7-1 Life Is Cellular - hcs.stier.org 7 Complete (1)2.pdf · Why are cells so small? 1. Nutrients...
Transcript of 7-1 Life Is Cellular - hcs.stier.org 7 Complete (1)2.pdf · Why are cells so small? 1. Nutrients...
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The Discovery of the Cell
The cell theory states:
• All living things are composed of cells.
• Cells are the basic units of structure
and function in living things.
• New cells are produced from existing
cells.
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Exploring the Cell
Electron Microscopes
Electron microscopes reveal details 1000 times
smaller than those visible in light microscopes.
Electron microscopy can be used to visualize only
nonliving, preserved cells and tissues.
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Exploring the Cell
Transmission electron microscopes (TEMs)
• Used to study cell structures and large protein
molecules
• Specimens must be cut into ultra-thin slices
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Prokaryotes and Eukaryotes
Prokaryotes and Eukaryotes
Cells come in a variety of shapes and sizes.
All cells:
• are surrounded by a barrier called a cell
membrane.
• at some point contain DNA.
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Prokaryotes and Eukaryotes
Cells are classified into two categories, depending on
whether they contain a nucleus.
The nucleus is a large membrane-enclosed structure
that contains the cell's genetic material in the form of
DNA.
The nucleus controls many of the cell's activities.
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Prokaryotes and Eukaryotes
Eukaryotes are cells that contain nuclei.
Prokaryotes are cells that do not contain nuclei.
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Prokaryotes and Eukaryotes
What are the characteristics of
prokaryotes and eukaryotes?
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Prokaryotes and Eukaryotes
Prokaryotes
Prokaryotic cells have genetic material
that is not contained in a nucleus.
•Prokaryotes do not have membrane-bound
organelles.
•Prokaryotic cells are generally smaller and
simpler than eukaryotic cells.
•Bacteria are prokaryotes.
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Prokaryotes and Eukaryotes
Eukaryotes
Eukaryotic cells contain a nucleus in
which their genetic material is separated
from the rest of the cell.
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Prokaryotes and Eukaryotes
•Eukaryotic cells are generally larger and more
complex than prokaryotic cells.
•Eukaryotic cells generally contain dozens of
structures and internal membranes.
•Many eukaryotic cells are highly specialized.
•Plants, animals, fungi, and protists are
eukaryotes.
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7-1
The cell theory states that new cells are
produced from
a. nonliving material.
b. existing cells.
c. cytoplasm.
d. animals.
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7-1
The person who first used the term cell was
a. Matthias Schleiden.
b. Lynn Margulis.
c. Anton van Leeuwenhoek.
d. Robert Hooke.
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7-1
Electron microscopes are capable of revealing
more details than light microscopes because
a. electron microscopes can be used with live
organisms.
b. light microscopes cannot be used to
examine thin tissues.
c. the wavelengths of electrons are longer
than those of light.
d. the wavelengths of electrons are shorter
than those of light.
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7-1
Which organism listed is a prokaryote?
a. protist
b. bacterium
c. fungus
d. plant
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7-1
One way prokaryotes differ from eukaryotes is
that they
a. contain DNA, which carries biological
information.
b. have a surrounding barrier called a cell
membrane.
c. do not have a membrane separating DNA
from the rest of the cell.
d. are usually larger and more complex.
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Eukaryotic Cell StructuresStructures within a eukaryotic cell that perform
important cellular functions are known as organelles.
Cell biologists divide the eukaryotic cell into two major
parts: the nucleus and the cytoplasm.
The Cytoplasm is the portion of the cell outside the
nucleus.
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Plant Cell
Nuclear envelope
Ribosome
(attached)
Rough endoplasmic
reticulum
Cell membrane
Ribosome (free)
Mitochondrion
Golgi
apparatus
Vacuole
Nucleolus
Nucleus
Smooth
endoplasmic
reticulum
Cell wall
Chloroplast
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Eukaryotic Cell StructuresSmooth endoplasmic
reticulum
Ribosome (free)
Ribosome (attached)
Golgi apparatus
Mitochondrion
Rough
endoplasmic
reticulum
Cell membrane
Nucleus
Nuclear envelope
Nucleolus
Centrioles
Animal Cell
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Nucleus
The nucleus is the control center of the cell.
The nucleus contains nearly all the cell's DNA and
with it the coded instructions for making proteins
and other important molecules.
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Nucleus
The Nucleus
Nucleolus Nuclear envelope
Nuclear
pores
Chromatin
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Ribosomes
One of the most important jobs carried out in the cell
is making proteins.
Proteins are assembled on ribosomes.
Ribosomes are small particles of RNA and protein
found throughout the cytoplasm.
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Endoplasmic Reticulum
What is the function of the endoplasmic
reticulum?
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Ribosomes
Endoplasmic Reticulum
There are two types of ER—rough and smooth.
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Mitochondria and Chloroplasts
What is the function of the mitochondria?
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Mitochondrion
Mitochondria
Nearly all eukaryotic cells contain mitochondria.
Mitochondria convert the chemical energy stored in food into compounds that are more convenient for the cell to use.
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Chloroplast
ChloroplastsPlants and some other organisms contain chloroplasts.
