Phases of Mitosis

Last class, we spent most of class looking at plant and animal cells under microscopes in order to see all the different phases of mitosis.  This was pretty easy to see on the plant cells, but wayyyyy harder on the animals cells.  Then we reviewed mitosis, so here's a quick general review:

PHASES OF MITOSIS:

Your Inner Fish: Chapter 6

Embryology is the study of the development of embryos from the fertilization to fetus stage. Interestingly, most embryos look generally alike.

During embryonic development, embryos have three layers of tissue, or germ layers. These layers are called endoderm, mesoderm, and ectoderm.

Endoderm: innermost layer with flattened cells that develops digestive organs
Mesoderm: middle layer that develops skeleton, muscles, and blood system
Ectoderm: outer layer that helps form nervous system and lining of mouth, nails, and nosrils

There is also a DNA control layer that regulates genes and shows genes how to collaborate.

Lab Day :D

After getting our tests back, we began a lab studying cells. Firstly, Mr. Quick taught us all how to use the lab microscopes. I must interject that these microscopes are AMAZING, and I really, really, really, love using them.....

Anyways, moving away from technology and going back to bio, we first began by looking at a dead flea under a microscope so here you go:

 

Next, we swiped toothpicks across the inside of our cheeks and placed these cells underneath the microscope. Here's what my cheek cells looked like:

Next, we looked at a dry plant leaf underneath the microscope. In this picture, you can see the chloroplasts:

Pedigrees

Wellllll today, we learned about pedigrees. Though most people seemed to find them easier to understand than Punnett Squares, I'm not quite sure I'm on the same page.  Pedigrees look like family trees, except for they focus on all the genetics aspects of a family.   Different symbols are used to represent gender and whether or not someone carries a disease, has a disease, or is not a carrier at all.

Here's an example of a very simple pedigree, with the blue, colored-in shapes representing someone that has the disease:

Corn??

Last class, we practiced our knowledge of genetics by looking at different types of corn.  We had to count the individual kernels of corn and use the ratio between colors to determine the genotypic and phenotypic ratios of the corn and also to determine it's parents. The corn looked like the one shown below, soooo yeah it was quite difficult to count but a great way to practice genetics problems.

Day 25/26: GENETICS!

We spent the first part of classes reviewing the tests we took last class. I was happy with my performance on the multiple choice section, but definitely need to improve my short answer questions.

We then reviewed monohybrid crosses as a class. (Lucky for me, because I had trouble understanding it the night before!!)  We first went over basic vocabulary involved in genetic crossing and then reviewed the general procedure for genetic problems:

                 Step 1: Write down information about dominant and recessive traits eg. Dom: BB or Bb                                       Rec: bb
                 Step 2: Figure out parent's genotype eg. Aa x Aa
                 Step 3: Write down possible gametes
                 Step 4: Create and label square
                 Step 5: Fill in square
                 Step 6: Figure phenotypic and genotypic ratios eg. Phenotypic: 3 dom :1 rec
                             Genotypic: 1AA:2Aa:1aa

Then we did several, more difficult practice problems before taking a quiz. Here are some examples:

Unit 3 Review and Summary of past classes

For fulfillment of SP 2/1 and SP 8/3:

Lab Overview +Chapter Summary

Last class we began our pGlo lab, in which we are trying to make our bacteria grow and glow. The lab won't be finished until next class, though, so I'll post all the details next time. For now, here's the chapter summary for chapter 3 of "Survival of the Sickest."

This chapter provided a lot of information on vitamin D. Sunlight helps our bodies to create vitamin D and gets rid of our body's reserves of folic acid. Different populations have adaptations that help protect folic acid but also allow sufficient vitamin D production. Our skin converts cholesterol to vitamin D when exposed to ultraviolet B sunlight (UVB). Skin color is determined by the amount/type of melanin  produced by our body. Melanin, which is made by cells called melanocytes, is a special pigment that absorbs light. Nina Jablonski and George Chaplin charted the connection between skin color and sunlight and produced an equation to show the relationship between a population's skin color and its yearly exposure to UV rays. The chapter also present the final idea that one might be able to reduce their excess cholesterol just by getting enough sunlight to convert it to vitamin D. Interesting huh?

