science 1 eukaryotes

• Eukaryotes, or eukaryotic cells, may be unicellular or

  multicellular organisms.
• Unlike prokaryotic cells, the

  DNA of eukarvoicellar contained inside a

  membrane-bound organelle called nucleus.
• Eukaryotes can reproduce either asexually (binary

  fission or mitosis) or sexually (meiosis).
• Most of

  the time when people refer to “cell division,” they mean mitosis, the

  process of making new body cells.
• Meiosis is the type of cell

  division that creates egg and sperm cells.
• Mitosis is a fundamental process for life.
• During mitosis, a cell

  duplicates all of its contents, including its chromosomes, and splits

  to form two identical daughter cells. Because this process is so

  critical, the steps of mitosis are carefully controlled by certain

  genes.
• When mitosis is not regulated correctly, health problems such as

  cancer can result.
• meiosis - ensures that humans have the

  same number of chromosomes in each generation.
• It is a two-step

  process that reduces the chromosome number by half—from 46 to

  23—to form sperm and egg cells.
• When the sperm and egg cells unite at conception, each contributes

  23 chromosomes so the resulting embryo will have the usual 46.

  Meiosis also allows genetic variation through a process of gene

  shuffling while the cells are dividing.
• All protists, fungi, plants and animals are composed of

  eukaryotic cells.
• Eukaryotic cells contain membrane-bound organelles
• Mitochondria produce ATP (energy) from food molecules.
• The nucleus contains DNA and controls protein synthesis.
• Protists are composed of algae and protozoans.
• Protozoa are nonphotosynthetic protists that feed by engulfing other living things.
• Protozoans

  are unicellular eukaryotes.
• They move by using cellular

  extension such as pseudopods, flagella, or cilia.
• protozoans - They are

  usually found in pond water.
• Algae are photosynthetic-protists.
• Fungi may be unicellular or multicellular. Unicellular forms of

  fungi are molds and yeasts. Mushrooms, which are

  multicellular fungi, may look like plants, but they do not

  perform photosynthesis.
• They can be seen only with an electron

  microscope. They are not composed of the basic structural

  components common to most cells.
• For this reason, they are considered acellular.
• A virus particle

  contains a core of nucleic acid--DNA or RNA but never both.
• The

  core is surrounded by a protein coat and sometimes enveloped

  with an additional lipid membrane.
• Viruses can live and reproduce only by

  using the cellular machinery of their

  infected hosts.