- We have already looked at the basic structure of animal cells and plant cells
- It is important to note that not all cells look like this
- A lot of cells are what we call specialised cells
- The specialization of cells is a fundamental characteristic of living organisms.
- Most cells, when they have finished dividing and growing, become specialised.
- When cells are specialised:
- they do one particular job
- they develop a distinct shape
- special kinds of chemical change take place in their cytoplasm.
- Chemical reactions within the cytoplasm of specialized cells enable them to perform their specific functions.
- This specialization of cells is sometimes referred to as the “division of labour” within the organism.
- Mitochondria, ribosomes, and other organelles within cells may also be specialized to perform specific functions.
- Specialized cells combine to form tissues, which are groups of cells with similar structures and functions working together.
- Tissues, in turn, combine to form organs that perform specific functions in the body.
- Below we will discuss various specialized cells found in plants and animals, and how they work together to enable organisms to function properly.
Bacterial Cells:
- Smallest living cells, found in almost every environment.
- Lack a nucleus and other membrane-bound organelles.
- Have a cell wall made of peptidoglycan.
- Some have flagella for movement.
- Some have pili for attaching to surfaces.
- Can undergo conjugation to transfer genetic material.
Ciliated Cells:
- Found in the respiratory tract, oviducts, and other areas.
- Have cilia, which are hair-like structures that beat in coordinated waves.
- The movement of cilia helps to move substances across a surface, such as mucus in the respiratory tract.
- Have a large surface area due to the presence of many cilia.
Root Hair Cells:
- Found in plant roots and are responsible for absorbing water and minerals from the soil.
- Have long, thin extensions called root hairs that increase the surface area for absorption.
- Lack chloroplasts as they are not involved in photosynthesis.
Palisade Mesophyll Cells:
- Found in the leaves of plants and are responsible for photosynthesis.
- Have numerous chloroplasts to capture light energy.
- Are closely packed together in parallel rows to maximize the surface area for the absorption of sunlight.
Neurons:
- Specialized cells that transmit signals in the nervous system.
- Have long extensions called axons and dendrites that help to transmit signals over long distances.
- Have a high concentration of ion channels and neurotransmitters to facilitate signal transmission.
Red Blood Cells:
- Carry oxygen from the lungs to the body’s tissues.
- Lack a nucleus and other organelles, allowing more space for oxygen-carrying haemoglobin.
- Have a unique biconcave shape that increases the surface area for oxygen exchange.
- Are flexible and can change shape to pass through small blood vessels.