Survival of the Sickest: Chapter 6 summary

     Chapter 6 began by explaining the origin of vaccinations and then used this information to provide the cliffhanger that "genes could change." Then, chromosomes and recessive/dominant genes are explains. It begins talking about non-coding DNA, mitochondria, and notes that DNA hasn't adapted to viruses and bacteria, it has been shaped by it. Next, the book talks about mutations and explains that antigenic drift is when a mutation occurs in the DNA of a virus while antigenic shift is when a virus obtains new genes from a similar strain. The next major topic covered is the "jumping gene," discovered by Barbara McClintock. She discovered this by observing the genetic of corn, in which the plants seemed to be undergoes a kind of intentional mutation. The jumping genes sometimes copy and paste, cut and paste, stay in place, or are removed or suppressed. The two types of jumping genes are DNA transposons and retrotransposons.  Finally the book came back to the topic of the "junk" non-coding DNA to say that transposons are an important part of our non-coding DNA...so perhaps this non-coding DNA is in fact not junk........................

Structure of DNA Day

In class, we reviewed the structure of DNA, using the video we watched for homework, Mr. Quick's powerpoint, and DNA diagrams as a guide. Then, we took out our creative talents (of which I have none) to create a paper model of DNA. Once we were done cutting everything out, we used tape to act as the bonds: 2 pieces for A and T and 3 pieces for C and G.
Next class, we're going to simulate DNA replication, so we started this by "unzipping" or cutting one of our DNA model's bonds where the replicating will begin.

"From Atoms to Traits" Questions

1. Explain the significance of Mendel.

Though Darwin's Theory of Evolution was revolutionary, even he knew that some parts were problematic, especially the theory of blended inheritance. Gregor Mendel's discoveries in 1900 helped clarify this confusion with his pea breeding experiments. Mendel discovered that when true-breeding different types of pea plants the offspring had traits of one of the two parents. When further breeded, both forms of the trait could reappear in future generations without dilution. Thus, Mendel's experiments altered the perception of heritable variants from blendable to entities that are passed down from parents to offspring. He also discovered that though these variants are not always visible, they are always present.

2. Draw the structure of DNA and who discovered this structure.

The double-helix structure of DNA was discovered by Francis Crick and James Watson.

3. Explain each of the five examples of variations that occur to DNA and give an example of each.

1) point mutation (single base-pair change) ~ whippet dogs
2) insertion (insertion of new letters into the sequence) ~ pea plants
3) gene copy number (duplication of entire genes) ~ chimpanzees
4) duplication (error in duplication of letters) ~ pigs
5) regulatory changes (changes in the regulatory regions of a single gene that controls cell division patterns) ~ bushy teosinte and its descendent the modern cornstalk

4. What is evo-devo?

Evo-devo is a subspeciality within evolutionary biology which concentrations on researching the effects of changes in developmental genes and how they relate to evolution.

5. Make a connection between human migration and the mutation of lactose intolerance.

Only a minority of people continue to be able to produce lactase (and thus tolerate lactose) after childhood, and the ability to produce lactase was traced in Europeans to a mutation in regulatory DNA. Cultures, such as East African and Saudi Arabian populations, who herd milk-producing animals are also more likely to have the trait of lactose tolerance.  In "Journey of Man," we learned how African peoples migrated all over the world. This would explain how this trait can be traced from Europe to Saudi Arabia to East Africa.

Finish "Journey of Man"

In this class, we finished "Journey of Man," and though the first part was interesting, I found the second half of the movie to be the most intriguing. Most fascinating to me was Dr. Wells trip to visit the Chukchi people. Their unique and isolated lifestyle coupled with their unique and effective survival techniques was amazing to me. In addition, I had never seen the extraction of DNA from blood, and was interested to see this done in the movie. Overall, I truly enjoyed "Journey of Man," and felt that it throughly covered the topic of genetic and evolution in detail. 

"Traces of a Distant Past"

     The article entitled"Traces of a Distant Past," published in 2008 edition of "Scientific American" by Gary Stix, explores the genetic family tree that begins with the San people of African (as shown in "Journey of Man" and ends with South American Indians. Through artifacts and bones, scientists can trace paths of migration, but can only go so far as these objects are difficult to find. However, by using DNA, scientists can compare contemporary humans to determine how long a population has lived in a region.  After decades of genetic sampling, the latest studies envelop entire genomes and provide maps of human migration across the world. The studies also depict certain adaptations relating to peoples' genes, such as those relating to diet, climate, and disease.

