Transcript Cell Structure and Function

• All living things are made up of one or more cells – from the
tiniest bacterium to the largest whale. A _____ is the smallest
unit that can carry on all of the processes of _____.
• Before the seventeenth century, no one knew that cells existed.
• Most cells are too _____ to be seen with the unaided _____.
• Cells were not discovered until after the invention of the _____
in the early seventeenth century.
• Cell Video (2:55)
• One of the first microscopes was made by the Dutch drapery
store owner _____ _____ _____.
• With his hand-held microscope, Leeuwenhoek became the first
person to observe and describe microscopic _____ and living
_____.
• In 1665, the English scientist _____ _____ used a microscope to
examine a thin slice of _____ and described it as consisting of
"a great many little boxes.”
• They reminded him of the small rooms in which _____ lived, so
he called them "Cells.” He was the FIRST person to actually see
____.
• In 1838, German botanist _____ _____ concluded that all
_____ are composed of _____.
• The next year, German zoologist _____ _____ reported that
_____ are also made of _____.
• In 1855, German physician _____
_____ stated that "THE ANIMAL ARISES
ONLY FROM AN ANIMAL AND THE
PLANT ONLY FROM A PLANT" or
“_____ ONLY COME FROM OTHER
_____.”
• His statement contradicted the idea
that life could arise from nonliving
matter, a.k.a., _____ _____.
• The combined work of Schleiden, Schwann, and Virchow make
up what is now known as the modern _____ _____.
• The Cell Theory consists of THREE Principles:
• A. All living organisms are composed of one or more _____.
• B. Cells are the basic units of _____ and _____ in an organism.
• C. Cells come only from reproduction of _____ _____.
• Cell Overview (3:35)
Review of Cell Theory (6:12)
• Not all cells are alike. Even cells within the same organism show
enormous diversity in size, shape, and internal organization. Your
body contains over _____ different cell types.
• Cells come in a variety of specific
shapes.
• THE _____ OF A CELL DEPENDS ON
ITS _____.
• Notice how cells of the nervous system
that carry information from your toes to
your brain are long and threadlike.
• Notice how blood cells are biconcave
disks that can carry the optimum
amount of _____. They are also
flexible allowing them to squeeze
through microscopic _____ _____.
• A few types of cells are large enough to be seen by the
unaided eye. The female _____ _____is the largest cell in the
human body and can be seen without the aid of a microscope.
The male _____ _____ is the smallest.
• Most cells are visible only with a _____.
• Cell Size and Scale
• Cells are limited in size by the RATIO between their outer _____
_____ and their _____.
• A SMALL CELL HAS MORE SURFACE AREA THAN A LARGE CELL
FOR A GIVEN VOLUME OF CYTOPLASM. This is important
because the nutrients, oxygen, and other materials a cell
requires must enter through its _____. As a cell grows larger, at
some point its surface area to volume _____ becomes too small
to allow these materials to enter the cell quickly enough to meet
the cell's need.
• In other words, THE CELL'S _____ CAN ONLY CONTROL A
CERTAIN AMOUNT OF LIVING, ACTIVE _____.
• Cells fall into two broad
categories depending
whether or not they have a
_____.
• _____ - a large membraneenclosed structure that
contains the cell’s genetic
material in the form of
_____.
• Generally smaller and less _____ than eukaryotic cells
• Have genetic material not contained in a _____.
• Carry out every activity associated with living things.
• _____ and more complex than prokaryotic cells.
• Contain dozens of structures and internal _____, many of which
are highly specialized.
• This _____ _____ membrane regulates what passes into and
out of the cell.
• All cells, from all organisms, are surrounded by a plasma
membrane.
• The cell membrane is a thin layer of _____, proteins,
carbohydrates, and _____ groups that separate the cell's
content from the world around it.
• The cell membrane functions like a _____, controlling what
enters and exits the cell.
• Cell membranes are made mostly of _____ molecules.
(phosphate + lipid)
• A phospholipid is a molecule that consists of two _____ (tails),
and a _____ group (heads).
• The phosphate head is _____ meaning "water-loving". The
phosphates will turn themselves toward _____ molecules.
• The lipid tails are _____ meaning "water-fearing". The tails
will turn themselves away from _____.
• Cells are bathed in an _____, or watery, environment. Since the
inside of a cell is also an aqueous environment, both sides of the
cell membrane are surrounded by _____ molecules. These
water molecules cause the phospholipids of the cell membrane
to form two layers.
