2. 2
3.1: Introduction
• The basic organizational
structure of the human body is
the cell.
• There are 50-100 trillion cells
in the human body.
• Differentiation is when cells
specialize.
• As a result of differentiation,
cells vary in size and shape
due to their unique function.
4. Cell Membrane
(aka Plasma Membrane)
• Outer limit of the cell
• Controls what moves in and out of the cell
• Selectively permeable
• Phospholipid bilayer
• Water-soluble “heads” form surfaces (hydrophilic)
• Water-insoluble “tails” form interior (hydrophobic)
• Permeable to lipid-soluble substances
• Cholesterol stabilizes the membrane
4
6. 6
Cytoplasm
• Cytosol = water
• Organelles = solids
Cytoplasm is really like a Jello fruit
salad where the Jello is the cytosol and
the fruits (oranges, grapes, bananas,
maybe walnuts, etc.) are the
organelles.
13. 3.3: Movements Into
and Out of the Cell
There are 2 ways substances move through the cell
membrane.
13
•Passive mechanisms do
not require energy.
• Simple diffusion
• Facilitated diffusion
• Osmosis
• Filtration
Active mechanisms require cell
energy
• Active transport
• Endocytosis
• Exocytosis
• Transcytosis
14. 14
Simple Diffusion
•The process by which molecules or ions scatter or spread
spontaneously from a higher concentration to a lower
concentration
• Oxygen and carbon dioxide can diffuse readily through the cell
membrane
•Equilibrium is reached.
Time
Solute molecule
Water molecule
A B A B
(2) (3)
Permeable
membrane
A B
(1)
16. 16
Facilitated Diffusion
• Substances that are not able to pass through the lipid
bilayer need the help of membrane proteins to get across,
this is called Facilitated Diffusion
•Carrier molecules “revolving doors” are used to carry large
molecules (transported substance) across the membrane.
• Ex. Glucose and amino acids
Region of higher
concentration
Transported
substance
Region of lower
concentration
Protein carrier
molecule
Cell
membrane
17. 17
Animation:
How Facilitated Diffusion
Works
Please note that due to differing
operating systems, some animations
will not appear until the presentation is
viewed in Presentation Mode (Slide
Show view). You may see blank slides
in the “Normal” or “Slide Sorter” views.
All animations will appear after viewing
in Presentation Mode and playing each
animation. Most animations will require
the latest version of the Flash Player,
which is available at
http://get.adobe.com/flashplayer.
19. 19
Animation:
How Osmosis Works
Please note that due to differing
operating systems, some animations
will not appear until the presentation is
viewed in Presentation Mode (Slide
Show view). You may see blank slides
in the “Normal” or “Slide Sorter” views.
All animations will appear after viewing
in Presentation Mode and playing each
animation. Most animations will require
the latest version of the Flash Player,
which is available at
http://get.adobe.com/flashplayer.
23. 23
Active Transport:
Sodium-Potassium Pump
• Active transport mechanism
• Creates balance by “pumping” three (3) sodium (Na+)
OUT and two (2) potassium (K+) INTO the cell
• 3:2 ratio
34. Mitosis
• Daughter cells have the same number of
chromosomes as that of the parent cell(46
chromosomes- diploid)
• Daughter cells have the same characteristics
as with the parent cells.
• For growth and repair.
34
35. 35
3.5: Control of Cell Division
• Cell division capacities vary greatly among cell types
• Skin and blood cells divide often and continually
• Neuron cells divide a specific number of times then cease
• Chromosome tips (telomeres) that shorten with each
mitosis provide a mitotic clock
• Cells divide to provide a more favorable surface area
to volume relationship
• Growth factors and hormones stimulate cell division
• Hormones stimulate mitosis of smooth muscle cells in uterus
• Epidermal growth factor stimulates growth of new skin
• Tumors are the consequence of a loss of cell cycle control
• Contact (density dependent) inhibition
37. 37
3.6: Stem and Progenitor Cells
• Stem cell:
• Can divide to form two new stem cells
• Self-renewal
• Can divide to form a stem cell and a progenitor cell
• Totipotent – can give rise to every cell type
• Pluripotent – can give rise to a restricted number of cell
types
• Progenitor cell:
• Committed cell
• Can divide to become any of a restricted number of cells
• Pluripotent
39. Meiosis
• The form of cell division by which gametes, with
half the number of chromosomes, are produced.
• Diploid (2n) haploid (n)
• Meiosis is sexual reproduction.
• Two divisions (meiosis I and meiosis II).
40. Fertilization
• The fusion of a sperm and egg to form a zygote.
• A zygote is a fertilized egg
n=23
egg
sperm
n=23
2n=46
zygote
41. Meiosis
• Sex cells divide to produce gametes (sperm or
egg).
• Gametes have half the # of chromosomes.
• Occurs only in gonads (testes or ovaries).
Male: spermatogenesis
Female: oogenesis
• Meiosis is similar to mitosis with some
chromosomal differences.
49. Fermentation
• Occurs when O2 NOT present (anaerobic)
• Called Lactic Acid fermentation in muscle
cells (makes muscles tired)
• Called Alcoholic fermentation in yeast
(produces ethanol)
• Nets only 2 ATP
50. Central Dogma-
Replication, Transcription,
Translation
• DNA contains the complete genetic
information that defines the structure and
function of an organism.
• Proteins are formed using the genetic
code of the DNA.
• Conversion of DNA encoded information
to RNA is essential to form proteins.
50
51. Central Dogma-
Replication, Transcription,
Translation
• Thus, within most cells, the genetic
information flows from – DNA to RNA to
protein.
• The flow of information is followed through
three different processes which are
responsible for the inheritance of genetic
information and for its conversion from one
form to another:
• Replication: a double stranded nucleic acid51
52. Central Dogma-
Replication, Transcription,
Translation
• Replication: a double stranded nucleic acid
is duplicated to give identical copies. This
process perpetuates the genetic information.
• Transcription: a DNA segment that
constitutes a gene is read and transcribed
into a single stranded sequence of RNA.
The RNA moves from the nucleus into the
cytoplasm.
• Translation: the RNA sequence is 52
