Transcript IB Topic 2 - Blended Biology

IB Topic 2
Cells
Cell Theory
A. There are 3 main points
1. All living organisms are composed of
cells.
2. Cells are the smallest unit of life.
3. All cells come from pre-existing cells
Cell theory: history and evidence
A. The discovery of cells is linked to
technological advancements (microscopes)
B. 1590-Jansen developed the compound
microscope (it had two lenses)
C. 1665-Robert Hooke discovered the cell
1. Looking at cork
2. Thought the cells looked like chambers
3. Called them ‘cells’, as in jail cells
D. 1675-Leeuwenhoek
discovered unicellular
organisms
E. 1838-Mathius Schleiden
discovered all plants are
made of cells
F. 1839-Theodore Schwann
discovered all animals are
made of cells
G. 1855-Rudolph Virchow discovers all
organisms are made of cells
**organism=any living thing
Characteristics of Life
1. Order (organization) – from small to large
-Ex: Organelles make up cells.
Cell make up tissues.
Tissues make up organs.
Organs make individuals.
2. Metabolism- organisms take in and
release energy
3. Response (to the environment)- response
to stimuli
4. Growth and development-heritable
programs of DNA direct growth and
development (change in one’s shape
during life)
Examples:
5. Homeostasis-organisms have regulatory
mechanisms to maintain their internal
environments
Examples: body temperature
blood sugar
osmoregulation
6. Reproduction-the ability to reproduce
ones own kind
-This follows the theory of biogenesis
(life only comes from life)
7. Evolutionary adaptation-life evolves as a
result of interaction between organisms
and their environment
***Any organism (single cell or multi-cell)
that is considered alive must exhibit all of
these characteristics.
Multicellular organisms
A. Multicellular organisms show emergent
properties
B. Emergent properties arise from interaction of
the components
*The whole is greater than the parts (Ex: a
heart cannot function without the whole
body)
*A single cell can do nothing on its own,
but when you put all of the cells together they
can perform many functions
Multicellular organisms and
differentiation
A. Multicellular organisms differentiate to
carry out specialized functions
B. All cells originated from the same place
and all carry the genetic information to
perform any function (your toe cell could
have been a brain cell)
C. In each cell there is only a small amount of
activated genetic material
Ex: All cells have the genes for taste. The
only cells with activated ‘taste’ genes are on
your tongue.
D. Cell differentiation is determined by a cells
position relative to the others and chemical
gradients
E. Stem cells retain the capacity to divide and
have the ability to differentiate along different
pathways
Stem Cells
1. Have ability to reproduce and
differentiate
2. Embryo cells all start out as stem cells
3. Valuable for scientific research
4. May be able to differentiate stem cells to
desired cell type
5. These may replace damaged cells
Example of stem cell differentiation
Homework-Outline one therapeutic use of
stem cells for humans or some other
animal.
DO NOT USE WIKIPEDIA AS YOUR
RESOURCE!!
You may use any government or university
website. Their websites generally end in
.edu or .gov.
Viewing Cells
1. Light microscopes allow us to:
-see color images
-have a larger field of view
-prepare samples easily
-observe living and non-living material
**We cannot see most cell organelles
2. Electron microscopes allow us to:
-see more detail because they have a
higher resolution
Comparing microscopes
Focus beams
Light
microscopes
Electron
microscopes
Lenses
electromagnets
Resolving power 200 nm
0.2 nm
Color
No staining
required/can
see color
Requires metal
dyes/black and
white only
Object
Alive or dead
Dead only
Expense
High school
range/cheap
Universities/high
cost
Microscope Vocabulary
1. Resolution-describes clarity of pictures
-higher resolution = more detailed pictures
-human unaided resolution= 0.1mm
(anything further apart than 0.1 mm is
viewed as two objects)
2. Magnification-makes objects larger
3. An increase in magnification may reduce
the resolution
Calculating Linear Magnification
A. The formulaMagnification = size of image
size of specimen
B. Example-the object is magnified by two
This is the original
object.
Diameter of the image=4cm
Diameter of the specimen=2 cm
Find the magnification.
This is the magnified
image.
