1. Chemical origin of Life

2. Cells are the structural and functional units of life
Two distinct groups of cells exist
1. Prokaryotic cells
Simple and small
Do NOT contain a nucleus or membrane-bound organelles
Bacteria are prokaryotic
Regardless of the group studied, cells are enclosed by a membrane and use DNA as their genetic information.
Student Misconceptions and Concerns
1. Many students enter our courses with a limited appreciation of the diversity of life. Ask any group of freshmen at the start of the semester to write down the first type of animal that comes to mind, and the most frequent response is a mammal. As the diversity of life is explored, the common heritage of biological organization can be less, and not more, apparent. The diverse forms, habits, and ecological interactions overwhelm our senses with striking distinctions. Emphasizing the diversity as well as the unifying aspects of life is necessary for a greater understanding of the rich evolutionary history of life on Earth.
2. We live in a world that is largely understood by what we can distinguish and identify with our naked senses. However, the diversity of life and the levels of biological organization extend well below the physical scale of our lives. For many students, appreciating the diversity of the microscopic world is abstract, nearly on par with an understanding of the workings of atoms and molecules. The ability to examine the microscopic details of the world of our students (the surface of potato chips, the structure of table salt and sugar, the details of a blade of grass) can be an important sensory extension that prepares the mind for greater comprehension of these minute biological details.
Teaching Tips
1. Consider asking students to bring to class a page or two of some article about biology that appeared in the media in the last month. Alternatively, you could have each student a Web address of a recent biology-related news event to you. You might even have them relevant articles to you for each of the main topics you address throughout the semester.
2. The scientific organization Sigma Xi offers a free summary of the major science news articles appearing each weekday in major U.S. news media. The first paragraph or so of each article is included in the with a hyperlink to the rest of the article. The diverse topics are an excellent way to learn of general scientific announcements and reports. Typically, 5–10 articles are cited in each . To sign up for this free service, go to
3. Help the class think through the diverse interactions between an organism and its environment. In class, select an organism and have the class develop a list of environmental components that interact with the organism. Items in this list will likely fall into living and nonliving categories.
4. Here is a simple way to contrast the relative size of prokaryotic and eukaryotic cells. Mitochondria and chloroplasts are thought to have evolved by endosymbiosis (see Chapter 16). Thus, mitochondria and chloroplasts are about the size of bacteria, contained within a plant cell. A figure of a plant cell therefore provides an immediate comparison of these sizes, not side-by-side, but one inside the other!
5. Examples of biological form and function relationships are nearly endless. Those immediately apparent to your students will be easiest to comprehend. Have your students examine (in photos or in specimens) the teeth of various vertebrates. The diet of these animals is implied by the shape of the teeth (sharp teeth in carnivorous cats and blunted molars in a rat). Sliding your tongue over your teeth reveals our omnivorous history, with sharp canine teeth for slicing flesh and flat rear molars well-suited for grinding plant material.

3. Possess organelles separated by membranes Contain a nucleus
2. Eukaryotic cells
Possess organelles separated by membranes
Contain a nucleus
Plants, animals, and fungi are eukaryotic

4. Modern Cell Theory Also States:
Life’s chemical processes, such as metabolism, occur inside of cells.
Cells contain hereditary material. Single cells are the units of reproduction.
But...
If all cells arise from other cells, where did the first cell come from?

5. Abiogenesis Revisited
Could early cells have formed from nonliving matter?
Alexander Oparin and J.B.S. Haldane in the 1920’s thought they could, but not in today’s oxygen-rich atmosphere.
Could this hypothesis be tested?

