Eukaryotic Cells: Cell Specialisation (A-level Biology)
What is Cell Specialisation?
The definition of cell specialisation is cells that have a distinctive structures and provide unique functions in the body. They work together in groups to form different tissue types, for example in nerves or muscles. These tissues form organs, which support bodily functions.
- In multicellular organisms, cells specialise to perform specific functions. Cells adapt their structure to particular functions – e.g. red blood cells adapt to transporting blood.
- Specialised cells look different from each other. Cells can adapt by changing the shape and the composition of organelles. Therefore, cells with different functions often times look drastically different from each other.
- There can be a change in the number of a specific organelle. A specialised cell can have more of one organelle relative to another cell – e.g. sperm cells have more mitochondria to enable them to obtain more energy to swim.
Examples of Cell Specialisation
Red Blood Cells (Erythrocytes)
- RBCs transport blood. RBCs, also known as erythrocytes, are responsible for transporting oxygen throughout the body.
- RBC have no nucleus. The only function of RBCs is to carry oxygen, so they want to maximise the space for haemoglobin (which binds to oxygen) inside the cell. Therefore having no nucleus helps to increase storage capacity. Because they have no nucleus, red blood cells do not have DNA and do not divide or carry out most other functions carried out by typical cells.
Neutrophils
- Neutrophils are white blood cells. Neutrophils are white blood cells, and are part of the body’s immune system.
- Neutrophils engulf foreign materials. Neutrophils are responsible for engulfing and breaking down foreign material such as pathogens. They are adapted to do so due to:
- Their flexible shape which can mould to the shape of its target
- Having a much higher amount of lysosomes in their cytoplasm – this provides them with the digestive enzymes needed to break down their target
Squamous and Ciliated Epithelial Cells
- The respiratory tract has ciliated epithelial cells. The beating movement of mobile cilia allows mucus to travel upwards in the respiratory tract.
- Squamous epithelial cells ensure efficient gas exchange. The respiratory tract, in particular the alveoli in the lungs where gas exchange happens, is made up of squamous epithelial cells which are very thin and flat. This allows gas exchange to happen efficiently across the cells.
Sperm Cells
- Sperm cells are involved in sexual reproduction. Sperm cells carry genetic information (from the male) to the egg (of a female) during sexual reproduction.
- Sperm cells have many mitochondria to provide energy. It takes a lot of energy to travel the long distance to the egg, so sperm cells have extra mitochondria to help meet this energy requirement.
- Sperm cells have a flagellum tail to help swim. Sperm cells have a special tail-like structure called a flagellum which helps them “swim” through the vaginal canal of a female and into the uterus.
Palisade Cells
- Palisade cells are the primary site of photosynthesis. They are specialised to have the greatest number of chloroplasts per cell compared to other plant cells.
Root Hair Cells
- Root hair cells absorb water from the soil. Not only do they have a large surface area, they have a large permanent vacuole which increases the rate of osmosis so that water uptake happens faster. Root hair cells also lack chloroplasts as they are in the soil and do not perform photosynthesis.
- Root hair cells have additional mitochondria. This helps generate the extra energy required for active transport of substances into the root cell.
Guard Cells
- The structure of guard cells allow it to easily change its shape. Guard cells are pairs of cells around stoma, which are small openings on the surface of leaves that permits gas exchange necessary for photosynthesis. Guard cells have thin outer walls and thick inner walls. When water enters guard cells in the presence of sunlight, the guard cells become turgid (swell) and its structure allows it to bend outwards, revealing the opening of the stoma. Gas exchange can then take place across the stoma so that photosynthesis can occur.
Cell Organisation
- Cells with a similar function group together to form a tissue.
- Epithelial cells make up epithelial tissue.
- Muscle cells make up muscular tissue.
- Epithelial cells can also make up glandular tissue.
- Neurones make up nervous tissue.
- Blood cells, make up hematopoietic tissue (yes, blood is a tissue!).
- Different types of tissues group together to form an organ.
- The stomach is made up of epithelial tissue, glandular tissue, muscular tissue, and small bit of nervous tissue.
- Different organs with similar functions group together to form an organ system.
- The digestive system is made up of the mouth, oesophagus, stomach, small intestine, pancreas, gallbladder, and the large intestine.
- Different organ systems group together to create an organism.
- Humans have many different organ systems: the cardiovascular system, respiratory system, nervous system, digestive system, endocrine system, immune system, excretory system, musculoskeletal system, and the reproductive system.
What are Eukaryotic Cells?
A eukaryotic cell, or eukaryote, is a cell or organism that has a defined nucleus. The eukaryotic cell has a membrane surrounding the nucleus. Inside this are chromosomes, which is where hereditary material is stored.
How big are eukaryotic cells?
Eukaryotic cells have diameters from 10 to 100 μm (micrometers).
Examples of eukaryotic cells
Some of the cells mentioned above are eukaryotic cells because they have a distinctive nucleus, membrane and contain chromosomes, such as a sperm cell. Example of eukaryotic cells include:
- Muscle cells
- Stem cells
- Bone cells
- Cancer cells
- Plant cells
- Meristematic cells
- Ova
- Fungal cells
Eukaryotic cells are a type of complex cells found in organisms such as plants, animals, and fungi. They have a well-defined nucleus, membrane-bound organelles, and a cytoskeleton.
Cell specialization is the process where cells develop specific functions and structures to carry out specific tasks within an organism. This leads to the formation of different types of cells, each with its own unique characteristics and functions.
Cells become specialized to perform specific functions more efficiently and effectively. This allows the organism to carry out its vital processes with greater accuracy and speed, and ultimately increases its chances of survival.
There are many different types of specialized cells, including muscle cells, nerve cells, blood cells, and skin cells, among others. Each type of cell has specific structures and functions that enable it to carry out its unique role within the organism.
When a group of similar cells work together to perform a common function, they form a tissue. For example, when multiple muscle cells come together, they form muscle tissue. Tissues then combine to form organs, which carry out specific functions within the organism.
Differentiation refers to the process where a single cell becomes a specific type of cell, with a specific function and structure. Specialization refers to the development of specific functions and structures within a cell, after it has differentiated.
Specialized cells often have specific structures, such as specialized membrane proteins, that allow them to communicate with other cells in specific ways. This helps coordinate the activities of different cells within the organism and ensures that vital processes are carried out efficiently.
Specialization of cells allows organisms to carry out their vital processes with greater accuracy and speed, which can ultimately increase their chances of survival. A well-functioning organism requires coordination between its various cells and tissues, and specialization is crucial in achieving this.
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