Variations Lab

Guiding Question: Does the number of peas in a pod affect its length?



Hypothesis:

Looking at the guiding question from a logical point of view, I believe that the larger the number of peas is, the longer the pod will be. However, I am not yet sure why there is a variation in the number of peas in pods. It could be that certain types of peas need to have more peas in a pod, because of the difficult circumstances in the habitat. If the habitat/environment is very difficult for the species to survive in, the plant would probably need much more seeds to reproduce, because not all of them would necessarily be able to grow. However, a reason for different numbers of peas in pods could be as simple as a genetic mutation. Just like there is a genetic difference between pods with wrinkled and smooth peas, there could be a genetic trait that determines whether the pod will have more or less peas.

Variables:

My controlled variable is the unit of measurement (centimeters) that I will be using on all the pea pods. My manipulated variable are the pea pods. I will be measuring different pea pods, to determine their different lengths. Finally, my responding variable is the number of peas in pods. Based on the changes in the pods’ length, the number of peas will also change.

Exploration:

For this lab, I didn’t use very many materials, because the tests were very simple. I basically only used a ruler and different pea pods. I examined them, measured them in centimeters, and then counted the peas in the pods. I also recorded all of my findings, as well as the different interesting observations that I came across.


Record and Analyze:

-TABLE:


                         Length (cm)                           Number of peas

8	7
7	6
8	7
7	8
7.5	6
9	9
7	5
8	8
7	6
7.5	7
6.5	7
7	8
6.8	7
7.8	6
9	9
7.6	7
8	7
8	6
7.5	6
7.5	8

-GRAPHS:

Data Analysis:

               From all of the data that I have collected, I have noticed a few things that I didn't expect at the beginning of the lab. For example, in the pods that were not that long, the peas inside were of much smaller size, when compared to the peas in the pods that were longer. I wasn't really counting on that when I first set up the experiment. 
                I was also extremely surprised with the fact that there wasn't very much variety in the actual length of the pods. Looking at the results that I have gathered, I can see that there wasn't a single pod that I measured, that was smaller then six or larger then nine centimeters. This is a very small difference, only three centimeters. I was expecting the variety to be much larger.
                The results were also really unexpected for the number of peas inside the pods, as well. As I said above, some of the peas were much smaller in size then others, which, previously, I didn't think about at all. It was also quite strange to find that in certain situations, the peas didn't fill up the entire pod. This left me wondering why this could have occured. Maybe, the certain pea plant that the pod was taken from didn't have enough nutrition to produce enough peas. This could have meant the lack of sun or water. However, it could be that some pods are not completely filled with peas because of certain genetic mutations, that cause the pea plants to produce a lack of peas.  However, overall, despite the fact that I didn't really measure the diameter of the peas, I can see from the results in the table that I have obtained, that most peas take up on centimeter of the pod's length.

Conclusion:

From the graphs, the tables, as well the data analysis, I can see that the length of the pods does affect the number of peas that are inside it, but only to a certain extent. Some peas adapt to the smaller size of the pod, and they, thus, grow to be smaller. That is why, in some cases, there can be the same number of peas in two different-sized pods. I have also learned that, when it comes to peas, there isn't a very big variety in pod length. The biggest length difference between the pods was three centimeters, which was quite surprising for me.

Further Inquiry:

Evulating this lab, I do believe that I conducted everything well, and i do not believe that there was much room for error, due to the fact that the actual conducting and gaining results was fairly simple. I did measure the pods as accurately as I could, and it was extremely easy to count the peas inside. If I was to do this lab again, I do think there are a few things that I could potentially improve on. I would deffinitely extend this lab a little bit more, if I was to do it again. This means that I would probably add another component to the examination of the pea pods. For example, I would not only measure the length, but I would also weigh all the pods, before counting how many peas were inside. If I were to conduct a lab, or do a research report, after this lab, I would probably try to find the reason why peas are of different sizes. Is the reason genetical, or is it just simpley environmental (lack of nutrition, etc)...?

Selection and Survival Tortoise Lab

Hypothesis:

I think that, over time, there would be more long-neck tortoises, Despite the fact that the long-neck trait is recessive, the short-neck population would start slowly dying out, leaving the heterozygous and homozygous long-necks behind. This could lead to the birth of new short-necks, but they wouldn't survive for very long, because of the lack of food. On the other hand, the homozygous long-necks would live much longer, and reproduce further.

