There are two different types of cell: Prokaryotic cells and Eukaryotic cells. Prokaryotic cells are typically Bacteria whereas Eukaryotic cells are Plants and Animals. Both type of cell is made up of different Organelles (little organs). There are a few differences between the Organelles contained inside each type of cell. The main difference between the structures of the two cells is that a Eukaryotic cell contains a Nucleus and a Prokaryotic cell does not. The Nucleus is the largest of the Organelles found within a cell, the nucleus is the powerhouse of the cell and controls the activity of the cell. The Eukaryotic cell’s DNA (Deoxyribonucleic Acid) is stored within the Nucleus whereas the DNA inside a Prokaryotic cell is a single strand contained within the Cytoplasm.
There are many other differences in the structure of Organelles within the two different cell types. Many parts of the cell structures are quite similar and they do share a lot of organelles. Chloroplast however is an organelle that is only found within a plant cell and is used for creating food for a plant by trapping the suns energy.
Above is a diagram comparing the structures of both Eukaryotic (plant and animal cells) and a Prokaryotic cell (bacteria). Many of the organelles included in the table, plus some others unique to each type of cell. For example, the Eukaryotic cells both have an endoplasmic reticulum. There are two different kinds of Endoplasmic reticulum: a rough endoplasmic reticulum (Rough ER) and a smooth endoplasmic reticulum (Smooth ER). They both have different jobs within the cell. The Rough ER is used to make proteins and transports them to various places in and out the cell. It is associated with Ribosomes. The Smooth ER contains no Ribosomes and its main function is to create lipids (fats and oils).
There are many different specialized cells and two examples of specialized Eukaryotic cells are a Red Blood cell and a Sperm cell. The structures of these cells are different to help them better with their function.
The Red Blood Cell, which main function is to carry oxygen from the lungs around the body and to carry carbon dioxide as a waste product back to the lungs, has a Biconcave surface. This helps the function of the cell by increasing its surface area, therefore, increasing the amount of Oxygen that can be transported around the body. The biconcave surface also increases the speed the cell absorbs oxygen, because of this the life cycle of a red blood cell is short lived and usually lasts around 100/120 days.
A Sperm cell is a gamete (sex cell) which is perfectly adapted to move by itself with the aid of a flagellum (which is tail like) to give it momentum and therefore makes its journey towards an Ovum a lot easier. The sperm cell is the only cell in the human body that has a flagellum. The Sperm cell also has an adapted head called an acrosome which helps the sperm to penetrate the membrane of an ovum and deliver the nucleus to complete fertilization. Sperm cells survive inside a female body for around 5 days after ejaculation.
The structure of the membrane of a cell is primarily composed of proteins and lipids, this is called the Phospholipid bilayer. “The phospholipids in the cell membrane are constantly moving while the proteins are scattered among them, so that the structure proposed is called the fluid-mosaic model.”
The phosphate (head) is hydrophilic meaning it likes water and the lipid (tail) is hydrophobic meaning it does not like water. The phospholipid bilayer is where simple diffusion, also known as passive transport, of small molecules like water (H20) and oxygen (02) occurs. It is known as simple diffusion because no energy is needed during this process. The cell membrane is also composed of other parts including specialized proteins called protein channels, which help with the transport of larger molecules like glucose using facilitated diffusion. The shape of the protein channel helps the molecules to pass through and this is also passive transport. The Protein carrier is also an important part of the structure of the cell membrane. This uses ATP (Adenosine Triphosphate) to transport molecules through the cell membrane by aid of a protein carrier. The protein carrier uses ATP to change its shape while molecules and ions such as Sodium Na+ and Potassium K+ bind themselves to it. This is known as active transport as the process uses an energy source (ATP) to move the molecules through the cell membrane.
