Cell – the smallest units from which all organisms are made. Organisms are unicellular and multicellular • Unicellular made of just a single cell • Multicellular contains millions of cells. Cell membrane • Is a thin layer that surround every cell • It is composed by protein and fats • Partially permeable which mean that some substances pass through but not others Function 1. It controls the entry and exit of dissolved substances. 2. Surround the cytoplasm, Hold the cell together. 3. Separates the cytoplasm from its environment. Cytoplasm • It is clear jelly • Nearly all water 70% • contain a lot of substances dissolved in it. Function 1. Many chemical reaction including anaerobic respiration 2. Organelles in eukaryotic cell are placed in cytoplasm 3. Genetic material in prokaryotic cell is placed in cytoplasm Nucleus (plural: nuclei) • • • • • It is composed by two membrane. The nucleus is where the genetic information is stored. The information is kept on the chromosome The chromosomes are made of DNA. A chromosome is a length of DNA found in the nucleus that stores the genetic information in form of gene. DNA function 1. Contan genes 2. Codes for specific proteins. Vacuole • Is a fluid – filled space surrounded by its own membrane (tonoplast in plants is the name of this membrane). • Contain cell sap ( solution of sugars ) • Animal cells have much smaller vacuoles called vesicles that contain solutions plant large and permanent one. Function In plants • Helps to keep it shape • Contain water necessary to provide turgor pressure • May store ions and molecules In animal • Are involved in digestion ( phagocytes) • Are involved in excretion ( contractile vacuoles may remove excess water) • Secretory vesicle contain hormones or enzyme. Cell wall ( only in plant cell ) • • • • Strong covering Outside the cell membrane Is composed by cellulose that is a polymer of glucose and it forms fibers in different directions. Allows water to pass through it so it is fully permeable to water and dissolved substance . Function 1. It protect and support the cell ( pressure of cell contents leads to cell turgidity) 2. The cell wall stops it bursting when cell absorb water by osmosis. 3. Defining cell a certain shape Chloroplasts • are found in plant cell. • contain the green colouring or pigment called chlorophyll. • Chlorophyll absorbs energy from sunlight, and this energy is then used in making food for the plant by photosynthesis so contain the enzyme for photosynthesis reactions. • Chloroplasts often contain starch grains, ( white color in microscope) which have been made by photosynthesis • Contain two membrane Mitochondria (singular: mitochondrion) • Mitochondria are found in almost all plant and animal cells. • Contain two membranes • Aerobic respiration ( oxygen is needed ) take place there and release energy from glucose. • Can be seen only with electronic microscope. • There are many of them in cell that require a lot of energy like nerve cells, muscle cells, and liver cells. Ribosomes • • • • • . are tiny structures found in almost all animal cells and plant cells. Ribosomes are the site of protein synthesis. Are common in cell that produce proteins like liver cells Are found free in cytoplasm or in the surface of endoplasmic reticulum. They are so small that we can only see them with an electron microscope. Animal cell Plant cell Heterotrophic nutrition Autotrophic nutrition Cell membrane Cell membrane Cytoplasm Cytoplasm Nucleus Nucleus Vacuoles Very small and temporary Vacuoles large and permanent Mitochondria Mitochondria Rough endoplasmic reticulum Rough endoplasmic reticulum Ribosome Ribosome Absent very irregular shape Cell wall ( regular shape ) Absent Chloroplast Glycogen is the storage form of carbohydrate Starch is the storage form of carbohydrate Smaller in size about 25µm or 0.025 mm larger in size 60 µm or 0.06 mm Bacteria Cells • Bacteria do not have a nucleus so are also known as prokaryotic cells. • They have a circle of DNAthat floats in the cytoplasm. This is sometimes called a bacterial chromosome. •They are microscopic single-celled organisms ( unicellular orgnisms) •Possess a cell wall (made of peptidoglycan, not cellulose), cell membrane, cytoplasm and ribosomes. •Plasmids are sometimes present - these are small rings of DNA (also floating in the cytoplasm) that contain extra genes to those found in the chromosomal DNA •They lack mitochondria, chloroplasts and other membrane-bound organelles found in animal and plant cells • Some bacteria also have a flagellum (singular) or several flagella (plural). These are long, thin, whip-like tails attached to bacteria that allow them to move Microscope Light microscope • Can magnify about 1500 times • Use light to see image • A photograph taken using a light microscopy is called a photomicrograph with color. All the structures– cell membrane, cell wall, cytoplasm, vacuoles, nucleus and chloroplasts – can be seen with a good light microscope but not mitochondria 1mm = 1000µm Animal cell under light microscope The magnification of an object is how many times larger it is than the real object. • Make sure that all the numbers in your calculation have the same units. • Magnification is always written with a multiplication sign in front of it, ×. 1mm = 1000µm and 1cm = 10,000µm Electron microscope • Can magnify up to 500 000 times • You can see more in detail • They use beam of electron instead of light • An image made using an electron microscope is called electron micrograph that provide image images without color. Root Hair cell Palisade cell Red Blood cell Sperm Cell
