Transcript Cell Structure and Function

BIOLOGY CLASS
Chapter 7
Cell Structure and Function Unit
Cell- the smallest unit of matter that can carry
on all the processes of life.
Discovery of cells was made in the early
seventeenth century by the development of the
microscope
Robert Hooke – English scientist
In 1665 he used a microscope to look at a thin slice of cork
He saw “little boxes” and found similar structures when
looking at other plants
Reminded him of where monks lived so he called them cells.
Anton Van Leeuwenhoek – Dutch microscope maker
First to observe living cells (in 1673)
The Cell Theory
All living things are composed of one or more
cells
Cells are the basic units of structure and
functions in an organism
Cells come only from the reproduction of
existing cells
Not all cells are alike. Even cells within the
same organism may show diversity in size,
shape, and internal organization.
Size:
Most cells are only visible with a microscope
Some cells can be seen with naked eye (frog egg
cells)
Cells are limited by the ratio between their outer
surface area and their volume
Shape:
Cells come in a variety of shapes
Diversity of the form reflects the diversity of the
function
Long extensions (nerve cells)
Allows cells to send and transmit signals
Flat shape (dead skin cells)
Suited for function of covering the body
Change their shape (white blood cells)
They are able to leave the blood and move through narrow
openings
Internal Organization:
Cells contain a variety of internal structures
called organelles
They perform specific functions for the cell
Organelles maintain the life of the cell.
Cell membrane
Thin membrane that surrounds the entire cell
Nucleus
Large organelle near the middle of the cell
Cell Structure and Function
Unit
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Cell Structure and Function Unit
Cell Membrane:
All cells must take in nutrients and other materials
while also disposing of the wastes they produce
Both nutrients and waste must pass through the cell
membrane
Some substances easily cross the membrane while
others can not at all.
The cell membrane is selectively permeable.
Structure of the membrane depends on the
functions the cell performs
All cell membranes are made primarily of lipids(fats)
and proteins
Cell Structure and Function
Unit
Zoomed
in View
Fluid Mosaic Model
With use of scanning electron microscopes they
were able see that cell membranes are very
dynamic
The lipid bilayer that makes up the membrane acts
more like a fluid than a solid,
Lipids and proteins move laterally in the bilayer
Cell Structure and Function Unit
Cell Membrane Continued…
Composed of phospholipids and proteins—a
double membrane
· Regulates movement of materials in and out
of cell
-O2 and nutrients in
-waste out
· Allows for communication b/w cells
· Boundary b/w cell and outside
Cell Structure and Function Unit
· Fluid portion of the cell
· Suspends organelles
· Enzymes and proteins are produced here
Liquid
between cell
membrane
and
Nucleus
•Most functions of eukaryotic cell are controlled
by the cell’s nucleus
•Nuclear envelope – a double membrane
surrounds the nucleus (also called the nuclear membrane)
•Scattered over the nuclear envelope are nuclear
pores which are small channels
•Hereditary information is in the cell’s DNA
which is stored in the nucleus, also contains
chromosomes
Entire Animal Cell
Zoomed in image of NUCLEUS
· Found inside the nucleus
· Synthesizes ribosomes
2 types: Rough ER and Smooth ER
ROUGH ENDOPLASMIC RETICULUM
•Interconnecting membranes inside the
cell
·Transport materials in the cell
•Covered with ribosomes
· Involved in membrane production
· Involved in antibody production
SMOOTH ENDOPLASMIC RETICULUM
·Transport materials in the cells
•Involved in synthesis of lipids
· Detoxification of drugs and poisons
· Not covered with ribosomes
· Involved in:
protein synthesis
enzyme production
· Assembles according to DNA
· Not membrane bound organelle—whether
they are free in cytoplasm or on rough ER
· Sites of Cell Respiration
· Production of ATP
· Double membrane
· Food molecules broken down to
release energy
Also known as Golgi Complex or Golgi Body
· Flat membrane sacs
· Functions are: synthesis, storing, sorting
and shipping of materials.
· 2 Faces—cis and trans, cis close to ER and
trans away—gives rise to vesicles full of
material and pinches off
· Function is intracellular digestion
· Digest worn out cell parts, food particles,
invading viruses or bacteria
· Membrane prevents from digesting cell or
its proteins
· Can fuse with vacuoles to digest materials
· Surrounded by a membrane—used for
storage
· Store food, enzymes, or other materials
needed by cell
· Some store waste products
· Single celled org—collect excess water and
pumps out of cell
· Plant cells have single large vacuole; store
water/other things
· Cylindrical structures found in cytoplasm
· Function during cell division
Mitosis or Meiosis
· Found rarely in plant cells—mostly in
animal cells
· Network of thin, fibrous layers that act as a
scaffold to provide support for organelles
· Helps cell keep its shape
· Microtubules and Microfilaments make up
the cytoskeleton, are made of protein, and
assist organelles to move within the cell
Hair-like structures on the outside of cell.
Help with movement
· Found on cells in respiratory tract
· Trap dust particles in mucus to prevent
them from entering lungs
Long whip-like structures (usually only 1-2
per cell if any)
Example: Sperm cell
· Primarily found in plant and algae cells
· Site of photosynthesis
· Main pigment is chlorophyll (green)
· Transforms light energy into usable
chemical energy and store this as food
molecules
· Contains grana and stroma which is where
energy from sun is trapped
· Double outer membrane
· Only found in plants, fungi, bacteria, and
some protests (not in animal cells)
· Plant cell wall contain cellulose, which
form fibers—make a strong network that
protects the outside of the cell and gives
plant support
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