1. Biology 11 IB Earland
Topic 2 – Cells
2.1 Cell Theory
2.1.1 Outline the cell theory 2.1.6 Explain the importance of the surface area to volume ratio as a function of
2.1.2 Discuss the evidence for the cell theory limiting cell size
2.1.3 State that unicellular organisms carry out all the functions of life 2.1.7 State that multicellular organisms show emergent properties
2.1.4 Compare relative sizes of molecules, cell membrane thickness, viruses, 2.1.8 Explain that cells in unicellular organisms differentiate to carry out
bacteria, organelles, and cells, using the appropriate SI units specialized functions by expressing some of their genes but not mothers
2.1.5 Calculate the linear magnification of drawings and the actual size of 2.1.9 State that stem cells retain the capacity to divide and have the ability to
specimens in images of know magnification differentiate along different pathways
2.1.10 Outline one therapeutic use of stem cells
Text Book Pages 1-14 Workbook Pages 57-65
The Cell Theory is Summarized into five points listed below:
1. All living things are composed of cells
2. Cells are the smallest unit of life
3. New cells are formed only by the division of pre-existing cells
4. The cell contains inherited information (genes) that provide instructions for growth and development
5. The cell is the site of all the chemical reactions of life (metabolism)
*** 4 & 5 were not part of the original cell theory!
Evidence that Supports the Cell Theory:
Fill in the table below using Table 1.2 p. 4 in your text (in your own words please)
Theory Statement Evidence
Living things are made up of cells
Cells are the smallest units of life
Cells come from pre-existing cells
Cells contain a blueprint for growth,
development, and behavior
Cells are the site of the chemical reactions of
life
So How Big are these Cell Things?
Reference Fig 1.18 in your text & P. in your workbook
Below is a table of the microscope sizes that you should be familiar with:
Unit Abbr. Metric Conversion Conversion factor
Kilometer km 1000m 103 m
m 1m
Centimeter cm 102 m
mm 0.001m
micrometer um 0.000 001m
nm 10-9 m
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2. Biology 11 IB Earland
Feature Actual Size Relative Size Comparison
Molecule 1 nm 1 dime
Membrane thickness 10nm 10x larger 3 text books stacked
Virus 100 nm 100x Grade 8 student
Bacteria 1um 1000x A large classroom
Organelle 10 um 10,000 x school
Animal cell 100 um 100,000x campus
*Molecules are too small to be seen with any time of microscope!
Recall SI Units and Unit Conversions:
5mm = ? nm 4.4cm = ?nm 6.8mm=? um 3.5cm = ? cm 7.1 um = ? cm 1520nm = ?mm
Surface Area to Volume Ratio
Read P. 5 of your text book & Complete p. ` in your Workbook
Write a paragraph in the space below explaining the importance of the surface area to volume ration as a factor limiting
cell size. There are two hints below to help you.
 The rate of heat production/waste production/resource consumption of a cell is a function of its volume
 The rate of exchange of materials and energy (heat) of a cell is a function of its surface area
Drawing Specimens: Complete p. in your workbook
Finding Total Magnification and the Diameter of the Field of View
Total Magnification = (power of the eye piece) x (Power of the objective lens)
Field of View = diameter of circle you can see for each magnification
Using a ruler, you find the field of view for low power (4.5 mm)Then, from this measurement, the FOV for the
other powers is calculated using the formula:
FOVx = FOV low x Maglow Ex: FOVmed = 4.5mm x (40/100) = 1.8 mm
Magx
Power Total Magnification Diameter of FOV in mm Diameter in um
High 400x 0.45 mm 450 um
Medium 100x 1.8 mm 1800 um
Low 40x 4.5 mm 4500 um
Actual Size of Specimen: estimate how many could fit end to end across the diameter of the field of view, then use the
following formula Size of Specimen = diameter of FOV
# of objects the fit across
Drawing Magnification: this is used to determine how many times bigger your drawing is than the actual size
Drawing Magnification = drawing size
Actual size
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3. Biology 11 IB Earland
Scale Bars: Images often carry a scale bar which is a line on the image that shows how long the line is in the real
specimen. The easiest way to add a scale bar is to find the actual size of the specimen and then draw a line beside the
specimen indicating the measurement
Functions of Life:
All organisms exists in either a unicellular or multicellular form and must be able to carry out the following functions:
 Metabolism  Reproduction  Homeostasis
 Growth  Response  Nutrition
Cells
There are two fundamentally different types of cells:
prokaryotes (before a nucleus) - includes bacteria and cyanobacteria (photosynthetic bacteria)
eukaryotes (true nucleus) – where DNA is organized into chromosomes, involving proteins includes
both plant and animal cells
Cell Reproduction & Differentiation:
Unicellular organisms are structurally simple in that they perform all the functions and activities of life within a single cell
Multicellular organisms in contrast, are made up of many cells and therefore most of their cells are highly specialized to do
specific functions.
