Transcript Cell powerpoint - Valhalla High School

The cell and cell
organelles
Life’s building blocks
What are cells?
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The cell is the very smallest unit of living
matter.
All living things are made up of one or more
cells
There are an estimated 75-100 trillion cells
in your body.
75,000,000,000,000-100,000,000,000,000
That’s a lot of zeros!
The cell theory
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A theory is a well-substantiated explanation
of an aspect of the natural world that can
incorporate laws, hypotheses and facts.
A theory is not a guess, but an idea that is
supported by the work of many scientists
usually over the course of many years.
Some of the scientists whose work helped
to develop the cell theory are Hooke,
Schlieden, Schwann, Brown and Virchow.
The 3 components of cell theory
1.
2.
3.
The cell is the basic unit of structure for all
living things. This means that all life is
made of one or more cells.
The cell is the basic unit of function of all
living things. This means that the life
processes are carried out within the cells.
All cells arise from pre-existing living cells.
This means that life doesn’t spontaneous
appear from non-living matter.
Exceptions to cell theory.
As with other rules and theories, there are
some exceptions.
1. Viruses. While they carry out some life
processes, they aren’t made of cells.
2. Slime molds. During one part of their
weird lifecycle, they are not differentiated
into cells.
3. The very 1st cell. By definition, it couldn’t
have arose from a pre-existing cell.
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The organelles
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A specialized structure within a cell,
analogous to organs.
The term organelle literally means, “little
organ”.
The first organelle to be discovered was the
nucleus by an English biologist named
Robert Brown.
It is in the organelles that the life processes
are carried out.
The Nucleus
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The nucleus is
responsible for
controlling and
coordinating all
cellular activity.
The nucleus contains
our deoxyribonucleic
acid (DNA).
The nucleolus
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A dark spherical mass located within the
nucleus.
Composed of RNA.
Creates Ribosomes.
The cytoplasm
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The jelly-like matrix of the cell. Mostly
water.
All of the other organelles are suspended in
the cytoplasm.
Sometimes referred to cystol.
Endoplasmic Reticulum
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Series of tubules running throughout the
cell.
Aid in the transport of molecules.
Rough E.R. has ribosomes in it’s
membrane and synthesizes proteins.
Smooth E.R. has no ribosomes in it’s
membrane and synthesizes lipids.
Mitochondria
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The mighty mitochondria is the
powerhouse of the cell.
Site of cellular respiration.
Possess their own DNA and
replicate independently of the
rest of the cell.
Thought to once have been a
free living prokaryote.
Golgi Bodies (apparatus)
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Serve as temporary storage
sites for proteins and lipids.
Modifies and packages
these molecules prior to
secretion to other parts of
the cell, or out of the cell.
Ribosomes
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Serve as the site of protein
synthesis.
Ribosomes are found in the
membrane of rough
endoplasmic reticulum as
well as in the cytoplasm.
Vacuoles
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Storage sites for water, nutrients
and waste products.
Small in animal cells and very
large in plant cells.
In plant cells the central vacuole
helps to support the cell through
hydrostatic pressure.
Lysosomes
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The suicide sac.
Lysosomes digest worn out
organelles and help to break down
proteins.
When a cell begins to break down,
the lysosome swells up and bursts,
digesting the entire cell. This is
called autolysis.
Absent in plant cells.
Cell membrane
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Consists of a phospholipid bilayer which is
selectively permeable.
Regulates what enters and exits the cell.
Centrioles
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Found in animal cells
only.
These paired structure
are found next to the
nucleus and aid in cell
division.
Cell Wall
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Absent in animal cells.
Made of cellulose, the cell wall helps to
support the plant cell and give it it’s shape.
Cellulose is the most common organic
material on planet Earth.
Chloroplasts
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Found only in plant cells, the
chloroplasts are the site of
photosynthesis.
Filled with chlorophyll, which
gives green plants their color.
Chloroplasts contain their own
DNA, just like mitochondria.
Perhaps another example of
Endosymbiosis.
Review questions
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Which organelles are found only in animal cells?
Centrioles and lysosomes.
Which organells are found only in plant cells?
Chloroplasts and Cell Walls.
Which two organelles possess their own DNA?
Mitochondria and Chloroplasts.
Where in the cell is chromatin located
In the nucleus.
Where are proteins modified and packaged in the cell?
Golgi body.