Cells: The Basic Unit of Life

1
Cells The Basic Unit of Life

• Where does life come from?!? The answer may seem
  very obvious to us now, but people who lived long
  ago had some interesting ideas. Originally,
  people thought that life came from the heavens
  mostly through rain. Later, as the world became
  more scientific, they thought that life must
  generate spontaneously.

2

• This was disproved through a famous experiment
  where Aristotle placed a piece of meat in an open
  jar, and one in a closed jar. What do you think
  happen? What did the Prove?

3

• The open jar quickly filled with maggotts, flies,
  and worms.
• The closed jar didnt get any insects.
• This meant that life had to come from somewhere
  it couldnt generate inside the closed jar.

4

• Eventually, with the invention of the microscope,
  people realized that all living organisms are
  made up of one or more cells. All of the cells
  that makes up plants have the same structures
  inside. The cells that name up animals are also
  similar to each other, but slightly different
  than the plants.

5
Animal Cells

• All animal cells have the same structures.
• The first is the cell membrane.
• This is like, a gatekeeper, surrounding the whole
  cell and controlling the movement of materials
  into and out of the cell.

6
The Nucleus

• The nucleus of the cell is like the brain or
  the control center.
• It directs all of the cells activities. Inside
  the nucleus is the nucleolus.
• Also in the nucleus there are chromosomes which
  contain all of the genetic information (the stuff
  passed down by the parent cells). The chromosomes
  look like balled up strings.

7

• Each chromosome contains many genes, which
  determine the specific characteristics of an
  individual.
• The cytoplasm is the area of the cell where all
  of the work happens. This is where nutrients
  are absorbed, transported, and processed. You
  could think of it like the blood of the cell.

8

• Each Cell also has a number of organelles. These
  are kind of like our organs. The have a
  specialized purpose and do a specific job.

9
Plant Cells

• Plant cells contain ALL of the structures and
  organelles found in animal cells, plus a few
  more.
• Plant cells have a rigid cell wall that surrounds
  the cell membrane. This gives the cell protection
  and support.

10

• Plant cells also contain larger vacuoles, which
  are spaces filled with liquids containing water,
  sugar, minerals, and proteins.
• They also have chloroplasts which are organelles
  that are filled with chloroplasts. This gives
  plants their green color, and helps with
  photosynthesis.