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1.2Unit 1: Cells and organisms

Animal cells

5 min read 6 parts Lesson 2 of 4 1 quiz

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Lesson summary

1.2 Animal cells — CHECKPOINT BIOLOGY 0893 notes: Name the parts of an animal cell, compare animal and plant cells, and describe how to look at animal cells with a microscope.All animals are made of cells, including humans.No one knows exactly how many cells a person has.One esti…

  • Cell membrane
  • Mitochondria
  • Methylene blue
  • Mitochondrion
  • No one knows exactly how many cells a person has.One estimate is about 100 trillion (100 000 000 000 000) cells
  • Cytoplasm — a clear jelly where the chemical reactions that keep the cell alive take place

Section 1 of 6Animals are made of cells

  • All animals are made of cells, including humans.
  • No one knows exactly how many cells a person has.
    • One estimate is about 100 trillion (100 000 000 000 000) cells.

Section 2 of 6Parts of an animal cell

  • Cell membrane
    • the thin, flexible outer layer that controls what goes in and out of the cell.
  • Cytoplasm
    • a clear jelly where the chemical reactions that keep the cell alive take place.
  • Nucleus
    • controls the activities of the cell.
  • Mitochondria
    • the parts where energy is released from food.
  • Animal cells have no cell wall, so they have no fixed shape.

Section 3 of 6Plant cells compared with animal cells

PartPlant cellAnimal cell
Cell membraneYesYes
CytoplasmYesYes
NucleusYesYes
MitochondriaYesYes
Cell wallYes, made of celluloseNo
ChloroplastsOften, in cells that get sunlightNo
Sap vacuoleYes, large and filled with cell sapNo large vacuole
  • The three features that show a cell is a plant cell are the cell wall, chloroplasts and a large sap vacuole.

Section 4 of 6Deciding whether a cell is plant or animal

  • Look for a cell wall, which appears as a clear straight outline.
  • Look for green chloroplasts.
  • Look for one large clear space, the vacuole.
  • If these features are present the cell is a plant cell, and if none are present it is an animal cell.
  • A cell with a regular fixed shape is likely to be a plant cell, and one with a round or irregular shape is likely to be an animal cell.

Section 5 of 6Looking at cheek cells

  • Stain = a dye added to cells to make them easier to see under a microscope.
    • Methylene blue stains cheek cells blue.
  • Method:
  1. Gently rub a cotton bud along the inside of the cheek to collect loose cells.
  2. Rub the cotton bud on the surface of a clean microscope slide.
  3. Add a drop of methylene blue with a dropper pipette.
  4. Lower a cover slip carefully over the drop of stain, avoiding air bubbles.
  5. Place the smallest objective lens over the stage and put the slide on the stage with the cells over the hole.
  6. Looking from the side, turn the focussing knob until the lens is close to the slide.
  7. Look down the eyepiece and slowly turn the knob to move the lens upwards until the cells are in focus.
  8. Turn to a larger lens for a more magnified view, then draw and label one or two cells.
  • The cells cannot be seen on the slide with the eye alone because they are too small.

Section 6 of 6Storage in cells

  • Plant cells store carbohydrate as starch, and animal cells store it as glycogen.

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