Lecture 3 Meiosis & Mitosis Flashcards
In Mitosis - What phase follows the G2 phase and what are the 4 sub-phases called
Mitotic Phase
- Prophase
- Metaphase
- Anaphase
- Telophase
What phases of Mitosis are the organelles copied?
G2 Phase
How many chromosomes/ pieces of DNA are in a cell during Interphase
Depends on the stage
46 in G1
92 by end of S phase
Why does a cell phave 92 pieces of DNA
Because it is going to divide into 2 daughter cells that will have 46 each
What are the phases of interphase
G1
S
G2
What is the non-dividing portion of the cell life
Interphase
What happens during Prophase
Nuclear envelope dissolves
Centrosomes push each other to opposite ends of cell
Chromatin condenses to form chromosomes
Identical copies of DNA - known as Sister Chromatids pair up
What is Chromatin
DNA that is loose and uncoiled - accessible for ribosomes to read
What are Chromosomes
Coiled version of chromatin - tightly coiled DNA
What are Sister Chromatids
identical copies of DNA that pair up and are connected with a centromere
What events happen during Metaphase
DNA are lined up on mid-line called metaphase plate
Micro tubules connect to centromere
What events happen during Anaphase
Micro-tubules pull DNA to opposite ends of cell
Centromere breaks
What events happen during Telopphase
New nuclear enveloped form around DNA
Cleavage furrow formed by micro-tubules and deepens from tightening of micro-tubules eventually causing cytokineses
Through what cell cycle are gametes formed - what are gametes
Meiosis
Sex cells - sperm & egg cells
How many pieces of DNA in the primary sex cell
46
How many pieces of DNA in the secondary sex cells
23
What is Meiosis part 1 in the male sex cell life cycle
The reduction division when the Primary sex cells divides into 2 secondary sex cells that each have 23 pieces of DNA each
What happens in Meiosis 2 in the male sex cell life cycle
Both priimary sex cells duplicate into 2 indentical cells known as Spermatids each have 23 pieces of DNA
What is the female Primary sex cell known as
Oocyte - has 46 pieces of DNA
What happens in Meiosis 1 in a female cell cycle
Primary Oocyte divides into a Secondary Oocyte and a 1st polar body - takes on average 14 days
What is a 1st polar body
The secondary oocyte that has too small of a cytoplasm to survive and therefore does not mature
What happens to the Secondary Oocyte that does mature
Ovulated in response to the Lutinizing Hormone - typically does not go through Meiosis 2, but if fertilization happens it will go through Meiosis 2
Meiosis 2 in a Secondary Oocyte only occurs when
If fertilization happens with a sperm
What are the products of Meiosis 2 in the female cell cycle
2nd polar body - has too small of cytoplasm and dies
&
Ovum are created
Ovum then goes through Mitosis and a Zygote with 46 pieces of DNA is created which then continues to replicate becoming an embryo with stem cells
