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Anatomy and Physiology
Chapter Three: Cells & Tissues
Text Pages 55-77
I.
The Cellular Basis of Life
As you are already aware, cells contain a large percentage of water. In addition to the
intracellular water, cells are surrounded by interstitial fluid. This fluid is found
between and outside of all cells.
What is meant by the phrase “structure reflects function”?
II.
Anatomy of the Animal Cell
A. What are the 3 parts of the cellB. The nucleus
Contains & houses the genetic material of the cell.
1. Nuclear envelope (membrane): double membrane, porous,
selectively permeable
2. Nucleoplasm: suspends the nucleoli & chromatin
3. Nucleoli: assemble the ribosomes
4. Chromatin: the genetic material in a nondividing cell
5. Chromosome: the genetic material in a dividing cell
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C. The cytoplasm
The “factory” area of the cell.
1. Cytosol: semitransparent fluid inside the cell; suspends the
organelles
2. Inclusions: chemical substances within the cell
Most are stored nutrients or cell products.
3. Organelles: “machinery of the cell”
All organelles are bound by the same plasma membrane that
surrounds the cell itself. This compartmentalization of the cell
enables it to become more complex and to divide up the cell’s
labor.
a. mitochondria: produces cellular energy in the form of ATP
“powerhouse of the cell”
b. ribosomes: made of protein & rRNA
site of protein synthesis
Some are attached to endoplasmic reticulum
(bound) while others are found alone inside the
cytosol (bound).
c. endoplasmic reticulum: channels within the cell that carry
substances (most often proteins) throughout the cell
rough ER: cell’s membrane factory
How much is found within the cell depends on how
much protein a cell makes.
smooth ER: Has no role in protein synthesis. The function
of SER is to produce cholesterol, metabolize fat &
to detoxify drugs within the body.
d. golgi apparatus: modifies & packages proteins in the cell
e. lysosomes: clean up the cell with digestive enzymes
(found in large amounts in leukocytes)
Produced by the golgi apparatus.
f. peroxisomes: Similar to lysosomes in that they contain powerful
enzymes that detoxify harmful, poisonous materials.
(ex: alcohol)
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Are not produced by the golgi apparatus.
g. cytoskeleton: “bones & muscles” of the cell
give the cell shape & support & provide the cell
with a transportation system
microfilaments: provide the cell with shape and assist with
cell motility
(actin & myosin)
microtubules: give the cell shape & determine organelle
distribution
intermediate filaments: form desmosomes (anchoring
joints between cells)
h. centrioles: made of microtubules
direct the production of the spindle that is used for
cell division
D. cilia: move substances along the surface of the cell
E. flagella: movement of an entire cell
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F. Plasma membrane
Discuss the structure in the space below:
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1. microvilli: finger-like projections that increase the surface area of a cell
for absorptive reasons
2. junctions:
a. tight junctions: impermeable, bind cells together tightly
plasma membrane to plasma membrane
b. desmosomes: hold cells together (like skin cells)
c. gap junctions: allow cells to communicate
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III. Cell Diversity
The body contains roughly 200 different kinds of cells in it. These 200 different
kinds can be grouped into 7 different categories.
A. Cell Specializations
1.
2.
3.
4.
5.
6.
7.
IV. Cell Physiology
A. Membrane Transport
Intracellular fluid: nucleoplasm & cytosol
Interstitial fluid: fluid outside of the cell “nutrient-rich”
Cells must take what it needs from the interstitial fluids. Because the
membrane is selectively permeable the movement of materials in & out
of the cell is regulated.
1. Passive Transport
During passive transport, no energy is used by the cell.
a. Diffusion
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concentration gradient: place
were two unlike concentrations
meet
osmosis: the diffusion of water
through the pores in a membrane
isotonic solutions:
hypertonic solutions:
hypotonic solutions
See page 69 “IV therapy and Cellular Tonics”
simple diffusion:
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facilitated diffusion:
b. Filtration
pressure gradient: instead of a concentration gradient
2. Active Transport
During active transport, energy in the form of ATP is used by the
cell to move materials that are too large or fat insoluble. Active
transport is also used to move materials against the concentration
gradient (from low to high concentration).
a. solute pumping
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b. bulk transport
exocytosis:
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1. endocytosis:
phagocytosis: “cell eating”
white blood cells
pinocytosis: “cell drinking”
aka: bulk-phase
endocytosis
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B. Cell Division
The life cycle of a cell = interphase + cell division
1. Interphase
During this phase, the cell grows, prepares for cell division and
continues to do the job it is supposed to do for the body.
2. Cell Division
Cell division = mitosis + cytokinesis
a. Mitosis
Cells in the human body divide on average every 2 hours!
One somatic cells divides into 2 somatic cells each with 46
chromosomes..
1. Prophase
Chromatin coils to form chromosomes. (already been
replicated)
Centrioles separate and move to the poles of the cell.
Spindle apparatus begins to form between the centrioles.
The nuclear envelope begins to break down.
2. Metaphase
The chromosomes line up in the middle of the cell.
3. Anaphase
Sister chromatids are pulled apart and the chromosomes move
to the poles of the cell.
4. Telophase
“prophase in reverse”
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b. Cytokinesis
Cleavage furrow forms due a contractile ring of microfilaments
that pinch the original cell into 2 separate cells.
* Some cells skip cytokinesis and the result is a multinucleated
cell. (common in the liver)
Somatic cells go through mitotic divisions while gametes go through
meiosis.
What are the differences?
This type of division ensures us that when the sperm cell (haploid)
fertilizes the egg cell (haploid) that a diploid zygote is formed.
C. Protein Synthesis
1. Genes
DNA that codes for 1 protein or polypeptide sequence.
1 gene can be anywhere between 300 & 2000 base pairs in length.
In DNA, each 3 letter sequence of bases (codon) “codes” for 1 specific
amino acid.
2. RNA
RNA assists the decoding of DNA in the nucleus & the building of
proteins in the cytoplasm of the cell.
a. transfer RNA (tRNA)b. ribosomal RNA (rRNA)c. messenger RNA (mRNA)-
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3. Protein Synthesis
a. Transcription
mRNA is made from one strand of DNA.
Occurs in the nucleus of a cell.
Triplets: 3 base sequence on DNA
Codons: 3 base sequence on mRNA
b. Translation
The process when mRNA is read by rRNA & a protein or
polypeptide sequence is made.
rRNA “reads” each codon.
tRNA brings the appropriate amino acid to the ribosome.
Amino acids are linked together by strong peptide bonds.
Each polypeptide sequence begins with a start codon and
ends with a stop codon.
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