Download Unit One: Matter and Energy for Life Historical Development Cell

Unit One: Matter and Energy for Life
Historical Development Cell Theory
Biology is “the study of life”.
Living things are composed of individual units called cells.
Cell
- the basic unit of structure and function
- smallest unit capable of displaying characteristics of life
- the human body is made up of trillions of cells and every one
carries out the same life processes as a single-celled organism.
Cell biologists
- early cell biologists paved the way for cell study
- they each built on previous knowledge, modified techniques and
changed the way science viewed the origins of life
- i.e. a paradigm shift occurred
- a paradigm shift is a rare but significant change in how we view
the world
- often controversial when first proposed but becomes accepted
as a major advance in scientific knowledge/understanding.
- have discovered the cell theory
Cell Theory
Four hypotheses include:
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All living things are composed of one or more cells.
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Cells are the basic units of structure and function in all
organisms.
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All cells are derived from pre-existing cells.
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In a multicellular organism, the activity of the entire organism
depends on the total activity of its independent cells.
The idea that life arises from life is called biogenesis.
Prior to the cell theory, (late 19th century), many people believed that
small living organisms could arise suddenly from non-living or onceliving things.
This idea was known as spontaneous generation, later renamed
abiogenesis by Thomas Huxley.
Scientist contributions:
Read:
Chapter 1, p 7-10 and handout.
(Significant Events in Biological history, related to the Cell
Theory)
Biology 2201
Contributions of Scientists ( Read p. 7 - 10 )
Aristotle (Ancient Greece)
- classified all organisms into 2 kingdoms - plants or animals
- wrote that living organisms can arise from non-living matter (abiogenesis)
Robert Hooke ( 1635 -1703 )
- did illustrations of once living matter (called them cells)
- modification of microscope for clearer images
Antony van Leeuwenhoek ( 1632 - 1723 )
- designed simple microscopes ( single lens )
- observed tiny life ( “animalcules” ) in standing water
- observed plaque ( bacteria )
Francesco Redi ( 1629 - 1697 )
- conducts a controlled experiment ( ie. maggots in meat )
- refer to Fig. 1.2, p. 8
John Needham ( 1713 - 1781 )
- designs an experiment to support spontaneous generation ( ie. meat broth )
- refer to fig. 1.3, p. 9
Lazzaro Spallanzani ( 1729 - 1799 )
- was skeptical of Needham’s results and conclusions
- repeated Needham’s experiment and came to a different conclusion
Robert Brown ( 1773 - 1858 )
-observed that cells have a darker region (nucleus) near the centre
Matthias Jacob Schleiden ( 1804 - 1881 )
- “ All plants are made of cells”
Theodor Schwann ( 1810 -1882 )
- “All animals are made of cells”
Alexander C. H. Braun ( 1805 - 1872)
- wrote “The cell is the basic unit of life”
Rudolph Virchow ( 1821 -1902 )
- “ Where a cell exists, there must have been a pre-existing cell.”
Louis Pasteur ( 1822 - 1895 )
- disproves spontaneous generation
- concludes that living organisms do not arise from non-living matter
- refer to Fig. 1.4, p. 10 for experimental design
The Microscope: (Pg 12-22)
The microscope permitted scientists to discover
the existence of cells in that:
- it was a tool with such a great resolving power
(the ability to distinguish between small objects
close together) that it allowed people to view
things that had been too small to see,
- lenses had distorted images (color aberrations and blurry
images); improvements in glass making and lens grinding
removed the distortion effects.
Microscopes (Two types:)
1. Light
- light energy is passed through the
specimen to allow the image to be
viewed
- glass lenses are used to magnify the
image
- resolution is commonly -> 1000x
- two kinds of light microscopes are:
(a) simple -> one lens eg.
magnifying glass
(b) compound -> two or more
lenses (commonly used in
labs)
2. Electron
- a flow of electrons are used (instead
of light)
- magnetic lenses are used to focus
the electrons
- resolution is commonly -> 50 000x
(new model can magnify image
500 000x showing molecular
structure!)
Two types of electron microscopes are:
(a) scanning electron microscopes, (SEM)
- They scan the surface of a specimen
showing details of the outside.
(b) transmission electron microscope, (TEM)
- They take slices of the specimen to show
the inner structures.
Light microscopes are adequate for most microscope work and they
are less expensive.
However, electron microscopes are sometimes chosen over the light
microscope as objects can be distinguished more clearly (better
resolution), and magnification is so much greater.
