Ch 3: Cells - p. 44
3.1 World of the Cell - p.45
• At the Edge of the Cell
- All organisms are made of
cells.
- Cells are surrounded by an
outer layer called the cell membrane.
- The cell membrane separates
the contents of the cell from the environment and allows only certain materials
to pass in and out of the cell.
• What Limits the Size of a Cell
- The growth of cells is limited
to a factor of the ratio of the cell’s surface area to its volume. Cells
cannot become so large that the surface area is too small to exchange enough
material for the corresponding volume to survive.
• Water and the Cell
- Water is a polar molecule
... part of the molecule is partially positive and part is partially negative.
- The polar nature of water
is what gives it many of its special properties.
- The force that holds water
molecules together is hydrogen bonds.
• Water and the Cell Membrane
3.2 Membrane Architecture - p. 50
• Structure of the Lipid Bilayer
- The cell membrane is composed
of phospholipids and proteins.
• Characteristics and Functions of the Lipid Bilayer
- They form a lipid bilayer
which is fluid.
- It acts as a fluid because
the phospholipids and proteins are not rigidly connected; they can move
about.
• Roles of Cell Membrane Proteins
- The proteins in the cell membranes
have 3 functions.
1 - some contain
channels that allow only certain materials to pass through
2 - some act
as receptors to transfer information across the membrane
3 - some act
as markers to identify the cell
• Proteins: A Limitless Variety
3.3 Inside the Cell - p. 56
• Two Types of Cells
- There are two basic types
of cells: prokaryotic and eukaryotic.
1 - Prokaryotes
- have no nucleus
- have no membrane-bound organelles
- only bacteria
2 - Eukaryotes
- have a nucleus
- have organelles
- all other cells (other than bacteria)
- nucleus - controls the cell’s
activities; contains the DNA
- cytoplasm - jellylike substance
that fills the inside of a cell
- ribosomes - make proteins
• Eukaryotic Cells Have Compartments
- Organelles are specialized
parts of a cell.
• Cells Perform Basic Functions of Life
- mitochondria - produce energy
in the cell
- chloroplasts - contain chlorophyll
in plants; this is where the plant’s food is produced
- endoplasmic reticulum - passageways
in the cytoplasm that allow materials to move through the cell easier
- Golgi body - stores, processes,
and secretes materials
- nucleus - controls the cell’s
activities; contains the DNA
- cytoplasm - jellylike substance
that fills the inside of a cell
- cell wall - rigid surrounding
of plant cells
- vacuoles - membrane-bound
spaces that store water, food, etc. in plants
• Kinds of Eukaryotic Cells
- Only plant cells have cell
walls, chloroplasts, and vacuoles.
• How Did Eukaryotes Evolve?
- Prokaryotes are considered
to be the most primitive cell. It is theorized that a larger prokaryotic
cell “swallowed” a smaller one. The smaller one developed into an organelle
of the larger. This type of evolution is thought to be the cause of the
development of eukaryotic cells |