Cells don’t all look the same.They have different structures to suit their different functions.
Cells differentiate to become specialised
- Differentiation is the process by which a cell changes to become specialised for the job.
- As cell change, they develop different subcellular structures and turn into different types of cells. This allows them to carrry out specific functions.
- Most differentiation occurs as an organism develops. In most animal cells, the ability to differentiate is then lost at an early stage, after they become specialised. However lots of plant cells don’t ever lose this ability.
- The cells that differentiate in mature animals are mainly used for repairing and replacing cells, such as skin or blood cells.
- Some cells are undifferentiated cells – they’re called stem cells.
You need to know these examples of specialised cells
SPERM CELLS are specialised for REPRODUCTION
The function of a sperm is basically to get the male DNA to the female DNA. It has a long tail and a streamlined head to help it swim to the egg. There are lot of mitochondria in the cell to provide the energy needed. It also carries enzymes in its head to digest through the egg cell membrane.
NERVE CELLS are specialised for RAPID SIGNALLING
The function of nerve cells is to carry electrical signals from one part of the body to another. These cells are long (to cover more distance) and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.
MUSCLE CELLS are specialised for CONTRACTION
The function of a muscle cell is to contract quickly. These cells are long (so that they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction.
ROOT HAIR are specialised for absorbing WATER and MINERALS
Root hair cells are cells on the surface of plant roots, which grow into long “hairs” that stick out into the soil. This gives the plant a big surface area for absorbing water and mineral ions from the soil.
PHLOEM and XYLEM CELLS are specialised for TRANSPORTING SUBSTANCES
Phloem and xylem cells from phloem and xylem tubes, which transport substances such as food and water around plants. To form the tubes, the cells are long and joined end to end. Xylem cells are hollow in the centre and phloem cells have very few subcellular structures, so that stuff can flow through them.
Organelle: a specialised part of a cell that has its own function, a structure within a cell (e.g. nucleus, vacuole, cytoplasm and chloroplast are all organelles of a plant cell).
Cell: the smallest part of a living structure that can operate as an independent unit e.g. the red blood cell
Tissue: a group of cells with similar structures, working together to perform a shared function e.g. muscle tissue
Organ: a structure made up of a group of tissues, working together to perform specific functions e.g. the heart
Organ system: a group of organs with related functions, working together to perform body functions e.g. respiratory system
Organism: an individual made of organ systems which work to keep that organism alive e.g. a cat
Key definition
A tissue is a group of cells with similar structures, working together to perform a shared function.
Key definition
An organ is a structure made up of a group of tissues working together to perform a specific function.
Key definition
A system is a group of organs with related functions, working together to perform a body function.
