This essay will discuss the structure and functions of prokaryotic and eukaryotic cells. It will elaborate the structure and purpose in two chosen specialised cells, Spermatozoon (sperm) and ovum (egg). There will also be focus on the structure of the cell membrane highlighting its functionality of movement of substances both in and out of the cell.
Science Daily (2018) described a cell are the smallest structural and functional unit of living matter. According to Deduve, C, 1991, a cell is described as a unit of life. There processes includes: reproduction, movement, respiration digestion and excretion, with a further exception on the fact that not all cells are capable of having these abilities (Parker and Winston, 2007).
Fox (2004) stated that eukaryotic are decedents from Prokaryotic (bacteria) cells with the ability to evolve and carry energy making mitochondrion dating over 3 billion years ago.
Scoville (2017) argued that Symbiogenesis is an evolution term that relates to the cooperation between species in order to increase their survival. However, Kabnick and Peattie (1991) further argued that the evidence to prove this theory is hard to trace.
Cells are categorised into two different types, the prokaryotic and eukaryotic cells (Parker and Winston, 2007).
The prokaryotic cells are unicellular such as eubacteria and archaea (prokaryotes). Whereas, eukaryotic cells can be grouped into four different types, which are animal, protozoa, plants and fungi and they can be unicellular or multicellular. (Klazema, A 2014).
According to Klazema (2014 ) eukaryotic and prokaryotic cells have many similarities, which are;
* Deoxyribonucleic acid (DNA), which is the genetic information.
* Ribosomes, which are small organelles that makes protein.
* Cytoplasm where replication and growth occurs.
* Cell membrane, which controls what, enters and exits the cell maintaining homeostasis.
* Klazema (2014 ) stated that some prokaryotes have a cytoskeleton that helps cells to divide and keep shape.
Shmoop Editorial Team (2008) stated that each cellular components plays a critical role in the growth, survival, and reproduction of prokaryotic cells.
The (Fig1) illustrates an example of a bacterium cell structure and function depicting its simplicity compared with eukaryotic cell. They are different in their internal organization from eukaryotic cells as they lack a nucleus and membranous organelles. The DNA is spread throughout the cytoplasm in long circular threads.
Eukaryotic cells (fig 2 ) which is a animal cell larger in size with more complex unit that has miniature membrane bound organelles such as a Nucleus that contains the genome which produces DNA and RNA synthesis, the Mitochondria which aids energy production, Golgi apparatus that folds and packages protein. These and many others are specialised organelles that perform specific roles within a cell.
The reproduction process involves the penis being filled with blood to effect erection for an intercourse to take place. Stimulation is required as it enhances the ejaculation of Spermatozoon (Sperm) (Shmoop Editorial Team. 2008).
The Spermatozoon (fig3) is the male sex cell, known as a gamete cell. It is involved in the sexual reproduction and it is called a Haploid cell (Klazema, A 2014). It contains only a single set of chromosomes (genetic information) unlike its partner cell the ovum that is also a gamete cell that contains 23 chromosomes and when combined, forms a single complete chromosome set of 46.
According to Murnaghan (2018), the sperms function is to pass on biological information during the process of fertilizing a female egg to produce a Totipotent Zygote. With the help of mitochondria, the flagellum is given enough energy to drive through the seminal fluid and up the female uterine tract towards its destination the Ovum (egg cell).
The Ovum (fig 4), contains a lot of cytoplasm that enables it to divide many times to make an embryo. The ovum is very large in size making it almost visible to the naked eye. Unlike like the sperm, the ovum is internally mobile and externally passive Gelder (2001). The large size of the ovum gives it the ability to adequately nourish the embryo until a connection is made between it and the mother.
For an egg to be released, a follicle-stimulating hormone is secreted causing growth. A second hormone is released once the egg matures causing the egg to release from the ovaries and this process is known as ovulation.
(Fig 5) is the cell membrane which protects the inside of a cell, It is semi permeable, therefore, the membrane would require different functions of transporting molecules and substances such as oxygen, carbon dioxide and ions into and out from the cell.
Phospholipids are composed of two layers, the hydrophilic that is water attracting phosphate head and hydrophobic which is water repelling fatty acid tail (Parker and Winston, 2007).Both components protect the cell by acting as a barrier. Molecules such as water, carbon dioxide and oxygen can freely cross the membrane. On the other hand, highly charged molecules such as ions, large carbohydrates and amino acids cannot directly pass without the need to pass through protein channels (transport protein).
According to Shmoop Editorial Team (2008), proteins are made up of hundreds or thousands of smaller units known as amino acids all attached to each other in a long chain. 20 different types of amino acids can form a protein and the sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function. Proteins can be described according to their large range of functions in the body.
Even though prokaryotic and eukaryotic cells have similarities in their structures and functions, distinctive and characterised in its own specific structural form