cells and life

• The cell membrane is the outermost layer that separates the inside from the outside.
• robert hooke built a microscope more than 300 years ago
• Matthias Schleiden looked at plant cells
• Theodor Schwann studied animal cells
• Rudolf Virchow proposed all cells come from preexisting cells
• All living things are made of one or more cells
• the cell is the smallest unit of life
• all new cells come from preexisting cells
• macromolecules are created by many small molecules joining together
• why is water important to the cell?

  it surrounds and insulates the cell
• water molecules have a positive end and a negative end
• what are the four macromolecules in cells?

  proteins, lipids, carbohydrates and nucleic acids
• nucleic acids contain DNA
• Proteins can break down nutrients, communicate, transfer substances and provide support
• lipids do not mix with water
• carbohydrates store energy
• Ribosomes make proteins
• what is the cell membrane?

  the cell membrane is a flexible covering that protects the inside of a cell from the environment outside the cell
• cell membrane made of lipids and proteins
• cell membrane protects the cell
• plant cells have the cell wall
• a cell wall is a stiff structure outside the cell membrane
• a cell wall helps maintain the cells shape and provide structural support
• what are the two types of cell appendages?

  flagella and cilia
• cilia are short, hairlike structures
• cilia moves cells or molecules away from a cell
• flagella are tail-like, long appendages that whip back and forth
• flagella move the cell
• the cytoplasm is a fluid inside a cell that contains salts and other molecules
• the cytoskeleton is a network of threadlike proteins that are joined together
• the cytoplasm contains the cytoskeleton
• cytoskeleton gives the cell its shape
• what are the two types of cells?

  prokaryotic and eukaryotic
• prokaryotic cells have DNA not surrounded by a membrane
• Most prokaryotic cells are unicellular
• eukaryotic cells have DNA surrounded by a membrane
• EUkaryotic cells have organelles
• most eukaryotes are multicellular
• the cell membrane protects the inside of the cell from the environment outside the cell
• the cell wall protects a cell from attack by harmful substances