Lesson 3: Karyotype And Abnormal Meiosis Flashcards
What is a karyotype?
A karyotype is when chromosomes are organized in homologous pairs through appearance, size, and gene sequences.
How many chromosomes do humans have?
Humans have 46 chromosomes in our cells, which is 23 pairs.
What are the sex chromosomes in humans?
The sex chromosomes are pair #23. Females have XX and males have XY.
What are autosomal chromosomes?
22 pairs (#1-22) are autosomal chromosomes, one maternal and one paternal chromosome that pair up during meiosis.
What is nondisjunction?
Nondisjunction is the loss or gain of entire chromosomes that can happen during meiosis I or II.
What can result from nondisjunction in humans?
Nondisjunction can result in having 24 or 22 chromosomes, which is an incorrect number.
What happens during nondisjunction of homologous chromosomes in meiosis I?
Nondisjunction can lead to gametes with abnormal chromosome numbers.
What happens during nondisjunction of sister chromatids in meiosis II?
Nondisjunction can also occur during meiosis II, affecting sister chromatids.
What is a homologous chromosome?
A homologous chromosome is a pair of chromosomes that are similar in size and carry the same genetic information.
What is Trisomy?
Trisomy is the presence of 3 homologous chromosomes in a homologous pair.
What is Monosomy?
Monosomy is the presence of a single chromosome in place of a homologous pair.
What is the karyotype notation for a female with Down Syndrome?
The karyotype notation for a female with Down Syndrome is (47,XX,+21).