Videos showing “How to Use” a microscope:
Microscope part 1/3
http://www.youtube.com/watch?v=oUsJfttUZw&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
Microscope part 2/3
http://www.youtube.com/watch?v=AEzzTCRRlEE&NR=1&safety_mode=true&persist_safety_mode=1&safe
=active
Microscope part 3/3
http://www.youtube.com/watch?v=btjyDha4II0&feature=related&safety_mode=true&persist_safety_mode=1
&safe=active
Slide show showing how to calculate Field of View (FOV):
Magnification and field of view
Q:\Lane\Microscope Calculations Slideshow.mht
Quiz student on “parts of the Microscope!!”
Using the Microscope Pre-lab Exercise
Using the following diagrams and the information from p.16 in your text, give the function of
each of the following parts of the microscope.
eyepiece/ocular lens
body tube
arm
stage
stage clips
course adjustment
fine adjustment
diaphragm
condenser lens
revolving nosepiece
objective lenses
light source/lamp
base
Cells:
Cells may be classified as either:
Prokaryotes
Eukaryotes
eg. bacteria, *archaea
eg. plants, animals, fungi, protists
smaller in size
larger in size
less complex structures
more complex structures
no nucleus
- has a concentrated area called
a nucleoid
has a nucleus and contains
membrane-bound *organelles
* archaea - live in extreme environments (extreme heat eg.in volcanoes,
acid, salt, eg. in Dead Sea or salt flats)
* organelles - highly specialized structures that have certain functions
(jobs) to do.
- work together as a team to carry out cell processes and the work
tasks of the cell.
eg. making proteins, packaging, transport, etc.
**Cell Organelles and Their Functions.
- Referring to pages 25-30 in your text, complete the table of the
cell organelles.
Plant vs. Animal Cell Characteristics
Most of the organelles found in animal cells are also found in plant
cells ( eg. mitochondria, ribosomes, nucleus, etc.), but there are
some differences.
Animal Cells
Only
1. centrioles
2. lysosomes
Plant Cells Only
1. Cell wall
- in addition to the cell membrane, a thick outer
cell wall gives strength and support to cells. eg. it
allows a blade of grass to stand tall.
2. Plastids
- double membrane sacs that may be:
(a) chloroplasts
- contain green coloring pigment, chlorophyl, that
traps solar energy in photosynthesis to make food.
(b) chromoplasts
- contains various pigments also useful tophotosynthesis
(responsible for vibrant colors of flower petals)
(c) leucoplasts
- has no color and functions to store starch
Note:
Animal cells have small vacuoles and a variety of shapes.
Plant cells have large vacuoles and shapes tend to be geometrical
eg. rectangular (onion skin - later in the lab!)
Animal Cell:
Plant Cell:
Biology 2201
Animal and Plant Cells
Label the following diagrams.
This is a/an ______________ cell.
1. __________________
2. __________________
3. __________________
4. __________________
5. __________________
6. __________________
7. __________________
8. __________________
9. __________________
10. __________________
11. __________________
12. __________________
13. __________________
14. __________________
This is a/an ________________ cell.
1. __________________
2. __________________
3. __________________
4. __________________
5. __________________
6. __________________
7. __________________
8. __________________
9. __________________
10. __________________
11. __________________
12. __________________
13. __________________
Interactive Websites to Teach Cell Organells and Functions:
1)
Interactive cell structure game:
http://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/cell_s
tructure.htm
2)
Drag the name of the cell to the part in the diagram (Excellent for recognizing parts of cell in
diagram)
http://www.mrphome.net/mrp/CellPartsDragandDropres/frame.htm
3)
Eucariotic Cell Organelle Identification (pretty neat)
http://www.wisc-online.com/Objects/ViewObject.aspx?ID=ap11604
4)
Drag and Drop cell organelles (Names) to match their function (good activity)
http://www.execulink.com/~ekimmel/drag_gr11/organell.htm
5)
Inside a Cell:
http://learn.genetics.utah.edu/content/begin/cells/insideacell/
Sites for Biology 2201 Microscope Preparation: Lab #2
How to prepare a wet mount Slide:
http://vimeo.com/28981480
Preparing wet mount slides and staining:
http://vimeo.com/11687298
Rules for Drawing Biological Sketches (pg. 17 & 18)
1. Give a title.
2. Use 1/4 - 1/3 of the page to draw two or three cells.
3. Indicator lines are to be drawn to the right of the sketch.
4. All indicator lines end parallel to each other and in the same vertical
plane.
5. Label in capital letters and PRINT!
6. Use pencil.
7. No shading! For texture or depth, stipple only ( use pencil to make dots).
8. Give magnification (at bottom of sketch). eg. Mag. 400x
9. Give estimated size (when required), ie. Length x width
10. Label fully.
Biology 2201 Lab #2 - Animal and Plant Cell Lab
Here are the web sites for the lab.
The first part is done in the lab (making wet mount) then the drawing of human blood, frog
blood, cheek cells, etc... can be put up on the smartboard and done as a class.
