Lecture for DP Biology Topic 1.1 Introduction to Cells

1. 1.1 Introduction to Cells
DP Biology
R. Price
v. 1 2015

3. #1: According to cell theory, living organisms are composed of cells.
Essential Cell Theory
1. Cell membrane separates cell
from everything else outside.
2. Genetic material as
information for cell’s activities.
3. Many activities are chemical
reactions, catalyzed by
enzymes
4. Own energy release system
5. Smallest living structures

4. Light microscopes

8. Skill: Calculation of magnification & actual size

11. Application: Questioning the cell theory using atypical examples, including
striated muscle, giant algae, and aseptate fungal hyphae
Striated muscle: muscle
fibers are large (30 mm and
can have hundreds of nuclei)
Fungi hyphae may
have long
structures with
many nuclei
Giant algae (Acetabularia)
can be 100 mm across with
only 1 nucleus

12. #2: Organisms consisting of only one cell carry out all functions of life in that cell
Functions of life
• Nutrition
• Metabolism
• Growth
• Response
• Excretion
• Homeostasis
• Reproduction
Paramecium
Chlamydomonas

14. #3: Surface area to volume ratio is important in the limitation of cell size
Surface Area to Volume Ratio
Metabolism
• Substances needed by the cell
must cross the cell membrane
• Waste products must cross the cell
membrane (accumulate issue)
Heat
• Heat produced lost over cell
surface (overheating issue)

15. #4: Multicellular organisms have properties that emerge from the interaction
on their cellular components
Whole is greater than its parts
Caenorhabditis elegans
• 1 mm long & 959 cells
• Cooperative groups of cells
• Mouth, pharynx, intestine,
anus
• Hermaphrodite
• Third of cells are neurons
• Cells organize themselves
interactBy Bob Goldstein http://labs.bio.unc.edu/Goldstein/movies.html (Own work) [GFDL
http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via
Wikimedia Commons

16. What looks like a large inflatable tube is actually
a pyrosome. And while it appears to be one behemoth
creature, it is actually many hundreds or thousands of
animals called zooids embedded in a gelatinous tube.
“One long pyrosome is actually a collection of thousands
of clones, with each individual capable of copying itself
and adding to the colony,” writes marine biologist Rebecca
Helm inDeep Sea News.
The creature's name means “fiery body” due to its
bioluminescence, a bright green-blue glow that can light
up the colony when disturbed….
These “cylinders in the water” can grow to formidable
sizes, sometimes exceeding 12 meters (40 ft) in length.
Each zooid feeds by sucking in water, filtering small
particles and blowing the waste back out. This is also the
method that propels the colony into motion, albeit at a
very slow pace. When the zooids pause this process, the
colony can sink 500-700 (1,640-2,295 ft) meters below the
surface of the sea, according to New Scientist.

17. #5:Specialized tissues can develop by cell differentiation in multicellular
organisms
Cell division of labor
• Ideal structure
• Necessary enzymes
• Cell development to carry
out specific function is
called differentiation.
Muscle cells
Neuron
Red blood cells

18. #6: Differentiation involves the expression of some genes and not others
in a cell’s genome
Same Genetics
• Each cell in a multicellular organism
have the same set of genes
Gene Expression
• Gene is turned on, and information
used.
• Protein or other product made
Cell differentiation happens because
a different sequence of genes is
expressed in different types of cells
The control of gene expression is the key to development.

19. #7: The capacity of stem cells to divide and differentiate is necessary in
embryonic development.
Animal life Reproduction
1. Sperm fertilizes egg -> zygote
2. Zygote divides -> embryo
3. Embryo cells divide many times
4. “Stem cell” = name for zygote &
early embryo cells
Stem cells can divide many times to
make large amounts of tissue. Stem
cells will differentiate into any cell
type.
By Mike Jones [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons

20. Properties of stem cells suitable for therapeutic uses
Stem cell properties
• Can divide many times to make
copious amounts of tissue.
• Useful to grow tissues or
replace lost, damaged, or
malfunctioning cells.
• Not fully differentiated. Can
differentiate in many ways to
make different cell types.
By OpenStax College [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

21. By Mikael Häggström (All used images are in public
domain.) [Public domain], via Wikimedia Commons

22. Stem cells and Stargardt’s disease
Stargardt’s Disease
• Stargardt’s macular dystrophy
• Develops in children between 6 & 12
years
• Recessive mutation of gene ABCA4
• Membrane protein in retina cells to
malfunction
• Photoreceptive cells fail
• Can cause blindness By Mchollrigl (Own work) [CC BY-SA 3.0
(http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

23. Stem cells and Stargardt’s disease
Stargardt’s Disease Treatment
• November 2010, United
States
• Adult woman, age 50,
Stargardt’s
• 50,000 retina cells from
embryonic stems cells
injected into her eyes
• Cells attached to the retina
• Cells stay attached for 4
month trial
• Improvement in vision, no
side effects
Source: Irina Klimanskaya / Advanced Cell Technology
Credit: Nelson Hsu, Melanie Taube, Julia Ro / NPR

24. Stem cells and Leukemia
Leukemia
• Type of cancer (non
tumor)
• Mutation in genes for cell
division
• Leukemia -> production of
abnormally high numbers
of white blood cells
• To cure leukemia, must
destroy the bone marrow
cells over producing white
blood cells
(chemotherapy)
By Mikael Häggström (All used images are in public domain.) [Public domain], via Wikimedia Commons

25. Stem cells and Leukemia treatment
1. Fluid is removed from patient’s
bone marrow.
2. Adult stem cells are extracted
from fluid and frozen.
3. Patient is treated with
chemotherapy. Cancer cells in
the bone marrow is destroyed.
4. Adult stem cells returned to
patient. Stem cells multiply and
produce red & white blood cells.
This may cure leukemia completely
Stem cell transplant. (Step 1): blood from a
vein in one arm of the donor, who could be the
patient or other person is removed. The blood
passes through a machine that separates the
stem cells. The blood then returns to the donor
through a vein in the other arm. (Step 2): the
patient receives chemotherapy to kill cells that
form the blood and can also receive
radiotherapy (not shown). (Step 3): the patient
receives stem cells through a catheter placed
in a blood vessel in the chest.
http://www.cancer.gov/espanol/pdq/tratamiento/leucemia-mieloide-adultos/Patient/page3

26. Sources of stem
cells and the ethics
of using them

27. Sources
Content
Allott, Andrew, and David Mindorff. Biology: Course Companion. 2014
ed. Oxford: Oxford UP, 2014. Print. Oxford IB Diploma Programme.
Walpole, Brenda. Biology for the IB Diploma. 2nd ed. Cambridge:
Cambridge UP, 2014. Print.
Images
Unless otherwise noted, images are obtained from Pixabay
(www.pixabay.com) and used under the CC0 Public Domain license.