• Cell membranes consist of two phospholipid layers called a
_____ _____.
• _____ phosphate heads face the watery fluids inside and
outside the cell; _____ lipid tails are sandwiched inside the
bilayer.
• A variety of _____ are embedded in the lipid bilayer.
• Some proteins are attached to the surface of the cell
membrane; these are called _____ _____, and are located on
both internal and external surfaces.
• The proteins that are embedded in the lipid bilayer are called
_____ _____.
• Some integral proteins extend across the entire cell membrane
and are exposed to both the inside of the cell and the exterior
environment (_____ _____).
• These proteins help to _____ material into and out of the cell.
• Integral proteins exposed to the cell's external environment
often have _____ attached to them that serve as _____ badges
that allow cells to recognize each other and may act as sites
where viruses or chemical messengers such as hormones can
_____.
Membrane Video (1:26)
Another One (1:23)
• They are cellular _____ that extend from the plasma _____.
• They function in _____ cells together and are especially
important in cells where shearing forces would easily tear them
apart (muscle tissue, intestinal walls, epidermis).
• Membranes are _____ and have the consistency of vegetable
oil.
• The lipids and proteins of the cell membrane are always in
_____.
• Proteins in and on the membrane form patterns, or _____.
• Because the membrane is FLUID with a MOSAIC of proteins,
scientists call the modern view of membrane structure the _____
_____ model.
• The nucleus is often the most prominent structure within a
eukaryotic cell.
• The nucleus is the _____ _____ (brain) of the cell.
• Most cells have a single nucleus; some cells have more than one.
• The nucleus is surrounded by a double-layered membrane
called the _____ _____.
• The nuclear envelope is covered with many small _____ through
which proteins and chemicals from the nucleus can pass.
• The nucleus contains _____.
• The DNA is in the form of long strands called _____, which is a
matrix of protein and DNA.
• During _____ _____, chromatin strands coil and condense into
thick structures called _____.
• Most nuclei contain at least one _____ (plural, nucleoli).
• The nucleolus synthesizes _____, WHICH BUILD PROTEINS.
• When a cell prepares to reproduce, the nucleolus _____.
• They are organelles that exist in pairs
and are made of a _____ called
tubulin.
• They are usually located near the
nucleus, which makes sense because
they seem to assist in organizing cell
division by moving _____ to opposite
ends of the cell via fibers they
produce called _____ fibers.
• However, their main function is to
produce the cell’s _____, cilia, and
flagella.
• They are not found in _____ cells.
• Mitochondria are the sites of _____ reactions that transfer ____
from organic compounds to ATP. Energy contained in food is
released and converted to _____. ATP is the molecule that
nearly all cells use as their main source of _____.
• Nickname: THE “_____” OF THE CELL.
• Mitochondria are usually more numerous in cells that have a
high _____ requirement like _____ cells.
• Mitochondria are surrounded by TWO _____.
• The outer membrane serves as a _____ between the mitochondria
and the cytosol.
• The inner membrane has many long folds, known as cristae (KRIStee). The cristae greatly increase the _____ _____ of the inner
membrane, providing more space for chemical reactions to occur,
making the mitochondria more _____.
• Mitochondria have their own _____ (from the ovum), and new
mitochondria arise only when existing ones grow and divide.
• Unlike most other organelles,
ribosomes are NOT surrounded
by a _____.
• Ribosomes are the sites of _____
_____ in a cell.
• They are the most numerous
organelle in almost all cells.
• Some are free in the cytoplasm;
others line the membranes of
_____ _____ _____.
• The ER is a system of membranous tubules and sacs.
• The ER functions primarily as an intracellular _____, a path
along which _____ move from one part of the cell to another.
• The amount of ER inside a cell varies, depending on the cell's
activity.
• Poisons, wastes, and other toxic chemicals are made harmless
(detoxification).
• ER is an extensive network of membranes that connect the
nuclear envelope to the _____ _____.
• Can be ROUGH or SMOOTH.
• Rough ER is studded with
_____ and it processes
PROTEINS to be exported from
the cell.
• Smooth ER IS NOT covered
with _____ and processes
LIPIDS and CARBOHYDRATES.
• The Smooth ER is involved in the
synthesis of steroids in gland
cells, the regulation of calcium
levels in muscle cells, and the
breakdown of toxic substances
within _____ cells.
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• The Golgi apparatus is the processing, _____, and secreting
organelle of the cell.