Animal Cells:
Red Blood Cell:
http://www.mc.vanderbilt.edu/histology/labmanual2002/labsection2/Blood_hematopoiesis03_files/imag
e002.jpg
Frog Blood Cell:
http://phs.psdr3.org/science/forensics/images/blood/frogblood.jpg
Human Cheek Cell:
http://schoolworkhelper.net/wp-content/uploads/2011/02/cheekcell.jpg
Note:
Only draw 3 or 4 cells for the human blood cell, frog blood and the cheek in the field of view. Don’t
forget to label them.
Plant Cell:
Onion Cell for #8 - Proper Biological Drawing
http://faculty.ntcc.edu/mhearron/onionep1.jpg
Lettuce Cells:
http://www.bing.com/images/search?q=lettuce+cells+under+microscope&view=detail&id=3E0C74406
16EA237FBC0745B5B2AF796724C5547&FORM=IDFRIR&adlt=strict
Note:
For your proper biological drawing of the onion, you are only drawing one onion cell lengthwise on a
blank sheet of paper. Follow the guidelines you were given on your handout.
Animations describing Passive and Active Transport
Great descriptive animation on;
Passive and Active Transport:
http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.ht
ml
http://www.northland.cc.mn.us/biology/Biology1111/animations/index_page_
for_animations.htm
Lysosome Animation:
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__lysosomes
.html
Osmosis Animation:
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_osmo
sis_works.html
Facilitated Difussion Animation:
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_facil
itated_diffusion_works.html
Difusion Animation:
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animation__how_diff
usion_works.html
Transport Mechanisms
- are ways in which materials enter or leave the cell.
- crucial in transport is the...
Structure of the Cell Membrane
The cell membrane functions:
(1) not only to protect and
(2) contain the cell parts
(3) but also to regulate what materials go in and out.
Its structure allows it to do this.
- it is a double membrane (2 layers) of phospholipid molecules
(refer to diagram page 51-2)
phosphate heads:
- polar and is attracted to water (hydrophilic)
- this end able to dissolve in water
lipid tails:
- nonpolar fatty acids not attracted to water (hydrophobic)
- they are insoluble in water
This arrangement of polar heads facing outside and nonpolar lipid
tails facing inside is what allows the cell membrane to act as a
barrier between the tissue fluid (extracellular fluid) and the
cytoplasm (intracellular fluid) of the cell.
Thus, water, oxygen and carbon dioxide can pass through the cell
membrane freely.
Other substances, like big glucose molecules or ions must pass
through specialized transport proteins.
Transport mechanisms may be:
A. passive (3 types)
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
B. active
C. bulk (creation of vesicles) (2 types)
1. Endocytosis
2. Exocytosos
A. Passive Transport (3 types)
1. Diffusion
- atoms/molecules of substance move randomly, collide and
bounce off in all directions eg. perfume diffuses throughout a
room
-materials diffuse from an area where there is a lot (greater
concentration) to an area where there is less (lower conc.)
- requires no additional energy (other than kinetic molecular
energy) and so is termed passive.
- in a closed system, materials will diffuse until they are
scattered evenly throughout.
- if the substance is colored, the color fades as diffusion
continues.
- diffusing materials may be solid, liquid or gaseous.
Diffusion explains how some molecules move back and forth across
the cell membrane, but once molecules have diffused inside, their
rate of diffusion slows down.
Surface Area to Volume Ratio: (refer to handout)
- Having a large surface area relative to its volume increases the area
available for materials to diffuse in and out of a cell.
- The smaller the surface area/volume ratio, the bigger the cell and the
less efficient it will be to diffuse enough materials in to serve the mass of
the cell.
- Thus when the cell reaches a size where diffusion becomes inefficient, it
divides.
- Now two small cells have formed, thus increasing the surface/volume ratio
and diffusion efficiency.
2. Osmosis
Some membranes only allow certain materials to pass through.
The membrane is said to be selectively or semi-permeable.
When a liquid, usually water, is passing through a selectively permeable
membrane, the process is called osmosis.
-requires no energy so it is passive
-operates from high -> low concentration (ie. ‘along’ the concentration
gradient)
- osmosis continues until the concentration is the same on both sides
of the membrane (ie. equilibrium is reached)
Starch, water, and iodine activity
Diffusion is occurring with:
a) water molecules
- water diffuses into the bag in an attempt to equalize the
concentration on both sides (obtain equilibrium). Bag swells.
b) iodine molecules- iodine diffuses into the bag, reacting with
starch, observable as a color change from red-brown to blueblack, but...
Some molecules, eg. starch, are too big to diffuse through the bag.
The water outside remains the red/brown color of iodine indicating
a negative test. (Starch turns blue/black in the presence of
iodine.)
Osmosis continues even after equilibrium is reached. Molecules
are then diffusing in at the same rate as they are diffusing out.
We say that osmosis is dynamic.