Punnett Squares:

Round 1:

                                                                     

                  Male

NN	nn
NN	nn

                Female

NN	nn
NN	nn

Round 2:

 Round 3:

 

Round 4:

DATA ANALYSIS:  

Looking at the results my group and I acquired over the course of this lab, I can see that, over the course of several generation the tortoises with short necks started diminishing, despite the fact that this trait is dominant. For example, you can clearly see that, in the great grandchildren's generation, or Round 4, there is only two short-necks left, and they are heterozygous, meaning that, despite having a short neck, they still carry the recessive short-neck trait. This is very different compaaring to the results from the generation of children or Round 2,  where there were olny two long-neck tortoises. This data shows that, as time passed, over the course of several generations, the short-neck turtles started dying out, because they couldn't sustain their trait and their species any longer, due to the severe lack of nutrition. However, the long-neck turtles lived on, because they did have food, despite the fact that the trait they carry is recessive.

If none of the long-neck tortoises mated with each other after Round 4, but there was still no food left for the short-necks, I believe that the exactly same situation would occur. At the beginning, there may be more short-necks, but the lack of food would cause their slow downfall, just like it did in the first four generations that we originally tested.

I believe that there is a lack of food for a certain type or sub-type of a species, there is only three things that can occur. If the lack of food is sudden, meaning that it is caused by a natural disaster, such a tsunami or earthquake, the species would probably go extinct, considering the fact that they would literally have no source of nourishment. However, if the food starts decreasing gradually, the species could either start evolving to adapt to the new habitat or environment, or it could start slowly diminishing, the way it did in this lab.

Sex-Ed Reflection

At the beginning of this unit, which only lasted for about three weeks, I had no idea that we would actually learn as much as we did. I really gained a lot of knowledge on subjects such as diseases, pregnancies, contraception, etc. Many of the information that we learned throughout this unit will be very beneficial for all of us in later life. One of the most important things I learned, in my opinion, is the consequences STI's can have. I had no idea that some of them, such as chlamydia, herpes, etc. Viruses such as HIV can also be fatal in many cases, if not detected on time. It was quite shocking to find out how easy it is to contract certain STI's. Some of them you can get by just simply using the infected person's toothbrush, or sleeping in the same sheetes they did. Over the course of this unit, we also learnt about the different stages of pregnancy, as well as what parts of the fetus develop in certain weeks. For example, the lungs are completely developed at the very end of the pregnancy, so that the baby won't choke on the amniotic fluid while practicing breathing. I also really liked the fact that we not only learnt about the facts and statistics about STI's, contracpetion, etc. but also that the unit was fitted for our age group. In the very last class, the class talked about the pressures of sex that are constantly surrounding us. It was really shocking to see that there are many girls out there who are my age, and already either pregnant or have a child. They rushed into things they were not ready for too fast, and they have to pay the consequences at an extremely young age. It is actually quite sad to see that many of them won't properly experience their teenage and childhood years.
Overall, I really liked this unit, because it was informational, and yet interesting and different from the units we have done before.

Substance Abuse during Pregnancy

When you are pregnant, it is important to understand that you are not only eating, drinking or consimung other substances for yourself, you are doing it for one person, which is your unborn baby. All the bad decisions you make, and all the bad substances you put in your body will automatically go to the fetus, as well. However, some mothers still choose to keep going with their unhealhy and dangerous habits, despite being warned that they could severely hurt their baby. When the mother smokes, the nicotine, as well as other cancer-causing substances pass through the baby's blood stream. This could result in premature birth, which ultimately puts the baby at a very low chance of survival. The nicotine can also keep the fetus from getting the vitamins, protens and other nourishment that is essential for their development.
When the mother exposes hers, and the baby's body to alcohol, the consequences can be catastrophic. When large quantities of alcohol constantly pass through the baby's bloodstream, through the umbilical cord, the baby has a very high risk of developing what is called the fetal alcohol syndrome. With this syndrome, the fetus wil usually encounter poor development, as well as many other negative effects, even years after it has been born. The baby may have poor coordination, and various heart defects. The symptoms of the fetal alcohol syndrome can also be seen on the fetus's face, as all the babies who have this syndrome usually tend to have a small head, small upper jaw, and narrow eyes. Studies also show that babies whose mothers consistently drink alcohol during their pregnancy almost never have normal brain development.
Some mothers also have an addiction from illegal drugs, that they cannot break, even during their pregnancy. When the mother takes illegal drugs during the pregnancy, her baby is taking the drug too. This means that the fetus can be born with an addiction. Even though the baby is very young and small, it can still experience the symptoms of withdrawal, in which case the doctors will have to keep giving it the drug, cutting back on the amount each time, until they completely cleanse the baby. However, the baby is severely affected by the drugs while it is sill in the uterus. The substances can severely damage many of its vital organs, including the heart and the brain.

DNA + Electrophoresis

By doing the DNA fingerprinting activity, I realized that the one whose blood was found on the scene is Suspect 4. When I was trying to figure out whose blood was found, I looked for the same pattern of the lines in the blood, trying to find an identical match. People's DNA patterns differ greatly because their parents carry a number of different genes, and alleles, that are completely different from anybody else on Earth. Hence, when their recessive and dominant alleles for traits combine, their offspring will inherit a completely unique genotype, or DNA sequence. If suspect four had an identical twin, my conclusions would be a little bit different. Identical twins come from the same zygote that gets split in half during pregnancy, meaning that their DNA would be the same. However, every person has different fingerprints. So, to come to a definite conclusion about whose blood was found on the crime scene, the forensic investigators would have to do a search for fingerprints, and see if they could find a pair that would match one of the identical twins. If no fingerprints were recovered, the detectives would just have to interrogate both of the twins, or send them for a lie-detector test, to figure out which one could have commited the crime. However, even if they did find who the blood belonged to, I do not believe that it would be enough evidence for the prosecutors to convict the client of a crime. Maybe, the suspect was just a by-stander who got hurt by the killer for witnessing the crime. On the other hand, the suspect could also have been just walking at the place the crime occured, not having the slight suspicion of what had happened. While walking, the suspect could have accidently hurt themselves by falling, slipping, etc. leaving their blood behind. So, in my opinion, the prosecution would need MUCH more evidence then a few blood samples.

Gel Electrophoresis:

A way that scientists can associate DNA from blood, saliva, etc. to a certain individual could be by using a method called electrophoresis. The electrophoresis basically helps scientists determine the guilty suspect by examining the length of their DNA strands. Electrophoresis functions in a fairly simple way. The samples of DNA are placed in tiny holes that are located within the gel, which acts as a filter for sorting the DNA. Once the DNA is placed, an electrical current is run through the gel, which makes the strands of DNA move across, from one end of the gel to another. Shorter strands will always move in front of, and faster then, the longer strands. Thus, after a period of time, the clumps of short and long strands will be seperated from each other, and grouped together. In this way, the DNA sorts itself. By staining the groups of DNA, they become visible to the naked eye. By comparing the different lengths of DNA strands and their groupings, the scientists can figure out whether the suspect is guilty. The online simulation is not that much different from the actual gel electrophoresis we did on our field-trip. The online simulation had a little bit more details, and I believe some parts of the process were better explained online than in the actual lab. Another difference is, obviously, that the actual real-life, lab application was much more difficult than the one online. It takes scientists a lot of practice to master the skill of handling the gel electrophoresis well, and being able to acquire helpful results for a certain case.

Dominance

Question: Is dominance always dominant?

By doing the online lab activity, I have realized that alleles are not always completely dominant. There are three types of dominance. The first type is dominance. That is when one allele is completely dominant over the other, and that is where Mendel's hypothesis's can be considered true. An example of dominance would be the color of pea plants. There are two colors, purple and white. The purple is the dominant, while the white is the recessive allele. If both are homozygous, and are crossed, all of the offspring will be purple. The next type of dominance is co-dominance. That means that both of the alleles of a certain trait are expressed equally. An example of this would be the human blood types. If the mother has blood type A, and the father has blood type B, the children will have blood type AB, meaning that the both of the alleles are expressed. Finally, the last type is incomplete dominance. This means that one allele for a specific trait is not completely dominant over the other. An example of this would the snapdragon flowers. If red and white flowers were bred together, the offspring would end up being pink, meaning that both of the alleles "mixed" together, to create a completely new color of snapdragon.

