Cells Review Packet PDF

Cells ❑ Cells are the basic units of structure and function in all organisms ❑ Smallest unit that can carry out all of the functions of life ❑ In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork ❑ The cork appeared t...

Cells ❑ Cells are the basic units of structure and function in all organisms ❑ Smallest unit that can carry out all of the functions of life ❑ In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork ❑ The cork appeared to be made of tiny, empty chambers ❑ Hooke called them “cells” because they reminded him of rooms in a monastery ❑ Hooke did not see living cells, he only saw parts of the cell walls of dead cells ❑ Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things ❑ In 1675, Anton van Leeuwenhoek became the first person to observed living cells ❑ He discovered that the water was filled with tiny, single-celled organisms, which he called animalcules ❑ Memorize this: The cell theory is a fundamental concept of biology and it states that: 1) All living things are composed of one or more cells 2) Cells are the basic units of structure and function in living things 3) New cells are produced from existing cells ❑ Cells fall into two broad categories, depending on whether they contain a nucleus. 1) Eukaryotes are cells that contain nuclei. 2) Prokaryotes are cells that do not contain nuclei. ❑ The nucleus is a large membrane-enclosed structure that contains the cell’s genetic material in the form of DNA. How are Prokaryotes and Eukaryotes similar? ❑ Both eukaryotes and prokaryotes have ❑ a cell membrane ❑ genetic material (DNA) ❑ ribosomes ❑ cytoplasm Do not spend a lot of time learning what each scientist did because it is not TESTED. Instead, learn about how contributions of scientists such as Van Leeuwenhoek, Hooke, Schwann, Schleiden, and/or Virchow aided in the development of the cell theory but remember that we will not assess what each scientist contributed. VENN DIAGRAM: Complete the diagram below that compares prokaryotes and eukaryotes PROKARYOTES EUKARYOTES BOTH  Write Show your teacher when completed. ◼ Water can interact with the polar heads and repel the nonpolar lipids tails. ◼ The polar heads of the phospholipids point toward the water inside and outside the cell. ◼ The tails are buried in the interior of the membrane, directing themselves away from the water. ◼ Basic building block of the cell ◼ This double layer of phospholipids forms a flexible membrane is a kind of lipid lipid bilayer. molecule called a ◼ Particles in a solution tend to move from an area phospholipid. where they are more concentrated to an area where ◼ Short “head” is joined to two they are less concentrated by a process called long “tails.” diffusion. ◼ The head contains ◼ When the concentration of the solute is the same phosphorous and nitrogen, B throughout a system, the system has reached which make it polar. equilibrium. ◼ Hydrophilic head ◼ Because diffusion depends upon particle ◼ The long tails of fatty acids movements, substances diffuse across membranes are nonpolar. without requiring the cell to use energy. ◼ Hydrophobic tails ◼ Most biological membranes are selectively permeable, meaning that some substances can pass across them and others cannot. ◼ Osmosis is the diffusion of water through a selectively permeable membrane. ◼ If the concentration of H2O is lower inside the cell than outside, there will be a net movement of H2O to the inside until equilibrium is reached. ◼ In isotonic solutions the concentration of the two solutions is the same. ◼ A hypertonic solution is the solution with the greater concentration of solutes. ◼ A hypotonic is the solution with the lesser concentration of solutes. ◼ A few molecules seem to pass through the cell membrane much more quickly than they should. ◼ Cell membranes have protein channels that make it easy for certain molecules to cross the membrane in a process known as facilitated diffusion. ◼ Hundreds of different protein channels have been found that allow particular substances to cross different membranes. ◼ Facilitated diffusion does not require the use of cell’s energy. ◼ BUT During active transport cells move materials against a concentration difference. ◼ Requires energy. ◼ Carried out by transport proteins found in the cell membrane. ◼ Moves molecules in only one direction.