Your cells are being bathed in tissue fluid.
Materials the cells need, glucose, oxygen, etc., diffuse from the
blood vessel capillaries into the tissue fluid, then across the cell
membrane into the cells.
Waste products in the cells diffuse out of the cells, into the tissue
fluid and into the blood vessels.
Question: How will the direction of water flow be affected if the
solute concentration outside the cell is:
a. higher than inside the cell?
b. lower than inside the cell?
c. the same as inside the cell?
The terms hypertonic, hypotonic, and isotonic refer to the
solute concentration of a solution.
Hypertonic
When cells are placed in a hypertonic solution, we say the solution
is hypertonic to the cytoplasm (and the cytoplasm is hypotonic to
the solution).
Greater solute = lower water concn outside; therefore the greater
water concentration is inside .
Osmosis will result in more water diffusing out of the cell, where
the water concn is less, and continues until equilibrium is reached.
Cells shrink.
Hypotonic
The solution is hypotonic to the cell cytoplasm when the solute
concn is lower in the solution than the cytoplasm.
Lower solute= higher water concn, so more water will diffuse from
the outside to the inside, until equilibrium is reached.
Cells swell and may burst before that happens.
(Note that the cell cytoplasm was also hypertonic to the outside
solution.)
Isotonic
The solute concentration is the same on both sides of the cell
membrane.
Osmosis continues with water diffusing into the cell at the same
rate as it is diffusing out.
No observable change in cell size.
The cell cannot prevent this movement of water because it is
permeable to water molecules. Refer to page 55 in text to
compare all three osmotic conditions in animal and plant cells,
paying particular attention to the role played by the cell wall in
plant cells. ( use shoe box / balloon for demo.) Students do web
link page 57.
3. Facilitated Diffusion
Substances that cannot diffuse through the phospholipid
layer of the membrane (eg. Molecules that are too big, insoluble
in the lipid layer or charged ions) may be transported with the help
of specialized transport proteins (refer to p.52). Each transport
protein will help only one type of molecule, depending on its shape,
size and electrical charge.
Two types of transport proteins include:
a) carrier proteins
- accepts only non-charged particles; eg. glucose
- allows the particles to move in or out of cell (see diagram
p.57)
- changes shape (rocking motion) to transport molecule
b) channel proteins
- accepts charged particles that are opposite in charge to
itself; ie. a negative channel protein accepts a positively
charged particle (note Bio Fact p. 58 in text)
- has tunnel shape that allows the particle to pass through
Reminder: Since no energy is required and materials move along
the concn gradient, diffusion, osmosis and facilitated diffusion are
all forms of passive transport.
B. Active Transport
A cell may need to concentrate nutrients for growth inside,
completely rid itself of toxic wastes to the outside or create an
electrical potentiel across a membrane to allow nerves and muscles
to work (see square bullets p.59 for more examples). Passive
transport would not be sufficient for this. In active transport...
- materials move against the concn gradient (low -> high)
- energy is required ( in the form of ATP)
- transport proteins are used to make active transport
pumps,(like fac. diff. but against the concn gradient.) eg. the
sodium-potassium pump allows sodium ions to leave and
potassium ions to enter a cell by changing the shape of a
transport protein, with the help of an ATP energy molecule.
See diagram p.60 for details.
C. Bulk Transport (vesicles)
Macromolecules may be too big or too polar to be transported by
passive or active transport. The cell membrane folds in on itself to create a
membrane-enclosed, bubble-like sac,or vesicle. The cell may use these
vesicles to take materials in (endocytosis) and expel them out (exocytosis).
See p.62-4.
Endocytosis has three forms:
1. pinocytosis (“cell-drinking”)
- a vesicle is created involving the intake of a small droplet of tissue
fluid, together with any dissolved substances or very small particles it
may contain.
- occurs in nearly all cell types all the time (See p. 62)
2. phagoctosis (cell-eating)
- a vesicle is created involving the intake of a large droplet of
tissue fluid and matter such as bacteria or bits of organic
matter; digestive enzymes are necessary to digest the matter
- occurs only in specialized cells; eg. amoeba or macrophages of
our immune system
3. receptor-assisted endocytosis
- vesicles are created when special molecules with ‘tags’
bond to matching ‘receptors’ on the cell membrane; once
inside the vesicle splits in two parts - one carrying receptors
returns, once again, to become part of the cell membrane and
the other, containing the food molecule, empties into the cell
cytoplasm
-membrane receptors fit the shape of only one specific
molecule; eg. cholesterol (See diagram page 63)
Exocytosis
- a vesicle is formed using membrane from an organelle;
eg. ER, golgi apparatus
- the vesicle moves to the cell surface, joins the cell
membrane, emptying (secreting) its contents into the tissue
fluid; eg. the pancreas secreting the hormone insulin