Bell ringer Complete the revision questions Pt 1: Cell structure

Cell essays – good practice Make sure for each organelle you state one of the MAIN functions Be careful not to confuse Golgi apparatus and ER The centrosome is involved in mitosis, not the centrioles.

Lesson objectives 1.1 e,f outline key structural features of typical prokaryotic cells Compare and contrast the structure of typical prokaryotic and eukaryotic cells Outline key features of viruses

Cell Organisation: Prokaryote Cell Eukaryote Cell Prokaryotes have a simple structure and probably the first life on Earth! Eukaryotes probably evolved from prokaryote cells around 1000 million years ago!

Tasks: Prokaryotes and Viruses Draw a diagram of a typical bacterium. Identify structure that are always present vs. additional structures Make a table comparing eukaryotes and prokaryotes including the following aspects: size, cell wall, nucleus, genetic material, mitochondria, chloroplasts, ribosomes, endoplasmic reticulum, cytoskeleton, cilia and flagella, slime capsule Draw a simple diagram of a virus (key words: protein coat and DNA/RNA) Would you describe viruses as "living organisms"? Explain your answer. (Make sure to show arguments for both sides before coming to an conclusion!

made of cellulose/lignin in plants, made of chitin in fungi Structure Eukaryotic cell Prokaryotic cell Size  40 µm 0.5 – 5 µm Unicellular or multicellular Mostly multicellular Unicellular Cell wall made of cellulose/lignin in plants, made of chitin in fungi Made of murein a peptidoglycan (almost always present) Nucleus  yes No Genetic material DNA in form of chromatin/chromosome s (associated with proteins) within nucleus Naked circular DNA in the cytoplasm, sometimes plasmids are present mitochondria no chloroplasts  in plant cells  no ribosomes  yes (80s) Yes (70s) Endoplasmic reticulum cytoskeleton yes Cilia and flagella  in animal cells Slime capsule Most cells

Viral structure

Are viruses alive? Yes No Cells X Reproduce Cannot reproduce by themselves Use energy Response to environment Can interact with cells Contact with cells is not active and only based on chemical makeup of virus and it’s environment Universal genetic code Evolution Grow and develop Homeostasis

Viruses: Most viruses found in animal cells and those attacking bacteria (bacteriophages) have the nucleic acid DNA. Cause a variety of infectious diseases in humans, animals and plants. Extremely small and can only be seen with an electron microscope. Other animal and plant viruses contain RNA. Can be called ‘non cells’ as they have no cytoplasm, organelles and no chromosomes. A widely studied virus is T2 phage, a bacteriophage, which infects the bacterium Escherichia coli (E. coli). Exist as an inert ‘viron’ when outside a cell. Take over a cell’s metabolism and multiply within the host cell. Each virus particle has a core of nucleic acid surrounded by a protein coat called the capsid.

Test your understanding Revision questions - viruses

Plickers

Understanding the mark scheme Peer mark your homework

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