The Cell and Its Structures
All living things are composed of one or more cells.
A single-celled organism is called a unicellular organism (ex. Bacteria).
A multicellular organism is composed of many cells (ex. Wolverine)
Multicellular organisms are more complex and larger than unicellular organisms. As a result of the greater number of cells and different types of cells (kidney cells, eye cells, heart cells) multicellular organisms develop different ways of meeting their requirements.
Unicellular organisms are just as diverse and important as multicellular organisms (for example: synthesizing penicillin, decomposing matter)
Cells come in different sizes and shapes, and although some functions may be specific to specialized cells, the basic functions of all cells are similar.
Work on pond water safari on page 116-117.
Work on Lab – observing plant and animal cells on page 118-120.
Hand in labeled drawings (bacteria, plant, animal cells) and all questions.
Cell parts you can see with a light microscope:
-cytoplasm – jellylike material in which other parts of the cell float.
-Cell membrane – surrounds the cell and protects its contents.
-Cell wall – only in plants – thick covering outside the cell membrane.
-Nucleus – control centre of cell.
-Vacuole – storage sites of cell
-Chloroplast – only in plants – contains the green pigment chlorophyll.
Cell parts
All cells obtain energy, make products, and get rid of wastes. Cells have structures called organelles which help to carry out these functions. Each organelle is vital and plays a specific role in the cell.
See page 122-123.
Draw each cell.
Come up with 3 differences between plant and animal cells.
Cell size and function
Read page 125.
Cell size is restricted because of the way in which cells must obtain required materials and rid themselves of wastes. Materials leaving and entering the cell must do so across the cell membrane, so therefore size is governed by the relationship between surface area and volume.
As the size of an object increases, given that shape remains more or less constant, its volume increases more rapidly than its surface area. This means, that a larger cell, which because of its size has more volume and requires more material than a smaller cell, has relatively less surface area (cell membrane) by which materials may enter and leave the cell.
The relative sizes of cells
Plant and animal cells = 10-50 um
Bacterial cells = 1-5 um
Page 126 #1-7, omit 3
Page 127 #1-8, 10