Transcript of the cell or - rebekahhammett

Cell Structure
1
Common Cell Traits
• A cell is the smallest unit that is capable of
performing life functions.
• All cells have an outer covering called a cell
membrane.
• Inside every cell is a gelatin like material
called cytoplasm (SI tuh pla zum).
• In the cytoplasm of every cell is hereditary
material that controls the life of the cell.
Cell Structure
1
Comparing Cells
• A nerve cell in your leg could be a meter long.
• A human egg cell is no bigger than the dot on
an i.
• A human red
blood cell is
about one-tenth
the size of a
human egg cell.
Cell Structure
1
Comparing Cells
• A bacterium is even smaller—8,000 of the
smallest bacteria can fit inside one of your red
blood cells.
Cell Structure
1
Comparing Cells
• The nerve cell has many fine extensions that
send and receive impulses to and from other
cells.
• Though a nerve cell cannot change shape,
muscle cells and some blood cells can.
• In plant stems, some cells are long and
hollow and have openings at their ends.
• These cells carry food and water throughout
the plant.
Cell Types
•
Scientists have found that cells can be
separated into two groups.
1. Prokaryotic
2. Eukaryotic
• Brain POP – Cell Specialization
Cell Structure
1
Prokaryotic
• Cells without a nucleus
and membrane-bound
organelles.
• Found in single-celled
organisms such as
bacteria.
Cell Structure
1
Eukaryotic
• Eukaryotic cells have a
nucleus that holds the cell’s
DNA and membranebound organelles. Many
eukaryotes are
multicellular. Examples:
Protists, Fungi, Plants, and
Animals.
Cell Structure
1
Cell Wall – Plant Cells
• Cell walls are tough,
rigid outer covering
that protect the cell
and provides support
and gives shape.
• Plants, algae, fungi,
and most bacteria are
enclosed in a cell
wall.
Cell Structure
1
Cell Wall - Support and Protection
• A plant cell wall is mostly made up of a
carbohydrate called cellulose.
• Long, threadlike fibers of cellulose form a
thick mesh that allows water and dissolved
materials to pass into and out of the cell.
• Plant cells responsible for support have a lot
of lignin in their walls.
Cell Structure
1
Cell Membrane- Plant and Animal Cells
• Protective layer that has tiny openings or
pores around all cells.
• In plant cells, the cell
membrane is just
inside the cell wall.
• In animal cells, it
forms the outer
covering of the cell.
Cell Membrane – Similar to A Window
Screen.
• Provides support and protection for the animal cell.
• Regulates movement of materials between the cell
and the environment similar to a doorway or window
Screen.
• Selective Permeable - It allows some things to enter
or leave the cell while keeping other things outside or
inside the cell.
• Move three ways- Diffusion, Osmosis and Active
Transport
Cell Structure
1
Cytoplasm – Plant and Animal
• A clear, thick gelatin like substance that
moves constantly in the cell membrane.
• Area between nucleus and
cell membrane where cell
organelles are located.
• Throughout the cytoplasm
is the cytoskeleton, which
helps the cell maintain or
change its shape.
Cell Structure
1
Cytoplasm
• Within the cytoplasm of eukaryotic cells are
structures called organelles.
• Some organelles process energy and others
manufacture substances needed by the cell or
other cells.
• Most organelles are surrounded by
membranes.
• The nucleus is usually the largest organelle in
a cell.
• http://www.classzone.com/books/ml_scien
ce_share/vis_sim/chm05_pg7_cell/chm05
_pg7_cell.html
• Cell Models: An Interactive Animation
Cell Structure
Nucleus – Plant and Animal Cell
Large, oval structure.
• Directs all cell
activities and is
separated from the
cytoplasm by a
membrane.
• The nucleus contains
the instructions for
everything the cell
does.
1
1
Cell Structure
Nucleus – “Brain” of the cell or manager which directs
daily operations and passes on information
• Contains nuclear membrane, nucleolus and
chromosomes.
• These instructions are found on long,
threadlike, hereditary material made of DNA.
• DNA is the chemical that contains the code
for the cell’s structure and activities.
• Hereditary material coils tightly around
proteins to form chromosomes
Nucleolus -Found in plant and
animal cells.
• Dark, round area found within the Nucleus
• Produces Ribosomes.
• Ribosomes are involved in the protein-making
process in the cell.
