IB Topic 2

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IB Topic 2

• Cells

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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

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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

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• 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

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• G. 1855-Rudolph Virchow discovers all organisms
  are made of cells
• organismany living thing

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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

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• 4. Growth and development-heritable programs of
  DNA direct growth and development (change in
  ones shape during life)
• Examples

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• 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)

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• 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.

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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

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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)

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• 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

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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

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Example of stem cell differentiation
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• 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.

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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

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Comparing microscopes
Light microscopes Electron microscopes
Focus beams 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
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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

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Calculating Linear Magnification

• A. The formula-
• Magnification size of image
• size of specimen
• B. Example-the object is magnified by two

This is the original object.
This is the magnified image.
Diameter of the image4cm Diameter of the
specimen2 cm Find the magnification.
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• C. Scale bars - lines added to micrographs of
  drawing to help show the actual size of
  structures
• Ex.
• You must know how to convert between SI Units
  to perform a magnification problem correctly!!
• Ex 1mm 1 x 10-3 m

1 mm
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Common SI Unit Conversions

• 1nm (nanometer) 1 x 10-9 m
• 1um (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

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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.

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• 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.

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• 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
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• 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. 71.25um 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)

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• 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

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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.

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• 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.

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• H. Example

SA l x w x of sides V l x w x h
SA 96 in2 V 64 in3
4
SA 24 in2 V 8 in3
2
4
2
Volume increases faster than the surface area.
In this example the SA increased by 4 and the
volume increased by 8.
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How Big Is A Cell?
OBJECT SIZE
Eukaryotic 10-100 µm
Prokaryotic 1-5 µm
Nucleus 10-20 µm
Chloroplast 2-10 µm
Mitochondrion 0.5-5 µm
Large virus (HIV) 100 nm
Ribosome 25 nm
Cell membrane 7.5 nm
DNA dbl. helix 2 nm
H atom 0.1 nm
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Prokaryotic Cells
E. coli
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Diagram of a typical prokaryote
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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 cells organelles and enzymes
• 4. Pili-help the cell hold
• on to other structures
• and aid in movement

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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)

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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
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Another diagram of a prokaryote
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Prokaryote reproduction

• 1. Most prokaryotes
• divide by binary fission
• 2. Some reproduce by
• budding or filamentous
• growth

http//www.bact.wisc.edu/Microtextbook/index.php?m
oduleBookfuncdisplayarticleart_id112
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Eukaryote Cells
Animal cell
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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

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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

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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

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Diagram of a plant cell
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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

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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

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Homework Outline the roles of extracellular
components in plants (cell wall) and animals
(extracellular matrix).
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Summary of differences between eukaryotes and
prokaryotes!
Prokaryotic Cells Eukaryotic cells
small cells (lt 5 mm) larger cells (gt 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
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Cell Membranes

• A. The Fluid Mosaic Model-model of the plasma
  membrane
• B. Designed by Singer and Nicolson

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• 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
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• E. Amphipathic- has a polar head and a non-polar
  tail
• F. Hydrophilicwater loving (polar)
• -found on inner and outer edges of cell membrane
• G. Hydrophobicwater fearing (non-polar)
• -found inside the cell membrane

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• 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

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• 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

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• O. Protein functions
• -antibody recognition -hormone binding sites
• -electron carriers
• -channels for passive transport
• -pumps for active transport

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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)

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• C. Illustration of diffusion

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• D. Osmosis-passive movement of water from an area
  of low solute concentration to an area of high
  solute concentration
• E. Hypertonic solution-high solute/low solvent
• F. Hypotonic solutions-low solute/high solvent
• G. Isotonic solution-equal solute/solvent

http//www.tvdsb.on.ca/westmin/science/sbi3a1/Cell
s/Osmosis.htm
Look at the red blood cells, not the black
circles.
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• 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)

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GET YOUR BOOK.
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• I. Active Transport
• -requires energy
• -used when diffusion cannot occur
• -substances move up the concentration gradient
  (move from low to high concentrations

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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

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J. The Sodium Potassium Pump (continued)

• -ATP phosphorylationa 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
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K. Other forms of cellular transport

• 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)

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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

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L. Membrane fluidity

• The cell membrane is highly fluid allowing it to
  creating vesicles for endocytosis and exocytosis
• In endocytosis the membrane becomes slightly
  smaller
• In exocytosis the membrane becomes slightly
  larger
• Animation for endocytosis and exocytosis

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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.
  

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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

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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

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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)

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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

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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

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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

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C. Mitosis (continued)

• 4. The stages
• b. Metaphase-
• -Chromosomes
• move to metaphase
• plate
• -centromeres attach
• to spindle fibers

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C. Mitosis (continued)

• 4. The stages
• c. Anaphase-
• -sister chromatids separate and move to
  opposite poles
• -chromatids are now considered chromosomes

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C. Mitosis (continued)

• 4. The stages
• d. Telophase-
• -chromosomes
• arrive at poles
• -spindles disappear
• -chromosomes become chromatin
• -nucleus, nucleolus and nuclear membrane
  reappear

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D. Cytokinesis

• 1. Division of the cell (specifically, the
  cytoplasm)
• 2. It is hard to distinguish cytokinesis from
  telophase

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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?

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1. What happens in interphase?
2. What happens in mitosis?
3. What is the first stage of the cell cycle?
4. What is the second stage of the cell cycle?
5. What is the longest stage of the cell cycle?
6. List the steps of interphase (in order).
7. List the steps of mitosis (in order).
8. Draw and label all stages of mitosis.
9. Explain what happens in each step

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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

Animal
Plant
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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)

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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.

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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)

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• C. Causes (continued)
• -Viruses may cause cancer by injecting their
  genetic material into the hosts 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

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• C. Causes (continued)
• -Diet diets high in animal fat have been
  linked to cancer
• -Environment sun, asbestos, radiation
• -Genetics family history

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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

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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)

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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

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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)

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• Cancer video

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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

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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)

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Get an orange book

• Complete the following assignment.
• p. 40 1-2 and 4-6

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Miscellaneous

• Be sure your have an understanding of the
  differences between the following terms
• -haploid -centromere
• -diploid -centrioles
• -centrosome
• -chromatin
• -chromosome
• -chromatid