Final Exam Flashcards
What is interphase?
The period between one m phase to the next. It includes g1, s, and g2 phase
Which cyclin trigger g2 to m phase ? What is the name of it’s active form
M cyclin and M-cdk
What is the order of the cell cycle
G1 phase, S phase, G2 phase, and More have ( mitosis and cytokinesis)
Which cyclin binds to its cdk in the late G1 phase
S cyclin and G1/S cyclin binds to cdk to form S-cdk and G1/S-cdk
Which cyclin and cdk drive g1 phase to s phase
G1 binds to cdk to form g1-cdk
What is the function of cyclin-cdk complexes
Phosphorylate a set of target proteins in the cell
What is the function of anaphase-promoting complex (APC)
Degradation of m and s cyclin by tagging the cyclin with a chain of ubiquitin
What regulates the activity of cyclin cdk complexes
Specific protein kinases and phosphatases. The complexes can be activated by being dephosphorylated
What is the function of Cdk inhibitor protein? Why is this an advantage and give an example
The function is to block the assembly or activity of cyclin-cdk complexes. This allows for more time for the cell to grow or wait for more favorable conditions. P27(the hugging machine) is an example
True or false
Once the cell transitions to g1 phase to s phase, it will go all the way through the cell cycle
True
What are mitogens
Extracellular signals produced by other cells that stimulate the cell to divide
What happens if the cell is deprived of mitogens
The cell cycle arrest at g1 and after some time go into g0
How does a cell es ape the cell. Y or arrest
By accumulating cyclin by having the mitogens signal the cell to synthesize g 1 cyclin, g1/s cyclins and other proteins involved with DNA synthesis and chromosome duplication. This buildup will progress the cell into the s phase
What is the function of retinoblastoma (Rb) protein
A transcription regulator that prevents the cell from activating genes that causes the cell to divide
Describe the relation ship between mitogens and Rb
Mitogens causes the cell to active g1-cdk and g1/s-cdk in order to deactivate Rb by phosphorylating it to its inactive form
What happens if dna is damaged in the g1 phase
A protein called p53 is activated to its stable form and promoted the transcription of a gene that enforced for a cdk inhibitor protein called p21. P21 binds to the g1/s cdk and s-cdk to prevent them from dvijg the cell into s phase. This gives the cell some time to repair the dna or if it is too severe causes apoptosis
What happens is p53 is missing
There is a high rate of mutation and cells tend to become cancerous
What is the purpose of cdc6
In g1 phase, it’s concentration increases and will open up the double helix if dna and ready the origin of replication with ORC protein complex
What signals to commence replication if dna and how
S-cdk will activate the dna helicases and promote the assembly of the other proteins at the replication fork. It “pulls the trigger for dna replication”
How does s-cdk prevent re-replication
It phosphorylate cdc6 so it can be degraded
Where is the cdc6 position and when does it leave
It is on top of the ORC and leaves once helicase binds
What is the m phase
Mitosis
How does the m cdk remain inactive if the dna is damage before going into m phase
M cdk is inactive when phosphorylated. In order to activate it, it is dephosphorylated by cdc25. In order to pause the cell from entering the m phase with damaged dna, cdc 25 must be inactive
Describe the positive feed back m cdk experiences at the end of g2 phase
Activating m-cdk completes phosphorylate and activate more cdc 25 that activates more m-cdk
What is the difference between condensins and cohesin
Condensin assemble on the individual sister chromatid to coil up more and cohesins keep the Sister chromatids together
What is the order of mitosis
Prophase prometaphase metaphase anaphase and helping have
What must happen in order for m phase to begin
Dna must be fully replicated and centrisomes must be duplicated
What are asters
Microtubules that forms when the centrosomes separate in mitosis
What happens in pro phase?
