Lecture 2 Flashcards
What is a Ploidy?
The number of complete sets of chromosomes in a cell
What is a Cell with One complete Set of Chromosomes
Haploid
What is an Example of a Haploid Cell?
Sperm cell or an egg in vertebrates
What is a Diploid Cell?
Has two complete sets of chromosomes (one from mother and one copy from the father)
What is an example of a Diploid cell?
A somatic cell such as a leaf cell, skin cell or a stem cell in your colon
What can a Haploid Cell be represented by?
“n”
What can a Diploid cell be represented by?
“2n”
What happens to a Diploid Cell after S-phase?
The amount of DNA has doubled (4 complete set of chromosomes)
What does not change in Mitosis?
The Ploidy Level
Is meiosis a terminal event?
Yes. It stops.
Can mitosis keep happening?
Yes.
How many interphase in Meiosis?
1
What happens in the first division of Meiosis?
It randomly separates homologous chromosomes
What happens in the second division of Meiosis?
Results in the splitting of sister chromatids
What is the end result of meiosis?
4 genetically unique daughter cells
What is each genetically unique daughter cell at the end of meiosis?
Haploid (unlike mitosis)
What happens at the end of mitosis?
2 identical daughter cells
What is the first stage of Prophase I
Chromosomes first become visible as thin threads. DNA replication is already complete.
What is the second stage of Prophase I
Homologous chromosomes continue to condense and undergo synapsis (gene for gene pairing)
What is the third stage of Prophase II
When synapsis is complete, each pair of homologous chromosomes forms a bivalent. Each chromosome consists of two chromatids.