C. Scale bars - lines added to micrographs
of drawing to help show the actual size of
structures
Ex.
1 mm
**You must know how to convert between SI
Units to perform a magnification problem
correctly!!
Ex: 1mm = 1 x 10-3 m
Common SI Unit Conversions
1nm (nanometer) = 1 x 10-9 m
1ųm (micrometer) = 1 x 10-6 m
1mm (millimeter) = 1 x 10-3 m
1cm (centimeter) = 1 x 10-2 m
1m (meter) = 1m
1km (kilometer) = 1 x 103 m
Calculating linear magnification
Calculating linear magnification
1. Use a ruler to find the length of the scale bar.
2. Measure the length of the picture using the
same unit that you used to measure the scale
bar.
3. Divide the length of the picture by the length of
the scale bar and multiply by the number in the
scale bar.
4. If you did this correctly you should have only
one unit left (it should be the unit that was in the
scale bar). This is the size of the object in the
picture.
6. Once you have the size of the object you can
calculate magnification.
7. Divide the measured size of the picture by the
actual size of the object and multiply by the
scale bar (with units).
8. When you do this be sure your units are the
same. When you divide they should cancel out.
9. If you did this correctly, your magnification
should not have a unit.
Example:
Go to p. 169 Figure 10.1-C. Calculate the
magnification.
1. Length of scale bar = 0.8 cm
2. Length of picture = 5.7cm
3. 5.7 cm x 10.0 μm = 71.25 μm = actual
0.8 cm
size of object (photo)
Number given in
scale bar of
picture
4. To calculate the magnification you must convert the
actual size of the object and the measured size of
the photo to the same units (meters are usually the
easiest).
5. How it looks:
a. 5.7 cm= 5.7 x 10-2m or 0.057 m
(IMAGE SIZE)
b. 71.25ųm = 71.25 x 10-6m or 0.00007125 m
(ACTUAL SIZE)
*In (a) the decimal was moved to the left
two times (x 10-2) and in (b) the decimal was
moved to the left six times (x 10-6)
6. Magnification = 0.057 m
=800
0.00007125 m
7. The picture is magnified 800 times.
Assignment
Calculate the magnification for the following
images.
1. p. 169 Figures 10.1 d and e
2. p. 860 Figure 43.19
3. p. 921 Figure 46.10
4. p. 114 Figures 7.3 a and b
Limitations to Cell Size
A. Cells cannot grow indefinitely
B. They reach a maximum size and divide.
C. Bigger cells are less efficient.
-They have to transport materials further.
-The smaller the surface area to volume
ratio the harder it is for the cell.
D. As surface area increases so does the
volume.
E. Volume increases more rapidly than
surface area.
F. The rate at which cells can move things in
or out depends on the surface area.
G. The rate at which things are used or
produced depends on the volume.
H. Example:
SA = l x w x #of sides
V=lxwxh
4”
2”
SA = 96 in2
V = 64 in3
SA = 24 in2
V = 8 in3
2”
4”
**Volume increases faster than the surface area. In this
example the SA increased by 4 and the volume increased by 8.
How Big Is A Cell?
OBJECT
Eukaryotic
Prokaryotic
Nucleus
Chloroplast
Mitochondrion
Large virus (HIV)
Ribosome
Cell membrane
DNA dbl. helix
H atom
SIZE
10-100 μm
1-5 μm
10-20 μm
2-10 μm
0.5-5 μm
100 nm
25 nm
7.5 nm
2 nm
0.1 nm
Prokaryotic Cells
E. coli
Diagram of a typical prokaryote
Prokaryote organelles
1. Cell wall-gives the cell structure and strength
2. Plasma membrane-separates the internal
features from the outside environment
3. Cytoplasm-holds cell’s organelles and
enzymes
4. Pili-help the cell hold
on to other structures
and aid in movement
More prokaryote organelles
5. Flagella-aid in organism movement
6. Ribosomes-make protein from mRNA
7. Nucleoid-area containing naked DNA
8. Slime capsule-a protective barrier around
the cell (may help
shield it from
antibiotics)