Emergent Properties of multicellular organisms: the properties in total of a multicellular organism are greater
than the sum of the individual parts
Cell Specialization in Multicellular organisms:
The nucleus of each cell contains DNA in Chromosomes. Chromosomes are linear sequences of Genes, and genes control the
development of each cell.
Gene:
 A specific region of a chromosome which is capable of determining the development of a specific characteristic of an
organism
 A piece of the DNA which codes for a protein
Differentiating: is when a cell becomes specialized because only some of its genes are being activated and expressed. (all cells
contain all the DNA, but each individual cell only uses parts of its DNA depending on its specialization).
 Once a cell has differentiated and become specialized, it can not change its specialization and can only reproduce cells
of the same specialty
Stem Cells: Cells that have not differentiated. Ie. They maintain the ability to divide and differentiate into any cell type.
Research:
o growing embryonic stem cells so they can be used to replace lost cells due to injury
o repair lost brain cells due to Alzheimer’s and Parkinson’s
o Diabetes cure
Controversy: stem cells come from embryos often from IVF laboratories resulting in the death of the embryo.
http://www.youtube.com/watch?v=3Axkn8G18t8
Read p.18 & Understand Fig 1.16
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4. Biology 11 IB Earland
2.2 Prokaryotic Cells
2.2.1 Draw and label a diagram of the ultra-structure of Escherichia coli as an example of prokaryote
2.2.2 Annotate the diagram with the functions of each named structure
2.2.3 Identify structures from 2.2.1 in electron micrographs of E.coli
2.2.4 State that prokaryotic cells divide by binary fission
What is a Prokaryotic Cell?
 First cells on earth
 Common ancestor of all other cells
 Smaller than Eukaryotic cells (<1um)
 Lack membrane bound organelles
 DNA is not enclosed in a membrane
 Cell wall made of peptidoglycan
 Cells divide by Binary Fission (asexual)
 Ex. bacteria
 Basic Features:
o Cell wall o Flagella o Pilli
o Plasma o Ribosomes o Cytoplasm
membrane o Nucleoid
Draw and Annotate Fig 1.15 p. 16 Below of Escherichia coli
What is a disadvantage of prokaryotic cells having DNA free in the cytoplasm without a nuclear membrane?
What is a disadvantage of prokaryotic cells lacking membrane bound organelles?
2.3 Eukaryotic Cells
2.3.1 Draw & Label a diagram of the ultra structure of a liver cells as an example of an animal cell
2.3.2 Annotate the diagram with the functions of each named structure
2.3.3 Identify structures from 2.3.1 in electron micrographs of liver cells
2.3.4 Compare prokaryotic & eukaryotic cells
2.3.5 State three differences between plant and animal cells
2.3.6 Outline two roles of extra cellular components
Read Extension p. 17
Watch “Cell Biology” http://www.youtube.com/watch?v=zufaN_aetZI
-Write a paragraph to summarize what you learned in the video regarding how it is believed that Eukaryotic cells
organelles were once prokaryotes and the evidence that supports this theory.
