Putting Mitosis and Onion Root Cells Together For a Blog :)

Begining note: My apologies. I thought that this blog post was posted a couple months ago. I guess it wasn't :( So here is a very late post on Mitosis! 

In Biology we have been working on having a better understanding of the cell cycle and mitosis. We examined onion root cells with the microscopes and although I was not able to get pictures of what I saw I did find some on the internet to better show the different phases.

The picture on the right shows two onion cells in the first phase of mitosis- Interphase. The nucleus (C) is filled with chromatin. These chromosomes inside it are stretched out so that they cannot be seen individually. The dark spot that you see in the nucleus (I) is the nucleolus. Most cells in interphase have 1 or more nucleoi.
Prophase is the second step of mitosis that you see in the onion root cell on the left. While prophase i soccuring, the chromosomes coil and become visible as pairs that are withing the nucleus. The chromosomes often form an "X" shape. The cell's centrioles move to opposite sides of the cell. Tiny fibers attach themselves to the centrioles of each chromosome forming the spindle fibers that will pull the chromosomes to opposite sides of the cell. During this phase the nuclear membrane disappears.

Metaphase is the next step. During metaphase the chromosomes form a line in the middle of the cell. Now each chromosome consists of two exact copies (clones) of the cell's original chromosome. All of the  copies, or chromatids, are held all together at the centromere.  Metaphase ends when the centromeres are ready to separate and allow the chromatids to be drawn to opposite ends of the cell. (Picture to the right)

That gets us to Anaphase. During this step in mitosis the pairs of identical chromatids separate at their centromeres and are drawn to the opposite sides of the cell by the spindle fibers. This makes it so that each daughter cell will have a copy of the cell's original chromosomes. (Picture to the left) 



Once anaphase is over Telophase begins.  During telphase the handy little spindle fibers break down. In return, a new nuclear membrane forms around the chromosomes in each half of the cell. (Picture shown on right) 





After the division of the nucleus and in the last part of telophase the cell begins to visibly separate into two new cells. The process of dividing the cell in half is called Cytokinesis.  Cytokinesis actually starts hapening during the process of telophase.(Picture to the left) 

DNA Extraction!

Below is a overview that me and Sierra Frentress made about our DNA Extraction Lab! :)

Our Little Friends, Greg and Olga (That poor poor girl!)

Greg and Olga were worried about starting a family because they both had some diseases in their families. They decided to visit a genetic counselor to find out the chances of the diseases showing up in any future children.

Part I: Pedigree Construction

1. I constructed a pedigree for Greg and Olga. Here is what it would look like...

Greg and Olga's Pedigree

Part II: Autosomal Dominant Traits

1) Do autosomal dominant disorders skip generations? 

• Autosomal dominant disorders do not skip generations. 

2) Could Greg or his mother be carriers of the gene that causes myotonic dystrophy?

• No, Greg and his mother don't have the disorder therefore they can not possibly be carriers.

3) Is there a possibility that Greg’s aunt or uncle is homozygous for the myotonic dystrophy (MD) gene?

• No, there is not a possibility. Greg's grandmother would have also had to to be homozygous for the MD gene. You know that she is not homozygous because her husband did not have MD and only two of their four children have the disorder. Therefore Greg's grandmother, aunt, and uncle are all heterozygous.

4) Symptoms of myotonic dystrophy sometimes don’t show up until after age fifty. What is the possibility that Greg’s cousin has inherited the MD gene?

• Well, the good news is, Greg's cousin has a 50% chance of not inheriting the Mytonic Dystrophy gene. The bad news is, she has a 50% chance of inheriting it.

5)What is the possibility that Greg and Olga’s children could inherit the MD gene?

• Happy news for Greg and Olga! There is no chance that their future kids will inherit the MD gene. Neither Greg nor Olga have it so there is a 0% chance of their kids having it. Congrats you guys!

Part III: Autosomal Recessive Traits

1) What are the hallmarks of an autosomal recessive trait?

            -This is what I know:

• The traits are found in the siblings of the person that is affected, but not in the parents or the children of that person (it skips generations).
• Females and males are equally likely to be affected
• It has been found that the recurrence risk for an unborn child of the affected sibling is 25%
• The trait, to the blind eye, may appear as an isolated event in smaller families with only a few children
• The parents of the affected children could possibly be there own "kin". The more rare the trait is in the general population, the more probable it is that inbreeding was involved.

2) What does consanguineous mean? Why is this concept especially important when discussing recessive genetic disorders?

• Consanguineous is a term to describe being related by blood or family. This is important when discussing these genetic disorders because consanguineous mating causes a higher risk of passing the ressesive disorder. 

