Biology Quiz #1 practise

• Cytokinesis is the process that follows mitosis, during which the cytoplasm divides and two daughter cells are formed.
• Mitosis is a process where a single cell divides into two identical daughter cells (cell division) → asexual reproduction
• There are 4 stages in mitosis:

  1. Prophase       2. Metaphase         3. Anaphase        4. Telophase
• the cell cycle has 3 phases:

  • Interphase
  • Mitosis
  • Cytokinesis
• Interphase:

  • Non-dividing phase
  • Genetic material is duplicating (chromatin)
  • Centrioles are duplicating
• Prophase:

  • DNA condenses → chromosomes
  • Nucleolus and nuclear envelope disappear
  • Spindle fibers form off the centrioles
  • Centrioles migrate to opposite ends of the cell
• Metaphase:

  • Chromosomes line up in the middle of the cell
  • Spindle fibers attach to the centromeres of the chromosomes → mitotic spindle
• Anaphase:

  • Centromeres split and sister chromatids separate

  Chromosomes move to opposite ends of the cell
• telophase:

  • Chromosomes become thinner → chromatin
  • Spindle fibers disappear
  • Nuclear membrane and nucleolus reappear
  • Division of the nucleus is complete!
• Cytokinesis

  • Cytoplasm begins to divide
  • Cell divides into two identical daughter cells
• The number of chromosomes remains constant throughout mitosis.
• In order for something to be classified as a living thing, it must have the following characteristics:

  • Able to grow
  • Able to reproduce
  • Able to move without help
  • Respond to its environment (stimuli)
  • Made of cells
• Cell theory:

  • Living things are made from one or more cells
  • Cells come from existing cells by division
  • An organism’s life functions occur within cells
  • A cell is the smallest unit of a living thing
• Cytoplasm-

  • Mostly composed of water and can change from jelly-like to liquid. The cytoplasm suspends all organelles of the cell
• Cell memtrane:

  • Packages the entire cell and acts as a gate keeper, controlling what goes in and out of the cell
• Nucleus:

  • Contains the genetic information (DNA) of the cell
  • DNA stands for deoxyribonucleic (dee-OK-see-ri-bo-new-klee-ik) acid
• Nucleolus:

  • Produces ribosomes for the endoplasmic reticulum
• Chromosomes:

  • Are the genetic information of the cell
• Mitochondria:

  • Provide energy to the cell by converting glucose (sugar) and oxygen into usable energy and release carbon dioxide
• Endoplasmic Reticulum:

  • Fluid-filled tubes that run all throughout the cell and transport different materials (hormones, proteins, etc) throughout the cell
• Ribosomes:

  • Cellular machines that help make proteins
• Golgi Bodies:

  • Remove waste from the cell and secrete mucus
• Vacuoles:

  • Single layer membrane enclosing fluid in a sac
  • Have many functions including waste removal and maintaining internal fluid pressure
• Chloroplast:

  • Absorbs the sun's energy and uses that energy to make glucose for the plant
  • Usually gives plants a green color
  • Only found in plant cells
• Only plant cells have cell walls, chroloplasts, and a center vacoule
• Functions of cell division: Cells divide for 3 reasons:

  1. To heal damaged tissue
  2. To grow
  3. To reproduce new organisms
• The nucleus controls the functions of the cell
• Main structures in the nucleus:

  • Nucleolus: manufactures ribosomes
  • Nuclear Envelope: membrane around the nucleus
  • Genetic Material (DNA)
• 1. Chromosomes

  • DNA is tightly packed (can be seen with a light microscope)
  • Found only during cell division
• Chromatin:

  • DNA is loosely packed and cannot be seen with a light microscope
  • Found when the cell is not dividing
• Interphase:

  • the longest stage in the life cycle 
  • the cell carries out all life activities except for cell division (growing, respiration, specialized functions)
• stages of Interphase

  • G1 Phase → cell grows, genetic material (DNA) appears as chromatin 
  • S Phase → DNA is replicated (makes a copy)
  • G2 Phase → cell prepares for division by producing organelles and structures
• Metaphase: chromosomes line up at equator of cell
• Prophase: nuclear envelope breaks down; spindles form; chromatids condense into visible chromosomes
• Prophase: chromatin condenses into visible chromosomes; nuclear envelope breaks down; centrioles move apart and form spindles; mitotic spindle forms between poles of cell
• Anaphase: sister chromatids separate from one another and move to opposite poles of the cell
• Cytokinesis: formation of a cleavage furrow which separates the cytoplasm into two daughter cells.
• Telophase: nuclear envelope forms around new sets of chromosomes; mitotic spindles disappear; cytoplasm divides into two cells
• During mitosis, the genetic material (DNA) in the nucleus divides.
• Stages of Mitosis

  1. Prophase 
  2. Metaphase 
  3. Anaphase 
  4. Telophase