biology

• a prokaryote is a single-celled organism that does not have a nucleus, it is smaller than a eukaryote. Its ribosomes are 70S
• a eukaryote has a membrane bound nucleus with chromatin inside.
• the cell wall of plants is made up of cellulose which gives the plant strength and support
• Obligate aerobes: require continuous oxygen supply, so only live in oxic (with oxygen) environments.
• Obligate anaerobes:  inhibited or killed by oxygen, so only live in anoxic (without oxygen) environments.
• Facultative anaerobes: use oxygen if available, so can live in either oxic or anoxic environments.
• Every cell has a membrane barrier separating the interior from its surroundings.This is needed to allow internal chemistry to become different from that outside the compartment. 
• The lipid bilayer of the cell membrane is composed of subunits called phospholipids.
• •Cell wall•Non-cellulose structure•Homeostasis: prevents bursting
• •Cell (plasma) membrane•Phospholipid bilayer•Partially permeable - controls what enters and exits the cell
• •Cytoplasm•Fluid, gel-like•Contains free floating molecules•Enzymes, ribosomes•Metabolism: Location of chemical reactions
• •Nucleoid•Dense region of circular DNA•Reproduction: controls cell activities
• •Ribosomes (70s)•Responsible for protein synthesis•Size: 70s [Svedberg]
• •Flagella (sing., flagellum)•Long, thin, whip-like structures•Made from protein ‘flagellin’•Use energy to move cell
• •Pili (sing., pilus)•Hair-like protein structures•Used to adhere or “stick” to other bacteria cells to exchange DNA•Not found in eukaryotes
• Methanogenic archaea found in the rumen and the lower segments of the intestines of ruminants produce methane, which these animals burp out.
• Archaea are all unicellular, prokaryotic organisms. It is thought that archaea are the most ancient organisms on the planet.
• Many archaea are extremophiles, preferring extreme hot or cold, extreme salinity, or other conditions that are hostile to most other forms of life on earth. 
• the 3 domains
• a plant cells contains
• a plant cell contains a cell wall, a cell membrane, a nucleus, a cytoplasm and a large vacuole, ribosomes, ER, mitochondria and choroplasts
• Mitosis: a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.
• There are 6 main phases in mitosis

  Interphase

   

  Prophase

  Metaphase

  Anaphase

  Telephase

   

  cytokinesis

   
• What is the abbreviation for remembering mitosis (I PMAT C)
• Interphase: A cell spends most of its time in what is called interphase, and during this time it grows, replicates its chromosomes, and prepares for cell division. Pre- mitosis.
• Prophase (2 phases): During prophase in mitosis, the nuclear membrane breaks down and chromatin condenses. During prophase one of meiosis, the chromosomes group together and crossing over occurs. During prophase two, the chromosomes condense and are attached to spindle fibers where they can be moved.
• Metaphase: a stage during the process of cell division (mitosis or meiosis). Normally, individual chromosomes are spread out in the cell nucleus. During metaphase, the nucleus dissolves and the cell's chromosomes condense and move together, aligning in the center of the dividing cell.

   
• Anaphase: the stage of cell division in which separated chromatids (or homologous [like] chromosome pairs, as in the first meiotic division) move toward the opposite poles of the spindle apparatus.

   
• Telephase: In telophase, the cell is nearly done dividing, and it starts to re-establish its normal structures as cytokinesis (division of the cell contents) takes place. The mitotic spindle is broken down into its building blocks. Two new nuclei form, one for each set of chromosomes. 4N Nuclear membranes and nucleoli reappear.

   
• Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells. It occurs concurrently with two types of nuclear division called mitosis and meiosis, which occur in animal cells.
• Daughter cells:

  Daughter cells are cells that are the result of a single dividing parent cell. Two daughter cells are the final result from the mitotic process while four cells are the final result from the meiotic process. For organisms that reproduce via sexual reproduction, daughter cells result from meiosis.
• DNA is a double heix structure, with anti-parralel strands, separated by hydrogen bonds that have complementary bases, Adenine and Thymine and Guanine and Cytosine

   
• All cells come from pre-existing cells
• Cells cannot be created nor destroyed
• Cell


  The smallest unit of life
• All cells contain


  • DNA
  • Ribosomes
  • Cytoplasm
  • Cell membrane
• Levels of biological organization

  • Specialized cells
  • Tissues
  • Organs
  • Organ systems
  • Organisms
• Taxonomic levels


  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Prokaryotes


  Unicellular organisms (usually bacteria)
• Eukaryotes


  Multicellular organisms