-Make a time-line outlining the events that the video addressed
Eukaryotic Cells:
Using p. 15 & 16 of your text. Annotate a drawing of both a plant and an animal cell:
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Note: The Nucleus, Endoplasmic Reticulum, Ribosomes, Golgi Apparatus work together in Protein Synthesis
Note: The Chloroplast and Mitochondria work together in Energy production
PLASMA (CELL) MEMBRANE the thin, outer membrane that separates the cell's interior from its external environment. The
plasma membrane also separates each cell from its neighboring cells, so that each cell is an individual entity. It is very thin
(about a billionth of a meter) and requires an electron microscope to see it. Sometimes, the plasma membrane forms fingerlike
projections called MICROVILLI. These microvilli increase the surface area of the plasma membrane.
Some body cells have projections on the cell surface that are involved in cellular movement. CILIA are hairlike cellular
projections that occur in large numbers on the surface of certain cells. The cilia move in unison, creating a current that propels
substances in one direction across the cell surface. FLAGELLA are long in proportion to the size of the cell and are used in
moving the entire cell.
CYTOSOL
The term CYTOPLASM refers to all of the cellular contents located between the plasma membrane and the nucleus. The
semifluid portion of the cytoplasm is the CYTOSOL. The organelles are suspended in the cytosol. So, the cytoplasm includes the
cytosol and all the organelles (except the nucleus). The CYTOSOL is a thick, elastic, semitransparent fluid which contains
mostly water (75-90%). It also contains proteins, lipids, carbohydrates, salts, and other solutes. Many chemical reactions take
place in the cytosol.
CYTOSKELETON
Suspended in the cytosol are very small tubules and filaments that make up the cytoskeleton which provides support and
shape to the cell, and is involved in cellular movement (ex of cilia & flagella). It is the bone and muscle of the cell.
CELL INCLUSIONS
Suspended in the cytosol of some cells are what are called CELL INCLUSIONS. Cell inclusions are chemical substances that are
produced by specific cells and stored in their cytosol.
GLYCOGEN which is a starch-like complex carbohydrate that is stored in liver cells. When the body needs some quick
energy, the liver cells can break down the glycogen into glucose and then use it for energy.
FATS are cell inclusions found in fat cells. Fat can also be broken down to produce energy.
The pigment MELANIN is a cell inclusion stored in certain cells of the skin, hair and eyes.
NUCLEUS is the control center of the cell. It is surrounded by a double-layered membrane called the nuclear envelope. The
nucleus contains DNA, the hereditary genetic material of the cell. DNA controls the structure and activities of a cell by
providing the instructions for protein synthesis. Proteins act as hormones, enzymes, pigments, and structural components of
organelles. A dark staining body, the NUCLEOLUS (or up to four nucleoli) inside the nucleus is the site of ribosome synthesis.
RIBOSOMES receive genetic instructions from the nucleus to produce specific proteins. So, ribosomes are the sites of protein
synthesis. Some of the ribosomes float free in the cytosol; free ribosomes synthesize proteins that are to be used inside the cell.
Other ribosomes are attached to the outer membranes of the ENDOPLASMIC RETICULUM (ER). The ribosomes embedded on
the ER are involved in the synthesis of proteins that are to be exported or SECRETED outside the cell. *All organelles, with the
exception of the ribosomes, are surrounded by a phospholipid bilayer membrane, similar to the plasma membrane.
ENDOPLASMIC RETICULUM is an extensive system of interconnected membrane tubes or channels that coils and twists
through the cytosol. The endoplasmic reticulum membrane is continuous with the nuclear envelope of the nucleus and the
plasma membrane. Endoplasmic reticulum consists of parallel membranes that enclose narrow channels. There are 2 types of
endoplasmic reticulum (ER): smooth ER and rough ER. The SMOOTH ER is smooth because it does not have ribosomes on its
surface. ROUGH ER has ribosomes embedded on its surface.
