Blog: 4B

4.B.1

All living organisms contain DNA. The DNA is a chain of attached polypeptides, which are composed of nucleotides (adenine, thymine, guanine and cytosine), a five-carbon sugar and a phosphate group.  The DNA in the cell is copied by RNA, which is then sent out of the nucleus of the cell to a ribosome. It is then translated and a protein is made from what the mRNA sequence coded for. These proteins

Enzymes are things that speed up or slow down a reaction on a molecular level. What they do specifically is determined by the pattern of their DNA. When the structure is changed it can result in a change in function of the system. IF the function is changed then the enzyme becomes denatured, meaning it doesn’t work.

Things like very incorrect environmental factors such as acidity and temperature can easily denaturize an enzyme. If an enzyme is denatured it cannot latch on to anything or receive the substrate to start speeding up reactions. The substrate works and fits into the enzyme like a key in a lock.

Sometimes enzymes have cofactors, or coenzymes, which attach to the enzyme and allow the substrate to connect to it to activate the original enzyme. It apparently changes how fast the enzyme works with the chemical reactions.

There are also types of molecules that attach to the enzyme and prevent the substrate from attaching to it and activating the enzyme. They are called inhibitors and bind to the activation site. The kind of molecule that binds to the allosteric site on the enzyme can be either an allosteric activator or inhibitor. 

4.B.2

In order to increase the efficiency of cellular processes in cells they have evolved to have something called compartmentalization. Compartmentalization increases the surface area within the cell and its organelles. An increased surface area allows cells to move materials quicker and overall increase efficiency. It occurs also to support the cell, cell colonies called tissues and then the organ systems and organism. They must simultaneously work together to keep the organism functioning.

An example would be the digestive system. The mouth chews and adds enzymes (in the saliva) that begin breaking down the food. The food travels from the oral cavity down the esophagus and into the stomach, which contains more enzymes and microbes (microscopic bacteria aka gut flora) which breaks it down even more. The broken down food goes through the intestines where the nutrients is absorbed and it is broken down more. The remaining wastes are excreted from the rectum and anus after leaving the large intestine.

 

4.B.3

Ecosystems contain many different species that constantly interact with one another.  They interact with eachother through symbiotic relationships. Predation, which one benefits and the other dies, parasitism in which one benefits (the parasite) and one becomes weaker and/or dies (host). Mutualism, in which both benefit and commensalism, where one benefits and the other is unaffected.

Species are also limited by environmental factors like food, shelter and space, which keep the population at or below the ecosystem’s carrying capacity. 

Every environment has a species that all the other organisms revolve around. This species feeds and eats others and if it is removed the entire ecosystem falls apart. These certain species are known as keystone species.

4.B.4

Human impact causes dozens of species to go extinct annually. Acts such as deforestation, habitat fragmentation, poaching, industrial monocropping agriculture and pollution are major impacts. Climate change also has huge impacts on some species, as when the temperature changes so does the habitat and the species must migrate to a new habitat in order to survive.

Invasive species introduced by humans to new habitats also have large, generally negative impacts. They have no natural predators and often devastate the populations of native species in the area.

A couple of prime examples are kudzu plants in the northern southeast and large anaconda snakes in the everglades. Natural disasters can also wipe out populations but they generally recover within a few decades.

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