Cell Organelles PDF

Cell surface membrane ​ Very thin membrane, surround cytoplasm of ourselves ​ Controls the exchange of materials between the cell and its environment (regulates nutrient and waste transport) ​ Partially permeable Nucleus ​ Large structure ​ Stains intensely because of chrom...

Cell surface membrane ​ Very thin membrane, surround cytoplasm of ourselves ​ Controls the exchange of materials between the cell and its environment (regulates nutrient and waste transport) ​ Partially permeable Nucleus ​ Large structure ​ Stains intensely because of chromatin (a mass of coiled threads) ​ Contains chromosomes DNA and nucleolus ​ Double layered membrane (together forms the nuclear envelope) with pores Nuclear envelope ​ Double membrane surrounding the nucleus ​ Outer membrane of the nuclear envelope forms part of the ER ​ Contains many nuclear pores, which controls the exchange between nucleus and cytoplasm Nucleolus Made of proteins RNA, DNA Function: ribosome production using the information in its own DNA Contains a core of DNA from one or more chromosomes which contain the genes that code for rRNA Also contains the genes to make tRNA Ribosome synthesis: rRNA genes —> make ribosomal subunits —> units exit nucleus —> combined with proteins cytoplasm —> form functional ribosomes Different parts of the nucleolus separates during nuclear division, ribosome production ceases Rough endoplasmic reticulum Surface covered in ribosomes Production and processing of proteins to be secreted Smooth endoplasmic reticulum Lipid and steroid production Also produces oestrogen and testosterone Calcium ion storage Carbohydrate metabolism Drug/poison detoxification Golgi body Single membrane lined sec filled with liquid and nutrients Stack is constantly being formed at one end by vesicles that bud off from the ER Broken down again at the other end to form golgi vesicles (carries their contents to other parts of the cell or to the cell membrane for secretion) Clicks and processes molecules (proteins) from RER Contains hundreds of enzymes Mitochondria Number depends on tissue and energy required Site of aerobic respiration Reactions of respiration take place in solution in the matrix (nutrient rich liquid containing enzymes) Contain small circular DNA (coding functional proteins) Ribosomes Mostly bound to RER, also a free floating in cytoplasm and within other organelles Eukaryotic cells contain 80S and prokaryotic cells contain 70S ribosomes Protein synthesis, allows all molecules together in one place (mRNA, tRNA, amino acids and regulatory proteins) Side of translation during protein synthesis Mitochondria and chloroplast contains 70S ribosomes (prokaryotic origins) The mass of ribosomes are made of approximately half rRNA and half protein Lysosomes Single sacs surrounded by a single membrane Contains hydrolytic digestive enzymes Endo and exocytosis Self digestion (autolysis/autophagy) Destroys and engulfs unwanted cell components Removes waste products Microtubules Long, hollow, rigid tubes made of tubulin protein Alpha and beta-tubulin combine to form dimers, which then join to make protofilaments Microtubules forms the cytoskeletal of the cell During nuclear division, a spindle made of microtubules is used to separate chromatids/chromosomes Centrioles A pair of centrioles lie near the nucleus perpendicular to each other Hollow cylinder made from a ring of short microtubules Needed for the production of cilia Cilia Move cell, transport fluid/materials past them Structure: two central microtubules and a ring of nine microtubules doublets around the outside Microtubules surrounded by an extension of cell surface membrane Microvilli Very small finger like extensions of cell surface membrane Greatly increases surface area Absorption/secretion Chloroplasts Photosynthesis Chlorophyll pigment found in the membranes Membrane system consists of fluid filled sacs called thylakoids Thylakoid stack and forms structure called grana Stroma converts carbon dioxide into sugars Contain small circular DNA Double lipid membrane with embedded proteins Cell wall Office structural support to cell and protects cell Prevent cells from bursting Freely permeable Cellulose fibres = criss-cross, strong and elastic Plasmodesmata Channels of cytoplasm between cells (pore like) Links neighbouring plant cells to allow transport of substances Allows communication between cells Lined with cell surface membrane Large permanent vacuole Plant vacuole is surrounded by tonoplast which controls exchange between vacuole and cytoplasm Sac like Fluid in vacuole is a solution of pigments, sugars, enzymes etc Storage, food reserves, waste products Keeps plant rigid (turgidity) Provides additional structural support Cytoplasm Depends on cell size/vacuole size Jelly matrix of dissolved nutrients and salts Contains organelles, sugars, amino acids and proteins for growth and reproduction Aids material movement, cell shape and organelle network