6. Conditions on early Earth made the origin of life possible
Conditions on early Earth made the origin of life possible
A recipe for life
Raw materials +
Suitable environment
Energy sources
Student Misconceptions and Concerns
1. Students might not have considered that cells today are not created from scratch. Unlike baking a cake or constructing an automobile, where components are assembled to create something new, the reproduction of cells does not currently involve anything other than cells.
2. Some students might think that scientists have answers for all of life’s questions. Other students might rely upon supernatural explanations when faced with scientific uncertainty. The material in this chapter provides a good opportunity to further distinguish between the process of science and other ways of knowing.
3. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60  60  24   31,557,600) or how much money you could spend each day if you spent $1 million dollars a year ($1,000,000/365  $2,739.73/day).
4. Students may need to be reminded that one billion is 1,000 million. Many students (and some politicians) easily confuse million and billion without realizing the scale of the error. Challenge students to translate either of the examples above to illustrate one billion. (For example, one billion seconds equals about 31.7 years. If you were to spend one billion dollars in a year, you would need to spend $2,739,730 each day of that year!)
Teaching Tips
1. Students who have studied cell theory might wonder how the first cells formed. Furthermore, they might wonder if spontaneous generation of cells could occur today. Module 15.1 describes how conditions on the surface of Earth when life first formed were dramatically different from today. Furthermore, if new life were evolving on Earth today, it would face competition from the vast amount of life already present.
2. Consider pointing out the logic of the theory of spontaneous generation, given the state of scientific knowledge during that period in history. Piles of manure and rotting flesh left in the open would apparently produce flies out of nowhere. At that time, so little was understood about eggs, sperm, and fertilization that spontaneous generation was a logical conclusion.
3. The four-stage hypothesis for the origin of life is a little like a recipe for building cells from the bottom up. If your students do not remember details about biological molecules and basic cell structure, you may need to review them before addressing these stages.
4. At some point in the presentation of the four-stage hypothesis for the origin of life, students should be encouraged to consider at what point “life” exists. Are self-replicating, RNA-based, membrane-bound structures alive? Discussing the evolution of the first cells helps clarify definitions of life.
Copyright © 2009 Pearson Education, Inc.

7. The possible composition of Earth’s early atmosphere
The possible composition of Earth’s early atmosphere
H2O vapor
Compounds from volcanic eruptions present:
N2, nitrogen oxides, CO2, CH4 (methane), (ammonia) NH3 , H2, and H2S
As the Earth cooled
water vapor condensed into oceans,
hydrogen escaped into space
Student Misconceptions and Concerns
1. Students might not have considered that cells today are not created from scratch. Unlike baking a cake or constructing an automobile, where components are assembled to create something new, the reproduction of cells does not currently involve anything other than cells.
2. Some students might think that scientists have answers for all of life’s questions. Other students might rely upon supernatural explanations when faced with scientific uncertainty. The material in this chapter provides a good opportunity to further distinguish between the process of science and other ways of knowing.
3. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60  60  24   31,557,600) or how much money you could spend each day if you spent $1 million dollars a year ($1,000,000/365  $2,739.73/day).
4. Students may need to be reminded that one billion is 1,000 million. Many students (and some politicians) easily confuse million and billion without realizing the scale of the error. Challenge students to translate either of the examples above to illustrate one billion. (For example, one billion seconds equals about 31.7 years. If you were to spend one billion dollars in a year, you would need to spend $2,739,730 each day of that year!)
Teaching Tips
1. Students who have studied cell theory might wonder how the first cells formed. Furthermore, they might wonder if spontaneous generation of cells could occur today. Module 15.1 describes how conditions on the surface of Earth when life first formed were dramatically different from today. Furthermore, if new life were evolving on Earth today, it would face competition from the vast amount of life already present.
2. Consider pointing out the logic of the theory of spontaneous generation, given the state of scientific knowledge during that period in history. Piles of manure and rotting flesh left in the open would apparently produce flies out of nowhere. At that time, so little was understood about eggs, sperm, and fertilization that spontaneous generation was a logical conclusion.
3. The four-stage hypothesis for the origin of life is a little like a recipe for building cells from the bottom up. If your students do not remember details about biological molecules and basic cell structure, you may need to review them before addressing these stages.
4. At some point in the presentation of the four-stage hypothesis for the origin of life, students should be encouraged to consider at what point “life” exists. Are self-replicating, RNA-based, membrane-bound structures alive? Discussing the evolution of the first cells helps clarify definitions of life.
Copyright © 2009 Pearson Education, Inc.

