National 4/5 Biology - Multicellular Organisms Section 1 – Cells, tissues & organs

Cell structure review 3) Identify the structures labelled above 4) Which of these would NOT be found In an animal cell? Which of the labelled structures above suggests this is a plant cell? 2) What is the name of this structure?

All of these are different cells found in humans

And these are all found in plants

Why are there so many different types of cells? How do we get all these different types of cell?

Learning Outcomes Today we will learn: - how cells are organised - examples of tissues and organs in the human body - why many different cell types can arise from an original cell

Cells, Tissues & Organs Cells are the basic unit of life - they can carry out all the functions needed for life Many living organisms are composed of only one cell - e.g. an amoeba Most living organisms are made of many millions of cells It would be inefficient if every cell performed exactly the same function So, cells are arranged into tissues - groups of cells specialised to form a particular function Some of these are arranged into distinct structures – organs - e.g. nerve cells form tissues which form the brain

How many other organs do you know? Lungs (Breathing system) Heart (Circulatory system) Liver Stomach (Digestive system) Large intestine Small intestine SCN 3-12a

Specialised Cells An organism with many different cells is multicellular Cells will vary in size, shape, and structure - this allows these cells to perform different functions - e.g. a liver cell and brain cell have very different structures and functions Liver Cell Brain cell

Specialised cells & functions All cells in a particular organism start off identical All of these will contain the same genes As they start to specialise, some genes switch off -whilst others stay on The genes left on will carry information for specific functions E.g. a nerve cell will have genes for producing nerve fibres switched on http://www.twigonglow.com/films/different- types-of-cell-1042/

Video Quiz 1) Genes control the activity of the cell. In which part of a cell are they found? 2) Which substance do red blood cells transport around the body? 3) Which organelle allows leaf cells to absorb sunlight 4) What is the function of a root hair cell in a plant?