Gorilla Genome Analysis

It is believed that humans and gorillas last shared a common ancestor around ten million years ago. This hypothesis was made by sequencing and studying the whole gorilla genome, which was recently completed and analyzed. Gorilla are the last of all the great apes to have their DNA sequenced. The complete genome of humans, chimpanzees and orangutans has already been completed. The research that was led by scientists from Cambridge and Houston came to a number of very interesting conclusions. For example, it was discovered that 15% of the gorilla's genome is much closer, and much more similar, between us and the gorillas, in comparison to us and chimpanzees, which are believed to be our closest relative in the animal kingdom. However, it was also found out that humans and chimps share around 98% of the same genes, while humans and gorillas have 96% of the same DNA. The genomes of all three species have shown that the brain evolution is very accelerated in all of them, as well as that humans and gorillas have similar genes that characterize hearing and sensory perception. It was believed that the evolution of humans' hearing was related to the fact that many millions of years languages startes to emerge. However, this theory was disproven when scientists discovered that the gene that is associated with gorillas' hearing has been evolving at the same pace. The research has also shown that gorillas have very rough and hard knuckles because of a gene that creates protein, which makes the skin particularly harder. However, the main reason scientists wanted to find out gorillas' genome sequence is because they have the opportunity to learn more about evolution. Before, it was believed that the seperation of different ape species happened relatively quickly. However, now, it is believed that speciation happened over a longer period of time.
I think that it is really amazing that sceintists are not only stopping at sequencing our DNA, but also discovering the genomes of other animals. Further research could really tell us about how humans as a species evolved over time, and maybe, even, how we began. Sequencing more genomes from different species could broaden our knowledge and understanding, not only about how genes work, but also about our existence on Earth, which is quite extraordinary.



Link to Original Article: http://www.guardian.co.uk/science/2012/mar/07/gorilla-genome-analysis-new-human-link
Author: Alok Jha
Date: March 7th, 2012

Cytokinesis and Mitosis Reflection

In class, we did two virtual lab activities, that were supposed to broaden our knowledge od cell division, as well as nuclear division. From the first lab, there are quite a few things that I learned, but also a few things that surprised me. I learned all parts of the cellular devision cycle, and I was quite surprised that there are so many. The first part of the cell division is interphase. That is when the chromosomes, as well as the DNA, duplicate themselves within one cell. The next stage is the prophase. In the prophase, the chromosomes start becoming visible under the microscope, and they also begin moving. In the metaphase, the chromosomes all allign at the center of the nucleus, preparing for the next stage. Finally, in anaphase, the chromosomes move to the opposite poles of the cell. The last stage is telophase, when new membrane starts being created around the daughter nucleii, preparing for cell division. Even though there are so many stages of this cycle, most of the time the cell takes to duplicate is spent on the interphase (about 80-90%). In the second lab activity, I have learned to tell apart the nucleus of a dividing and non-dividing cells. I noticed that when the cell is not dividing, the nucleus is pure black, possibly being in interphase. However, in a dividing cell the chromosomes are visible on the onion tip root. The reason the tip of the onion root is used for these types of experiments is because the roots of plants are constantly growing, searching for nutrients in the soil. Thus, cell division is constantly taking place in those parts of the plant. What I really likes about the second lab was the fact that it allowed us as students to be scientists, and determine in what division stage the different cells are. Another thing that I found really interesting was the fact that there are some slight differences between the division of animal and plant cells. I did a little research, and found that there are two major differences between the cell division in animals and plants. Animal cells have centrioles, that help the chromosomes move to the opposite poles. Plants, on the other hand, do not have them. Another difference can be spotted during telephase. A plant cell creates a cell plate, which later turns into a cell wall. However, since animal cells do not have a cell wall, it doesn't create that cell plate.
Finally, there is one simple difference between mitosis and meiosis. During mitosis, the cell undergoes a simple division in two, where both of the daughter cells get exactly half of the original chromosomes created during interphase. However, meiosis is a cell division between sex cells. During this process, four daughter cells are created, since there are two nuclear divisions.

 

"Make the Right Call!" Lab

Guiding Question: How can you predict the results of genetic crosses?

Hypothesis:
I believe that the best way of prediction genetic crosses, and the inheritance of specific traits is through Punnett Squares. Punnett Squares combine the two different, either dominant or recessive alleles, of both of the parents, to see what the different genotypes of their offspring could be. However, I also do think that Punnett Squares are not always 100% accurate, hence the word "probability in genetics". Sometimes, the offspring may have a completely different genotype for a certain trait then you expected him/her to.

