Ch.11 Flashcards
How cells regulated?
- one cell becomes two
- the division of all cells must be regulated and coordinated with both cell growth and DNA replication in order to ensure the formation of progeny cells containing intact genomes.(liver cell)
Process of the division cycle of cell
- cell growth -accumulate enough nutrient for division
- DNA replication-you need lot of nucleotide.
- distribution of duplicated chromosome to daughter cells-genetic information(lipid)ER is broken down.
- cell division-cytokinins, cute 2 cells and finish them separately.
Interphase
Period between mitosis when the chromosomes are decondensed and distributed throughout the nucleus, so the nucleus appears morphologically uniform.
Cytokinesis
Division of a cell following mitosis or meiosis
M phase
Correspond to mitosis, which is followed by cytokinesis
G1 phase
Corresponds to the interval or gap between mitosis and initiation of DNA replication.
S phase
Process which DNA replication takes place
G2 phase
Process in which cell growth continues and proteins are synthesized in preparation of mitosis.
Why don’t we have a gap phase in early embryonic development?
Gap phase put a pause to allow them to make protein.
G0 stage
Quiescent stage, where the cells remain metabolically active but no longer proliferate unless vs,led on to do so by appropriate extra cellular signals.
FACS
Use laser to detect a fluorescence
The progression of cells through the division cycle is regulated by what?
Extra cellular signals from the environment as internal signals that monitor and coordinate the various process that take place during different cell cycle phases.
What is the start point for cell signal in yeast?
Start(nutrient, mating factor and cell size)
Budding yeast
Parent cell produces one or more projection called buds, which later develop necessary structure and detach to grow into new individuals.
Fission yeast
The parent cell splits into 2 equal halved, each on which develop into a new individual.
What is the start point for cell signal in animal cell?
Restriction point(growth factor)
Starting cell cycle in somatic cell
G1
Starting cell cycle in vertebrate
G2(oocyte)
Cell cycle check point
- Prevents entry into the next phase of the cell cycle until the events of the proceeding phase have been completed.
- function to ensure that incomplete or damaged chromosome are not replicate and passed on to daughter cells.
G1 checkpoint
Prevents damaged DNA being replicated in S phase
S phase checkpoint
- Ensures DNA replicates correctly and no DNA damage
- the molecular mechanism that restricts DNA replication to once let cell cycle involves the action of MCM helicasr proteins that bind to replication origins together with the origin recognition comolex(ORC) proteins.
G2 checkpoint
Prevents the initiation of mitosis prior to the completion of s phase, thereby ensuring that incompletely replicated DNA is not distributed to daughter cells.
Spindle assembly check point
Cell cycle check point that maintains the integrity of the genome occurs toward the end of mitosis.
How do cells ensure each replication of DNA only happen once?
MCM can only bind to ORC at G1
ORC
Cells stop DNA replication
The cell cycle of all eukaryotes is controlled by what?
By conserved set of protein kinase, which are responsible for triggering the major cell cycle transition.
Maturation promoting factor(MPF)
Present in somatic cells where it induced entry into M phase of the mitotic cycle.
2 key subunits of MPF of cell cycle
Cyclin B+CDk1
Who is responsible for regulating different cdk’s?
Cdk inhibitors or CKI
Mechanism of Cdk regulation
- Association with cyclin
- Activity phosphorylation of threonine around position 160
- Inhibitory phosphorylation of threonine 14 and tyrosine 15
- Association with Cdk inhibitors(CKI)
Cdks
Cyclin dependent protein kinase that control the cell cycle of eukaryotes
How cells are passing through start as well as entry into mitosis in yeasts?
G1 cyclins, or Clns are yeast cyclins that control passage through start.(cdk1)
How cells pads through restriction point?
2 engine: cdk4,6/cycD
Cdk2/cycE
Both in G1
DNA damage controlled by 2 proteins
ATM or ATR
What does ATM do?
ATM phosphorylate CHK2, inactivates Cdc25A and promotes the activation of cdk2. As a result G1 and S phase arrest
What does ATR do?
ATR activates CHK1, inactivates Cdc25C, promotes activation of cdk1. As a result G2 arrest.
What is the purpose to stop Cdk activity?
It give the cell time to repair damage
P53
Phosphorylated by both ATM and ATR
Transcription factor responsible for making mRNA
Role of p53 in cancer development(G1)
P53, a transcription factor, is normally rapidly degraded Phosphorylation stabilizes p53 More p53 increases p21 expression P21 is a CKI,inhibits cyclin E/cdk2 G1 arrest
