cells structure and function input from ms. thomas (ib teacher) and heinemann book
TRANSCRIPT
CellsCells
Structure and FunctionInput from Ms. Thomas (IB teacher) and Heinemann Book
Topic 2 Section 1: Introduction to the Topic 2 Section 1: Introduction to the CellCell
Discovery of CellsDiscovery of Cells
The invention of the lens
Robert Hooke (1665): observed a thin slice of cork (dead plant cells) with a microscope. He described what he observed as “little boxes” (cells).
Discovery of CellsDiscovery of Cells
Anton van Leeuwenhoek (1675): was the first person to observe living cells.
MicroscopesMicroscopes
Magnification: refers to the microscope’s power to increase an object’s apparent size
Resolution: refers to the microscope’s power to show detail clearly
Light MicroscopeLight Microscope
Light MicroscopeLight Microscope
Elodea - Aquatic Plant
40X 400X
Transmission Electron Microscope (TEM)Transmission Electron Microscope (TEM)
Transmission Electron Microscope (TEM)Transmission Electron Microscope (TEM)
Herpes Virus
Plant Root Cell
Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)
Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)
Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)
Mosquito Head
200X 2000X
Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)
Fly Eye
Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)
Inside of Stomach
Surface of TongueNeuron
Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)
PollenYeast
Red Blood Cell, Platelet, and White Blood Cell
TEM vs. SEMTEM vs. SEM
Viruses leaving a cell
The Cell TheoryThe Cell Theory
Who developed the cell theory?– Matthias Schleiden (1838):
concluded that all plants are composed of cells
– Theodor Schwann (1839): concluded that all animals are composed of cells
– Rudolph Virchow (1855): determined that cells come only from other cells
2.1.1Out line the cell theory
The Cell TheoryThe Cell Theory
What is the cell theory?
1. All living things are composed of one or more cells.
2. Cells are organisms’ basic units of structure and function.
3. Cells come only from existing cells.
2.1.1Out line the cell theory
Functions of LifeFunctions of Life
2.1.3State that unicellular organisms
carry out all functions of
life
Growt
hMet
abolis
m
All organisms exist in either a unicellular or a multicellular form.And all organisms carry out all the functions of life. These functions include:
Functions of LifeFunctions of Life
2.1.3State that unicellular organisms
carry out all functions of
life
Response
Nutrition
homeostasis
Reprod
uction
Functions of LifeFunctions of Life
All of the functions are tied together to produce a functioning living unit
Cell DiversityCell Diversity
SizeShapeInternal Organization
Cell Diversity- Cell Diversity- SizeSize
2.1.4 Compare relative
sizes of molecules, cell
membrane thickness, viruses, bacteria,
organelles and cells, sing
appropriate SI units
Cell Diversity- SizeCell Diversity- Size
6 inches long, 5 inches wide, 3 pounds
Smallest Cells:
Longest Cells:
Ostrich Egg
Biggest Cells:
2.1.4
Cells and SizesCells and Sizes
Magnification = size of image divided by the size of the specimen
2.1.5
Limiting Cell SizeLimiting Cell Size
You may wonder why cells do not grow to larger sizes, especially since growth is one of the functions of life.– There is a factor called the surface area to
volume ratio that effectively limits the size of the cells.
– In the cell, the rate of heat and waste production and rate of resource consumption are functions of (depends on) its volume
Limiting Cell SizeLimiting Cell Size
Most chemical reactions occur in the interior of the cell and its size affects the rate of these reactions. – The surface of the cell, the membrane,
controls what materials move in and out of the cell.
• Cells with more surface area per unit volume are able to move more material in and out of the cell, for each unit volume of the cell
Limiting Cell SizeLimiting Cell Size
As the width of an object such as a cell increases, the surface are also increases but at a much slower rate than the volume– This means that a large cell has
relatively less surface area to bring in needed materials and to rid the cell of waste, than a small cell.
Limiting Cell SizeLimiting Cell Size
Because of this, cells are limited as to the size they can attain and still be able to carry out the functions of the life.
Surface Area to Volume RatioSurface Area to Volume Ratio
SA = 6 mm2
SA = 24 mm2
SA = 96 mm2
V = 1 mm3
V = 8 mm3
V = 64 mm3
SA/V = 6:1
SA/V = 3:1
SA/V = 1.5:1
V increases faster than SA
SA = 6lwV = lwh
2.1.6
Cell Diversity- ShapeCell Diversity- Shape
Cells differ widely in shape.Most cells are roughly
cuboidal or spherical.
Multi-cellular organisms show Multi-cellular organisms show emergent propertiesemergent properties
Emergent properties arise from the interaction of the component parts; the whole is greater than the sum of the parts'.
2.1.7
Cells Cells DifferentiateDifferentiate
2.1.8
Differ
entiat
ion:
Cells
within
a
multi
cellul
ar
organi
sm spe
cializ
e
their
functi
on.
Specia
lized
cells
have
switch
ed on
partic
ular
genes
(expre
ssed)
that
correl
ate to
these
specia
list f
unctio
ns.
These
specif
ic gen
e
expres
sions
produc
e
partic
ular s
hapes,
functi
ons an
d
adapta
tions
within
a
cell.
Stem cells : What they are and Stem cells : What they are and therapeutic usestherapeutic uses
2.1.92.1.10
Stem cellsStem cells
They are a population of cells within organisms that retain their ability to divide and differentiate into various cells types– In the early 1980’s, scientist found
pluripotent or embryonic stem cells in mice. These cells retain the ability to form any type of cells in a organism and can even form a complete organism
Stem cellsStem cells
When stem cells divide to form a specific type of tissue, they also produce some cells that remain as stem cells.– This allows for continual production of
a particular type of tissue. – Medical experts immediately noted the
possibilities of such cells in treating certain human diseases
Stem Cell Research and treatmentsStem Cell Research and treatments
Some of the most promising research recently has been directed towards growing large numbers of embryonic stem cells in culture so that they could be used to replace differentiated cells lost due to injury and disease.– Alzheimers, Parkinsons, diabetes
Stem Cell Research and treatmentsStem Cell Research and treatments
Besides embryonic or pluripotent stem cells, there are also tissue specific stem cells.– These cells reside in certain tissue
types and can only produce new cells of that particular tissue.
• Leukemia patients
Stem Cell Research and treatmentsStem Cell Research and treatments
There are important ethical issues involved in stem cell research.– Especially controversial is the use of
embryonic or pluripotent stem cells. – This is because the cells come from embryos
often obtained from laboratories carrying out IVF
• To gather these cells involves death of the embryo and opponents argue that this represents the taking of a human life
Where do you stand in the debate about the nature of stem cell research? How do you feel about the source of pluripotent stem cells