Title: Cell Structure
1Cell Structure Function
2Cells the basic units of life.
- The cell theory, set forth in the 1850s, says
that - All living things are composed of cells.
- The cell is the smallest unit that retains the
properties of life. - Under current conditions, all cells come from
preexisting cells.
3Question
- Which of the following statements is NOT part of
the cell theory? - All living things are composed of cells.
- All cells are surrounded by an outer membrane.
- The cell is the smallest unit that retains the
properties of life. - Under current conditions, all cells come from
pre-existing cells.
All cells DO have an outer membrane (called the
plasma membrane), but this observation is not
considered part of the cell theory.
4Light Microscope(LM)
- Shows the entire cell and its interior
5Scanning Electron Microscope (SEM)
- Shows a cells surface structure
6Transmission Electron Microscope(TEM)
- Shows internal details of a preserved cell
7Question
- Biologists generally rely on the ________
microscope to study the surface structures of
cells and the ________ microscope to study the
internal structure of cells. - light electron
- light transmission electron
- scanning electron transmission electron
- transmission electron scanning electron
Specimens for both types of electron microscopes
must be killed and preserved before they can be
examined. For this reason, light microscopes are
still useful for observing living cells.
8Basic Cell Structure
9Question
- Which of the following correctly labels the
three major parts of the cell shown below? - 1-nucleus, 2-cytoplasm, 3-plasma membrane
- 1-cytoplasm, 2-plasma membrane, 3-nucleus
- 1-plasma membrane, 2-nucleus, 3-cytoplasm
- 1-nucleus, 2-plasma membrane, 3-cytoplasm
10Internal Cell Structures
- Cell membranes divide the cytoplasm of eukaryotic
cells into functional compartments called
organelles. - Organelle mini organs
11Plant Cell Structures
12Animal Cell Structures
13Eukaryotic vs. Prokaryotic
14Internal Cell Membranes
- Organelle membranes physically separate important
chemical reactions in the cytoplasm and allow
them to take place in an orderly fashion.
15Selective permeability
- Cell membranes are said to be selectively
permeable membranes, meaning that they allow
some, but not all, materials to simply pass
through them.
16Question
- Which of the following is NOT an accurate
analogy for a cell membrane? - a window screen
- the US Mexico border
- the Kansas Colorado border
- a university admissions department
The Kansas Colorado border is a permeable
barrieranyone can cross the border at any time.
All of the other barriers in the list are
selectively permeable because they allow some
things but not others to pass through.
17Membrane Composition
- A phospholipid bilayer forms the basic unit of
the cell membrane.
18Question
- Where in this diagram of a cell membrane would
you expect to find the FEWEST water molecules?
A
The fatty acid tails of the phospholipids are
hydrophobic. They would repel any water
molecules that came into that area of the
membrane.
B
C
19Membrane Composition
- Proteins embedded in the bilayer help the cell
transport materials in and out. - Carbohydrate chains attached to some membrane
proteins help the cell communicate with other
cells.
20Structure of the Cell Membrane
21Question
- What type of membrane molecules are responsible
for cell-to-cell communication? - lipids
- proteins
- phospholipids
- carbohydrates
22A Fluid Membrane
- The lipid molecules have hydrophilic
(water-loving) heads and hydrophobic
(water-hating) tails. - Therefore, if you puncture a membrane, it will
come together and seal itself.
23(No Transcript)
24Cell Membrane Analogy
- The cell membrane is similar to the walls that
surround a house.
25Both help protect the inside from the outside.
26A house needs a way of receiving fuel and power
from the outside. Supply lines pass through the
walls of the house to bring in these materials.
27A cell receives fuel and power from the outside
through protein channels in the membrane.
28Doors are sometimes needed to bring in food and
take out the trash.
29Channels in the membrane allow the cell to bring
in food and get rid of waste.
30People in a house also need to communicate with
the outside.
31Carbohydrates in the membrane allow the cell to
communicate with other cells.