When Mitosis goes wrong

Today we started with the following daily questions

Thursday January 31^st

What do you think would happen if a cell moved right into the Synthesis phase without making sure that G1 correctly occurred?

To answer this you needed to look and see what happens during the G1 phase.  During G1 the cell is growing and building more organelles.  If the cell just flew through to the S-phase there could be the chance that the cell had not grown large enough or built enough organelles to continue with the cell cycle.

What would happen if the cell did not properly go through the S phase and moved into G2 then mitosis?

For this questions we need to look at what is happening during the S phase.  During the S phase DNA is being replicated.  If the cell did not make sure that happened properly the cell may not have made a full copy of the DNA or the newly replicated DNA may be damaged and that will the be passed on to the daughter cell.

The Eukaryotic cell cycle takes MUCH longer than the prokaryotic cell cycle.  What are TWO reasons this may be?

Let's think about the differences between eukaryotic and prokaryotic cells.  The MAIN difference between eukaryotic and prokaryotic cells is the presence of a nucleus in eukaryotic cells.  Therefore, eukaryotic cells must perform mitosis and prokaryotic cells do not.  A second reason is that Eukaryotic cells have a LOT more DNA than prokaryotic cells and DNA replication would take much longer.

The goal of these daily questions was to get you minds to start thinking about when the cell cycle DOESN'T go as planned.  We will be talking about cell cycle controls and cancer next.  To introduce this though, I let you watch the following National Geographic clips about real life giants.  We will be seeing that signals sent from different cells determine how often cells divide.  In people with gigantism or acromegaly to much growth hormone is being released which acts as a signal for cells to continue to divide.

Mitosis Activity

Wednesday January 30^th

During Mitosis what do you think would be the result if Metaphase was skipped and the cell went straight into Anaphase? (Draw a Picture of what this would look like)

  The chromosomes would not separate equally and each of the resulting Nuclei would have different DNA. - Or as Mia so PERFECTLY put it during 3rd period "It would be like telling a bunch of 1st graders the ice cream man is here and giving away free ice cream but now making them line up in a single file"

 

 

I look under a microscope and notice a group of cells. Some cells have a nucleus that looks very “messy” with no defined structures.  There is one cell though that has very distinct structures forming within the nucleus.  What are these structures, what is so important about them being visible now, what stage of mitosis could we infer it is in?

 The Structures are Chromosomes, what is important about them being visible now is that they have condensed (this marks the beginning of mitosis) therefore this would be a cell in prophase

What about the “messy” cells – what stage of the cell cycle are they in? The other cells around would be in interphase.  At this time the DNA is uncoiled and looks just like a "blob".
 

THEN we turned the classroom into a nucleus.  With all 46 chromosomes that would be present in of our cells.  Check the pics below and their descriptions for more details on that.

 

Mitosis Activity

FIRST, i placed a couple chromosomes on each of your desks.  Once there were 46 chromosomes "visible" in the room our nucleus would be in prophase. (The chromosomes have become visible because they have condensed) Then we moved into metaphase

You lined up the sister chromatids at the center of our nucleus

Making sure to line them end to end and NOT next to each other

Next step was Anaphase!

You started to pull the sister chromatids away from
each other.  (you were acting like the spindle fibers
at this point.)

Mitosis Notes

Tuesday January 29^th

The two most important stages of mitosis to understand are metaphase and anaphase.  These two phases make sure that DNA is divided equally between the two “daughter cells” What is happening during these two phases? 

During Metaphase sister chromatids are lining up in the middle of the nucleus and the splitting apart during anaphase.

We then went through the following notes and did worked through mitosis with our chromosome models.

These would be chromosomes that have condensed
and became visible but have not "arranged" themselves
yet.

the chromosomes have lined up at the center of your
nucleus so that sister chromatids will be separated.

Intro to Mitosis

Monday January 28^th

During the S phase of interphase DNA is replicated.  At his point we have made duplicated chromosomes.  These will then be split apart in a process known as mitosis.  Mitosis ONLY occurs in Eukaryotic Cells.  With this information we can infer that mitosis is the division of the Nucleus which stores genetic information in Eukaryotic cells.

