But embryos contain a special type of cell called stem cells. These can grow into any type of cell found in the body. They are not specialised. Stem cells can be removed from human embryos that are a few days old, for example, from unused embryos left over from fertility treatment

Nucleus | Contains genetic material, which controls the activities of the cell
Cytoplasm | Most chemical processes take place here, controlled by enzymes
Cell membrane | Controls the movement of substances into and out of the cell
Mitochondria | Most energy is released by respiration here
Ribosomes | Protein synthesis happens Cell wall | Strengthens the cell
Chloroplasts | Contain chlorophyll, which absorbs light energy for photosynthesis
Permanent vacuole | Filled with cell sap to help keep the cell turgid

Prokaryotes (bacteria) undergo a vegetative cell division known as binary fission, where their genetic material is segregated equally into two daughter cells. All cell divisions, regardless of organism, are preceded by a single round of DNA replication.

For simple unicellular microorganisms such as the amoeba, one cell division is equivalent to reproduction – an entire new organism is created. On a larger scale, mitotic cell division can create progeny from multicellular organisms, such as plants that grow from cuttings. Mitotic cell division enables sexually reproducing organisms to develop from the one-celled zygote, which itself was produced by meiotic cell division from gametes. After growth, cell division by mitosis allows for continual construction and repair of the organism.^[3] The human body experiences about 10 quadrillion cell divisions in a lifetime.^[4]

The primary concern of cell division is the maintenance of the original cell's genome. Before division can occur, the genomic information that is stored in chromosomes must be replicated, and the duplicated genome must be separated cleanly between cells. A great deal of cellular infrastructure is involved in keeping genomic information consistent between generations.

Mitosis is a fundamental process for life. During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. ... The other type of cell division, meiosis, ensures that humans have the same number of chromosomes in each generation

Cell structureDescriptionFunctionCell typeCell wall | Freely permeable layer surrounding cell membrane. The cell wall of plant cells is made from cellulose. This gives them a rigid structure. | Supports and strengthens cell | Plant cell, fungal cell or bacterial cell
Cell membrane | Selectively permeable double layer of lipid and protein molecules | Controls which substances can enter and leave the cell | All cell types
Cytoplasm | Fluid enclosed by the cell membrane, containing organelles and ribosomes  | Location of many chemical reactions | All cell types
Mitochondria | Rod-shaped structures found in cytoplasm | Location where aerobic respiration occurs and most of the cell's ATP is produced | Animal cell, plant cell or fungal cell
Chloroplasts | Disc-shaped structures found in cytoplasm | Location where photosynthesis occurs and sugar is produced | Plant cell
Vacuole | Compartment in cell containing solution of salts and sugars (cell sap) | Water storage and maintenance of turgor within the cell | Plant cell
Ribosomes | Small complexes found in cytoplasm | Location where amino acids are connected together to produce proteins  | All cell types
Plasmids | Small circular DNA molecules | Contains genes that help cell to function, eg genes for antibiotic resistance | Bacterial cell
Nucleus | Compartment in cell where DNA is stored as chromosomes  | Controls activities of cell | Animal cell, plant cell or fungal cell 

All animals and plants are made of cells. Animal and plant cells have features in common, such as a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cell wall, and often have chloroplasts and a permanent vacuole. Note that cells may be specialised to carry out a particular function.

We use microscopes to see very tiny structures such as cells.

Bacterial cells are much smaller than plant or animal cells. They were first seen under a microscope by Anton van Leeuwenhoek in 1676. As microscopes have improved, scientists have come to understand bacterial cell structure better.

Using electron microscopes we now know that bacteria have a cell wall. This is similar to a plant cell wall but is more flexible. Bacteria do not have a nucleus. They do have two types of DNA – plasmid and chromosomal. The chromosomal DNA carries most of the genetic information. Plasmid DNA forms small loops and carries extra information. Some bacteria have a flagellum – a whip like tail. This helps the bacteria to move itself along. When we talk about these flagellum tails in multiple bacteria, we call them flagella.

Structure of a salmonella bacterium cell

Structure of a bacteria cell

Better treatment of these diseases could also give significant social benefits for individuals and economic gains for society