Writing in Biology - Section 1

In order to understand the human body, model organisms are used as replacements for humans in experiments.  These organisms are chosen for a variety of factors.  First, they must be genetically similar to humans or have enough similarities in the area of study.  Next, they need to have a short generation span so the effects of the study can be observed through the entire lifespan and into furture generations.  During their lifespan, model organisms need to produce a large number of progenies to increase the sample size of the population.  The gene crosses must be controlled as well and they must be suited to live in lab settings.  Finally, the organisms need to have an accumulated body of knowledge.

There are a variety of model organisms used in reasearch.  The type of organism chosen is determined based on the focus of the research.  Some common types of model organisms include E. coli and saccharomysoes.    E. coli is a species of bacteria.  Despite being a single-celled prokaryote, they have significant value to scientific studies.  They are especially useful in studying cell respiration.  Saccharomyoes or yeast is another type of organims used in laboratory settings.  Scientists use this model organims to study processes like protien scretion, control of the cell cycle, and cell differentiation.  

Chromatin Immunoprecipitation is an important molecular tool used to discover all parts of the genome that a transcription factor can bind to. Chromatin Immunoprecipitation, or CHip-Seq, involves the use of antibodies that bind to the transcription factor of choice in order to withdraw all the genetic material from the cells. The first step requires the crosslinking of proteins and DNA together. Once the Transcription factor has been attached to the DNA, the DNA is sheared into 300 base pair segments. Next beads with antibodies that recognize a specific transcription factor are added so that the DNA-transcription factor complex binds to it. The immunoprecipitation part of this experiment involves centrifuging the substance so that a pellet is formed containing only the beads that are attached to the DNA-transcription factor complex. The protein is then uncrosslinked from the DNA and the short strands now get sequenced. The sequenced DNA portions are then mapped on the genome to see where the transcription factors bind. This experiment can reveal valuable information when combined with RNA-Seq. RNA-Seq will give all the genes that are acitive so overlapping the results of a CHip-Seq test will tell you what genes are activated by a specific transcription factor.

Plants differ from animals in many ways, one of which is the incidence of viable polyploidy. Ploidy refers to the number of chromosome pairs an organism has and polyploidy is the phenomenon wherein an organism will have more than one complete set of homologous chromosomes. Over 80% of flowering plants are polyploids, while the occurrence of animal polyploidy is a phenomenon of great rarity, almost absent in mammals and scarce in fish. One of the major reasons for this difference is the fact that plants rarely require a mate to create offspring, whereas animals often need a mate to produce viable offspring. Thus, should a polyploid animal mate with an animal of normal ploidy, it will create an aneuploidic zygote that cannot create viable gametes. Plants can undergo two kinds of polyploidization, allopolyploidization and autopolyploidization. Allopolyploidization occurs when two different species hybridize and the resulting offspring is viable and reproductively isolated. Autopolyploidization occurs when a plant species self fertilizes to create offspring that is reproductively isolated from its parent species. There are two major ways polyploidization can occur. The first is mitotic nondisjunction and can best be explained when observing allopolyploidization. When the haploid gametes of two different species hybridize, the resulting zygote has one chromosome of each kind, thus lacking homologous pairings. An error in mitosis can occur where the doubled chromosomes end up in the same daughter cell, thus yielding a diploid individual with two chromosomes of each type. The chromosomes in the new plant species can now synapse properly during meiosis and create viable haploid gametes that allow for self-fertilization. The second method involves meiotic nondisjunction. This type of nondisjunction can occur during meiosis I or meiosis II, but in both cases the result is diploid gametes. These diploid gametes can be fertilized by haploid gametes to yield nonviable triploid individuals, or they can fuse with another diploid gamete to create a viable tetraploid individual. So, if a plant produces two diploid gametes through nondisjunction and they self-fertilize, the result would be a new, tetraploid species. This species is now reproductively isolated from its parent as if the two were to mate they would create nonviable triploid individuals.

