Cell Structure And Function
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The document summarizes the structure and function of organelles found within eukaryotic cells. It describes the cytoplasm and cytosol as well as various membrane-bound organelles including mitochondria, ribosomes, the endoplasmic reticulum, cilia and flagella, the nucleus, the Golgi apparatus, lysosomes, and the cytoskeleton. It also mentions cell walls, vacuoles, chloroplasts, and their respective functions in cellular structure and processes.
Cell Structure And Function
- 1. CELL STRUCTURE AND FUNCTION
- 2. ORGANELLES Cytoplasm lies between the cell membrane and nucleus and contains the organelles Cytosol is a gelatin like aqueous fluid that contains salts, minerals and organic molecules
- 3. Mitochondria Sites of chemical reactions that transfer energy from organic compounds to ATP ATP- main energy source for cells Cells with high energy requirements have more mitochondria ex: muscle and liver cells Have 2 membranes Smooth outer membrane serves as a boundary between the mitochondria and the cytosol Inner membrane has many folds called Cristae – they enlarge the surface area for more chemical reactions Have their own DNA ( for reproduction)
- 4. Ribosomes Most numerous Not surrounded by a membrane Made up of proteins and RNA RNA is packaged into the ribosomes then transported to the cytosol Some ribosomes are free Some are attached to the endoplasmic reticulum Protein is synthesized (produced) in the ribosomes Proteins to be used in the cytosol – free ribosomes Proteins to be exported or inserted in the cell membrane – ribosomes on the ER
- 5. Endoplasmic Reticulum System of membranous tubules and sacs Intracellular Highway – molecules move from one part of the cell to another 2 types – rough and smooth Rough covered by ribosomes – prominent in cells that make large amounts of proteins to be exported from the cell Smooth – no ribosomes Synthesis of steriods in gland cells Regulation of calcium in muscle cells Breakdown of toxic substances in liver cells
- 6. CILIA AND FLAGELLA Hairlike organelles that extend from the surface of the cell Assist in movement Cilia – short and present in large numbers Flagella – long and less numerous
- 7. Nucleus Most prominent structure Maintains its shape with a protein skeleton called the nuclear matrix Double membrane – nuclear envelope Inside the envelope – chromation (DNA & protein) When the cell is about to divide it forms the chromosomes Stores hereitary information in its DNA RNA is copied from DNA RNA travels from nucleus to the cytosol through small holes in the envelope – nuclear pores Contains the nucleolus – the site where ribosomes are synthesized
- 8. Golgi Apparatus Processing, packaging and secreting organlle System of membranes Series of flattened sacs with convex shape Works with the ER to modify proteins
- 9. LYSOSOMES Small spherical organelles Enclose hydrolytic enzymes within single membranes Digest proteins, carbohydrates, lipids, DNA and RNA Digest old organelles, bacterias, viruses Rare in plant cells
- 10. CYTOSKELETON Maintains the shape and size of cell Network of long protein strands Not surrounded by a membrane Participates in the movement of organelles 2 major components – microfilaments and microtubules Microfilaments – threads made of actin (protein) – smallest strands Microtubules – largest strands that are hollow tubes – help the cell divide by forming spindle fibers that extend across the cell
- 11. CELL WALL Lies outside of the cell membrane Helps support and protect the plant cell Contains long chains of cellulose – hardens the entire structure Pores in the cell wall allow ions to enter or exit the cell
- 12. VACUOLES Fluid filled organelles that store enzymes and metabolic wastes Some vacuoles may make up 90% of the cell
- 13. Chloroplast Surrounded by 2 membranes and contain DNA Some store starch or fats Some contain pigments that absorb visible light – chlorophyll Ex Chloroplasts – energy of sunlight is converted into chemical energy each chloroplast encloses a system of membranous sacs called thylakoids