        The article also makes a strong argument that from the genetics standpoint, the differences between all groups or rather ethnicities of people are not all that prominent. In fact, this has sparked a debate over what exactly constitute a race or ethnicity. From the viewpoint of many geneticist, the distinction between human diversity is miniscule.

"Journey of Man"

We started by reviewing the tests we took last class. A bit of a debate broke out about some of the questions and their answer (thinking Devonian vertebrates) but finally everything was resolved.

We then began a movie called the "Journey of Man" in which a geneticist named Dr. Wells sought to trace our earliest descent by revisiting the important landmarks in our evolutionary history. This complements the reading we have been doing on evolution and genetics, and I look forward to finishing the movie next class.

Test 2!

Today we took our test on Unit 2, in which we studied evolution. I loved the essay question from the test, and found it easy to write about. Hopefully all of my studying paid off!

Hardy-Weinberg

We began class by reviewing how our knowledge of genes and DNA relates to differences in traits natural selection:

Next, biology turned into math class (yay!!) as we learned the Hardy-Weinberg formula for calculating allele frequencies. Here are the bare basics you need to know:

      p^2 = homozygous dominant
      2pq = heterozygous
      q^2 = homozygous recessive
      p + q = 1
      p^2 + 2pq + q^2 = 1

See....math is easy (and fun!).

Mating Beads....?

Today we did a lab entitled "Evolution and Gene Frequencies: A Game of Survival and Reproductive Success," which is exactly what is was! We used beads (acting as tigers) to determine the effect of random mating in a population of tigers that possessed a recessive gene. We selected to beads (alleles) at a time and recorded the combination. After we were done we set aside the homozygous recessive "tigers" and threw the others back into the mating pool. After 10 times we compiled our data and determined the that recessive allele never completely disappears, it is always present.

Parents Day!

The first part of Parents Day was spent finishing up our Brine Shrimp lab. We found that the greatest hatching viability of the brine shrimp was in the 0.5% solution. This means that the traits of these brine shrimp are best adapted to survive and reproduce in a solution that is 0.5% salt.

The second half of the day was devoted to observing "attractive" traits in different people. With our parents and peers we were shown pairs of pictures, and for each pair we had to choose which one we found more attractive. Finally, we compiled all of our data to find if the majority of males found females with more feminine or masculine faces attractive and then vice versa.

...Brine Shrimp?

Today we began a lab about natural selection that dealt with brine shrimp. The population of brine shrimp are influence by environmental factors...specifically salinity. In the lab, we used different percentages of salt solution to test how some individuals of the population would be better adapted to develop and survive in the different conditions.  The solutions with eggs need to sit for while, so I'll post results in next post......

Surivival of the Sickest

Today, we reviewed topics learned from reading "Survival of the Sickest " by Dr. Sharon Moalem.

Specifically we focused on how specific traits of organisms allow them to be more likely to survive or more likely to die. For example fruits that produce a poison when eaten are more likely to survive and reproduce than one that tastes pleasant. As shown in Fava Beans some traits that produce unfavorable reactions at the time can also be favorable in another area. Fava Beans can cause anemia, but they also help fight malaria.

Evidence for Evolution Quiz

1) Evolution occurs through small changes in a population over a long period of time. Thus organisms of different kinds can by traced to a common ancestor. For example, modern whales can be traced back to their common ancestor, the Mesonychid. Over time, the Mesonychid went through a series of gradual changes. It is closely related to the Ambulocetus, which is closely related to Rodhocetus, which is most closely related to the modern whale.

2) Marsupials originated in North America.

3) Dragonflies, birds, and bats are examples of convergent evolution, because all these are parts of different species that evolved to have some of the same characteristics because of their environment: air.

4) In the Common Descent Lab, we showed how similarities in DNA are evidence for evolution.  For example, from the hemoglobin strands we showed that gorillas are most closely related to chimpanzees, which are closely related to humans. We also found that all these share a common ancestor.  It is important to note that humans did not directly evolve from chimpanzees, they just share a common ancestor.

5) Homology refers to similarities between structures due to common ancestry. For example, the common structure for limbs is 1 bone --> 2 bones --> blob of bones --> fingers/toes.