The sister chromatids condense And the mitotic spindles assembles between the two centrosomes and begin moving apart
What happens at the prometaphase
What he nuclear envelope is broken down and chromosomes are attach to the sound microtubules bus their kinetochores
What happens in metaphase
The chromosomes are aligned in the huddle
What happens in anaphase
The sister chromatids are pulled apart and the kinetochore are getting shorter
What happens in telophase
The two sets of chromosomes are at the opposite ends of the cells and the nuclear envelope is reassembly
What happens in cytokinesis
In an animal cell, the cytoplasm is divided into two by the actin and myosin filaments
What are kinetochores
Protein complexes that are in the centimeters of each of the condensed chromosome
What is bi-orientation
The microtubules attachment to chromosomes on opposite poles
Where is the aster microtubules, kinetochore microtubules, and interpolate microtubules
Aster microtubules are not attached to anything and is generally away from the sister chromatids. Kinetochore microtubules are attached to the kinetochore of the chromosomes. Interpolate microtubules are attached to microtubules at the opposite poles
How does the cell cleave the cohesins that bind the chromosomes together
Active APC degrades securin. Securin is a protein the inhibits separate. Once separate is activated, it cleaves the cohesins
Explain the process of cell necrosis
A cell dies from an acutely injury that causes it sell and burst. Spilling their contents all over their neighbors
What are Caspases
A family of protease that is responsible for apoptosis
What is the name of the inactive form of caspase
Procaspase
What are the two types of caspases and what is the function
Initiator caspase cleave executioner caspase to activate it. Executioner caspase can active more executioner caspase to kill the cell
What regulates the activity of caspases
Bcl2 family
Which are the two most are the most important bcl2 family to induce cell death
Bax and bac
What is the purpose of bax and bac
Cytochrome c is release form the mitochondria to form a large seven armed protein complex call apoptosome that recruits and activated procaspases( induces cell death). Thus leads to caspase cascade to apoptosis
How does survival factor promote cell survival
Largely by suppressing apoptosis
Give an example of death receptor
Fas is activated by its ligand and it’s on the surface of killer lymphocytes. These Killers induce apoptosis to other useless immune cell
What is APC (adenonmatous polyposis coli
A tumor suppressor gene
List the junctions of a epithelial cells
Tight junction
Adherents junction with actin circle surrounding it
Desmosome with IF strifes popping out of it
Gap Junction
Hemidesmosomes at the bottom
What happens in Paracrine signaling
Signal is diffused locally. Many of the signals regulate inflammation or control cell proliferation in a healing sound function
What Is contact dependent signaling
When cells make direct physical contact through signaling molecules
What are the two classes of extracellular signal molecules
Large hydrophilic signaling molecules that bind to the receptor. Small hydrophobic molecules that get into the cytosol to activate intracellular enzymes or bind to intracellular receptor proteins
Describe the pathway of steroid hormones
They pass through the plasma membrane and bind to receptor proteins In the cytosol or nucleus.
What is nuclear receptors
Cytosolic and nuclear receptors that act as transcription regulators in the nucleus
What happens to NO when it enters a cell
Converted to nitrates and nitriles
What does NO do
Causes smooth muscles in the adjacent vessel wall to relax
What is the function of intracellular signaling pathways
Relay messages
Amply signal received
Integrate signals
Distribute signal
Positive feed back can Generate all or none responses while negative feedback can generate responses of switching on and off
Yes
What are the two switches of cell signaling
Kinase that adds phosphates and phosphatase that takes away the phosphate
What are the two main types of protein kinase and what is their function
Serine/threonine that phosphorylate proteins on serines or threonines
Tyrosine kinase that phosphorylate proteins in tyrosine
What are gtp binding proteins
Intracellular signaling pathways that toggle between active and u active state baSed in being GTP GDP bound
What are the three main classes of cell surface receptor and they functions
Ion channel couples receptor that change the permeability of the membrane by altering the membrane potential
G protein coupled receptors that active trimeric GTP binding proteins (g proteins). G proteins function is to activate or Inhibit an enzyme or ion channel in the membrane causing a cascade
Enzyme coupled receptors that can act as enzyme or associate with enzymes inside the cell to activate a wide variety of signaling pathway
What are G proteins coupled receptors (GPCR)
A single polypeptide that threads back and forth across the lipid bilayer seven times
What happens when GPCR is bound to a extracellular signal
It’s undergoes a conformation change that activates G protein
What happens when GDP is bound to the alpha subunit if a G protein
It is inactive
What happens when a extracellular signal binds to a G protein
The alpha subunit exchanges GDP to GTP. The alpha can detached from beta gamma that is also active and both subunit complex can interact with its target proteins