8. Many energy sources existed on the early Earth
Many energy sources existed on the early Earth
Intense volcanic activity, lightning, and UV radiation
Evidence suggests that 3.5 billion years ago, photosynthetic bacteria appeared
Student Misconceptions and Concerns
1. Students might not have considered that cells today are not created from scratch. Unlike baking a cake or constructing an automobile, where components are assembled to create something new, the reproduction of cells does not currently involve anything other than cells.
2. Some students might think that scientists have answers for all of life’s questions. Other students might rely upon supernatural explanations when faced with scientific uncertainty. The material in this chapter provides a good opportunity to further distinguish between the process of science and other ways of knowing.
3. Most of us are unable to comprehend the vast lengths of time considered by geologists. Exercises and examples can increase this comprehension. Consider the number of seconds in a year (60  60  24   31,557,600) or how much money you could spend each day if you spent $1 million dollars a year ($1,000,000/365  $2,739.73/day).
4. Students may need to be reminded that one billion is 1,000 million. Many students (and some politicians) easily confuse million and billion without realizing the scale of the error. Challenge students to translate either of the examples above to illustrate one billion. (For example, one billion seconds equals about 31.7 years. If you were to spend one billion dollars in a year, you would need to spend $2,739,730 each day of that year!)
Teaching Tips
1. Students who have studied cell theory might wonder how the first cells formed. Furthermore, they might wonder if spontaneous generation of cells could occur today. Module 15.1 describes how conditions on the surface of Earth when life first formed were dramatically different from today. Furthermore, if new life were evolving on Earth today, it would face competition from the vast amount of life already present.
2. Consider pointing out the logic of the theory of spontaneous generation, given the state of scientific knowledge during that period in history. Piles of manure and rotting flesh left in the open would apparently produce flies out of nowhere. At that time, so little was understood about eggs, sperm, and fertilization that spontaneous generation was a logical conclusion.
3. The four-stage hypothesis for the origin of life is a little like a recipe for building cells from the bottom up. If your students do not remember details about biological molecules and basic cell structure, you may need to review them before addressing these stages.
4. At some point in the presentation of the four-stage hypothesis for the origin of life, students should be encouraged to consider at what point “life” exists. Are self-replicating, RNA-based, membrane-bound structures alive? Discussing the evolution of the first cells helps clarify definitions of life.
Copyright © 2009 Pearson Education, Inc.

9. “Primordial Soup” Theory
Early Earth had an atmosphere (H2O, NH3 ,& CH4)
(Life requires: Carbon, Nitrogen, Oxygen, & Hydrogen)
Energy source produced simple organic compounds
These compounds accumulated in a “soup” near shorelines, ocean vents, etc
Eventually more complex compounds formed, leading to life

10. The Miller-Urey experiment.
Several of the chemical compounds thought to have been present on the early Earth were mixed and subjected to electrical discharges. Within a few weeks, amino acids had formed.

11. Repeated Experiments
Stanley Miller repeated the experiments in Multiple ways using different energy sources, and refining the gas mixtures as scientists better understood the early earth’s atmosphere.
The results still showed that organic molecules can form under early Earth’s conditions.

12. Miller-Urey Experiment

13. Discoveries Since the Cell Theory

14. ENDOSYMBIOTIC THEORY
In 1970, American biologist, Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves
Supporting evidence included organelles with their own DNA
Chloroplast and Mitochondria

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16. http://highered. mheducation

17. Common Features of All Cells (Both Prokaryotic and Eukaryotic )
DNA
Cell membrane (plasma membrane)
Ribosomes
Cytoplasm

18. Organelles
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19. Organelles Very small (Microscopic)
Perform various functions for a cell
Found in the cytoplasm
May or may not be membrane-bound
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20. Animal Cell Organelles
Ribosome (attached)
Nucleolus
Ribosome (free)
Nucleus
Cell Membrane
Nuclear envelope
Mitochondrion
Smooth
endoplasmic
reticulum
Rough
endoplasmic
reticulum
Centrioles
Golgi apparatus
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21. Plant Cell Organelles
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22. The Control Organelle - Nucleus
Controls the normal activities of the cell
Contains the DNA in chromosomes
Bounded by a nuclear envelope/membrane
with pores
Usually the largest organelle

