Given set: XXY
A person with XXY sex chromosomes would develop a male reproductive system and would have 1 barr body in each cell.
Analyze an individual chromosome to determine the type of chromosomal abnormality that occurred (deletion, duplication, inversion, translocation, nondisjunction).
A chromosome with two genes that have been doubled has undergone duplication. A chromosome with a set of genes in reverse order from the original chromosome strand has undergone inversion.
Analyze a karyotype to determine the type of chromosomal abnormality that occurred (deletion, duplication, inversion, translocation, nondisjunction)
A karyotype that is missing a chromosome strand has undergone nondisjunction. A karyotype with a chromosome strand that has become smaller has undergone deletion.