Evidence for Evolution: LABS

Today we not only reviewed information that provides "evidence for evolution," but we also did labs that supported evolution. First, here's a list of all the topics we reviewed:

In the lab, we modeled hemoglobin strands from humans, chimpanzees, gorillas, and their common ancestor. We then analyzed them to see how much each one differed from the others. Here are our hemoglobin strands and the resulting cladogram we made form our data.

Intro to Evolution

Fun fact: My favorite scientist is Charles Darwin. I've read many books about him...not just his scientific theories, but also about his life. -- So naturally when I found out the next unit was about evolution, I became majorly excited (that's an understatement).

For homework, we read chapters 1, 2, and 11 of Your Inner Fish by Neil Shubin. These chapters talked about fossils and how they are formed, homology, and provided basic information and theories about evolution. It was interesting to read a book by Neil Shubin, because he found the fossil for the Tiktaalik (the transition fossil between water and land organisms) and I studied about the Tiktaalik last year in Honors Paleo.  Here's a picture of the Tiktaalik model in our very own Raymond M. Alf Museum of Paleontology:

As you can see, it has a flat head and wrist-like structures of an amphibian, but fins and scales like that of a fish.

Test Day!!!!

Me before the test:

Me after the test:

REVIEW DAY!!

Today in bio, we reviewed BIOCHEMISTRY!!  Here's a list of everything we covered:

After a reviewing of all of this, we studied for about 5 minutes with our partners, and then took a formative biochem quiz.











That pretty much took up the entire class period, but then my partner and I stayed after class to finish our Macromole "mystery compound" lab. My biology website will go up tomorrow with our results from the entire lab, but for now here are a couple pictures:

I'll give you a hint: the results have something to do with Mexican food..... hmmmmm....

Now it's time to put all of my lab results together and S.T.U.D.Y!!

Day 7: Organic Compound Mystery??!!

Today, we began my discussing the topics we took notes on for homework - mainly carbohydrates, monosaccharides, disaccharides, and polysaccharides.
 Then we were able to chose between two different labs, and I chose the "Who took Jerell's iPod? --An Organic Compound Mystery." First, we tests for the presence of glucose, starch, and lipids in vegetable oil, glucose, starch from corn/potatoes, powdered egg whites, and water.

Then, we tested for the presence of glucose, starch, and lipids in pretzels, butter, jelly, fat-free yogurt, and the dry and liquid part of Jerell's evidence.

We have not finished the lab yet, so I'll post the results and conclusion in a later blog post, but for now here are some pictures!

Day 6: Lab review and House Case introduction

In this class, we began with a quiz that asked review questions from our previous Osmosis/Diffusion lab and how to graph the data to find molarity.

We began discussing our first "House Case."  In this case, a 18 year old senior who runs cross country begins to feel a headache after practice. He feels tired, confused, and starts vomiting.  After further questioning, we further determined that he had chicken for lunch and had two glasses of water with lunch. He didn't take any medicine and only ran for about 7 miles. However, while he was running cross country, it was 104 degrees F outside, humid, and he drank 3 gallons of water while running.

These are results of his medical tests:

Most of the class thought that the diagnosis was overhydration, because of the abnormally high amount of water that the senior drank while running. However, this isn't correct, so I will have to further analyze the test results to solve this mystery..........

Day 5: Finishing Difussion/Osmosis Lab

On day 5, we finished up the final parts of he diffusion/osmosis lab. But first, we reviewed general graphing skills and how to apply those to find molarity.

For Part 1 of the lab, we recorded the original volume and surface area of a "cell" (we used agar). We cut two sets of small cubes, middle-size cubes, and large cubes. Then, we added KI to some and NaOH to the rest. After letting them sit for about 15 min, we again calculated the volume and surface area. The purpose of his experiment was to observe the time rate of diffusion of different substances and how it is affected by volume and surface. Here are the results:

For Part 2 of the lab, we tested how glucose and starch would diffuse through a semipermeable membrane.  Here was my group's hypothesis:

We filled a diffusion tube with a solution of glucose and starch and tested for glucose with a test strip. We placed the tube in boiling water, and after we let it set, we took a pipette full of the water and add it to a test tube. We then added a benedict solution (to test for glucose) and put it back in the boiling water. The solution in the tube turned orange, which indicates that there was glucose in the solution. Then we added iodine to the water and the solution inside the cell turned dark blue/purple which means that the starch diffused into the cell  From this we can see that our hypothesis was supported, because only the glucose molecule diffused through the cell into the beaker because it is a smaller molecule than the starch.