An electron micrographs of E. coli
** For IB you must be able to identify the structures on a micrograph.
http://www.cellsalive.com/index.htm
Another diagram of a prokaryote
Prokaryote reproduction
1. Most prokaryotes
divide by binary fission
2. Some reproduce by
budding or filamentous
growth
http://www.bact.wisc.edu/Microtextb
ook/index.php?module=Book&func
=displayarticle&art_id=112
Eukaryote Cells
Animal cell
General Eukaryote Information
1. All eukaryotes have enclosed nuclei and
other membrane bound organelles
2. Eukaryotes are true cells (‘eu’ = true)
3. Eukaryotic cells are present in protists,
plants, fungi and animal
Homework
1. Draw, label and annotate a diagram of a
eukaryotic animal cell
Include:
free ribosomes
rough ER
lysosomes
Golgi apparatus
mitochondria
nucleus
cytoplasm
centrioles
cell membrane
nucleolus
DNA (chromatin) smooth ER
The Secretory Vesicle
1. Animal cells have a secretory vesicle
-It secretes glycoproteins that makeup the
extracellular matrix
-The extracellular matrix functions in
support, adhesion and movement
Diagram of a plant cell
Plant Cells
1. Organelles found in plants only:
-cell wall
-chloroplasts-organelle required for
photosynthesis
-vacuole-membrane bound sac used
for storage of organic compounds
Plant Cells
2. More on the cell wall
-Found in all plants and some prokaryotes
-provides rigid support for the cells
-made mostly of cellulose
-plays important role in turgor (hardening
of cells by the intake of water)
-prevents cells from taking in too much
water
Homework: Outline the
roles of extracellular
components in plants (cell
wall) and animals
(extracellular matrix).
Summary of differences between
eukaryotes and prokaryotes!
Prokaryotic Cells
Eukaryotic cells
small cells (< 5 mm)
larger cells (> 10 mm)
always unicellular
often multicellular
no nucleus or any membrane-bound
organelles
always have nucleus and other
membrane-bound organelles
DNA is circular, without proteins
(naked)
DNA is linear and associated with
proteins to form chromatin
(not naked)
ribosomes are small (70S)
ribosomes are large (80S)
no cytoskeleton
always has a cytoskeleton
cell division is by binary fission
cell division is by mitosis or meiosis
reproduction is always asexual
reproduction is asexual or sexual
Cell Membranes
A. The Fluid Mosaic Model-model of the
plasma membrane
B. Designed by Singer and Nicolson
C. The model is a mosaic of proteins
embedded in a phospholipid bilayer
D. The phospholipid bilayer has two layers
of amphipathic lipids
Hydrophilic heads
Hydrophobic tails
E. Amphipathic- has a polar head and a non-polar
tail
F. Hydrophilic=water loving (polar)
-found on inner and outer edges of cell
membrane
G. Hydrophobic=water fearing (non-polar)
-found inside the cell membrane
Diagram of cell membrane
Hydrophilic heads
Hydrophobic tails
Cytoplasm
H. Lipids can move laterally through the cell
membrane
I. Cholesterol molecules found between the
phospholipids may reduce fluidity, but
prevent crystallization
J. Membranes must be fluid to work
K. Proteins make up the mosaic part of the
membrane (3 main types)
L. Integral proteins
-embedded in the membrane (partially or
completely
M. Peripheral proteins
-found in hydrophilic areas only
N. Glycoproteins
-proteins within the membrane that have
carbohydrates attached to them
O. Protein functions
-antibody recognition -hormone binding sites
-electron carriers
-channels for passive transport
-pumps for active transport
Types of Cellular Transport
A. Types of passive transport include
diffusion, osmosis and facilitated diffusion
B. Diffusion-passive movement of particles
from and area of high concentration to an
area of low concentration
-Particles move down the concentration
gradients (high to low)
C. Illustration of diffusion
D. Osmosis-passive movement of water from an area
of low solute concentration to an area of high solute
concentration
http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm
E. Hypertonic solution-high solute/low solvent
F. Hypotonic solutions-low solute/high solvent
G. Isotonic solution-equal solute/solvent
Look at the
red blood
cells, not
the black
circles.