SMOOTH ER is involved in the production of LIPIDS (fat-like substances). For example, smooth ER produces
CHOLESTEROL, which is part of the plasma membrane. Smooth ER produces STEROID HORMONES such as the sex
hormones (estrogen, progesterone, testosterone), which are secreted from the cell. The smooth ER is also involved in
the DETOXIFICATION of substances: Liver cells have a lot of smooth ER, because smooth ER detoxifies drugs and
alcohol.
ROUGH ER has ribosomes attached to the external surface giving it a granular appearance. As proteins are assembled
on the ribosomes, the proteins make their way into the rough ER channels (cisterns). The rough ER packages these
proteins into round membranous sacs called VESICLES. These vesicles pinch off from the rough ER and make their
way to the GOLGI APPARATUS.
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6. Biology 11 IB Earland
GOLGI APPARATUS looks like 4-8 flattened membrane sacs stacked like dishes. Tiny membranous sacs or VESICLES are
located nearby. The vesicles that bud off from the rough ER migrate to the Golgi apparatus and fuse with the Golgi apparatus
membranes. Inside the Golgi apparatus, the proteins that were made by the ribosomes of the rough ER are modified in some
way. These modified proteins are then packaged in vesicles and sent to their destination. Some of these vesicles contain
proteins that are to be SECRETED or released from the cell. These SECRETORY VESICLES migrate to the plasma membrane
and discharge their contents from the cell. Other vesicles produced by the Golgi apparatus are called LYSOSOMES.
LYSOSOMES are membrane-enclosed spheres that contain powerful digestive enzymes capable of digesting substances that
are inside the cell (intracellular digestion):
- white blood cells, which ingest bacteria, contain large numbers of lysosomes. The digestive enzymes in the lysosome are
used to digest and destroy the ingested bacteria
- Lysosomes can also engulf old, worn-out organelles and break them down with digestive enzymes. The digested
components of the organelles are then returned to the cytosol for recycling into new organelles
MITOCHONDRIA are small, kidney bean-shaped organelles. Each mitochondrion has a smooth outer membrane, but the inner
membrane is made up of a series of folds. Mitochondria are called the "powerhouses of the cell", because they produce ATP
(adenosine triphosphate). ATP is a molecule that stores a great deal of energy. When the cell breaks down ATP, it releases
energy that the cell can use. ATP is like the gasoline that powers your car or the electricity that powers your lights. Active cells,
such as muscle cells and sperm cells, have large numbers of mitochondria because they use a great deal of energy. During the
1980s, Lynn Margulis proposed the theory of endosymbiosis to explain the origin of mitochondria and chloroplasts from
permanent resident prokaryotes. According to this idea, a larger prokaryote (or perhaps early eukaryote) engulfed or
surrounded a smaller prokaryote some 1.5 billion to 700 million years ago. Instead of digesting the smaller organisms the
large one and the smaller one entered into a type of symbiosis known as mutualism, wherein both organisms benefit and
neither is harmed. The larger organism gained excess ATP provided by the "protomitochondrion" and excess sugar provided
by the "protochloroplast", while providing a stable environment and the raw materials the endosymbionts required. This is so
strong that now eukaryotic cells cannot survive without mitochondria (likewise photosynthetic eukaryotes cannot survive
without chloroplasts), and the endosymbionts can not survive outside their hosts. Nearly all eukaryotes have mitochondria.
Mitochondrial division is remarkably similar to the prokaryotic methods that will be studied later in this course.
PLASTIDS
Plastids are also membrane-bound organelles that only occur in plants and photosynthetic eukaryotes, and include
chloroplasts (site of photosynthesis), leukoplasts (storage of starch, proteins and oils) and chromoplasts (storage of pigments
associated with the bright colours of flowers and/or fruits). Chloroplasts are the sites of photosynthesis in eukaryotes. They
contain chlorophyll, the green pigment necessary for photosynthesis to occur, and associated accessory pigments (carotenes
and xanthophylls) in photosystems embedded in membranous sacs, thylakoids (collectively a stack of thylakoids are a granum
[plural = grana]) floating in a fluid termed the stroma. Chloroplasts contain many different types of accessory pigments,
depending on the taxonomic group of the organism being observed. Like mitochondria, chloroplasts have their own DNA,
termed cpDNA. Chloroplasts are thought to have originated by endosymbiosis of a prokaryotic alga.
