Molecular Biology Lecture 2

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By: Mary David
Created: 2012-04-30
Size: 85 flashcards
Views: 277

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What is MPF composed of?

Cyclin B and CDC2 protein

What is cdc in mammals?

CDK

What is the role of this MPF protein

To phosphorylate thesubstrate that permits the cell to go through the M phase

What happens when you phosphorylatenuclear lamins?

Breakdown of nuclearenvelope

-Important for mitosis to occur

What happens when you phosphorylate histone H1?

H1 playsa role in packaging DNA into chromosomes & phosphorylation may help into this chromosome condensation whichis important in splitting of the chromosomes inmitosis.

What happens when you phosphorylate phsosphorylates MAPs? What is MAPS?

- Microtubules associated with protein

-This protein plays a role inthe organization of microtubules in the organization of microtubules

MAPS is very important formitosis to occur b/c microtubules move around in the cell & grab onto thechromosomes that are involved in splitting them.

What are cyclin B and cdc2 members of?

CyclinB and cdc2 are members of large families of related proteins

Can the complex with cyclin B be combined with other cyclins? What does that regulate?

That complex in cyclin B although there are more than one cyclin Bwhich leads to progressthrough M phase but it can also comined with cyclin G & cyclin B & this differ cyclins controls differparts of cell cycle. So this differ cyclins might have differ substratesregulating differ things so it can lead to entry into differ parts of the cell cycle

higher eukaryotes not only have________ but _______.

multiple cyclinsbut also multiple cdc2related kinases

CDK

Cyclin-dependent kinase in higher eukaryotes

-highly conserved in their sequence & theirfunction

What are Cyclin D's subtypes and what CDKs can it be complexed with?

cyclin D and subtypes of cyclin D are (D1, D2 & D3) which can be complexed with differ CDK like CDK 2, 4 & 6

Why are cyclins called cyclins?

All them have rolesin differ parts of the cell cycle but they are all conserved in the way theyoperate the basic mechanism wherecyclin has to bind to CDK &they both have to be boundtogether in order to operate.

*** Cyclin parts of this complex is called cyclin b/c it is the parts that cycles(cyclin is present some ofthe time and other times, it gets degraded

Activitiesof CDKs are regulated by multiple mechanisms

Phosphorylates the substrates

-Italso phosphorylates the cyclin which leads to cyclin degradation

CDK gets phosphorylated by_____.

Certain Protein Kinases

If CDK is phosphorylated onthese 2 inhibitory sites, is it active or inactive?

Inactive because you need phosphatases to come in and dephosphorylate this siteright here. Dephosphorylationat this site leads to finally activation of the Second CDK complex.

In an active complex of cyclin and cdk, what do you have phosphorylated?

Cyclins bound to CDKhas one site phosphorylated and these other 2 sites are dephosphorylated

What does Cyclin B / CDK1 – regulate?

progression from G2 to M phase

What regulates the transition from S phase to G2 phase?

cdk1 and cyclin A

What regulates the transition from G1 to S phase?

cdk2 and Cyclin E

What is CKI?

Cyclin dependentkinase inhibitors

-p16 and p21

So the Cyclins can beregulated by different mechanisms

1. Phosphorylation and dephosphorylation.

2. Whether or not the Cyclin is bound to it, to the complex.

3. Whether or not the CKI is bound to the complex

4. Whether or not the cyclin and cdk complex are bound to each other.

What are the characteristics of an active MPF?

1. Complex with no CKI

2. phosphorylation site phosphorylated

3. Cyclinand CDK bound to each other

If it is operated at a different part of the cellcycle, is it still called an MPF?

It's called a Cyclin CDK complex

what are the 2main components of the MPF complex in mammalian cells?

CDK and Cyclin

Cyclin is the part that needs to bepresent in order for the CDK to have catalytic activity.

What stimulates Cyclin D?

-Growth factors

What disease is Cyclin D associated with?

Associated withcancer,they are important forcontrolling the progression through this cell cycle

What is the major function of Cyclin D?

Move from G0 to S phase

What does cyclin D 1,2,3 complex with?

CDK 2,4,6

What is the key substrate of Cyclin D1?

Rb Retinoblastoma protein

What kind of protein is Rb?

It is a tumor suppressor

-Puts a break in the cell cycle

loss of Rb of 2 alleles of Rb is associated with which kind of disease?

Retinoblastoma, a childhood eye cancerand also with other types of cancer.

What happens when Rb is unphosphorylated? What does it bind to?

It bind to the transcription factors called E2F and DP1.

E2F and DP1 bind to target proteins, targetgenes, their transcription factors, they bind to target genes and control theirtranscription.

