The cell: Structure and Function Cell- Smallest unit that can carry on all the process of lif e. Unicellular- One celled organisms ( paramecia, bacteria, amoeba). Multicellular- made of many individual cells. History of Cytology (Study of Cells) Began with the invention of microscope in the 1600s. Robert Hooke- English Scientist in 1665 was first to observe cells under microscope. Observed dead cork cells. Gave them the name cells since they looked like little boxes or rooms in a prison. Microscopes Why were the early microscopes limited in there magnification power? The diffraction or scattering of light makes it harder to pass through the specimen. Scanning Electron Microscope Scanning Tunneling Microscope Transmission Electron Microscope (Flagellum) Eukaryotes- cells with a true nucleus and membrane bound organelles. Eu- Means True SEM-Endoplasmic Reticulum Three main parts of Eukaryotic cell: 1.Cell Membrane- the outer boundary of the cell 2.Cytoplasm- Inside cell membrane, contains water, salts, and organelles 3.Nucleus- contains DNA and directs activities of the cell EX: Plants, Animals, Fungi, Protists CELL ORGANIZATION Colonial organism- collection of genetically identical cells that form a connected group Tissue groups of cells that carry out specific functions Organs- groups of tissues that perform jobs in the organism Organ system- group of organs that accomplish related tasks CellsTissueOrganOrgansystem Cell or Plasma Membrane Thin membrane, gives shape, support and flexibility to the cell. Selective Permeable Membrane- Thin membrane that regulates what molecules enter and leave the cell. ( Like bouncers or guards at the door) Lipid Bilayer- 2 layers of lipids (fatty acids).Lipids, Carbohydrates and proteins make up this layer. It layers Hydrocarbon tails face the inside of the layer, while the Carboxyl heads face the outside toward the aqueous solution. Hydrocarbon tails are Hydrophobic. Water Fearing Carboxyl heads are- Hydrophilic. Water Loving Proteins are also in bedded in this layer, and with proteins are able to move across membrane and change their positions. This is called the Fluid Mosaic Model. Cytoplasm and Organelles Cytoplasm- jelly like material inside cell membrane that contains organelles, water, salts, and organic molecule; it is in constant motion(Fluid like the membrane). Cytosol- part of cytoplasm that contains molecules and small particles, it is made of 20% proteins Cytoplasmic Streaming- this is the constant motion of the cytoplasm. Organelles- little organs each organ has a specific function in the cell. a)ribosomes- most numerous organelles, specific site of protein synthesis, very small spherical organelles. Mitochondria- tiny organelles transfer energy from organic molecules to ATP and it powers most of chemical reactions Proteins that are synthesized for use in the cell are produced by free floating ribosomes. Proteins that are exported outside the cell are made by ribosomes attached to a series of membranes called the endoplasmic reticulum. b) Endoplasmic reticulum- (ER) system of interconnected membranes, in between the 2 layers are canals used to transport ER products, and materials from the nucleus to the outer cell membrane. There are 2 kinds of ER, Smooth and Rough Rough Endoplasmic Reticulum Rough ER- Endoplasmic reticulum that is covered in ribosomes and found in cells that produce lots of proteins that are secreted to other areas of the body. RER- This is the site for protein synthesis. Smooth Endoplasmic Reticulum Smooth ER- it is ER that does not have any ribosomes, so it does not produce any proteins. It is thought to serve as an intracellular highway or storage are for proteins that are to be transported later. Smooth ER is often connected at the end of the Rough Endoplasmic Reticulum It is also linked to lipid synthesis and detoxification of drugs. Ex: Liver Golgi apparatus- system of flattened membranous sacs that transport proteins and lipids and modify vesicles as they go. They get address labels and are directed to various parts of the cell Lysosomes- vesicles that bud from Golgi Apparatus and have digestive enzymes. These enzymes break down proteins, carbs and nucleic acids. Within the cell lysosomes digest old and worn out organelles called autophagy The digestion of old cells is called autolysis, these process help to keep health and organism functioning In step 1, proteins are assembled by ribosomes on the rough ER. 2, vesicles transport proteins to the Golgi apparatus. 3, the Golgi modifies proteins and pack- ages them in new vesicles. 4, vesicles release proteins that have destinations outside the cell. 5, vesicles containing enzymes remain inside the cell as lysosomes, peroxisomes, endo- somes, or other types of vesicles. Cytoskeleton- made of network of thin tubes it gives cell shape and acts as tracks for items to move inside. Its functions based on microtubules, microfilaments and intermediate filaments Microtubules- hollow tubes made of protein called tubulin, each radiates from central point called centrosome Microfilaments- long threads of protein actin wrapped around each other and help with movement of white blood cells and muscle contractions Intermediate filaments- rods that anchor nucleus and some organelles in place ( hair follicle) Cilia and Flagella- hair like structures that extend from cell, cilia are numerous, flagella are longer and fewer. They aid in movement like oars on a boat or swimming motions Centrioles-occur in animal cells and consist of 2 short cylinders of microtubules and located in cytoplasm near nucleus and organize the microtubules of cytoskeleton during cell division PLANT CELLS Cell wall- rigid layer found in plants lies outside plasma membrane Central vacuole- large fluid filled organelle stores water, enzymes, waste, and can make up to 90% of cell volume Plastids- organelles surrounded by double membrane like mitochondria and have DNA. Chloroplasts, chromoplasts, leucoplasts Chloroplasts- use light energy to make carbohydrates from CO 2 and water Thylakids-system of flattened sacs Chlorophyll- contained in thylakids, green pigment absorbs light Chromoplasts-plastids that contain pigment and may or may not contribute to photosynthesis. (orange, red, yellow, white) Proplastid- precursor to amyloplasts, chloroplasts, chromoplasts Prokaryotes vs. Eukaryotes-Prokaryotes lack nucleus and membrane bound organelles, they have a nucleoid and lack inner membrane system Plant cells vs. Animal cells- Production of cell wall Large central vacuole Plastids