Unit 3 - Cells

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Unit 3 - Cells
I. Cytology -
The study of cells
A. Cell Theory
1. Cells are the basic unit of structural units
of all plants and animals.
2. Cells are the smallest functioning units of
life.
3. Cells are produced by the division of
pre-existing cells.
4. Each cell maintains homeostasis.
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B. Ways we visualize cells
1. Light microscopes 1000X, thin sections
2. Electron microscopes 1oo,oooX
a. Transmission very thin sections, show detail
of internal cellular structures
b. Scanning 3-D, surface, plasma membrane
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C. The typical cell The cell membrane
separates
1. Extracellular (Interstitial) fluid Watery
medium surrounding the cell
2. Cytoplasm cell contents made up of
a. CYTOSOL fluid inside
b. ORGANELLES little organs, structures that
perform specific functions
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D. Membrane Transport -
Selectively permeable
Allows some materials to pass, prevents others
(based on size, electrical charge, molecular
shape, lipid solubility, or combination.)
http//www.wisc-online.com/objects/index_tj.asp?ob
jIDAP1101
1. PASSIVE -
Move ions or molecules without an energy input,
through the lipid portion of the membrane or
through a channel protein.
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a. Diffusion -
Net movement from an area of high concentration
(many collisions) to an area of low concentration
(few collisions)
CONCENTRATION GRADIENT
http//www.wisc-online.com/objects/index_tj.asp?ob
jIDAP1903
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EX Osmosis -
Diffusion of water across a selectively permeable
membrane toward a solution that has the highest
solute concentration (due to substances
dissolved, etc. in solution)
Osmotic pressure the amount of pressure
required to stop osmosis across a membrane.
http//www.ac-creteil.fr/biotechnologies/doc_osmos
is.htm
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ISOTONIC -
equal tension equlibrium exists, no net
movement into or out of the cell., 0.9 NaCl
isotonic for RBC
HYPOTONIC -
below solute concentration is higher inside
the cell, water moves into the cell. Cell may
swell, rupture.
RBC HEMOLYSIS
HYPERTONIC -
above solute concentration is higher outside
the cell, water moves out and the cell shrivels.
RBC CRENATION
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http//www.tvdsb.on.ca/westmin/science/sbi3a1/Cell
s/Osmosis.htm
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b. Facilitated Diffusion -
Large and lipid soluble substances move across
the membrane with the help of carrier proteins.
Glucose and Aquaporins
c. Filtration -
Use of gravity or mechanical pressure to move
substances across a selectively permeable membrane
Capillaries, kidneys
http//www.wisc-online.com/objects/index_tj.asp?ob
jIDAP11103
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2. ACTIVE TRANSPORT -
Cell requires energy in the form of ATP to move
substances across a membrane against the
concentration gradient
EX Cytosis Vesicular transport
a. Endocytosis -
Large particles/molecules are surrounded by
plasma membrane and brought into the cell.
http//programs.northlandcollege.edu/biology/Biolo
gy1111/animations/transport1.html
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PHAGOCYTOSIS Projections of cytoplasm surround
and engulf cell, cell eating.
PINOCYTOSIS engulfed material is liquid a
droplet of liquid is attracted to the membrane
surface which folds inward and forms a pinocytic
vesicle.
RECEPTOR-MEDIATED recognition sites that attach
to specific molecules such as hormones,
nutrients, antibodies, neurotransomitters
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b. Exocytosis elimination of undigestible
particles.
http//www.stolaf.edu/people/giannini/flashanimat/
cellstructures/phagocitosis.swf
E. Protein Synthesis -
Cells are protein factories produce a large
of proteins, some structural, others regulatory
(hormones), antibodies, enzymes
1. The genetic code -
DNA Holds the instructions (genes) to produce a
protein.
a. Made up of nucleotides that are in turn made
up of a nitrogen base, phosphate, and deoxyribose
sugar.
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b. Located in the nucleus of eukaryotic cells,
cannot leave
c. Double-stranded molecule that is kept together
by H-bonds between complementary base pairs.
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2. Transcription -
Instructions are copied from DNA.
a. From double-stranded DNA, which cannot leave
the nucleus, the protein instructions are copied
as complementary base pairs into single-stranded
messenger RNA (mRNA).
b. The mRNA leaves the nucleus through the
nuclear pores to reach protein factories WHICH
ORGANELLE? WHERE LOCATED?
http//www-class.unl.edu/biochem/gp2/m_biology/ani
mation/gene/gene_a2.html
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3. Translation -
mRNA provides the template for a protein to be
made.
a. mRNA attaches to the small subunit of a
ribosome (one protein is made per ribosome) and
the large subunit then attaches.
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b. tRNA (transfer RNA) brings the specific amino
acid (20 different) with the complementary
triplet code (anticodon) to mRNA (tRNA UAC,
mRNA AUG)
c. The next tRNA brings another amino acid to the
next mRNA codon and these amino acids are joined
by a peptide bond.
d. Amino acids are attached one-by-one until the
protein is formed this process is stopped by a
stop codon.
b. c.
a.
d.
e. The protein is released from the ribosome.
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http//www-class.unl.edu/biochem/gp2/m_biology/ani
mation/gene/gene_a3.html
GENE A group of nucleotides on a DNA molecule
that serves as a set of instructions for a
protein. Average 100 nucleotide pairs in length.
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F. Cell Cycle Somatic cells
1. Why?
Heal wounds, growth, surface area to volume,
limited capability of nucleus
2. Two divisions
a. Nuclear
b. Cytokinesis
3. Phases - Nuclear
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a. Interphase -
Nondividing period (90 of cycle), separated into
three phases G1, S, G2. During S DNA is
replicated.
a.
c.
b.
b. Prophase
-chromatin shortens into chromosomes
-nuclear membrane begins to disappear
-centrosomes move to poles
c. Prometaphase
-Spindle fibers attach to centromeres
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d. Metaphase-
chromosomes line up on the equatorial plate
d.
e.
f.
e. Anaphase
-duplicated halves of each chromosome separate
and move to opposite poles
f. Telophase
-Nuclear membrane reforms
-Chromosomes re-condense into chromatin
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4. Cytokinesis -
Division of the cytoplasm
http//www.cellsalive.com/mitosis.htm http//highe
red.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?itsw
f535535/sites/dl/free/0072437316/120073/bio1
4.swfMitosis20and20Cytokinesis
5. Cancer cells duplicate without control

• Tissue is called tumor, growth, neoplasm

• Oncology The study of

• Cancerous is called malignant

• Non-cancerous is benign does not spread to
  other parts and may be removed

• Hyperplasia increase in frequency of cell
  division

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a. Malignant tumors duplicate continuously,
quickly and without control

• Hyperplasia

• Metastasis -

Spread to other parts, cancer cells secrete AMF
(autocrine motility factor) a protein which
allows them to metastasize hard to detect and
eliminate

• Often this invasion kills the normal tissues by
  starving it out

• Then they invade adjacent tissues and establish
  secondary tumors

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b. Causes
Chemical or environmental agent that causes
cancer (60-90 of human cancers) 90 of all lung
cancers caused by smoking, UV radiation

• CARCINOGEN -

• VIRUSES -

Mostly in animals

• ONCOGENESIS -

Genes found in human cells that trigger cancerous
growth when inappropriately activated

• ANTIONCOGENESIS

c. Treatment

• Chemotherapy

• Radiation

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