- Structure
All eukaryotic cells have certain characteristics in common; these are shown in the diagram below.
This table is take from , which shows the structural difference between animal and plant cells (both eukaryotic cells).
- Function
There are a variety of animal cells, all with different functions. A few examples of these are:
- A sperm cell (male gamete) is to fertilise the egg cell (female gamete).
- Epithelial cells are lining cells, for example, inside the cheeks.
- Red blood cells contain haemoglobin to carry oxygen to the cells.
- White blood cells are there to fight disease, either to engulf bacteria or make antibodies.
It is also the same for plant cells. There are many functions within these plant cells. A few examples of these are:
- A root hair cell takes water and mineral ions from the soil.
- A palisade cell carries out photosynthesis.
- An xylem is a pipeline carrying water from the roots to the leaves.
- Pollen grains (male gametes) fertilise the ovules (female gametes).
Prokaryotes
A prokaryote is a cell that does not have a membrane-bounded nucleus or membrane bounded organelles. Prokaryotic cells are less advanced than eukaryotic cells that evolved from them. A bacterium is a prokaryotic organism that only consists of one single prokaryotic cell.
There are three architectural regions within a general prokaryotic cell:
- a cell envelope which consists of a capsule, cell wall and a cell membrane
- a region containing the cell genome (DNA), ribosomes and various inclusions is called a cytoplasmic region
- Flagella and pili are appendages, which are sometimes present.
In the prokaryotic cell, the cell membrane takes over most of the functions of the organelles, such as mitochondria, chloroplasts and the gogli apparatus.
- Structure
Prokaryotic cells are organisms of simple construction compared to eukaryotes. Prokaryotes carry out cellular functions as individual units. There are five essential structural components of a prokaryotic cell; they are: genomes (DNA), ribosomes, cell membrane, cell wall and a surface layer which can or can not be part of the wall. Other than enzymatic reactions, the macromolecular structural components show cellular reactions incidental to life.
The structure and organisation of the macromolecules show the functional aspects of prokaryotic cells that are related to their cell make-up, i.e. – DNA, RNA, phospholipids, proteins and polysaccharides. The diversity that exists among these prokaryotes is accounted for from the diversity within the primary structure of the molecules.
Electron micrograph of an ultra-thin section of a dividing pair of group A streptococci (20,000X).
- Functions
I have found a summary of the characteristics and functions of typical bacterial cell structures that I believe is very useful. This table is taken from .
The Endosymbiotic Theory
Below I have selected a diagram that gives a functional look at the entire process and how specific organelles evolved.
A theory first proposed by Lynn …………are and . (Taken from Encyclopedia of Science at )
- Mitochondria
Mitochondria are self-replacing organelles that occur in the cytoplasm of all eukaryotic cells. They contain their own genome, which is separate to the one found in the nucleus of the cell.
There is a vital metabolic pathway for generating energy in eukaryotic cells; this is called the Kerb’s cycle.
-Chloroplasts
A chloroplast is an organelle found within the cells of green plants and eukaryotic algae, both of which contain chlorophyll and the enzymes necessary for photosynthesis.
From researching the eukaryotes and prokaryotes, and the Endosymbiotic Theory, I found a lot of information along with diagrams and tables, which were extremely informative and helpful with my research.
The information, diagrams and tables I used to help create my essay were from the web pages:
