Lecture 13 - Mitosis, Meiosis, and the Chromosomal Basis of Disease Flashcards
In what phase of the cell cycle does DNA replicate to form sister chromatids?
S Phase
The cell spends the greatest amount of time in ________; and a relatively short amount of time in ________.
greatest amount of time - interphase
short amount of time - mitosis
In what phase of the cell cycle does the cell begin to condense chromatin to form chromosomes?
G2 phase
What are the two general factors of meiosis that differ between sexes?
- Timeline
2. Products
The goal of meiosis is:
to create haploid daughters from the somatic precursor cell
In what phase of the cell cycle does the cell accumulate materials to be used for DNA synthesis, such as histones?
G1
In what phase of the cell cycle does the cell produce proteins like tubulin to make microtubules, and replicate its centrioles?
G2
In what stage of mitosis do sister chromatids move to opposite poles?
Anaphase
What happens during prometaphase of mitosis?
nuclear envelope breakdown; attachment of sister chromatids to spindle fibers
How are meiotic products difference between males and females?
Females - only one of the four meiotic products is retained, other 3 sets of chromosomes are segregated into polar bodies
Males - cytoplasm divides evenly and the four meiotic products all go on to form functional sperm
Absence of crossovers during Meiosis I prophase leads to:
chromosome missegreegation, resulting in aneuploidy
i.e. the chromosomes separate independently
What is a non-disjunction?
Chromosomes separate to the same pole
Homologous chromosomes can separate to the same pole, forming a non-disjunction. Upon fertilization, what results from this process?
Gametes with too many or too few chromosomes lead to monosomies and trisomies
After a nondisjunction during MI, all the oocytes from the mother either have two X chromosomes or none. The fusion of an oocyte carrying XX chromosomes with a sperm carrying the Y chromosome results in ______.
Kleinfelter Syndrome (XXY)
During MII, the sperm undergo a nondisjunction and resulting gametes either have 2 Y chromosomes or none. What syndrome occurs if the nullospermic sperm fuses with a normal egg?
Turner Syndrome (XO)