Chromosomes - Found in Plant and Animal
Cells
• Thick, rod-like strands floating in the
nucleus that contains hereditary material,
DNA, master instructions for building
proteins, and passes on traits. The rodlike object is created from hereditary
material (nucleic acids) that coils tightly
around proteins to form.
Cell Structure
1
Chloroplast – Plant Cell only - Energy
Producer for the Cell
• Large, irregularly shaped green structure
floating in cytoplasm
• Food for the plant is made here through the
process of photosynthesis.
• Photosynthesis is the process by which
plants and algae use sunlight, carbon
dioxide and water to make sugar and
oxygen.
Cell Structure
1
•
•
•
•
Chloroplast- Energy-Processing
Organelles
Chloroplasts contain the green pigment
chlorophyll, which gives many leaves and
stems their green color as well as captures
light energy (photosynthesis) that is used to
make a sugar called glucose.
Glucose molecules store the captured light
energy as chemical energy.
Many cells, including animal cells, do not
have chloroplasts for making food.
They must get food from their environment.
• BrainPop Movies Cell Structure
Cell Structure
1
Mitochondria- Powerhouse of the Cell
• Rod-shaped
structure,
somewhat
larger than the
ribosome.
• The energy in food is stored until it
is needed and then released by the
mitochondria.
Mitochondria - Found in Plant and
Animal Cells
• Energy is released during the break down
of food (sugar) into carbon dioxide and
water.
• This energy is stored in a substance called
ATP(adenosine triphosphate). The Cell
then uses ATP to do work.
Cell Structure
1
Ribosome - Found in Plant and Animal Cells
• Tiny, grain like bodies
produced in the nucleolus.
• Make proteins for
the cell.
• Proteins are part of cell
membranes. Other proteins
are needed for chemical
reactions that take place in
the cytoplasm.
Cell Structure
1 Ribosome - Protein Factories of the Cell
• Some ribosomes float freely in the cytoplasm;
others are attached to the endoplasmic
reticulum.
• Ribosomes receive
directions from
hereditary material
on how, when, and
in what order to
make specific
proteins.
Cell Structure
1
Endoplasmic Reticulum-Found in both Animal
and plant cells. Transportation System of the Cell
• It is a series of folded,
tubular membranes
throughout the cell which
carries materials such as
proteins from one part of
the cell to another.
• Extends from the nucleus to the cell
membrane.
Cell Structure
1
ER – Transportation of Materials
• The endoplasmic reticulum may be “rough”
or “smooth.”
• ER that has no attached ribosomes is called
smooth endoplasmic reticulum.
• This type of ER processes other cellular
substances such as lipids that store energy.
• Ribosomes attached the ER carry out the
job of making proteins.
Cell Structure
1
Golgi Bodies - Storage Area
• After proteins are made in a cell, they are
transferred to another type of cell organelle
called the Golgi (GAWL jee) bodies.
• The Golgi bodies sort
proteins and other cellular
substances and package
them into membranebound structures called
vesicles.
Cell Structure
1
Golgi Bodies - Storing Organelle
• The vesicles deliver cellular substances to
areas inside the cell.
• They also carry cellular substances to the cell
membrane where they are released to the
outside of the cell.
• Found in Plant and Animal Cells
• Series of closely stacked flattened membrane
sacs.
Cell Structure
1
Vacuoles – Storage Tank
• Cells have membrane-bound spaces called
vacuoles for the temporary storage of
materials.
• Vacuoles can store water, waste products,
food, and other cellular materials.
• Large, round water filled sac floating in the
cytoplasm
• Plant cells - one very large vacuole.
• Animal cells - small and only have a few.
Cell Structure
1
Lysosomes - Recycling Organelles
• Contain digestive chemicals called enzymes
that break down food molecules, cell wastes,
and worn-out cell parts.
• When a cell dies, a lysosome’s membrane
disintegrates. This releases digestive
chemicals that allow the quick breakdown of
the cell’s contents.
Lysosomes – Cleanup crew for the
cell
• Common in Animal cells and some in
plant cells
• Small, round structures
Resources
• http://library.thinkquest.org/5420/
• http://www.usoe.k12.ut.us/CURR/SCIENCE/scib
er00/7th/cells/sciber/orgtable.htm
• http://www.biology4kids.com/files/cell_main.html
• http://users.rcn.com/jkimball.ma.ultranet/Biology
Pages/A/AnimalCells.html
• http://micro.magnet.fsu.edu/cells/animalcell.html
• http://www.glencoe.com/sites/common_assets/s
cience/virtual_labs/E08/E08.html
• http://learn.genetics.utah.edu/content/begi
n/cells/insideacell/
Cell Structure
1
From Cell to Organism
• A tissue is a group
of similar cells that
work together to do
one job.
