Specialised cells

Erythrocytes

Biconcave shape to increase the surface area for diffusion and to increase the cell flexibility for it to fit through narrow capillaries. These cells have no nucleus so there is more space to hold haemoglobin to increase transport of oxygen.

Neutrophils

Has a lobed nucleus and granular cytoplasm. The cells are flexible to enable them to surround pathogens and engulf them. They contain lysosomes filled with the hydrolytic enzyme, lysozyme. They are made from stem cells in the bone marrow.

Sperm cells

The flagellum contains many mitochondria to release energy for locomotion to enable the sperm cell to move towards the egg cell. The acrosome in the head of the cell contains digestive enzymes to digest the wall of the egg cell so the sperm can penetrate and fertilise the egg cell.

Palisade cells

Located in the mesophyll tissue layer of leaves. They are rectangular, tightly packed cells that contain many chloroplasts to absorb and maximise light energy for photosynthesis. They have thin cell walls to reduce the diffuse distance of carbon dioxide.

Guard cells

These pair of cells have flexible walls, more so on one side, which results in the cells bending when turgid to open stomata and closing when flaccid and this helps control water loss by transpiration.

Root hair cells

These cells are on the surface of roots and have long projections to increase the surface area for osmosis of water and active transport of mineral ions. They have a thin cell wall to minimise diffusion distance.

Squamous epithelial cells

Usually only a single layer of flat squamous cells is in contact with the basement membrane of the epithelium. This provides a short diffusion distance. e.g. these form the linings of the lungs.

Ciliated epithelia

These are made up of cells have hair-like projections that sway to move substances, such as mucus, out of the lungs or an egg in the oviduct. Goblet cells are also located within the epithelium and these cells release mucus to trap molecules, such as trapping dust in the trachea.

Cartilage

A connective tissue that is firm and flexible, located in the outer ear, nose and the end of bones. It provides structural support and it prevents the bones from rubbing together which would damage them. It is made up of elastin and collagen fibres and chondrocyte cells within an extracellular matrix.

Muscle

Composed of tissues that can contract and relax to create movement. Skeletal muscles cause the skeleton to move and are made up of myofibrils containing the proteins actin and myosin. Smooth muscle is located within organs and cardiac muscle is within the heart. Muscles have multiple fibres connecting with connective tissues in between.

Xylem

The cells that make up the part of the vascular bundle in plants responsible for transporting water and mineral ions. The tissue is made up of elongated, hollow dead cells, with lignin in the walls to strengthen and waterproof the walls. Tissues are made from the stem cells in the meristem.

Phloem

The cells that make up the part of the vascular bundle responsible for transporting organic substances made in photosynthesis. It is made of sieve tube element cells, which have perforated end walls and are lacking most organelles to make transport of sugars easier, and companion cells, which contain organelles to provide resources for the sieve tube elements. Sieve tubes are made from the stem cells in the meristem.