Biology Assignment: Endosymbiosis, Organelles, and Cellular Processes

This biology assignment explores key concepts in cellular biology. It begins with an examination of the endosymbiont hypothesis and the origins of mitochondria and chloroplasts. The assignment then contrasts the functions of lysosomes and peroxisomes, highlighting their roles in metabolic processes. Cytoplasmic streaming is explained, emphasizing its importance in large cells for nutrient and protein transport. The concept of a metastable state is defined, and the assignment concludes by discussing the role of scaffold proteins in cell signaling pathways, emphasizing their function in relaying messages between the cell membrane and nucleus. References are provided to support the information presented.

Running head: BIOLOGY 1
Biology
Student’s Name
Institutional Affiliation

BIOLOGY 2
Biology
Question One
The endosymbiont hypothesis explains the source of the mitochondria and chloroplast.
The two organelles are hosted within numerous eukaryotic cells. The hypothesis claims that
mitochondria and chloroplasts incepted as distinct prokaryotic organisms which entered into a
eukaryotic cell. Some of the evidence used to support this thesis includes the commonalities
between bacteria and the two organelles. Both mitochondria together with aerobic bacteria utilize
oxygen to release ATP (Gray, 2017). Also, both chloroplasts together with photosynthetic
bacteria have related chlorophyll that traps and changes light to chemical energy.
Question Two
One of the structural differences between the two organelles is that while lysosomes are
made up of degradative enzymes that break down the cell’s biological polymers, peroxisome has
oxidative enzymes that perform oxidation reactions. On the other hand, both lysosomes and
peroxisomes play a vital role in metabolism. They have enzymes whose role includes breaking
down of fatty acids and amino acids, leading to the production of hydrogen peroxide.
Question Three
Cytoplasmic streaming involves a process where the fluid substances freely flow inside
the cell of a plant or an animal. In large cells, cytoplasmic streaming helps to solve the problem
of non-trivial transport (Wolff, Marenduzzo, & Cates, 2012). The process ensures that there is
the transportation of nutrients and proteins inside the cell.
Question Four
When a chemical compound is in a metastable state, it means that its form can remain
stable over a particular time scale. However, when transferred to another time scale, it will

BIOLOGY 3
become unstable. For instance, water remains liquid at a temperature below 0 degrees Celsius.
However, when vibrations are applied on it, crystallization occurs.
Question Five
A scaffold protein is a crucial regulator of several critical signaling pathways of cell
receptors. Its primary role involves the relaying of messages between the membrane of a cell and
nucleus quickly through reducing the proximity for numerous protein partners (Walther &
Ferguson, 2015). Consequently, the time needed for a particular protein to locate its partner is
reduced.

BIOLOGY 4
References
Gray, M. W. (2017). Lynn Margulis and the endosymbiont hypothesis: 50 years later. Molecular
biology of the cell, 28(10), 1285-1287.
Walther, C., & Ferguson, S. S. (2015). Minireview: role of intracellular scaffolding proteins in
the regulation of endocrine G protein-coupled receptor signaling. Molecular
Endocrinology, 29(6), 814-830.
Wolff, K., Marenduzzo, D., & Cates, M. E. (2012). Cytoplasmic streaming in plant cells: the role
of wall slip. Journal of the Royal Society Interface, 9(71), 1398-1408.