VACUOLES & VESICLES
Areas of storage for a cell. Vacuoles in plants may occupy salts, ions, and other substances in addition to water. The vacuole
helps keep the cell wall stiff and the plant body crisp. Vesicles is used to describe a cellular product packaged for secretion.
CENTRIOLES
Found in animal cells only, as a pair (in a region called the centrosome). They are composed of sets of microtubules (stringy
protein molecules that also appear near the cell membrane). They form the spindle fibres during cell division.
Summary of Eukaryotic Organelles and Areas
Name Main Function Cell Type
Cytoplasm Contains the Organelles Plant & Animal
Endoplasmic Reticulum Transportation Plant & Animal
Rough ER Protein transport & processing Plant & Animal
Smooth ER Lipid synthesis & transport Plant & Animal
Ribosomes Protein synthesis Plant & Animal
Lysosomes Intracellular digestion Animal & some plant
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7. Biology 11 IB Earland
Golgi Apparatus Storage, packaging & transport Plant & Animal
Mitochondria Cellular Respiration- ATP formation Plant & Animal
Nucleus Control center housing chromosomes Plant & Animal
Chloroplasts Photosynthesis- Glucose production Plant
Centrosome Aids in cell division No centrioles in plant
Vacuole Storage - water Plant Lg & animal sm
Comparison of Prokaryotic & Eukaryotic Cells
Prokaryotic Cells Eukaryotic Cells
DNA in a ring without protein DNA with proteins as chromosomes/chromatin
DNA free in cytoplasm Nucleoid region DNA in nucleus with a nuclear membrane
No membrane bound organelles Membrane bound organelles
Less than 10um More than 10um
Cell wall made of peptidoglycan Cell wall in plants & Fungi, made of cellulose
Small 70S ribosome’s Larger 80S ribosome’s
Comparison of Plant & Animal Cells
Plant Cell Animal Cell
Cell wall with cell membrane inside Plasma membrane with no cell wall
Chloroplasts No chloroplasts
Large central vacuoles No or very small vacuoles
Store carbohydrates as starch Store carbohydrates as glycogen
Do not contain centrioles within the Centrosome area Do contain centrioles within the Centrosome area
Cell wall gives a rigid cell shape that is often angular Lack of cell wall results in cell flexibility and rounding
Extracellular Components of Cells:
The extracellular matrix (ECM) of many cells is made up of collagen fibers & glycoproteins (sugars & proteins) that
form fiber like structures and anchor to the membrane.
 Allow attachment between adjacent cells The plant cell wall maintains cell
 Allow for cell-to-cell interactions shape, prevents excessive water
o Gene expression & coordinated cell action uptake, and holds the whole plant
o Directing differentiation up against the force of gravity.
 Cell migration & movement Animal cells secrete glycoproteins
that form the extracellular matrix.
Answer the following questions: This functions in support, adhesion
1. Why do muscle cells have large numbers of mitochondria? and movement.
2. Name two organelles that are similar to prokaryotic cells.
3. If plants have chloroplasts for photosynthesis, then why do they also need mitochondria
4. Are all Eukaryotic cells part of multicellular organisms? Explain
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8. Biology 11 IB Earland
2.4 MEMBRANES
2.4.1 Draw and label a diagram to show the structure of a membrane
2.4.2 Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes
2.4.3 List the functions of membrane proteins
2.4.4 Define diffusion and osmosis
2.4.5 Explain passive transport across membranes by simple diffusion and facilitated diffusion
2.4.6 explain the role of protein pumps and ATP in active transport across membranes
2.4.7 explain how vesicles are used to transport materials within a cell between the rough E.R., G.A., and plasma membrane
2.4.8 Describe how the fluidity of the membrane allows it to change shape, break and re-form during endocytosis and exocytosis
Membrane Structure: p.21-30
See Fig 2.13 p. 50
Polar Hydrophilic Region (water loving)
Non-Polar Hydrophobic Region (water hating)
See Cross-Sectional View of the Phospholipids bilayer Fig 1.19
p. 21. What is the functional implication of having a double layer of phospholipids?
