Transcript Cells
Cells Cell • Definition • 1. The structural, functional and biological unit of all organisms. • 2. An autonomous self-replicating unit that may exist as functional independent unit of life (as in the case of unicellular organism), or as sub-unit in a multicellular organism (such as in plants and animals) that is specialized into carrying out particular functions towards the cause of the organism as a whole. • 3. A membrane bound structure containing biomolecules, such as nucleic acids, proteins, and polysaccharides. (Science: Cell Biology) Eukaryotic and Prokaryotic • Animals & Plants (as well as Protocists and many Algae) have cells that contain membrane bound organelles: nucleus, mitochondria, chloroplasts etc. • These are Eukaryotes • Karyote from Greek karyon (meaning kernal or nucleus) Eu- meaning true • Prokaryotes do not have these internal membranes (Pro- meaning before) Eukaryotic Cells Organelles you need to know: • Nucleus – Chromatin – Nuclear envelope – Nucleolus • Mitochondria • Endoplasmic reticulum Rough and smooth • Ribosomes • Golgi Body • Lysosomes • Centrioles • Chloroplasts • Vacuoles • Plasmodesmata Nucleus • Largest Organelle (10-20μm) • Double membrane contains pores (nuclear envelope) • Contains nucleic acids and proteins • When not dividing, DNA bonded to protein forming chromatin • Nucleolus dense area, produces ribosomes Mitochondria • • • • Rod like structures (1μm wide x 10μm long) Powerhouse of the cell Undertake Respiration Produce ATP • Symbiotic evolution Centrioles • Usually a pair • Near the nucleus • Involved in cell division Endoplasmic Reticulum • Network of cavities bound by membranes • Transport system • Synthesis of chemicals • RER – ribosomes, protein synthesis/transport • SER - synthesis of steroids and lipids Ribosomes • Small at ~20nm • Made of a combination of RNA and Protein (65%:35%) • Involved in protein synthesis • DNARNAProtein Golgi Body • Took ages for science to discover what this did • Used radioactive tracers • Proteins transported there in vesicles, fuse and pass thru’ • Proteins altered (carbohydrates added etc.) • Put into vesicles which bud off Lysosomes • Digestive enzymes packaged into a vescicle • Fuse with food vacuoles taken in by endocytosis by single celled animals or with damaged organelles • Can rupture and destroy the whole cell apoptosis Chloroplasts • Large 4-10μm x 2-3 μm • Chlorophyll • Photosynthesis Vacuoles • Any fluid filled, membrane bound, space • Animal cells have temporary ones • Plant cells vac. is surrounded by a membrane called the tonoplast • Filled with cell sap • Osmosis keeps it ‘inflated’ Plasmodesmata Cytoskeleton • 3D, “web-like” structure filling the cytoplasm • Microfilaments (protein fibres) • Microtubules (protein tubes 20nm diameter) • Gives cytoplasm structure • Holds organelles in place • Linked to: cell movements transport Prokaryotes Bacteria Cause diseases good bacteria very very small (0.5 uM to 1 um in size) 1 cm . 1 mm 1 uM (a bacteria) Rod shaped Coccus shaped (round) ‘BAD’ bacteria – cause diseases meningitis Bacteria tuberculosis (E. coli) anthrax the plague gonorrhoea diarrhoea and vomiting Human intestinal cell Bacteria ‘FIGHT’ with the human cells and immune system to survive and cause disease syphilis gangrene leprosy Stomach ulcers Tooth decay plague Escherichia coli (E. coli) Rod shaped bacteria causes vomiting and diarrhoea can cause kidney failure and DEATH E. coli 1 E. coli 2 E. coli 3 E. coli 4 E. coli flagella Outer membrane Cell wall Glycogen granule Plasma membrane Lipid droplet ribosome Circular chromosome flagella Outer membrane Cell wall Plasma membrane Glycogen granule Lipid droplet ribosome Circular chromosome Viruses Viruses • • • • Smallest of the microorganisms 0.002 – 0.3 µm (50x smaller than bacteria) Viruses are not cells Merely arrangements of genetic material and protein Electron Micrographs of Viruses A. Bacteriophage T4 B. Potato virus X C. Adenovirus D. Influenza virus Structure of viruses • Viruses are geometric in shape • Considerable variation in the genetic material they have, structure of their protein coat (capsid) or whether they have an envelope Cellular Organisation Cells Tissues • Cells (basic units) – Organisms either unicellular or multi-cellular • Aggregations of Cells – Colonies show little co-ordination – More complex organisms show specialisation – If perform similar function organised into tissues Tissues • 4 main types in the human: – – – – Epithelial tissues (lining of surfaces) Connective tissue Muscle tissue Nervous tissue Tissues Organs • Organs are made up of a group of tissues together in one structure so that they can work effectively. Plant leaf as an Organ Tissues: • Epidermal • Palisade mesophyll • Spongy mesophyll • Vascular tissue (inc. phloem and xylem tissues) Organs Systems • When a number of organs work together to carry out a large scale function it is known as a system.