Honor Bio 10.4 Flashcards
What is nondisjunction
The failure of homologous chromosomes or sister chromatids to separate properly during meiosis or mitosis, leading to an abnormal number of chromosomes in gametes.
What is trisomy
A condition where an individual has three copies of a chromosome instead of two. Down syndrome - trisomy 21.
What is monosomy
A condition where an individual has only one copy of a chromosome instead of two.
What are autosomes
The pairs of chromosomes that are not sex chromosomes.
What are sex chromosomes
The X and Y chromosomes that determine sex. XX=Female, XY=Male
What is a Barr body
An inactivated X chromosomes in female somatic cells
What is a deletion chromosomal abnormality
When a segment of a chromosome is lost
What is a duplication chromosomal abnormality
When a segment of a chromosome is copied and inserted again, leading to extra genetic material
What is an inversion chromosomal abnormality
When a segment of a chromosome breaks off, flips, and reattaches in reverse order
What is a translocation chromosomal abnormality
When a segment of one chromosome breaks off and attaches to a different chromosome
How does non nondisjunction lead to an incorrect number of chromosomes
If chromosome fail to separate in meiosis I or II, gametes end up with extra or missing chromosomes, leading to trisomy or monosomy in offspring
What determines human biological sex at birth?
XX is female, XY is male
What happens to a zygote with a deletion
Missing genetic material can cause developmental issues
What happens to a zygote with a duplication
Extra genetic material can cause over expression of genes
What happens to a zygote with an inversion
Genes may be disrupted if breakpoints affect coding regions, but some inversion have no effect
What happens to a zygote with a translocation
if balanced, may have no effect; if unbalanced, can cause disorders
An individual has XXY sex chromosomes. What is their biological sex, and how many Barr bodies are in their cells
Would be male as there is a Y chromosome and there would be 1 Barr body as only one X is inactivated.
An individual has XXX sex chromosomes. What is their biological sex, and how many Barr bodies are in their cells
Female as no Y chromosomes, 2 Barr bodies as two X chromosomes are in inactivated
A chromosome has the sequence A-B-C-D-E-F. After mutation, it is A-B-C-F. What abnormality occurred?
Deletion
Chromosome sequence A-B-C-D-E-F. After mutation, it is A-B-C-D-E-D-E-F. What abnormality occurred
Duplication
A chromosome has the sequence A-B-C-D-E-F. After mutation, it is A-B-E-D-C-F. What abnormality occurred
Inversion
Chromosome 1 has A-B-C-D-E-F and chromosome 2 has G-H-I-J-K-L. After mutation chromosome 1 is A-B-C-J-K-L and chromosome 2 is G-H-I-D-E-F. What abnormality occurred?
Reciprocal translocation