• Tissues are organized
into organs.
Cell Structure
1
From Cell to Organism
• An organ is a structure
made up of two or more
different types of tissues
that work together.
• Your heart is an organ
made up of cardiac
muscle tissue, nerve
tissue, and blood tissues.
Cell Structure
1
From Cell to Organism
• A group of organs working together to
perform a certain function is an organ system.
Your heart, arteries, veins, and capillaries
make up your cardiovascular system.
Section Check
1
Question 1
Which of these cells is
found in a bacterium?
Section Check
1
Answer
Prokaryotic cells are only found in one-celled
organisms, such as bacteria. Prokaryotic cells
are cells without membrane-bound structures.
Section Check
1
Question 2
Which part of the cell protects the cell and
gives it shape?
Answer
Cell walls are tough, rigid outer coverings that
protect the cell and give it shape. The cells of
plants, algae, fungi, and most bacteria are
enclosed in a cell wall.
Section Check
1
Question 3
In what part of the cell is the cytoskeleton
found?
Answer
Cytoplasm is the gelatinlike substance within
the cell. The cytoskeleton is found throughout
the cytoplasm.
Viewing Cells
2
Magnifying Cells
• To see most cells,
you need to use a
microscope.
• A microscope has
one or more lenses
that enlarge the
image of an object
as though you are
walking closer to it.
Viewing Cells
2
Early Microscopes
• In the late 1500s, the first microscope was
made by a Dutch maker of reading glasses.
• In the mid 1600s, Antonie van Leeuwenhoek,
a Dutch fabric merchant, made a simple
microscope with a tiny glass bead for a lens.
Viewing Cells
2
Early Microscopes
• His microscope could magnify up to 270
times.
• Today you would say his lens had a power
of 270.
Viewing Cells
2
Modern Microscopes
• Depending on how many lenses a microscope
contains, it is called simple or compound.
• A simple microscope is similar to a
magnifying lens.
• It has only one lens. A microscope’s lens
makes an enlarged image of an object and
directs light toward your eye.
• The change in apparent size produced by a
microscope is called magnification.
Viewing Cells
2
Modern Microscopes
• The compound light microscope has two sets
of lenses—eyepiece lenses and objective
lenses.
• The eyepiece lenses are mounted in one or
two tubelike structures.
• Compound light microscopes usually have
two to four movable objective lenses.
Viewing Cells
2
Magnification
• The powers of the eyepiece and objective
lenses determine the total magnifications of a
microscope.
• If the eyepiece lens has a power of 10 and
the objective lens has a power of 43, then
the total magnification is 430 (10 times
43).
Viewing Cells
2
Electron Microscopes
• Things that are too small to be seen with
other microscopes can be viewed with an
electron microscope.
• Instead of using lenses to direct beams of
light, an electron microscope used a magnetic
field in a vacuum to direct beams of
electrons.
Viewing Cells
2
Electron Microscopes
• Scanning electron microscopes (SEM)
produce a realistic, three-dimensional image.
• Only the surface of
the specimen can
be observed using
an SEM.
Viewing Cells
2
Electron Microscopes
• Transmission electron microscopes (TEM)
produce a two-dimensional image of a thinlysliced specimen.
• Scanning tunneling
microscopes (STM)
are able to show the
arrangement of
atoms on the surface
of a molecule.
Viewing Cells
2
Electron Microscopes
• A metal probe is placed near the surface of
the specimen and electrons flow from the tip.
• The hills and valleys of the specimen’s
surface are mapped.
Viewing Cells
2
Cell Theory
• Cells weren’t discovered until the microscope
was improved.
• In 1665, Robert Hooke cut a thin slice of cork
and looked at it under his microscope.
• To Hooke, the cork seemed to be made up of
empty little boxes, which he named cells.
Viewing Cells
2
Cell Theory
• In the 1830s, Matthias Schleiden used a
microscope to study plants and concluded
that all plants are made of cells.
• Theodor Schwann, after observing different
animal cells, concluded that all animals are
made up of cells.
• Eventually, they combined their ideas and
became convinced that all living things are
made of cells.
Viewing Cells
2
Cell Theory
• Several years later, Rudolph Virchow
hypothesized that cells divide to form
new cells.
• His observations and conclusions and those
of others are summarized in the cell theory.