Cell Cycle Flashcards
A rare genetic syndrome in which some signs of aging are greatly accelerated.
PROGERIA
It has 23 chromosomes haploid cells.
GAMETES
It has 46 chromosomes Diploid cells.
SOMATIC CELLS
One copy of each chromosome.
HAPLOID (n)
Two copies of each chromosome.
Diploid (2n)
A series of events that takes place in a cell as it grows and divides.
CELL CYCLE
Divided into 2 gap phases and 1
synthesis phase.
INTERPHASE
Is divided into four stages plus
MITOSIS
When the cells separate.
CYTOKENESIS
Is a “time-out” when a cell “decides” which
course of action to follow
G0
- follows mitosis, when the cell resumes synthesis of proteins, lipids, and carbohydrates essential for early growth
- varies in different cell types
G1 Phase
- the cell replicates its entire genome
- takes 8 to 10 hours
- proteins involved in formation of mitotic spindle are synthesized
- microtubules form centrioles
S Phase
- occurs after DNA replication and before mitosis
- more proteins are synthesized
- prepares for cell division by assembling necessary structures
G2 Phase
- produces two daughter cells of the same quality and quantity of chromosomes as the parent cell
- “duplication division”
- karyokinesis + cytokinesis
- has 4 distinct stages: prophase, methaphase, anaphase, and telophase
MITOSIS
- DNA coils tightly, shortening and thickening the chromosomes.
- microtubules assemble from tubulin building blocks in the cytoplasm, forming the spindles.
- nuclear membrane breaks down.
- nucleolus is no longer visible.
Prophase
- chromosomes attach to the spindle at their centromeres and align along the center of the cell.
Metaphase
- chromatids have fully separated, becoming full fledged chromosomes that are pulled by the spindle fibers toward the opposite poles.
Anaphase
- the cell looks ike a dumbbell with a set of chromosomes at each end.
- spindle falls apart, and nucleoli and the membranes around the nuclei re-form at each end of the elongated cell.
- karyokinesis is complete
Telophase
- organelles and macromolecules are distributed between the two daughter cells.
- the microfilament band contracts like a drawstring, separating the newly formed cells.
Cytokinesis
After mitosis how many daughter cells are formed, with each having genetically identical chromosomes
2 diploid daughter
cells
They ensure that chromosomes are correctly replicated and apportioned into daughter cells.
Checkpoints
What are the 3 checkpoints?
- DNA damage checkpoint
- Apoptosis checkpoint
- Spindle assembly checkpoint
- a continuous process that begins when a “death receptor” on the cell’s plasma membrane receives a signal to die.
- enzymes called caspases are activated inside the doomed cell, stimulating each other and snipping apart various cell components.
APOPTOSIS
- necessary for sexual reproduction and formation of the gametes
- reduces the number of chromosomes into half
- produces variation in daughter cells
- has 2 distinct divisions: Meiosis I and Meiosis II
MEIOSIS
- begins as the replicated chromosomes condense and become visible when stained.
- special proteins cause the homologous chromosomes to stick together in pairs.
- has 5 sub-stages
Prophase I
What are the stages of the prophase of meiosis 1
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis
Replicated chromosomes condensed
Leptotene
Synapsis begins
Zygotene
A bivalent has formed and crossing over has occurred
Pachytene
Synaptonemal complex dissociates.
Diplotene
End of prophase 1
Diakinesis
generates genetic diversity by recombining genes, mixing parental traits.
Crossing over
- homologs align down the center of the cell.
- each member of a homologous pair attaches to a spindle fiber at an opposite pole.
Metaphase I
- homologs separate and move to opposite poles
Anaphase I
- each pole has haploid set of chromosomes
- followed by cytokinesis, producing two haploid daughter cells.
Telophase I
After meiosis, how many daughter cells are formed, with each having genetically different chromosomes
4 haploid daughter cells
How many chromosomes does haploid does
23 chromosomes
How many chromosomes does diploid have
46 chromosomes
conditions arise from stem cells in the testis that divide every 16 days, offering many opportunities for DNA replication to make a mistake, generating a dominant mutation.
“Paternal age effect”