H. Facilitated diffusion
-involves transport of charged molecules
-does not require energy
-charged molecules must diffuse through
special proteins (the cannot diffuse
through the cell membrane on their own)
GET YOUR BOOK.
I. Active Transport
-requires energy
-used when diffusion cannot occur
-substances move up the concentration
gradient (move from low to high
concentrations
J. The Sodium Potassium Pump
-An example of active transport
-Pumps ions against the gradient
-Translocates three sodium ions out of the
cell for every two potassium ions pumped
in
-ATP powers the changes in protein
structure to transport the ions
J. The Sodium Potassium Pump
(continued)
-ATP phosphorylation=a phosphate group
from the ATP is added to the protein
-When ATP is broken energy is released
-ATP
ADP
(adenosine triphosphate
adenosine
diphosphate)
Sodium Potassium Pump
Sodium Potassium Pump 2
K. Other forms of cellular
transport
1. Endocytosis-when a cell extends its
membrane around a substance in order
to engulf it
2. There are two types:
-Phagocytosis-when the cell engulfs a
solid (‘cell eating’)
-Pinocytosis-when the cell engulfs a
fluid (‘cell drinking’)
K. Other forms of cellular
transport
3. Exocytosis-the excretion of
macromolecules by vesicles fusing to the
plasma membrane
4. Homework:
Find an animation of each of the following:
-pinocytosis
-phagocytosis
-exocytosis
Send the website URLs to me in an e-mail
L. Membrane fluidity
A. The cell membrane is highly fluid allowing
it to creating vesicles for endocytosis and
exocytosis
B. In endocytosis the membrane becomes
slightly smaller
C. In exocytosis the membrane becomes
slightly larger
D. Animation for endocytosis and exocytosis
ASSIGNMENT
•
•
•
•
•
Due Tuesday
Compare osmosis and diffusion.
Compare facilitated diffusion and active
transport.
Compare endocytosis and exocytosis.
Due Wednesday
At home, watch the animations that are in the
notes. (Click on the hyperlinks and watch the
videos.)
Make a list of the ones that helped you the
most.
M. Functions of the Golgi
apparatus and rER in exocytosis
1. Golgi apparatus
-Prepares substances for exocytosis
-Wraps the substances with portions of its
own membrane
-Creates a vesicle that will join with the
cell membrane to release the materials
M. Functions of the Golgi
apparatus and rER in exocytosis
(continued)
2. rough ER-Functions in protein transport
-Assists in creating vesicles to move proteins
around the cell or out of the cell via exocytosis
-The vesicles created by the rER often fuse with
the Golgi appartus
-Eventually, new vesicles may be formed and
transported out of the cell
Cell division
A. The cell cycle consist of the following parts:
1. Interphase (3 stages)
-G1
-S
-G2
2. Mitosis (4 stages)
-Prophase
-Metaphase
-Anaphase
-Telophase
3. Cytokinesis (not truly separate from mitosis)
B. Interphase
1. G1-Characterized by cell growth and
appearance of cell organelles
S-Synthesis of DNA (DNA replication)
G2-Preparation for mitosis
2. DNA is found in the form of chromatin
(unraveled)
3. Interphase is an active period
4. Often makes up about 90% of the cell cycle
C. Mitosis
1. Purpose of mitosis is to increase the
number of cells without changing the
genetic material
2. The daughter cells are identical to the
parent cells
3. Mitosis can occur in haploid, diploid or
polyploid cells
C. Mitosis (continued)
4. The stages
a. Prophase-chromosomes coil
and become visible
-mitotic spindles begin
forming
-centrioles move to opposite poles
-nucleolus disappears
-nuclear membrane disappears
-sister chromatids are joined together
C. Mitosis (continued)
4. The stages
b. Metaphase-Chromosomes
move to metaphase
plate
-centromeres attach
to spindle fibers
C. Mitosis (continued)
4. The stages
c. Anaphase-sister chromatids
separate and move to
opposite poles
-chromatids are now
considered
chromosomes
C. Mitosis (continued)
4. The stages
d. Telophase-chromosomes
arrive at poles
-spindles disappear
-chromosomes
become chromatin
-nucleus, nucleolus
and nuclear membrane
reappear
D. Cytokinesis
1. Division of the cell (specifically, the
cytoplasm)
2. It is hard to distinguish cytokinesis from
telophase
1. What is the longest stage of the cell cycle?
2. List all steps of the cell cycle in order.
3. In what stage of the cell cycle does DNA
replication occur?
