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Cells
The Characteristics of Living Things (p. 95)
1) Living things grow in size, reproduce, and are able to repair
themselves.
2) Living things require energy.
3) Living things respond to changes in their environment.
4) Living things have a lifespan.
5) Living things produce waste.
6) Living things are made up of at least one cell (p. 96)
Cell (p.96): The cell is the basic structural and functional unit of living
things.
Cell Theory (p. 97):
1) All living things are composed of cells.
2) The cell is the basic unit of life.
3) All cells come from pre-existing cells.
Vocabulary (p. 104 – 107)
Organelles: A small structure found within a cell; performs a specific
function in a cell.
Cytoplasm: Watery substance in a cell where organelles are suspended.
Materials are transported through, waste is stored and chemical reactions
take place here.
Cell Membrane (in animal and plant cells): Surrounds the cell and
controls the movement of material into and out of the cell. It is the
gatekeeper of the cell, kind of like skin.
Nucleus: The control centre as it regulates all cellular activities. It is
usually surrounded by a nuclear membrane. Houses chromosomes.
Chromosomes: Rod-like structures within the nucleus, which carry
information that the cell needs to continue functioning and reproduce.
Vacuoles: Fluid filled compartments that the cell uses for storage or
food, waste. In plants – large and few and in animal cells – small and
many.
Mitochondria: Oval, bean-like structures. They produce energy by
breaking down food particles. Found in both plant and animal cells.
The powerhouse of the cell, where cellular respiration takes place. This
is when energy – stored in food like glucose (a type of sugar) is
converted into another type of energy.
Cell Wall (plants only): Rigid structure that surrounds cell membrane to
support and protect while it filters things moving in and out. It is made
of a substance called cellulose.
Chloroplast (plants only): Green organelle, which is the site of
photosynthesis: a process by which a plant uses the Sun’s energy to
make food. Chlorophyll is a green chemical contained within the
membrane of chloroplast that absorbs sunlight.
Flagella (flagellum): Long, tail-like structures that move the cell by
beating or corkscrewing. Usually a cell has no more than two.
Cilia (cilium): Tiny hairs surrounding the cell that help the cell to move.
Cell Membrane (p. 120) – Membrane is selectively permeable meaning
that it allows some substances through and does not allow others. It is
the gatekeeper. Made up of two layers of fat particles (called the lipid
bilayer) where many proteins are embedded it in a flexible structure.
Some of the proteins act as channels for materials to pass in and out of
the cell. DRAW PICTURE. Example of coriander with water and salt
able to pass through but not tennis balls.
Diffusion within cells – fluid movement (p.121). Diffusion is the
movement of particles from an area of high concentration to an area of
low concentration.
Concentration gradient – a difference in concentration of a substance
between to areas. Example – outside and inside a cell.
Osmosis (p. 124) – The diffusion of water across a selectively permeable
membrane from an area of high water concentration to an area of low
water concentration.
Water in stored in vacuoles within the plant cell. Vacuoles take up most
of the room within a plant cell.
Turgor pressure - When there is an increase of water within a plant cell
(taken in by osmosis) causing the cell to swell and push against the cell
wall. (p. 126)
Question: Why do plants wilt?
Endocytosis (p. 132) – the process by which a cell moves a large particle
inside itself.
Phagocytosis is one type of endocytosis where solids are moved into the
cell. On page 132 they show how this happens as the cell extends
‘pseudopods’ to wrap around a particple and pull it within. The particle
then remains in the cell in a vacuole. Often called cell eating.
Exocytosis (p. 133) – When a cell moves particles out. When a vacuole
needs to excrete particles it moves to the outside of the cell and fuses
with the cell membrane and releases the particles to the outside
environment.