3) What is it about the inheritance pattern of factor VIII deficiency seen in Greg and Olga’s pedigree that point toward it not being an autosomal recessive trait?

• The inheritance pattern of Factor VIII deficiency points more toward it being a sex-linked trait instead of autosomal recessive, because it is only seen in males on the pedigree.

Part IV: Sex-Linked Inheritance 

1) What are the characteristics of X-linked recessive inheritance?

• Males are more likely to be affected than females
• All the affected males in a family are related by their mothers
• The trait is usually passed down from an affected grandfather to his daughter, who then carries the trait and passes it on to 50% of her sons.
• The trait is never passed directly from father to son 

2) Why does a son never inherit his father’s defective X chromosome?

• A son will always be lucky enough to never inherit his father's defective X chromosome because he inherits Y from his father, not X

3) What is required for a woman to display a sex-linked recessive trait?

• The woman must be homozygous for the sex-linked recessive trait in order to display it.

4) Return to the pedigree drawn earlier for Greg and Olga; mark those persons who are carriers of the factor VIII deficiency gene.

• The people now labeled with the orange dot in the pedigree, are carriers of the factor VII deficiency gene.

5) What is the chance that Olga carries the gene for factor VIII deficiency? Calculate the probability that she will pass it to her offspring. Will male children be affected in a different way than female children?

• There is a 50% chance that Olga has the gene for Factor VIII deficiency. If she does, than there is also a 50% chance that she will pass it on to her children (so half of her children will probably have the gene as well) The male and female children will both be affected in the same way because they both have the same chance of inheriting it.

6) What is the chance that Greg carries the factor VIII gene? Can he pass the gene on to his sons? His daughters? How will each be affected?

• Sadly, it is a 100% guaranteed that Greg carries the factor VIII gene. He can not pass this on to his sons because they inherit the Y chromosome from him- not the X chromosome. Greg can pass the gene onto his daughter, who will then be a carrier and could pass it onto her children.

To get to the website about Greg and Olga, click here- http://www.sciencecases.org/sickness_and_health/sickness_and_health.asp 

Please Let This Raise My Grade For Data Analysis! :)

Yeah It's a Really Big Word!

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Our Photosynthesis "Dry Lab"! Oh The Excitement! :)

So I guess this week we went backwards.(Actually this last week- I forgot to post this. Oops) Instead of doing an experiment and writing down the observations, Mr. Ludwig gave us a set of observations and we had to write the procedure that went along with this experiment given. I was very confused at first but then I looked at other blogs and worked on it with a friend so this is our (mine and Chapin's) Photosynthesis "Dry Lab." Enjoy!



Materials

• Distilled Water
• Bromothymol Blue (BTB)
• Aquarium Snail
• Elodea
• Large Test Tubes
• Light
• Dark Space

Procedure

1. Put 15 ml of water and 15 drops of  BTB in a large test tube and let it sit for 3 hours under light. Record your observations.
2. Put 15 ml of water, 15 drops of BTB, and an aquarium snail in a large test tube and let it sit for 3 hours under light. Record your observations.
3. Put 15 ml of water, 15 drops of BTB, and a elodea (funny plant) in a large test tube and let it sit for 3 hours under light. Record your observations.
4. Put 15ml of water, 15 drops of BTB, an aquarium snail, and an elodea in a large test tube in the light for 3 hours. Record your observations.
5. Repeat Step 4 procedure but put it in the dark for three hours and let it sit. Record your observations.

(If your water doesn't turn blue after 15 drops of BTB keep putting drops in until it turns blue)


Observations:
Water plus BTB is blue-green.
         Water is neutral. It changes to the color of the substance that is put in it.


Water plus BTB and an Aquarium Snail is yellow in light.
          Animals respire (breath) and they let Carbon Dioxide out. Carbon dioxide in water produces carbonic acid. When there is acid in BTB and water it turns to yellow.


Water plus BTB plus elodea is blue-green in light.
          Green plants respire. Then they photosynthesize and use the Carbon Dioxide. The plant keeps the water from acid it stays a neutral at the blue green color.


Water plus BTB plus a snail plus elodea is blue-green in light.
          The plant and snail respire. But the plant photosynthesizes and uses the Carbon Dioxide so it turns to blue green and there is no carbonic acid.

Water plus BTB plus a snail plus elodea is yellow in dark.
          The snail and plant respire. Since there is no light the plant can't photosynthesize. The carbon dioxide is still in the water so it stays an acid and the color stays yellow.


Conclusion:
When BTB is added to water it turns yellow because Carbon Dioxide and water mixed together make a carbonic acid. It stays blue with just water because water is a neutral.

Photosynthesis

This is the poster that Sierra, Chapin, and I made on Photosynthesis and how plants make the magic happen.