• The Golgi is a system of _____ made of flattened sac-like
structures.
• Working closely with the ER, the Golgi modifies proteins for
_____ by the cell.
• Golgi also produces _____, which are transporting organelles.
• Cells contain several types of vesicles, which perform various
roles; especially involved in _____ of materials.
• Vesicles are small, spherically shaped sacs that are surrounded
by a single _____ and are classified by their contents.
• Vesicles often migrate to and merge with the _____ _____ to
release their contents outside of the cell.
The circular
structures are
vesicles that
have been
released from
the Golgi.
• Lysosomes are vesicles that contain _____ enzymes.
• Lysosomes are vesicles that bud (break off) from the _____
apparatus.
• They are the sites of “food” digestion in the cell. They can
_____ _____ large molecules such as proteins, nucleic acids,
carbohydrates, and lipids.
• Some white blood cells use
lysosomes to destroy _____.
• Within a cell, lysosomes digest
worn-out _____ and are also
responsible for dissolving _____
when it is time for them to die,
thereby maintaining an organism’s
overall health.
• Lysosomes are common in the cells
of animals, fungi, and protists, but
they are rare in _____ cells.
Lysosome Video (1:00)
• Just as your body depends on your _____ to maintain its shape
and size, a cell needs structures to maintain its shape and size.
• In animal cells, an internal protein framework called the _____
maintains the shape of the cell.
• The cytoskeleton (1) maintains the 3-D _____ of the cell,
(2) participates in the _____ of organelles within the cytosol,
and (3) helps the cell _____.
• The cytoskeleton consists of three types of proteins:
microtubules, microfilaments, and intermediate filaments.
• Microtubules are HOLLOW TUBES like plumbing pipes. They are
the largest strands of the _____.
• Microtubules are made of a PROTEIN called _____.
• Microtubules have three functions:
• To maintain the _____ of the cell and hold organelles in place.
• To serve as tracks for _____ and molecules to move along within
the cell.
• To form the centrioles.
• Microfilaments are NOT HOLLOW and have a structure that
resembles rope made of two twisted chains of protein called
actin.
• Microfilaments can _____, causing movement.
• _____ cells are LOADED with microfilaments.
• Cilia and flagella are organelles that extend from the surface
of the cell, where they assist in _____ and food acquisition.
• Cilia are short _____ projections, while flagella are long _____
projections.
• Unicellular organisms use cilia and flagella to move through
_____.
• In humans, cilia line parts of the upper _____ system, moving
dust particles and _____ away from the lungs. This is why you
should breathe through your _____, AND NEVER SMOKE! (The
chemicals destroy cilia.)
Bacterial cell with multiple flagella
The ciliary escalator in upper
respiratory tract
Cilia/Flagella Video (3:12)
• One of the most important differences between plant and
animal cells is the presence of a CELL _____ IN PLANT CELLS.
• _____ such as mushrooms and yeast also have cell walls.
• A cell wall DOES NOT REPLACE the cell _____; cells with walls
also have a cell membrane. Plant cells are surrounded by a
rigid cell wall that lies _____ the cell membrane.
• The rigidity of cell walls helps _____ and _____ the plant.
• Cell walls of plants contain a lot of _____, a complex
carbohydrate.
Cell wall
Membrane
Notice that the cell wall is MUCH thicker than the membrane.
• The vacuole is a large membrane-bound sac that takes up a
large amount of _____ in most plant cells.
• The vacuole serves as a _____ area, and may contain stored
proteins, ions, waste, or other cell products.
• Vacuoles of some plants contain _____.
• Cells of animals and other organisms also may contain vacuoles,
but they are much smaller and are usually involved in FOOD
_____.
• A third distinguishing feature of plant cells is the presence of
structures called plastids that make or store _____.
• They are surrounded by a double membrane and contain their
own ______.
• A common kind of plastid is the _____ (greenhouse), an
organelle that uses _____ to covert _____ _____ AND _____
into SUGARS. This process is called _____.
• Chloroplasts are green because they contain _____, a pigment
that ABSORBS THE _____ IN SUNLIGHT.
• Other plastids called _____ store reddish-orange pigments that
color fruits, vegetables, flowers, and autumn leaves.
• Colorless plastids that store STARCH, LIPIDS, and PROTEINS are
called _____ (bakery). They are found in the non-_____ parts
of plants (mainly roots).
Leucoplasts in
potato cell
Chromoplasts in red pepper cell