Methods: 

• Begin outside the BCRC main doors. 
• Facing away from the BCRC door, walk left down the hallway and take the stairs to the very first floor.  
• Exit the Morrill doors facing the East side of the campus. 
• Once you walk out, you should be facing the Shade Tree lab and the Franklin Dining Commons. 
• Go straight up until you reach Stockbridge road. 
• Make a left on Stockbridge road or walk North. 
• Walk up Stockbridge road past French Hall and the University Club. 
• Stop once you reach Wilder Hall. 
• Look right or East and you should see apple tree.
• The apple trees are near the Durfee Conservatory.
• Enter the first section of apples trees and walk to the end of the tree. 
• I found the evidence for phytophegy near the apple trees. 

Biotechnology has come extremely far in the last 10 years, with stem cell use in modern medicine and genome editing with CRISPR only being published seven ears ago, but has yet even further to go. Stem cell research was one of the hottest topics in the last decade, and the understanding of the implications has caught up to its discovery, the uses are breaking boundaries every day. Now we have 3-D printers that can use stem cells to produce complex tissues and we can grow in vitro organs from dishes from the exact same genetic coding in your body. One of the most widely benefitial research projects has been on prosthetics that are able to connect to live nerve tissue in amputations to allow the electrical signals recorded from prosthetics to equate to nerve impulses that the brain can read. Many of us live privilidged lives with all four of our original limbs, but hundreds of thousands of people in the U.S. alone are living with upper arm amputations or are born without complete limbs. This project was started to create a prosthetic hand that enabled that feeling of having a hand. The mechanism has sensors that collect data like the sensory receptors in our own hands: pressure, texture, temperature. The sensed data is then translated to electrical signals and interpretted into neural signals that travel through electrodes deposited into the nerve bundles in the limb. The nerves pick up the signals and send them to the brain for recognition and response in the body, as if all the feelings were real and the hand was human. 

Did you know that Machu Pichu, a city considered one of the greatest architectural achievements was deliberately built over major fault zones!​

Rualdo Menegat, a geologist from the Universidade of Rio Grande do Sul, research suggests that the legendary city of Machu Pichu are oriented along the direction lines of the main faults.

According to Dr. Menegat, this gave the Incas some advantages. For example, meltwater and rainwater flowed through the faults into the city, so there was always a filled spring there. In addition, the city was protected from avalanches and landslides. Faults and fissures beneath Machu Picchu also helped to drain this area during heavy rains.

#funfactfriday

Here is the link to the article: https://www.sciencedaily.com/releases/2019/09/190923140814.htm

Cortisol is a steroid hormone produced in the adrenal cortex of the adrenal medulla. It has various functions in the body. This includes increasing levels of blood glucose, and regulating metabolism. Sometimes, cortisol levels become high and can lead to stress and anxiety. Individual’s affected by Cushing’s disease have been exposed to high levels of cortisol for a long time. On the opposite spectrum, Addison’s disease is a condition where cortisol levels are too low, and because of this, individual’s rarely feel stress and are prone to being unmotivated. Cortisol is also part of a feedback loop. This begins with CRH, produced in the hypothalamus, ACTH, produced in the anterior pituitary, and ends with cortisol. Based on the levels of cortisol in the body, it will have a direct effect and change levels of CRH and ACTH. 

Skeletal muscle cells are different than the pacemaker cells we have in our cardiac muscle. When a skeletal muscle contracts, it is due to the voltage gated sodium channels opening and triggering the voltage gated calcium channels to open, bind to troponin, expose the tropomyosin binding site, and have myosin bind to actin to complete one cross bridge cycle. On a graph, before depolarization in a skeletal muscle cell, it is a flat line until there is a stimulus, then it rises, and repolarizes back to normal. Without stimulation, the skeletal muscle will not contract. 

In cardiac pacemaker cells, the heart begins to repolarizes even when it is generating maximum force. This is because the calcium channels that are triggered via the release of sodium are slow calcium channels. Due to this, the absolute refractory period is longer than a skeletal muscle’s absolute refractory period, and is the reason why the graph of a pacemaker potential does not have a straight line because the heart is overlappingly beating and resting. In cardiac cells, even without stimulation, the heart will beat.