Life Science Chapter 1-2 The Cell

What are cells? Smallest unit of life that exhibits all the characteristics of living things Within cells are organelles (specialized structures)

Cellular Organization Unicellular or multicellular Specialized structures Cell is basic unit of structure and function

History of Cell Research Scholars think Robert Hooke used this microscope when he prepared Micrographia, the first book describing observations made through a microscope. The middle glass of this three-lens instrument can be removed to more closely examine a specimen. 17th century scientist Robert Hooke was the first person to use the word "cell" to identify microscopic structures, describing cork: " . . . these pores, or cells, were not very deep, but consisted of a great many little boxes."

History of Cell Research In 1673, Anton van Leeuwenhoek began writing letters to the newly-formed Royal Society of London, describing what he had seen with his microscopes -- his first letter contained some observations on the stings of bees. For the next fifty years he corresponded with the Royal Society; his letters, written in Dutch, were translated into English or Latin and printed in the Philosophical Transactions of the Royal Society, and often reprinted separately.

Cell Theory All plants are made up of cells. Mattias Schleiden 1838 All plants are made up of cells. Theodor Schwann 1838 All animals are made up of cells. Rudolph Virchow 1858 Cells only come from other cells.

Plant Cell Animal Cell

Cell Boundaries Plasma Membrane – semi-permeable membrane Cell Wall Plants, Fungi, and Bacteria have this additional boundary Located outside the plasma membrane Provides additional support and protection (cellulose) Allows molecules to pass through (no selection)

Cytoplasm Clear, jelly-like fluid that supports the cell, site of chemical reactions, houses all of the other organelles

Nucleus Nucleolus Inside nucleus Makes ribosomes Controls cell processes (making proteins is the main function of cells) Contains DNA Membrane surrounding nucleus has pores to allow RNA, ribosomes to exit Nucleolus Inside nucleus Makes ribosomes

Endoplasmic Reticulum (ER) Highly folded membranes suspended in the cytoplasm Site of cellular chemical reactions (workbench) 2 types: Rough ER – area on ER where ribosomes attach, make proteins and transports proteins (cellular highway) Smooth ER – area where no ribosomes are attached, makes lipids, transports proteins, breaks down harmful substances

Ribosomes Found bound to rough ER and free-floating in the cytoplasm Site of protein synthesis (protein assembly) according to directions from the nucleus

Golgi Apparatus Flattened system of tubular membranes Modifies proteins by attaching carbohydrates and lipids Sends them to appropriate place in the cell in packages called vesicles “Post-Office”

Chloroplasts Only in plants Contain the green pigment Chlorophyll Site of photosynthesis - chlorophyll captures light energy to produce food

Vacuoles Sac-like structure Plants contain 1 large one, while animals have many small Storage of water, food and/or waste

Lysosomes Contain digestive enzymes to break-down old organelles, food, viruses, and bacteria Only animal cells “Clean-up” crew

Centrioles Animal cells only Made of microtubules Involved in cellular reproduction

Mitochondria Transform energy for the cell “Powerhouse” In plants and animals Found in varying numbers depending on the cell type (ex. Muscle cells have many)

Cytoskeleton Provides structure and support Works like poles of a tent Assists organelles in moving around the cell

Cilia Short, hair-like fibers (protein based) that move in a wave-like motion to propel (move) the cell or materials along surface of cell paramecium Tracheal cells (#3 is mucous particle)