npy

• Who first used the term "cell" to describe the basic units of life?


  Robert Hooke
• What did Robert Hooke observe when he looked at cork under a microscope?


  He saw structures that resembled a honeycomb.
• In what year did Robert Hooke make his discovery of cells?


  1665
• What was Anton van Leeuwenhoek known for in relation to microscopes?


  He made powerful microscope lenses and observed human cells and bacteria.
• Who were the two German scientists that proposed that cells are the basic building blocks of all living things?

  Theodor Schwann and Matthias Jakob Schleiden
• What did Rudolf Virchow propose about living cells?


  Living cells arise only from other living cells.
• What are the three main principles of cell theory?


  • All organisms are made of one or more cells.
  • All life functions of organisms occur within cells.
  • All cells come from already existing cells.
• What significant advancement in microscopy occurred in the 1950s?


  The invention of the electron microscope.
• What can scientists observe using an electron microscope that they could not with a light microscope?


  Tiny structures inside cells, including individual molecules and atoms.
• What are the common parts found in all cells?

  • Plasma membrane
  • Cytoplasm
  • Ribosomes
  • DNA
• What is the function of the plasma membrane?


  It forms the physical boundary between the cell and its environment.
• What is cytoplasm composed of?


  Cytosol and other cell structures.
• What role do ribosomes play in the cell?


  They are structures where proteins are made.
• What does DNA stand for?


  Deoxyribonucleic Acid
• What does the presence of similar cell structures across different organisms suggest?


  All life on Earth has a common evolutionary history.
• What are the functions of the plasma membrane and cytoplasm?


  • Plasma Membrane: Contains cell contents; double layer of phospholipids & proteins.
  • Cytoplasm: Viscous fluid containing organelles; includes interconnected filaments, fibers, and storage substances.
• What are cilia and flagella used for?


  They provide motility to cells.
• What is the role of centrioles in the cell?


  They play a role in cell division.
• What is the function of the nucleus in a cell?


  It acts as the control center of the cell.
• What does the nuclear envelope do?


  It separates the nucleus from the rest of the cell.
• What is the function of the nucleolus?


  It directs the synthesis of RNA and forms ribosomes.
• What is the role of the endoplasmic reticulum?


  It helps move substances within cells.
• What are the two types of endoplasmic reticulum and their functions?


  • Rough Endoplasmic Reticulum: Has ribosomes attached; manufactures and modifies proteins.
  • Smooth Endoplasmic Reticulum: No attached ribosomes; has enzymes that help build carbohydrates and lipids.
• What is the function of the Golgi apparatus?


  It is involved in the synthesis of the cell wall and acts as the packaging and shipping station of the cell.
• What do lysosomes contain and what is their function?


  They contain digestive enzymes that aid in cell renewal and break down old cell parts.
• What is the primary function of mitochondria?


  They release energy through cellular respiration.
• What do mitochondria have that is unique among organelles?


  They have their own DNA.
• What is the cell life cycle and its regulation?


  • Regulated by hormones or growth factors.
  • Most human cells divide 40 to 60 times before dying.
  • Steps include:

  1. Interphase
  2. Cell division (mitosis)
  3. Cytoplasmic division (cytokinesis)
  4. Differentiation
• What occurs during interphase of the cell life cycle?


  The cell obtains nutrients to grow and duplicates.
• What is mitosis?


  The division of the nucleus of a cell.
• What are the stages of mitosis?


  1. Prophase: Chromatin condenses, spindle fibers develop.
  2. Metaphase: Chromosomes line up at the cell's equator.
  3. Anaphase: Chromosomes are pulled apart to opposite ends.
  4. Telophase: Chromosomes unwind, nuclear envelope forms.
• What are the two phases of meiosis?

  1. Meiosis I
  2. Meiosis II
• What happens during prophase I of meiosis?


  Chromosomes condense and attach to the nuclear envelope; synapsis occurs.
• What occurs during metaphase I of meiosis?


  Tetrads align at the metaphase plate.
• What is the significance of synapsis during meiosis?


  It allows homologous chromosomes to line up closely together.
• What is the outcome of meiosis?


  It results in the formation of gametes with half the number of chromosomes.