-> Important in DNA synthesisand therefore, are important forentering into S phase.It becomes a break and inhibits the cell cycle

What is Rb’s phosphorylationis regulated by

The Cyclin D/ CDK complex

What regulates the Cyclin D/ CDK complex?

Cyclin D/ CDK complex in turn can be regulated by growth factors

What tumor suppressor controls cyclin D/ cdkcomplex?

p53

what activates p53?

Damaged DNA

What disease is associated with a mutated p53?

50% of cancers

What is the target gene of p53?

p21

Ø binds to p21 gene at the promoter, p21 mRNA isexpressed and nowp21 protein is made. p21 can act as ckI and inhibit the activity of cdk/cyclin complex such as cyclin D complex.

What are the functions of p21?

1. inhibit the activity of cdk/cyclin complex such as cyclin D complex

2. can bind to PCNA (Proliferating Cell nuclear antigen) which has role in replication so it can inhibit the DNA replication.

What inhibits Cyclin D progress?

1.UnphosphorylatedRb

2. p53

3. p21

4. TGFB (p15 and p27)

What CKI do TGFB produce?

CkI such as p15 and p27.

What serves as a normal resevoir for new cells needed to replace damaged or dying cells?

Stem cells

It has a lasting ability to multiply when called upon for examplethe skin cells and replace dead and dying skin. Blood cells are an example,too.

An example of adult stem cells

Hematopoietic stem cells

what does potency have to do with stem cells?

It has to do with the type of stem cells they turn into .

Which is the following is characteristic about stemcells?

A. Terminally differentiated.

B. Always has capacity to replicate.

C. They are found in only embryos.

D. All of the above.

E. None of the above.

B. Always has capacity to replicate.

What are the 3 characteristics of stem cells?

1. Not terminally differentiated

2. Have potential to divide without limit

3. When a stem cell divides, each daughter cell has 2 choices

1. Remain a stem cell

2. Begin a differentiation process

Stemcells can replicate and produce_____.

Stem cell can replicate and form two daughter cells.

-One could become terminally differrntiated, meaning it becomes a certain typeof cell.

-The other can remain a stem cell.

- One remains a stem cell or canbecome terminally differentiated. It has the capacity to do both and also thecapacity to proliferate

What happens in proliferation?

When the cell divides, it is usually rounded, often dividing cells, lose their characteristicsthat let them be a certain type of cell. For example, epithelial cell when it divides becomes roundedinstead of flat when dividing.

Differentiation

-Becoming aspecialized type of cell.

-It can become any type of cell, like an epithelial cell, which can be the lining ofthe gut. It can turninto a fibroblast or a lymphocyte…a neuron, liver cells.

-All these cells have certaincharacteristics and mayspecialize a certain type of protein or extracellular matrix or cytoskeletalprotein.

-So S-cellsbecome more specialized and more differentiated and will proliferate less.

What cell doesn't differentiate?

Neurons

What do we call it when a cell cannot proliferate anymore

Terminal differentiation

Example nerve cell

What is the building block of tissue?

Cell

What are the characteristics that ALL differentiated cell share?

. One differentiated cell can bedifferent from another…different nuclei, golgi apparatus, cytoskeleton, actin,etc.

***They ALL share the same basic characteristics and DNA of the organism.

In the skin, which cells can replicate and which can't

The cells on the top cannot replicate but the bottom layer cells can replicate (basal layer).Definition

The top layer has alot of called keratinocytes,it is a tough matrixprotein

Cells that under go terminal differentiation

Do not replicate anymore

Differentiation can occur in response to ____.

An extracellular factor

What happens when When cells undergo differentiation

Go into a G₀ Phase where they don’t enter S Phase anymore.

Some cells can be recruited

So stemcells are also not necessarily replicating all the time. You don’talways find adult stem cells constantly replicating.

The importantthing is that they can be recruited out of G₀ Phase and enter Sphase and enter the cell cycle.

What is a key characteristic of stem cells?

they can be in G₀ but they have the ability tocome out of G₀ and have the ability to replicate when called uponand have the ability to differentiate into certain types of cells.

What are must have characteristics of a stem cell? (Name 5)

1.Be able to exit Go and enter the cell cycle

2. Undifferentiated

3.Produce daughter cells that are also undifferentiated

4. Renew the stem cell population

5.Produce cells that will differentiate into a specific type.

Adult diseases can be divided into 3 problems at the cellular level

1. Too much cell division=Tumors

2.Too little cell division=inability to repair damaged tissue

3.Defective cell function

Eg HEMOPHILIA- lack of synthesis of blood clotting factors from the liver

True or False: Only Embryonic Stem Cells (ES Cells) hold promise for effective disease treatment.

