Writing in Biology

The cell cycle is the process by which cells replicate themselves. This requires a mechanism to control the cell cycle system. Too much proliferation can lead to cancer, while cells remaining in a quiescent state will result in no replication and cell death with no replacement. The cell cycle operates by activating and deactivating proteins that are required for DNA replication, chromosome segregation and cytokinesis. Two of the common ways to activate and deactivate proteins is through the addition or removal of a phosphate group. These proteins are regulated by kinases, which serve as the master cell cycle regulator. Kinases phosphorylate while phosphatases dephosphorylate. Phosphorylation is not always the driver of activation and can serve to deactivate proteins as well. The main kinase in cell cycle control is the cyclin-dependent kinase, CDK. Cyclin activity is controlled through the presence of cyclin proteins and through protein inhibitors. CDK levels remain constant throughout the cell cycle. The binding partner cyclin is what changes and is being made and degraded throughout the cell cycle to control the stage that is occurring.

A scientist by the name of Julian Rotter observed that individuals differ in their understanding of why things happen to them. The concept of fate is controversial as some believe that they should feel lucky for things that happen to them, rather than take credit for it. Rotter theorized that individuals who blame luck or a higher being as the reason things happen to them fall under the category of ‘external locus of control’. On the other hand, individuals who believe that they are their own driving force behind what happens to them, meaning they take credit for their choices, are a part of the category of ‘internal locus of control’. Rotter argued that believing or not believing in fate is a fundamental characteristic that can tell a lot about a person’s soul. Reinforcement from rewarded behavior shapes young kid’s understandings that they control their own future; they make choices to act a certain way or do a certain task that will eventually help them reach their end goal. This decreases the chance that kids will grow up to believe that the future is in the hands of fate, or a higher being. Rotter proposed multiple methods for testing whether an individual possesses the internal or external locus of control. He believed that people who had the internal locus of control would be more motivated to make good things happen for them, therefore, they would be more successful in life. The opposite goes for individuals with external locus of control because they would not feel the need to try hard in life to be successful as their fate is in the hands of a higher power. This idea relates to many aspects of society including socioeconomics. These are related as people of higher socioeconomic standings were most likely possessing an internal locus of control.  

To begin the muscle contraction cycle, an action potential arrives at the pre-synaptic cells. This causes voltage-gated Calcium channels to open, and acetylcholine to be released. The acetylcholine binds to the receptors on the motor end plate. This opens up the ligand-gated sodium channels, causing the depolarization of the muscle cell and leading to an action potential. The action potential travels down the T-tubules to the sarcoplasmic reticulum. This triggers calcium to be released from the stored vesicles, leading to a contraction. 

There is a relationship between the length of a muscle fiber and the tension of a muscle fiber. It is known that the shorter the muscle fiber, the less force they exert. This can be seen by a demonstration using your wrists and hands. If one flexed their hand downward so that the hand is perpendicular to the wrist, less force will be exerted when they try to grab another finger tightly with the hand in this position. However, with the hand normally extended, the hand can tightly grasp another finger with full force. This is due to the idea that muscles have an ‘optimal’ length. This optimal length is identified as the length that it most useful for exerting forces. The length of the muscle when in a normal position is optimal to allow the hand to grasp a small object, while the flexed position is not optimal. For example, if the thick and thin filaments in a sarcomere are further apart, there is a decreased number of motor proteins that can pull on the thin filaments to move inward. Therefore, the lower amount of touching motor proteins lowers the force that it able to be exerted on another object. This is also due the crossbridge cycle. The closer the thin and thick filaments are to eachother, the lower amount the muscle will be able to contract with the restriction of the crossbridge cycle. 

Muscle is the body’s motor because it converts chemical energy into mechanical energy. This means that the ATP that is synthesized through reactions in the body are used as energy to drive mechanical force of muscles and movement. Within skeletal muscle, there are muscle fascicles containing muscle fibers that generate movement. The muscle fibers are cells that have their own plasma membrane as well as multiple nuclei. The muscle fibers are separated by the endomysium while the muscle fascicles are separated by the perimysium tissue. It is important to know that the skeletal muscle is connected to bone by collagen fibers in the epimysium, endomysium and perimysium interwoven with collagen fibers in the periosteum and bone tissue. These connections are usually made are the origin of the muscle. Muscles contract and generate movement by cross bridge cycles of the thick and thin filaments. The thick filament has motor proteins called myosin that grab onto the thin filament and drag them closer together. This shortening is the muscle contraction. The thin filaments are composed of mostly actin and regulatory proteins: tropomyosin and troponin. Although these names sound similar, they perform very different functions which will be summarized in another class period. The signal for the contraction of the muscle is the calcium ion. 

Beagles are a popular breed of sweet, intelligent and gentle dogs, who will guide you in your home life and outside. They will accompany your children and your family for a very long time, due to having better health than most other dog breeds. Due to their close genetic relation with other dog breeds (Harriers, Southern Hounds, etc.), in time, we can hope to retrieve some of our closest friends with scientific advance.

Alongside its many logical advantages, we have a rich history with beagles. Their friendship with man can be traced back as far as Ancient Greece, when hounds of similar size and shape were used to help hunters. Both King Edward II and King Henry VII had packs of glove beagles and Queen Elizabeth I was very fond of her pocket beagle.  After the modern breed was developed by Revered Honeywood in England, The National Beagle Club of America was formed in 1888. Beagles were ranked #1 among American Kennel Club’s registered breeds between 1953 and 1959, and they made a reappearance as #5 (out of 155 registered breeds) in 2005 and 2006 (American Kennel Club). In recent times, Snoopy from the popular children’s series and comic strip, Peanuts, has made beagles a favorite household name all over the world.

Man’s best friend is now under attack from nature. But in this terrible time, we must react both logically and emotionally, and save at least one dog breed rather than let all of them perish. And, if we can only save one breed of domestic dog from this terrible new retrovirus, it must be a pregnant beagle and her babies.

The beagle will accompany and support you in both your home life and the outside world. It is a very intelligent and even-tempered breed of dog. With a gentle disposition and friendly nature, it is neither timid nor aggressive. It will easily be your child’s favorite playmate and your family’s favorite pet. But, it will still retain its natural properties as a scent hound: its superior tracking instinct and sense of smell. So, you can take it hunting or observe it at airports helping law enforcement for detection of illegal items. The beagle is also in excellent shape, with an inherited lack of health problems and good longevity.

Methods

• Have one spider each in a  tupperware container, (sample size of 3= 3 spiders in 3 tupperware containers). They would be fed at the same time, 6 PM, every day for 7 days- 3 flies put into their web each day. Observe feeding speed, spider movement, web activity/building, etc. daily.

• Have one spider each in a tupperware container (sample size of 3). They would be fed at the same time, 6 PM, every day regularly for 4 days. Then they would be starved for 3 days, and presented with 3 flies on the 7th day’s 6 PM. Observe feeding speed, spider movement, web activity/building, etc daily.

• Have one spider each in a tupperware container (sample size of 3). They would be starved (kept inside the container  and not given any food) for 6 days. They would be presented with 3 flies on the 7th day’s 6 PM. Observe feeding speed, spider movement, web activity/building, etc. daily.

Cellar spiders can survive without food for four to eight weeks, since they don’t use too much energy. We don’t expect to see significant behavioral change (feeding habits, aggression) between the 0-d and 3-d starved spiders. But, we expect to see significant difference in behavior for the 0-d/3-d and 7-d spiders, where the 7-d spiders will feed faster or act more aggressively.