All living cells, both prokaryotic and eukaryotic, have the following cell
structures: plasma membrane, cytosol, ribosomes, and at least one
chromosome. Choose any one of these. Describe its basic structure (including
molecular composition) as well as the function. Explain why a cell could not
exist without the function(s) performed by this cell structure.
The plasma membrane is a vital part of a cell’s structure. Without this critical
component, the cell would surely die as it would no longer be able to regulate its
inside or outside environment. The cell membrane is made up of a bi-layer of
phospholipids, with hydrophilic (water loving) heads and hydrophobic (afraid of
water) tails. This allows the membrane to bring in select molecules that may pass
through the membrane based on size and charge as well as chemical composition.
Furthermore, the membrane enables the cell to get nourishment by bringing food
inside to be broken down in to the component parts.
Cells can be categorized as either prokaryotic or eukaryotic. Only bacterial
cells are prokaryotic. For question two, answer any one of the following
comparison questions. Be sure to compare both molecular (physical)
structure and function in each answer. Compare the nucleoid area
(prokaryotic) to a nucleus (eukaryotic)? How do they differ; how are they
similar? Compare the bacterial flagellum (prokaryotic) to an animal cell
flagellum (eukaryotic)? How do they differ; how are they similar? Compare a
bacterial cell wall (prokaryotic) to a plant cell wall (eukaryotic)? How do they
differ; how are they similar?
This question properly points out that prokaryotic cells differ in many ways from
eukaryotic cells. For example, the nucleoid area of a prokaryotic cell is not bound by
a nuclear membrane, whereas the nucleus in a eukaryotic cell is surrounded by a
nuclear membrane that allows certain substances to enter and leave the nucleus,
much like the plasma membrane described above. Nevertheless, these areas are
similar as well. They both contain the molecular material for the cell: in prokaryotes,
this is the single loop of chromosomal material and in the eukaryote we see diploid
chromosomes.
Eukaryotic cells (in plants, animals, fungi, and algae) are bigger than
prokaryotic (bacterial) cells. This bigger size allows eukaryotic cells to have
more structural complexity. Choose any one of the following eukaryotic cell
structures for a short essay: Mitochondrion Cytoskeleton Golgi apparatus
Endoplasmic reticulum Lysosome Chloroplast (found only in photosynthetic
cells) In your answer, describe its basic structure (including molecular
composition) as well as the function. Why is the function important to keeping
the cell alive?
The mitochondrion is an essential organelle found within the eukaryotic cell. This is
often referred to as the “powerhouse” of the cell as this is where all the energy for
the cell, in the form of ATP, is formed. The mitochondrion is made up of two
membranes that house the inside material called the cristae. The cristae are the site
of energy production for the cell. Mitochondria act like a digestive system that takes
in nutrients, breaks them down, and creates energy for the cell. The process of
creating cell energy is known as cellular respiration. Most of the chemical reactions
involved in cellular respiration happen in the mitochondria. A mitochondrion is
shaped perfectly to maximize its efforts.
As mentioned, the mitochondrion is composed of two sets of membranes that
overlap to create the inner folds of the organelle, also known as the cristae. This is
where all the chemical reactions take place in the mitochondrion. All of those extra
folds increase the surface area of the organelle and allow it to carry out the chemical
work to create energy to keep the cell (and in essence, you) alive. Inside the cristae
is a fluid that is known as the matrix (Henze, 2003).
References
Henze K, Martin W (2003). "Evolutionary biology: essence of mitochondria".
Nature 426 (6963): 127–8.