Answer = FALSE. In fact even adult stemcells may turn out to be much more useful than we thought in treating differenttypes of diseases.

Hematopoietic cells

So hematopoietic cells, stem cells are expected todifferentiate only into blood cells. ***But ppl can manipulate them to maybedifferentiate into other cells like heart cells for example instead

Which cells are derived artificially?

Nuclearderived stem cells (inserting the nucleus of one organism into another(from one cell to another) CLONING

and artificially derived stem cells

What is a totipotent stem cell?

A totipotent stemcell is a cell that can differentiate into ANY kind of tissue including extra-embryonic tissue thatis found in an embryo (like a yolk sac and placenta). So the best example of atotipotent cell is a fertilized egg that can become anything. It can becomeyolk sac, it can become placenta, it can become a full person.

What is a pluripotent stem cell?

A pluripotent stem cell can become ANY type of tissue except for extra-embryonic tissue. So it can’t become placenta or yolk sac but can become any type of tissue (brain, liver, heart). This is really what the embryonic stem cells we talk about are – pluripotent. They can be differentiated into anything, and we don’t really need them to become placenta or yolk sac.Definition

What is a multipotent cell?

Multipotent: Can become many types of tissue but not every type.

Ø Hematopoieticstem cells- they can become different types of blood cells but they can'tbecome a heart cell or liver cell.

What is a unipotent cell?

Unipotent (progenitor): Only destined to become once certain type ofcell.

Which type of cell do we want to use to treat disease?

closest to pluripotent as possible

Fertilized egg

Totipotent

Large signal cell with a large nucleus.

Ø difficultto study because they don't grow in culture so the only source of eggs issurgical removal.

Embryonic stem cell

Pluripotent

Comefrom blastocyst of an embryo.

Adult stem cell

Multipotent

Where in the blastocyst does embryonicstem cells come from?

in the middle of it is ball

Early Embryogenesis stages (6 steps)

1. The egg

2.Meiosis

3.Fetilization

4. Cleavage

5.Blastocyst and Grastula stages

6. Implantation

Meiosis

Ø Thereare two stages or meiosis, Meiosis 1 and Meiosis 2. At the end of Meiosis 1 the egg splits intotwo cells. It becomes 2n. In the next arrests is relieved uponfertilization and splits again in 4 haploid cells which are 1n.

Itdoesn't really go from 1 cell to 4 cells. It goes from 1 cell then instead of splitting into 2 cells it splitsinto one cell and one polar body

Fertilization involves completion of meiosis and emission of _______.

- involves completion of meiosis and emission of second polar body.

- Egg witl one polar body gets fertilized by sperm. It is undergoing division from one cell to 2 cells.

what is a zygote?

First stage

where sperm and an egg nucleus have not yet joinedtogether. It's basically two pronucleiwhich eventually will merge together.

When are cells called blastomeres?

Starting @ the 2 cell stage

When does a morula form?

day 3 is 16 cell stage

Most cells enter the uterus at morula stage

What is outside the ball of the blastocyst and what is inside?

v The outside ball of cell is going to become extra embryonictissue (placenta and yolk cell), Ball of cell insideis going to become embryo.

Can embroyonic stem cells be injected directly into a patient?

False

1. )embryonic stem cells on their own not only have ability to differentiate butthey can also form tumorsas well so they can causecancer if directly injected into the patient. 2.) put embryonic stem cells in the patient but not sure thatthey will differentiate along the pathway we want them to go. So for these reasons the differentiationprocess must bestarted in in vitro, inculture and then put theminto the patient

What is a way that embryonic stem cells can be used in a disease?

To make dopaminergic cells for Parkinson's disease

cardiac precursor cells

liver cells

Which of the following defines a cellthat can differentiate into cells that make up all different tissues with theexception of extra embryonic tissue?

A)Unipotent

B)Multipotent

C)Pluripotent

D)Totipotent

C.Pluripotent – can become many kinds of tissue but cannot becomeextra embryonic tissue like the placenta

What is the best stem cell to use?

The embryonic stem cells have often beentraditionally thought of as the best stem cells for disease treatment becauseof their pluripotent nature – they can become heart cells, nerve cells, alldifferent types.

When an unspecialized cell gives rise toa specialized cell this is the process of:

A)Differentiation

B)Meiosis

C)Mitosis

A Differientiation

About this deck

By: Mary David
Created: 2012-04-30
Size: 85 flashcards
Views: 277

About StudyBlue

“Simply amazing. The flash cards are smooth, there are many different types of studying tools, and there is a great search engine. I praise you on the awesomeness.”
Dennis