Transcript MRS C GREN
MRS C GREN CELL Cell All living things are made up of tiny units called cells. No matter what kind of living thing we look at, the cells are similar in how they are made up and how they work. Cell theory states that: All living things are made up of cells and cells are only produced from other cells. Unicellular or Multicellular Multicellular All plants and animals are called multicellular as they consist of many cells. Some small plants and animals consist of a few thousand cells, while larger animals and plants such as humans and trees consist of billions of cells. There are many different types of cells found in plants and animals. Unicellular There are microscopic organisms (micro-organisms) that consist of one cell only. These unicellular organisms include bacteria, some fungi and protist. Plant cells are different from animal cells but they have many features in common. Most cells can be classified as either plant or animal cells. Although they are basically similar, they are some differences between the two. This is because plants and animal do some things the same but do other things differently. What do you think is the main difference between the plant and animal cells? Plant cells make their own food because they are producers but animal cells can’t make their own food. Both plants and animals are built out of cells. Plant cells have a thick cell wall outside of their cells, but animals cells do not have a cell wall. Plant Cell Animal Cell Organelle Cell membrane Cell wall Function Plant Or Animal Both Plant only Cytoplasm Both Nucleus Both Chloroplast Plant only Vacuole Both, small vacuole in animal Name two cell parts that are only found in plant cells. Chloroplasts, cell wall, large vacuole Name the cell structures that are found in both plant and animal cells. Cytoplasm, cell membrane, nucleus Name the substance that gives plants their green colour and where is it found? Chlorophyll found inside a chloroplast Name the structure which controls what chemicals go in and out of the cell? Cell membrane Why do plant cells need a cell wall and animal cells do not. Cell wall provides support as they grow vertically, towards the light(shoot) or water (roots). Describe what would happen to their sap vacuoles when a bean plant has not been watered for a long time. Sap vacuoles get smaller, reduces the pressure on the cell – the plant wilts. MULTICELLULAR ORGANISM CELLS Cells can look very different because they carry out different functions (roles) within an organism. The structure and shape of a cell allows it to carry out its function. Cells of the same type are generally found together. A group of similar cells is called a tissue. A tissue is a group of cells organised to do a particular job in the body. Example Muscle tissue that lines your stomach and gut is made from muscle cells Nerve tissue in the brain and spinal cord is made from nerve cells. Reproductive organs produce gamete cells (sperm or egg)During reproduction, a sperm cell fertilizes an egg to form a zygote. The zygote cell goes through cell divisions to form an embryo. Onion Skin cells To store food molecules Leaf guard cells To let gases in and out Muscle cells To make limbs move Nerve cells Ciliated cells To convey messages To sweep debris along Metabolism Chains of different chemical reactions occur inside cells, especially in the cytoplasm. The series of reactions are called metabolism, and are controlled by special chemicals called enzymes. In these reactions, new chemicals can be made or broken down. For example, cells make proteins, fats and carbohydrates. Cells are like ‘chemical factories’, so cells have been called living factories. KINGDOM Unicellular organisms • Organisms that are too small to be seen with the naked eye are called microorganisms. • Each micro-organism carries out all of the life processes that larger organisms carry out – movement, respiration, sensitivity, cell (metabolism), growth, reproduction, excretion and nutrition. Unicellular Organism Some organisms consist of only one cell. These single cells are complete organisms and can live independently from other organisms. Friend or foe? • Many micro-organisms play important roles as decomposers, recycling carbon and nitrogen as they break down dead organisms. • Others are used by humans in making cheese, yogurt, wine, bread and medical drugs. • Micro-organisms can be unhelpful when they make food go mouldy or off. • There are also many micro-organisms that cause diseases, such as tetanus, tuberculosis (TB), food poisoning, thrush and athlete’s foot. They are called pathogens. Feeding method: NUTRIENT • Extracellular digestion – Have no mouthpart. – In their cells, they make enzyme which can breakdown large molecules of food. – The enzyme help breakdown the large molecules of food. When enzyme pass out of the body, dead organism’s body is attacked and large molecules are broken down to smaller ones. These molecules are absorbed into the bacterial cell. REPRODUCTION • Bacteria reproduce by binary fission. The cell grows to a certain size and makes a copy of its genes. It then divides into two smaller cells, each with a copy of those genes. • Binary fission occur every 20minutes. Cell Processes of Unicellular Organisms Bacteria MOVEMENT RESPIRATION SENSITIVITY CELL GROWTH REPRODUCTION EXCRETION NUTRITION Euglena Paramecium