#detritus449

[milodoesscience]

Essential Knowledge 4.A.3

Demonstrate your understanding of how interactions between external stimulie and gene expression result in differentiation of cells, tissues, and organs. 

Pluripotent stem cells have the potential to become any type of cell, since they all have the same exact genetic makeup. Differentiation of these stem cells is a result of transcription factors. Transcription is the process of converting DNA to RNA, therefore, transcription factors induce this process making it a sort of starting pistol for gene expression. Internally, stem cells become unipotent by only expressing genes queued to it by transcription factors. An external example of transcription factors at work is the differentiation of female and male embryos. At five weeks, all embryos are exactly the same. However, at week six, the testes of a male embryo release the SRY gene that is the transcription factor which signals the production of certain proteins, making an embryo male. 

Cells can also be effected by transcription factors triggered by their environment. Environmental changes, such the temperature being too high, can trigger transcription factors called heat shock factors. These heat shock factors can protect the cell from changes in temperature by altering it’s structure, making a protective coat around it, until it is no longer needed.

[milodoesscience]

1.B.1

Describe three conserved core biological processes mentioned above using specific examples

1. Chromosomes -  in the nucleus of most living things, chromosomes carry genetic information in the form of genes.

2. Cytoskeleton - a structure unique to eukaryotic cells. The cytoskeleton is a structure that helps cells maintain their shape and enables cells to carry out essential functions like division and movement.

3.  The Endomembrane System in Eukaryotic Cells - All eukaryotic cells contain an endomembrane system. The endomembrane system is comprised of nuclear envelope, ER, Golgi apparatus, the plasma membrane and more.

Justify how these conserved core processes/features support the idea of common ancestry for all organisms

These conserved core processes/features support the idea of common ancestry for all organisms because they are found in many organisms (in this case, all the ones I have listed are found in all eukaryotes). Since all organisms share these traits/processes it suggests that there is some common ancestry for all lifeforms. 

[milodoesscience]

Work for Peppered Moth Simulation Questions #21-24

Justify how an evolutionary change in a population is related to a change in the environment. What role do humans play in this change? What is the impact in the future of this change?

Using the peppered moth simulation as an example, if there were moths in a light forest (the environment) then light colored moths would be better suited for survival than black moths since they are less visible to predators because they can blend into their surroundings while the others cannot. Therefore (as proved in #21), the ratio of colors in an environment would change, most of the population being a part of the group that is more fit for survival in that environment. So the evolutionary change in this population of peppered moths (one color being more abundant than the other) is due to the environment they are in. Since humans have been steamrolling over habits of countless animals for quite some time, we know that the destruction of those environments can lead to monumental changes in the chances of survival for many species.

In the future, more species will most likely become extinct as a result of this because they are not fit to survive in an environment different than their original habitat. This is especially true since the destruction of entire habitats can happen within months while the rate of adaptation to be better suited within that environment can take many years. Because these creatures do not have time to gradually adapt, they die off.

[milodoesscience]

Essential Knowledge 2.A.1

An exergonic reaction is a spontaneous reaction that has a net release in free energy. Since cellular respiration releases free energy by breaking down carbohydrates, it is exergonic.

On the other hand, an endergonic reaction is a non-spontaneous reaction in which free energy is absorbed/captured from the environment in order to do work. Since photosynthesis captures light energy in order to form carbohydrates, it is considered endergonic.