GO TO YOUR WORKBOOK P. 101 AND USE FIG. 1.17 P. 21 TO ANNOTATE THE DIAGRAM BELOW
A: glycoprotein (carbohydrate attached) to
extrinsic protein
B: carbohydrate (attached to lipid – glycolipid)
C: intrinsic protein
D: carbohydrate (glycolipid)
E: cholesterol
F: phospholipid
inside cells - cytoskeleton
Proteins: - embedded into Fluid Matrix
- Integral Proteins:
- Peripheral Proteins:
Basic Structure: =Proteins
Their 6 general functions are:
 Hormone binding sites  Cell-to-cell communication
 Enzymatic action  Channels for passive transport
 Cell adhesion  Pumps for active transport
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9. Biology 11 IB Earland
Carbohydrate (sugar) attached to proteins act as distinctive antigens by which cells can recognize each other
- glycoprotein -when attached to a protein, the complex is called a glycoprotein
- glycolipids -also exist in the cell membrane, a carbohydrate portion attached to a lipid molecule
Cholesterol is also present in the plasma membrane. Cholesterol is a LIPID (fat-like molecule) that gives rigidity and
strength to the plasma membrane, and is found in the hydrophobic area
Transport Across the Membrane: (IB learning Outcomes 2.4.4 2.4.8 p. 22-30)
- The structure of the cell surface membrane, the nuclear membrane and the membranes of the organelles allow them to
be selectively permeable, and provide for a variety of transport mechanisms.
- Control of the exchange across membranes depends on the physical and chemical properties of the membrane and the
molecules moving through them.
Passive Transport VS Active Transport
Transport Types
1. Diffusion (passive transport – no energy required)
- the movement of molecules from an area of high concentration to low (down a concentration gradient
- caused by random movement of molecules (Brownian motion) – dependent on temperature, size of the
molecules, and size of the gradient
- in cells, diffusion is limited to small molecules and ions that freely move across the membrane: water, oxygen and
carbon dioxide, lipid soluble molecules
- Recall: the rate of diffusion is instrumental in determining cell size
2. Osmosis (passive transport)
- the movement of water from an area of high concentration of water (low concentration of solute) to low
concentration of water (high concentration of solute) through a SELECTIVELY permeable membrane
- described in terms of tonicity of the solution with respect to the cell
- hypertonic solution: has a higher concentration of solute
- hypotonic solution: has a lower concentration of solute
- isotonic solution: has the same concentration of solute
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10. Biology 11 IB Earland
3. Facilitated Diffusion
- involves the use of transport proteins that are specific to
certain solutes – with specific binding sites
- it is believed that the protein changes shape to allow the
transport of a solute down a concentration gradient
4. Active Transport (active – requires an energy input from the
cell)
- involves the use of transport proteins, but takes place against a concentration gradient
- ex: the Na+/K+ pump
5. Endocytosis (active)
- used to transport larger molecules
across the membrane and INTO the
cell
- there are two types of endocytosis
(both consume cell membrane)
- pinocytosis – the cell gulps in
extracellular fluid into small
vesicles
- phagocytosis – the cell extends
pseudopodia and wraps the
particles into a vacuole, which will
later fuse with a lysosome for
digestion
6. Exocytosis (active)
- used to transport large molecules out
of the cell – usually vesicles budded
from the ER or GA
- a vesicle will move towards and fuse
with the cell membrane, spilling its
contents into the extracellular fluid
- exocytosis and endocytosis generally
balance each other resulting in no
change in the size of the cell
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