4. True or false? All new cells are the same as
the old ones.
5. Picture
6. Picture
7. In interphase the DNA is uncoiled. Is the
uncoiled DNA chromatin or chromosomes?
8. In what stage of interphase do cell grow and
develop organelles?
1.
2.
3.
4.
5.
6.
7.
8.
9.
What happens in interphase?
What happens in mitosis?
What is the first stage of the cell cycle?
What is the second stage of the cell cycle?
What is the longest stage of the cell cycle?
List the steps of interphase (in order).
List the steps of mitosis (in order).
Draw and label all stages of mitosis.
Explain what happens in each step
Comparing cell division in plants
and animals
A. Plant cells do not cleave like animal cells.
B. Plant cells do form a cell plate where the
metaphase plate was.
C. Both cell types will enter interphase after
cytokinesis
D. Cell division hyperlink
Plant
Animal
Procedures involving mitosis
A. Growth (when you get bigger)
B. Embryonic development (after the gametes fuse,
the cell divides)
C. Tissue repair (when you get a cut or abrasion)
D. Asexual reproduction (bacteria make copies of
themselves)
Daughter cells are genetically
identical
In mitosis all daughter cells are identical to
the parent cell.
They are genetic duplicates and have the
same DNA.
DNA is always replicated in S phase of
interphase.
There is no recombination or crossing over
of genetic material.
Cancer
A. Cancers (tumors) are the result of
uncontrolled cell division
B. They can occur in any organ or tissue
C. Causes:
-carcinogens: chemicals that increase
the probability of a proto-oncogene
mutation (proto-oncogenes control how
often a cell divides)
C. Causes (continued):
-Viruses: may cause cancer by injecting
their genetic material into the host’s
chromosomes
Example: HPV (human papillomavirus)
is linked to cervical cancer
-Age: changes required for a cell to become
cancerous could take a long time to
develop
-cancer is common in older people
-the longer we live the more chances
there are for mutations to occur
C. Causes (continued):
-Diet: diets high in animal fat have been
linked to cancer
-Environment: sun, asbestos, radiation
-Genetics: family history
D. Types of tumors
1. Benign: non-cancerous tissue caused by
excessive cell division
-typically not harmful, unless it becomes
significantly large
-weight and size can put pressure on
blood vessels, nerves or organs
2. Malignant: cancerous mass of tissue
-cells divide quickly and without order
-can spread to other parts of the body
E. Cancer treatments
1. Surgery: remove all cancerous tissue
before it spreads
-best chance for treatment
-only used when cancer is confined to one
area of the body (breast cancer/testicular
cancer)
E. Cancer treatments
(continued)
2. Radiation: use energy to kill cancer cells
and shrink tumors
-ionized energy is released in a beam and
directed to specific points
-the beam will damage the genetic
material of cancerous cells, making it
impossible for them to reproduce
-side effects: tiredness, skin reactions
E. Cancer treatments
(continued)
3. Chemotherapy: treatment of cancer with
drugs (chemicals)
-work by preventing cancer cells from
multiplying
-side effects: damage to normal cell
Ex: Hair and sperm producing cells
can be damaged (temporarily)
Cancer video
# 18. How cells prevent cancer
A. Tumor suppressor gene
-inhibits cell division
-repairs DNA mistakes
-tell cells when to die (apoptosis)
-about 30 tumor-suppressor genes have
been identified
-if they are inactivated cancerous cells
may develop
# 18. How cells prevent cancer
B. Proto-oncogenes-control how often a
cell divides
C. Oncogene-mutated forms of genes
-cause cells to grow out of control (leads
to cancer)
Get an orange book
1. Complete the following assignment.
p. 40 #1-2 and 4-6
Miscellaneous
Be sure your have an understanding of the
differences between the following terms:
-haploid
-centromere
-diploid
-centrioles
-centrosome
-chromatin
-chromosome
-chromatid