Plant and Animal Cells Plant and animal cells can be studies in greater detail using a light microscope. Light passes through a thin slice of the specimen. Lenses magnify the specimen many times. 7 Organelles Function Cell Membrane Controls movement into and out of the cell and holds the cell together. Nucleus Contains DNA (genetic material). Controls the cell Cytoplasm Where chemical reactions take place, contains enzymes. Mitochondria Where respiration occurs, transferring of energy. Cell Wall Made of CELLULOSE. Supports the cell and strengthens it. Vacuole Contains CELL SAP. Helps support the plant by keeping the cell rigid Chloroplast Contains CHLOROPHYLL. Absorbs LIGHT. Where photosynthesis takes place Ribosome's Where proteins are made.

B2.2 – Inside Bacteria Microscopes have improved in last 350 years. Light microscopes can magnify 1500x. Electron microscopes can magnify 2000000x. Electron microscopes produce very clear images. Electron microscopes show more detail of the specimen. 2 types of DNA 4 Organelles Function Chromosomal DNA A giant loop of DNA containing most of the genetic material. Plasmid DNA Small loops of DNA that carry extra information. Flagella Long whip like structures that aid movement. Cell Wall Provides support but is more flexible than a plant. Not made of cellulose.

Exam Questions answers Q1 – Diagram about Bacterium cell A is the cell membrane B is the cytoplasm C are the genes (or genetic material /chromosones) D is the cell wall

Exam Questions answers Q2 Animal Cell A --- is the Cytoplasm (1) and its function is where chemical reactions take place/carries organelles or chemicals (1) B --- is the Membrane (1), its function is that it controls what enters and leaves the cell/holds cell together (1) C --- is the Nucleus (1), its function is to contain all the genetic material in the cell/control the cell activity (1) DO NOT accept the Nucleus is the brain of the cell– it isn’t!!!!

Exam Questions answers Q2 Plant cell Chloroplast function: where photosynthesis happens (1) Cell Wall function: supports the cell upright/rigid (1) Vacuole function: keeps cell turgid/ reservoir for chemicals (1)

Exam Questions answers Q3 Table fill-in

What is a microscope? We’ll read the information on microscope. In your book, answer the following questions in full sentences. What is the main job of a microscope? What is magnification? What is resolving power (resolution)? What is the main advantage of using an electron microscope over a light microscope? Give a specific example. What is the main advantage of using a light microscope? Name 2 modern uses of microscopes. Which cell would require a bigger magnification to look at: a prokaryotic or eukaryotic cell? Why? How many micrometres in 1 metre? If a cell is 30μm, how many millimetres is it?

Green pens: tick if correct; change if not A microscope helps us see objects too small to see with the naked eye. Magnification is the number of times bigger the image is compared to the real object. Resolving power is the ability to distinguish between two objects. The higher the resolution the more clear the difference. An electron microscope allows us to see the details of sub-cellular structures such as mitochondria and ribosomes. A light microscope is cheaper than an electron microscope. Microscopes can be used to detect cancerous cells and to study the structure of unknown cells. A prokaryotic cell would require a bigger magnification because it is smaller (by 1 or 2 orders of magnitude) than a eukaryotic cell. How many micrometres in 1 metre? 1,000,000. If a cell is 30μm, how many millimetres is it? 0.03mm Orders of magnitude may need explaining: 10x bigger is one order of magnitude bigger. (101) 100 x smaller Is two orders of magnitude smaller (10-2) etc.

Units 1mm (millimetre) = 1000 μm (micrometre) Rule: x1000 to convert larger unit to smaller unit e.g. mm to μm Rule: /1000 to convert smaller unit to larger unit e.g. μm to mm. Explain these terms + check pupils understand them. Worksheet: converting units.

Cell Differentiation – summary As an organism develops, cells differentiate to form different types of cells 1 most types of animal cell differentiate at an early stage 2 many types of plant cells retain the ability to differentiate throughout life In mature animals, cell division is mainly restricted to repair and replacement As a cell differentiates, it acquires different sub-cellular structures to enable it to carry out a certain function It has now become a specialised cell Key points

Which Examples to learn…. Sperm Cells- Specialized for REPRODUCTION (long tail, streamlined, lots of mitochondria, enzymes) Nerve Cells- Specialised for RAPID SIGNALLING (long, branched connections) Muscles Cells- Specilaised for CONTRACTION (long, lots of mitochondria) Root hair cells specisalised for absorbing WATER AND MINERALS (big surface area) Phloem and Xylem are specialsied for TRANSPORTIN SUBSTANCES (cells joined end to end, very few subcellular structures, hollow)