Data Collected:

Data Table 1:

Trial	Allele from Bag 1 (female)	Allele from Bag 2 (male)	Offspring’s alleles
1	B	b	Bb
2	B	b	Bb
3	B	b	Bb
4	B	b	Bb
5	B	b	Bb
6	B	b	Bb
7	B	b	Bb
8	B	b	Bb
9	B	b	Bb
10	B	b	Bb

Data Table 2:

Trial	Allele from Bag 1 (female)	Allele from Bag 2 (male)	Offspring’s alleles
1	B	B	BB
2	B	B	BB
3	B	B	BB
4	B	B	BB
5	B	b	Bb
6	B	B	BB
7	B	b	Bb
8	B	B	BB
9	B	B	BB
10	B	B	BB

Data Table 3:

Trial	Allele from Bag 1 (female)	Allele from Bag 2 (male)	Offspring’s alleles
1	B	b	Bb
2	b	b	bb
3	B	b	Bb
4	B	B	BB
5	B	B	BB
6	B	B	BB
7	b	B	Bb
8	b	b	bb
9	B	B	BB
10	B	b	Bb

Questions/Data Analysis:

1) Make a punnett square for each of the crosses you modeled in Part 1, Part 2 and Part 3.

                         

              

2) According to your results in Part 1, how many diffrent kinds of offspring are possible when the homozygous parents(BB and bb) are crossed? Do the results you obtained using the marble model agree with the results shown by a Punnett square?

According to the results, as well as the Punnett Square, if the parents are homozygous, meaning that both of their alleles are either dominant or recessive, their offpsring will show the dominant trait. However, since one of their parents carry a genotype for the recessive trait (bb), the children will be carriers of the recessive trait. Their genotype would be heterozygous, or Bb. The results that we obtained do show that all of the offspring would have the allele combination of Bb. In this case, the Punnett Square was 100% correct.

3) According to your results in Part 2, what percentage of offspring are likely to be homozygous when a homozygous parent (BB) and a heterozygous parent (Bb) are crossed? What percentage of offspring are likely to be heterozygous? Does the model agree with the results shown by a Punnett square?

When looking at the results that we gathered for Part 2 (the crossing of a heterozygous and homozygous parents), I can gather that they are not quite similar to the results that the Punnett Squares have shown. The Punnett Squares show that the probability of the offspring being heterozygous is 50%. However, in our results, only 20% of the overall picks ended up with both blue and white marbles.The other 50% on the Punnett Square were supposed to be homozygous, or BB. However, in our results showed that the majority of the outcome had the BB combination of alleles (80%). This shows that the more complex the genotype of the parents is, the less reliable the Punnett Square will be.

4) According to your results in Part 3, what diffrent kinds of offspring are possible when two heterozygous parents (BbxBb) are crossed? What percentage of each type of offspring are likely to be produced? Does the model agree with the results of a Punnett square?

When two heterozygous parents are crossed, there are three possible outcomes that could happen. According to the Punnett Squares, if two heterozygous parents are crossed, the outcome would be as follows: 25% of the offspring would have the genotype of BB, 25% would be bb, and finally, 50% of the offspring would inherit exactly the same alleles for a trait as their parents, which is Bb. However, again, the results that I got from the model are quite different from the ones shown in the Punnett Square. It turned out that 40% of the outcomes were Bb, 20% were bb, and the final 40% were BB.

5) For Part 3, if you did 100 trails instead of 10 trails, would your results be closer to the results shown in a punnett square? Explain.

I don't know whether the results would be closer to the ones shown by the Punnett Squares, but I do believe that the data gathered from 100 picks would be more reliable then the one where only 10 picks were made. If 100 picks were made, the data would probably be more accurate, and more statistics would be proved.

6) In a paragraph, explain how the marble model compares with a Punnett square. How are the two methods alike? How are they different?

The two methods are quite similar in a sense that both of them can be used to predict the probability of the offspring inherting certain traits from their parents. However, they do have a major difference. While the Punnett Square is mostly used for predicting what the possible outcome for the genotypes could be, the marble model is a sort of a test for the Punnett Square, showing how reliable the results from the Punnet Square can really be, when applying them to real-life situations.