Specialised cells: diagrams and adaptations

How cells become specialised

Cells start with structures that allow them to carry out life processes. As a cell develops, it can change its structure to suit a particular function. This process is called differentiation. The resulting specialised cell has adaptations: features that help it do its job.

Most types of animal cell differentiate early in development. Many types of plant cell keep the ability to differentiate throughout life.

Start with the animal cell diagram and plant cell diagram to review the parts common to many cells. Not every cell has every part shown in a general diagram.

Specialised animal cells

A sperm cell carries genetic material to an egg. Its tail helps it move and its mitochondria release energy through respiration. The head contains a nucleus with half the usual number of chromosomes and an acrosome containing enzymes that help the sperm enter the egg.

A nerve cell, also called a neurone, carries electrical impulses. Its long fibre lets an impulse travel a long distance. Muscle cells contain protein filaments that slide past one another, allowing the cells to contract. Their mitochondria release energy for this work.

Red blood cells carry oxygen using haemoglobin. A mature human red blood cell has no nucleus, leaving more room for haemoglobin. Its biconcave shape is thinner in the middle, increasing its surface area compared with a sphere of the same volume.

Specialised plant cells and transport

A root hair cell has a long extension that increases the surface area in contact with soil. This helps it absorb water and mineral ions. Water enters by osmosis, while mineral ions can be taken up by active transport.

Xylem vessels carry water and dissolved mineral ions from the roots through the plant. Cells arranged end to end lose their contents and end walls as they mature and die. This forms hollow vessels. Lignin strengthens their walls. Xylem is a tissue containing vessels; a vessel is not a single living cell.

Phloem transports dissolved sugars around a plant. It contains living sieve tube cells joined end to end. Their end walls have pores that let material move between cells. Companion cells support the sieve tubes. Xylem and phloem are different transport tissues with different jobs.

Looking at cells and practising

A microscope can reveal some cell structures, but these simplified diagrams are not to scale. The light microscope diagram explains the parts of the instrument. You can practise finding them in Microscope Parts.

When explaining an adaptation, connect a feature to the job it helps with. For instance, say that a root hair gives a larger surface area for absorption, rather than only naming its shape. Return to the biology hub for more on cells.

What courses cover

AQA GCSE Biology names sperm, nerve and muscle cells, root hair cells, xylem and phloem when discussing specialisation. It covers red blood cells separately. Edexcel and OCR cover examples across their cell and transport topics. Your teacher can tell you which examples your course uses.