Cell Cycle and Mitosis Flashcards
What is the difference between chromatin and chromosomes?
CHROMATIN has DNA plus proteins that helps provide organization and structure
Chromosomes are made of DNA and have instructions in the genes.
What is the difference between autosomes and sex chromosomes?
22 of the pairs are autosomes, found in both male and females.
One pair is the sec chromosomes which control the gender of the child.
What are sister chromatids?
the identical parts that make up sister chromatids.
What is a centromere?
The region of DNA where the sister chromatids are held together.
What do karyotypes represent?
A picture of the chromosomes
What occurs in the G1 stage of the cell cycle?
The cell performs its normal function, doubling its organelles and accumulates the materials needed for DNA synthesis.
What occurs in the S stage?
DNA replication
After this stage, each chromosome as two identical sister chromatids (identical parts connected by a centrosome to form a homologous pair)
What is G0?
When cells like nerve and muscle cells do not complete the cell cycle and are permanently in G1.
It performs normal functions but does not divide.
Whats something interesting about Embryonic cells?
They spend very little time in G1 and complete the cell cycle in a few hours.
Stages G1, S and G2 are a part of what?
Interphase
Cell division consists of what?
Mitosis and cytokinesis(division of the cytoplasm)
What are the checkpoints (sensors to determine if the cell is in proper condition to divide) in the cell cycle?
G1 checkpoint
G2 checkpoint
Metaphase checkpoint
What is the purpose of the g1 checkpoint?
Cell cycle main checkpoint, if DNA is damaged, apoptosis will occur. Otherwise, the cell is committed to divide when growth signals are present and nutrients are available.
What happens at the G2 checkpoint?
Mitosis will occur if chromosomes are replicated properly.
Apoptosis will occur if DNA is damaged and cannot be repaired.
What happens at the M Checkpoint
Spindle assembly checkpoint between metaphase and anaphase. Mitosis will not continue if chromosomes are not properly aligned.
What does the p53 and Rb protein do>
p53 - turns on genes to stop the cycle and repair DNA, or even kill the cell if it cant be achieved (G1 and metaphase checkpoints)
Can stop the cell cycle and place is in G0.
Rb - Inhibits the transcription factor E2F, needed to activate genes for progression from G1 to S phase.
What are the external controls of the cell cycle.
Proto-oncogenes - stimulate cell division
Tumor suppressor - inhibit the cell cycle
What are the phases of mitosis?
Prophase Prometaphase Metaphase Anaphase Telophase
Cytokenis happens after mitosis, What happen during cytokinesis?
An indentation called a CLEAVAGE FURROW passes around the circumference of the cell.
Actin filaments form a contractile rings, as the ring becomes smaller, actin filaments form a CONTRACTILE RING and the cleavage furrow pinches the cell in half .
Whats the difference between mitosis and meiosis?
In mitosis , the daughter cells are genetically identical to each other and to the parent cells. Makes autosomes.
In Meosis, each daughter call Is genetically different from the parent cell. In sexual reproduction. produces gametes (sperm or egg)
Explain Mitosis to Meoisis
Mitosis
- Daughter cell becomes a diploid
Meosis
- Diploids (contains a pair of sister chromatids) create haploids
- Haploids (contain one individual chromosome) create zygotes
What happened in Prophase 1 of meiosis
Crossing over occurs (segments of chromosomes are exchanges with each other in crossing over)
metaphase 1 -
Bivalents (a pair of chromosomes) aligned along the spindle fibers in double rows
What happens in anaphase 1?
valets (pair of chromsomes). break but sister chromosomes stay together , the chromatids move to the opposite poles
What happens in telophase 1?
Sister chromatids have reached their poles and decondense and nuclear membranes reform.
What is the result at the end of meiosis 1?
Two haploid cells
What happens in meiosis 2 that makes it different from meiosis 1?
The 2 cells from meiosis 1 go through the steps again , each have 2 daughter cells that are genetically different.
What is trisomy?
Trisomy 21 causes Down syndrome (the Most common autosomal trisomy)
When 2 of the zygote have an extra chromosome because the second cell in meiosis 2 sins have any so two of the daughter cells have 2n+1 and 2 have 2n-1.
When a normal XX female has one of the X chromosomes inactivated it is known as a…
(Females can function with a single X chromosomes just like males do)
Barr body
All extra X chromosomes becomes Bar bodies so xxl males and poly-X males are survivable.
What are the 4 changes in chromosome structure?
Deletion
Duplication
Inversion
Translocation
What happens in chromosomal deletion?
Part of the chromosome is deleted.
What happens in chromosomal duplication?
Part of the chromosome duplicates in the strand
What happens in chromosomal inversion?
Part of the chromosome switches (like from cd to dc)
What happens in chromosomal translocation>
With two sister chromatids, part of the chromosome switches places.
The syndrome Cri-du-chat resulted from which change in the chromosomal structure?
deletion
The syndrome Alagille and Philadelphia chromosome resulted from changes in which chromosomal structure?
Translocation
