Niveditha
#CellStructure
#Biology
#BasicConcepts
Animal cell structure
• The main features of animal cells:
• They contain a nucleus with a distinct membrane
• Cells do not have cellulose cell walls
• Their cells do not contain chloroplasts (so they are unable to carry out photosynthesis)
• They contain carbohydrates stored as glycogen
Plant cell structure
• The main features of plant cells:
• They contain a nucleus with a distinct membrane
• Cells have cell walls made out of cellulose
• They contain chloroplasts (so they can carry out photosynthesis)
• Carbohydrates are stored as starch or sucrose
Bacteria cell structure
• Bacteria, which have a wide variety of shapes and sizes, all share the following biological characteristics:
• They are microscopic single-celled organisms
• Possess a cell wall (made of peptidoglycan, not cellulose), cell membrane, cytoplasm and ribosomes
• Lack a nucleus but contain a circular chromosome of DNA that floats in the cytoplasm
• 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
• Examples of bacteria include:
• Lactobacillus (a rod-shaped bacterium used in the production of yoghurt from milk)
• Pneumococcus (a spherical bacterium that acts as the pathogen causing pneumonia)