Chloroplasts capture energy from sunlight and convert it into chemical energy in a process called photosynthesis.
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Cytoskeleton
Centrioles are located near the nucleus and
help to organize cell division.
Cell Organelle Interactive
Plant and Animal Model Interactive
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7-2
In the nucleus of a cell, the DNA is usually visible
as
a dense region called the nucleolus.
the nuclear envelope.
granular material called chromatin.
condensed bodies called chloroplasts.
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7-2
Two functions of vacuoles are storing materials
and helping to
break down organelles.
assemble proteins.
maintain homeostasis.
make new organelles.
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7-2
Chloroplasts are found in the cells of
plants only.
plants and some other organisms.
all eukaryotes.
most prokaryotes.
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7-2
Which of the following is NOT a function of the
Golgi apparatus?
synthesize proteins.
modify proteins.
sort proteins.
package proteins.
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7-2
Which of the following is a function of the
cytoskeleton?
manufactures new cell organelles
assists in movement of some cells from one place
to another
releases energy in cells
modifies, sorts, and packages proteins
Why are cells so small?
1. Nutrients must get into the cell and wastes
must be removed;
what limits this exchange is the cell's
surface area-to-volume ratio.
2. Therefore, the smaller the cell the larger
the surface area this means more
materials can be exchanged with the
environment.
By minimizing its size, a cell is maximizing the
speed at which it can communicate, the rate at
which diffusion can occur, and the amount of
surface area at its disposal.
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All cells are surrounded by a thin, flexible
barrier known as the cell membrane.
Many cells also produce a strong supporting
layer around the membrane known as a cell
wall.
Cell Membrane
The cell membrane regulates what enters and leaves the cell and also provides protection and support.
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Cell Membrane
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Cell WallCell walls are found in plants, algae, fungi, and many
prokaryotes.
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Diffusion Through Cell Boundaries
Measuring Concentration
A solution is a mixture of two or more substances.
The substances dissolved in the solution are called
solutes.
The concentration of a solution is the mass of
solute in a given volume of solution, or
mass/volume.
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Diffusion Through Cell Boundaries
Diffusion
Particles in a solution tend to move from an area
where they are more concentrated to an area
where they are less concentrated.
This process is called diffusion.
When the concentration of the solute is the same
throughout a system, the system has reached
equilibrium.
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• When equilibrium is reached, solute particles continue
to diffuse across the membrane in both directions.
• Diffusion depends upon random particle movements.
Therefore, substances diffuse across membranes
without requiring the cell to use energy.
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Osmosis
OsmosisOsmosis is the diffusion of water through a selectively permeable membrane.
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Water tends to diffuse from a highly
concentrated region to a less concentrated
region.
If you compare two solutions, three terms can
be used to describe the concentrations:
hypertonic (“above strength”).
hypotonic (“below strength”).
isotonic (”same strength”)http://highered.mheducation.com/sites/0072495855/stud
ent_view0/chapter2/animation__how_osmosis_works.ht
ml
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Osmotic Pressure
Osmosis exerts a pressure known as osmotic
pressure on the hypertonic side of a selectively
permeable membrane.
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Facilitated Diffusion
Protein
channel
Glucose
molecules
http://highered.mheducation.com/sites/0072495855/
student_view0/chapter2/animation__how_facilitate
d_diffusion_works.htmlhttp://highered.mheducatio
n.com/sites/0072495855/student_view0/chapter2/an
imation__how_facilitated_diffusion_works.html
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Active Transport
Active TransportSometimes cells move materials in the opposite
direction from which the materials would normally
move—that is against a concentration difference.
This process is known as active transport.
Active transport requires energy.
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Active Transport
Molecular Transport
In active transport, small molecules and ions are
carried across membranes by proteins in the
membrane.
Energy use in these systems enables cells to
concentrate substances in a particular location,
even when diffusion might move them in the
opposite direction.
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Molecule to be carriedActive
Transport
Molecular Transport
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Endocytosis and Exocytosis
Endocytosis is the process of taking material into the cell.
Two examples of endocytosis are:
phagocytosis
pinocytosis
During exocytosis, materials are forced out of the cell.
https://www.youtube.com/watch?v=pvOz4V699gk
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7-3
Unlike a cell wall, a cell membrane
is composed of a lipid bilayer.
provides rigid support for the surrounding cell.
allows most small molecules and ions to pass
through easily.
is found only in plants, fungi, algae, and many
prokaryotes.
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7-3
The concentration of a solution is defined as the
volume of solute in a given mass of solution.
mass of solute in a given volume of solution.
mass of solution in a given volume of solute.
volume of solution in a given mass of solute.
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7-3
If a substance is more highly concentrated outside
the cell than inside the cell and the substance can
move through the cell membrane, the substance
will
move by diffusion from inside the cell to outside.
remain in high concentration outside the cell.
move by diffusion from outside to inside the cell.
cause water to enter the cell by osmosis.
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7-3
The movement of materials in a cell against a
concentration difference is called
facilitated diffusion.
active transport.
osmosis.
diffusion.
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7-3
The process by which molecules diffuse across a
membrane through protein channels is called
active transport.
endocytosis.
facilitated diffusion.
osmosis.