4.1.1

• The nucleus is the control center of the cell, containing genetic material.
• Mitochondria are responsible for energy production through aerobic respiration.
• Ribosomes are responsible for protein synthesis.
• eukaryotic cells have a nucleus, mitochondria, ribosomes, and a cell membrane
• prokaryotic cells are smaller than eukaryotic cells and have a single circular chromosome called plasmids
• plant cells have a cell wall, chloroplasts, and a permanent vacuole
• animal cells do not have a cell wall or permanent vacuoles
• cell membrane is a semi-permeable barrier that controls the movement of substances in and out of the cell
• cell wall is made of cellulose and is found in plant cells
• vacuole: a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid (cell sap)
• sperm cells are specialised for reproduction and have a long tail to help them swim, a head with enzymes to dissolve the egg's cell membrane, lots of mitochondria to release energy to get to the egg.
• nerve cells are specialised to carry electrical impulses around the body, they have a long axon to be able to carry impulses across long distances, and a dendrite to receive impulses from other nerve cells, many mitochondria for neurotransmitters
• muscle cells are specialised for contraction and movement, they have lots of mitochondria for energy
• As an organism develops, cells differentiate to form different types of cells.

  • Most types of animal cell differentiate at an early stage.
• • Many types of plant cells retain the ability to differentiate throughout life.
• 1. An electron microscope has much higher magnification and resolving power than a light microscope. This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures.