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CONSISTING OF INTERPHASE ,MITOTIC PHASE, & CYTOKINESIS. The Cell Cycle. The Mitosis Puzzle. Lay blank sheets lengthwise to each other and tape them together. Write Interphase, Prophase, Metaphase, Anaphase, & Telophase across the top of the sheet.

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The mitosis puzzle

The Mitosis Puzzle

Lay blank sheets lengthwise to each other and tape them together.

Write Interphase, Prophase, Metaphase, Anaphase, & Telophase across the top of the sheet.

Cut out the cell diagrams and tape/glue them across the top under the appropriate phase label.

Arrange each description beneath the appropriate picture to describe the cellular changes of that phase.


Why do cells divide
Why do cells divide?

  • Bacteria cells & unicellular eukaryotic organisms divide & produce an entire organism.

  • Multi-cellular organisms:

    • Development -Growth -Repair


What do you get at the end of the cell cycle
What do you get at the end of the cell cycle?

2 genetically identical daughter cells


Cellular organization
Cellular Organization

PROKARYOTIC

Approximately 2 m of DNA to copy & be separated

EUKARYOTIC



Does the number of chromosomes in an organism determine how complex the organism is
Does the number of chromosomes in an organism determine how complex the organism is?

Organize the following organisms in order from complex to simple


Parts of a chromosome
Parts of a chromosome complex the organism is?

THIS CHROMOSOME IS A DUPLICATED CHROMOSOME WITH 4 CHROMOSOMAL ARMS


The cell cycle1
The Cell Cycle complex the organism is?

  • Interphase

    • Accounts for 90% of the cycle

    • Divided up into 3 subunits


The cell cycle2
The Cell Cycle complex the organism is?

  • Mitotic phase

    • Includes both mitosis and cytokinesis

    • Usually the shortest part of the cell cycle.

and Cytokinesis


Mitotic spindle
Mitotic Spindle complex the organism is?

  • Begins to form during prophase & is complete during metaphase

Form from the breakdown of microtubules of the cytoskeleton

Not present in plant cells

Starts here




Cytokinesis
CYTOKINESIS condense before they are moved?


Binary fission
BINARY FISSION condense before they are moved?

PROKARYOTES (BACTERIA & ARCHEA)


Evolution of mitosis
Evolution of Mitosis condense before they are moved?

A protein is thought to anchor the DNA to specific spot on membrane


Timing is everything
Timing is everything! condense before they are moved?

  • The frequency of cell division varies with cell type.

    • EX: human skin cells vs liver cells

  • Some cells do not divide at all in a mature human.

    • EX: nerve cells and muscle cells


What Drives The Cell Cycle? condense before they are moved?

Hypothesis:

-Each event in the cycle

triggers the next.

What was concluded?

Molecules present in the cytoplasm of cells in the S or M phase control the progression of phases.


CELL CYCLE CONTROL SYSTEM condense before they are moved?


THE G condense before they are moved?1 CHECKPOINT


The cell cycle clock
The Cell Cycle Clock condense before they are moved?

  • Regulatory molecules (mainly proteins)

    • Protein kinases and cyclins


Protein Kinases & condense before they are moved?Cyclin

  • Kinases are enzymes

    • Activate or inactivate other proteins by

  • phosphorylating them.

    • Give the go ahead signals at the G1 and G2

    • checkpoints.

    • Present in a constant concentration in a growing

    • cell, but are mostly inactive.

    • To be active they must attach to a cyclin(a

    • protein) = cyclin-dependent kinases, or Cdks


The fluctuating activity of MPF (M-phase-promoting factor) condense before they are moved?

MPF triggers the cell’s passage past the G2 checkpoint into M phase.

Starts in late S phase. It is protected from degradation so it accumulates

Cdk is recycled.

During anaphase, degradation terminates M phase

Promotes mitosis


Cyclins and cyclin dependent kinases control the cell cycle
Cyclins condense before they are moved? and cyclin-dependent kinases control the cell cycle.


In summary
In summary condense before they are moved?

  • Internally:

    • The fluctuation of cyclin & cyclin-dependent kinases seems to control the cell cycle internally using checkpoints to tell the cell to proceed or not

    • The MPF complexes (cyclin + Cdk) initiates mitosis & can then go on to produce a cascade of other cell responses including phosphorylation of other proteins which:

      • Promotes fragmentation of nuclear envelope

      • Chromosome condensation and spindle formation


Example of a growth factor is PDGF condense before they are moved?(platelet-derived growth factor)

PDGF is required for the division of fibroblasts (a type of connective tissue)

Triggers a transduction pathway allowing the cells to pass the G1 checkpoint & divide.

An injury can instigate this growth factor to help heal a wound.


EXTERNAL FACTORS ON CELL DIVISION: condense before they are moved?

DENSITY-DEPENDENT INHIBITION


In summary1
In summary condense before they are moved?

  • Externally:

    • Growth factors secreted from the endocrine glands or platelet cells are present

    • A substrate to attach to is needed

    • Density of neighboring cells are a factor

    • Receptors (on outside of cell that’s dividing) are needed to receive each of the cell signals mentioned above.


When do cells fail to divide

When do cells fail to divide? condense before they are moved?

Note: there are more than 50 growth factors

If essential nutrients are missing.

If growth factors ( protein released by certain cells to stimulate other cells to divide) are missing.

How does a cell divide “wrong”?

Let’s look at a cell gone wrong in the video Non disjunction or non segregation in Mitosis


LOSS OF CELL CYCLE CONTROLS condense before they are moved?

  • Cancer cells to not follow the normal signals that regulate the cell cycle.

    • They don’t stop dividing even when there are no growth factors present.

    • Can continue dividing indefinitely in culture with ample nutrients.

      • EX: HeLa cells of 1951


MALIGNANT VS BENIGN TUMOR condense before they are moved?

Have too few genetic & cellular changes to survive elsewhere.

Have genetic & cellular changes that enable the cells to spread to new tissues & impair functions of organs = cancer

What does it mean if the cancer has metastasized?


Differentiation of human cells

Differentiation of Human Cells condense before they are moved?

A zygote starts development by dividing over and over until you get a few dozen identical cells. These cells are embryonic stem cells.


What are stem cells

What are stem cells? condense before they are moved?

What do you know about stem cell research?

WHAT SIDE DO YOU FALL ON???

LET’S READ AN ARTICLE!!!


Embryonic stem cells
Embryonic Stem Cells condense before they are moved?

  • Cells that start to take different development paths to become specialized cells, such as blood stem cells, which means they can no longer produce any other type of cell.

Can give rise to any and all tissues in the body

they can differentiate into some, but not all, cell types.


TOTIPOTENT condense before they are moved?VS PLURIPOTENT VS MULTIPOTENT

Totipotent cells can form all the cell types in a body, plus the extra-embryonic, or placental cells.

Embryonic cells within the first couple of cell divisions

after fertilization are the only cells that are totipotent.

Pluripotent cells can give rise to all of the cell types that make up the body; embryonic stem cells are considered pluripotent.

Multipotentcells can develop into more than one cell type, but are more limited than pluripotent cells; adult stem cells and cord blood stem cells are considered multipotent

Stem Cells –video on youtube


To condense before they are moved?generate cultures of specific types of differentiated cells—heart muscle cells, blood cells, or nerve cells, for example—scientists try to control the differentiation of embryonic stem cells. They change the chemical composition of the culture medium, alter the surface of the culture dish, or modify the cells by inserting specific genes.


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