Download Chapter 6 The Cell - Alaska Educator: Matthew W. Good

Chapter 6 The Cell
6.1 All organisms are made of cells.
Cell theory- The generalization that all living things are composed of cells,
and the cells are the basic unit of structure and function in living things.
Micrograph- the photograph of the view through a microscope.
Organelle- “mini-organ” each part of a cell with a specific job.
Similarities between plant and animal cells.
Plasma membranes- thin outer covering, which defines the boundary
the cell and regulates the traffic of chemicals between the cell and its
surroundings.
Nucleus- houses the cells genetic material in the form of DNA.
Cytoplasm- the entire region of the cell between the nucleus and the
plasma membrane.
Differences between plant and animal cells.
Presence of chloroplasts- the organelle in which photosynthesis
occurs. Photosynthesis converts light energy to chemical energy
stored in molecules of sugar and other organic compounds.
Cell wall- an encasing outside of a the plasma membrane that protects
The plant cell and maintains it shape.
There are two types of cells.
Prokaryotic cells- (bacteria) cells with no nucleus
Eukaryotic cells- cells with a nucleus and internal organelles bounded by
membranes.
6.2 Membranes organize cells activities
Membranes
-Membranes isolate teams of enzymes within a cell’s
compartments.
-Regulate the transport of substances across the boundary
- maintain a specific chemical environment within each cell
compartment.
Membranes are usually made up of proteins and a type of
lipid called a phospholipids.
Phospholipid molecule- a phospholipid molecule is made
up of a two fatty acid tail that is hydrophobic and a head
that is hydrophilic.
Phospholipid bilayer- is produced when two layers of
phospholipids molecules sandwich each other and create a
larger membrane.
See fig 6-8 pg 116.
Functions of membrane proteins
- Help cells within a multi-cellular organism
communicate and recognize each other.
- Move water and sugars across the membrane
- Regulate the amount of each substance that travels
across the membrane.
6.3 Membranes regulate the traffic of molecules
Diffusion
Diffusion- is the net movement of particles of a substance
from where they are more concentrated to where they ate
less concentrated.
Equilibrium- when the number of molecules moving across
a membrane are equal to the number of molecules moving
in the opposite direction.
Passive Transport (Fig 6-12)
Selectively permeable membrane- a cellular membrane that
allows some substances to cross the membrane more easily
than others and blocks the passage of some substances all
together.
Passive transport- diffusion across a membrane when no
energy is required by the cell. The cell is not actively
involved in the transport.
Facilitated transport- When transport proteins provide a
pathway for certain molecules to pass.
Osmosis (fig 6-13,6-14)
Osmosis- the passive transport of water across a selectively
permeable membrane.
Hypertonic- the solution with a higher concentration of
solute.
Hypotonic- the solution with the lower concentration of
solute.
Isotonic- Solutions in which the concentrations of solute
are equal.
Active transport
Active transport- when a cell expends energy to move
molecules or ions across a membrane.
- During active transport, a specific transport protein
PUMPS a solute across a membrane, usually in the
opposite way that it travels during diffusion.
- Active transport plays a large part in maintaining a
cells chemical environment.
Transport of large molecules
Vesicles- small membrane sacs that specialize in moving
products into, out of, and within a cell
Exocytosis- a process the removes contents from the inside
of a cell by fusing a vesicle containing exporting proteins
with the plasma membrane and releasing the product
outside of the cell.
Endocytosis- takes material into the cell within vesicles that
bud inward from the plasma membrane and spill its
contents into the cell.
6.4 The cell builds a diversity of products
Structure and Function of the Nucleus
-The nucleus of a cell contains most of the cells DNA
(genetic material).
-The nucleus is responsible for directing all of the cells
activities.
Nuclear Envelope- a pair of membranes that surrounds the
nucleus and only allows substances to move into a cells
cytoplasm.
Nucleolus- a ball like mass of fibers and granules that make
up organelles called ribosomes.
Ribosomes
Ribosomes- The DNA in the nucleus contains instruction
for making proteins. These proteins are constructed in a
cell by the ribosomes.
-Ribosomes work as protein assembly line for membranes
and transport proteins.
-Ribosomes themselves are a cluster of proteins and nucleic
acid.
The Endoplasmic Reticulum
Endoplasmic reticulum (ER)- an extensive network of
membranes within the cytoplasm of a cell that is arranged
as tubes and sacs that separate the inside of the ER from the
cytoplasm
-The ER is the main manufacturing and transportation
facility in a cell. It produces many of the cells molecules
needed for survival.
Rough ER- The rough ER gets its name from the bound
ribosomes that dot the outside of the ER membrane.
-These ribosomes produce proteins that are packaged in
vesicles.
Smooth ER- This part of the ER lacks the ribosomes that
cover the rough ER.
- The function of the smooth ER is to build lipid
molecules.
Golgi Apparatus
Golgi apparatus- many products that are made in the ER
travel in vesicles to the golgi apparatus, an organelle that
modifies, and routes proteins and other chemical products
to their next destination.
-The golgi apparatus looks like a series of flattened sacs
Vacuoles
Vacuoles- Large membrane sacs within the cytoplasm of a
cell that store undigested nutrients. Many plant cells have a
large central vacuole that stores chemicals essential for
plant growth.
Lysosomes
Lysosomes- membrane bound sacs that contain digestive
enzymes used to break down proteins, nucleic acid, and
polysaccharides.
-There function is to nourish the cell and destroy harmful
bacteria within the cell.
6.5 Chloroplasts and the Mitochondria Energize Cells
Chloroplasts
Chloroplasts- photosynthetic organelles found in some cells
of plants and algae.
- These organelles allow cells to convert light energy to
the chemical energy stored in sugars and other organic
compounds.
- Chloroplasts are like miniature solar collectors.
- These organelles are green colored due to the presence
of a pigment called chlorophyll that reacts with light.
Mitochondria
Mitochondria- organelles that are responsible for cellular
respiration (releasing the energy required to drive a cell) in
eukaryotic cells.
Mitochondria use cellular respiration to produce ATP.
ATP- (Adenosine triphosphate) The main energy source
that cells use for most of their work.
Within the mitochondria an envelope of two membranes
has many folds. The more folds there are in the membrane,
the more surface area, which means more sites for cellular
respiration thus maximizing the cells production of ATP
6.5 An internal skeleton supports the cell and enables
movement
Cytoskeleton
Cytoskeleton (cell skeleton)- a network of flexible fibers
that float within a cell’s cytoplasm.
Microtubules- Straight hollow tubes that give rigidity,
shape, and organization to a cell.
Microfilaments- Thin solid rods of protein that enable a cell
to move or change shape when protein subunits slid past
one another.
Flagella and Cilia
Many cells rely on external organelles to move and change
shape.
Flagella- are long, thin, whip-like structures, with a core of
microtubules that enable a cell to move.
Cilia- are smaller than flagella, but also contain bundles of
microtubules, however Cilia only lend to move in 2
directions. Like the ores of a boat.