There is actually a LOT we can learn/recall from this question.  Today I encouraged more of the THINKING behind the question than the answer itself.  The FIRST place your mind should have gone is determining what OTHER type of cell there is (since I told you that this occurs in Eukaryotic cells).  The other type of cell is prokaryotic.  The next place to go then is recalling the difference between eukaryotic and prokaryotic cells.  There are a couple differences between the two, but since I am asking about a part of the cell that "Stores genetic information" this should have jogged your memory that only Eukaryotic cells have a nucleus.  Therefore the answer was nucleus.
After that I had you at least write the stages of mitosis.  Tomorrow and the next day we will actually discuss these notes and work through a couple demonstrations to help you learn it.

DNA, Chromosomes, Cell Cycle wrap up

We started Friday with the following daily question and discussion.  After that we took our first daily question quiz of this nine weeks!

Friday January 25^th

DNA replication is said to be semi-conservative.  How are the two DNA molecules related to each other?  They are IDENTICAL sequences but each has one Old strand (or template strand) and one NEW strand.  Recall how we saw this with our Kinex models below.

The enzyme DNA polymerase has two very important functions.  First is they are responsible for adding new Nucleotide bases (accoridng to the base pairing rules) to each side.

The second is that it acts like a “ Proof reader"

What do you think would happen if DNA polymerase didn’t do it’s “Job”  The DNA may have a mistake in it.  ANY mistake in DNA (whether is changes the function of the cell or not) is known as a mutation.

DNA Replication Activity

Today we started with the following Daily Questions.  To help you answer them I played the two videos below.

Thursday January 24^th

What does DNA “make” (Provide the instructions for) Proteins

What is DNA COMPOSED of? (Made up of) Nucleotides

Each strand is said to be Complementary to the other.

During DNA Replication, what molecules in the cell do the “work” involved? Enzymes

Then we went through the three steps of DNA replication as we worked through the notes.  Here are the notes and some pictures of the activity.

More DNA Daily Questions

Wednesday January 23^rd

Which statement best describes the relationship between cells, DNA, and proteins?
(1) Cells contain DNA that controls the production of proteins.
(2) DNA is composed of proteins that carry coded information for how cells function.

This would be correct IF it said that DNA is composed of NUCLEIC ACIDS instead of protiens.  DNA is not COMPOSED of Proteins - DNA CODES for proteins.
(3) Proteins are used to produce cells that link amino acids together into DNA.
(4) Cells are linked together by proteins to make different kinds of DNA molecules.

(#3 and #4 are just INCORRECT)

What are genes composed of?
(1) offspring   (2) DNA   (3) cells  (4) traits (this would be correct if the question was what do genes CODE for)

 

DNA structure daily questions

Tuesday January 15^th

DNA is made up of nucleotides.  What are the three parts that make up a nucleotide?

A sugar (deoxyribose) a phosphate group and one of four nitrogen bases.

Of these, which two make up the backbone? The sugar and the phosphate groups

Which make up the “code” that writes our instructions? The nitrogen bases

There are 4 different “codes” in DNA, what are they and how do they pair up? Adenine, Guanine, Thymine and Cytosine

Adenine and Tymine (A and T) pair up

Guanine and Cytosine (G and C) pair up

When during the cell cycle does DNA replicate?

During the S-Phase (Synthesis phase)

After this we watched the first part of the following crash course (up until he starts talking about RNA) followed by a a worksheet that summarizes what we have learned so far about chromosomes, genes, DNA and the cell cycle.  This is due tomorrow!!

DNA Structure Notes

Eukaryotic Cell Cycle

Today we finished up the first section on how a cell prepares to divide and moved into the Eukaryotic cell cycle.  We started with the following daily questions.  After that, these are some of the slides that we used to answer the cell reproduction and Eukaryotic cell cycle notes.

Monday January 14^th

Which Cell provides the most efficient surface-area to volume ratio and WHY?

the FIRST cell (the smallest) because it would have the largest surface area to volume ratio.  This is important because molecules are moving into and out of the cell all the time, and the more surface area there is for substances to travel the more efficient the cell would be.   

 Before a cell can divide what must the cell make a copy of?

ALL of the DNA found in the cell must be copied so that each new cell has a full copy (not just half)

Draw out what a duplicated chromosome would look like labeling the different parts.  Then describe how the two sides are related.