23. Inside the Nucleus - The genetic material (DNA) is found
DNA is condensed & wrapped around proteins forming
as CHROMOSOMES in dividing cells
DNA is spread out
And appears as CHROMATIN in non-dividing cells
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24. Nucleolus Inside nucleus Makes ribosomes that make proteins
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25. Nuclear Envelope Double membrane surrounding nucleus
Also called nuclear membrane
Contains nuclear pores Connected to the rough ER
Nuclear pores
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26. Cytoplasm of a Cell Jelly-like substance enclosed by cell membrane
Contains organelles to carry out specific jobs
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27. Cytoskeleton Helps cell maintain cell shape
Also help move organelles around
Made of proteins called
Microtubules
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28. Cytoskeleton
MICROTUBULES
MICROFILAMENTS
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29. Cell or Plasma Membrane
Composed of double layer of lipids and proteins
Surrounds outside of ALL cells
Controls what enters or leaves the cell
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
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30. Cell Wall Found in plants, fungi, & bacteria
Supports and protects cell
Found outside of the cell membrane
Found in plants, fungi, & bacteria

31. Vacuoles Small or absent in animal cells
Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes
Small or absent in animal cells
Plant cells have a large Central Vacuole
No vacuoles in bacterial cells

32. Contractile Vacuole Found in unicellular protists like paramecia
Regulate water intake by pumping out excess (homeostasis)
Keeps the cell from lysing (bursting)
Contractile vacuole animation

33. Chloroplasts
Found only in producers (organisms containing chlorophyll)
Use energy from sunlight to make own food (glucose)
Contains its own DNA
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34. Endomembrane System
Includes nuclear membrane connected to ER connected to cell membrane (transport)
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35. Endoplasmic Reticulum - ER
Network of hollow membrane tubules
Connects to nuclear envelope & cell membrane
Functions in Synthesis of cell products & Transport
Two kinds of ER ---ROUGH & SMOOTH
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36. Rough Endoplasmic Reticulum (Rough ER)
Proteins are made by ribosomes on ER surface
They are transferred rough ER to be modified and transported
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37. Rough Endoplasmic Reticulum (Rough ER)
Has ribosomes
Makes membrane proteins and proteins for EXPORT out of cell
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38. Smooth Endoplasmic Reticulum
Smooth ER lacks ribosomes
Is attached to the ends of rough ER
Makes membrane lipids (steroids)
Destroys toxic substances (Liver)

39. Can be attached to Rough ER Be free (unattached) in the cytoplasm
Ribosomes
Can be attached to Rough ER OR
Be free (unattached) in the cytoplasm
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40.  Ribosomes “Protein factories” for cell
Join amino acids to make proteins
Process called protein synthesis 

41. Golgi Bodies CIS Transport vesicle Stacks of flattened sacs
Have a shipping side receiving side.
Receive proteins made by ER
Transport vesicles with modified proteins pinch off the ends
CIS
TRANS
Transport vesicle
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42. Golgi Bodies Modify, sort, & package molecules from ER
Look like a stack of pancakes
Modify, sort, & package
molecules from ER
for storage OR transport out of cell
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43. Golgi Animation
Materials are transported from Rough ER to Golgi to the cell membrane by VESICLES

44. Lysosomes Contain digestive enzymes
Break down food, bacteria, and worn out cell parts for cells
Programmed for cell death (AUTOLYSIS)
Lyse (break open) & release enzymes to break down & recycle cell parts)

45. Lysosome Digestion
Lysosomes digest the food & get rid of wastes

46. Generate cellular energy (ATP)
Mitochondrion
“Powerhouse” of the cell
Generate cellular energy (ATP)
Both plants & animal cells have mitochondria
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47. Interior called MATRIX
MITOCHONDRIA
Surrounded by a DOUBLE membrane
Has its own DNA
Folded inner membrane called CRISTAE (increases surface area for more chemical
Reactions)
Interior called MATRIX

48. Interesting Fact ---
Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …
You inherit your mitochondria from your mother!
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49. Cilia & Flagella Made of microtubules Function -moving cells
-moving small particles across the cell surface
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50. Cilia & Flagella Cilia are shorter and more numerous on cells
Flagella are longer and fewer (usually 1-3) on cells
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51. Centrioles Found only in animal cells Paired structures near nucleus
Made of bundle of microtubules
Appear during cell division forming mitotic spindle
Help to pull chromosome pairs apart to opposite ends of the cell
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52. Centrioles & the Mitotic Spindle
Made of MICROTUBULES (Tubulin)
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53. What is unique about Animal Cells?
Animal cells have centrioles which help in cell reproduction and division.
Animal cells typically have smaller vacuoles!
Animal cells have cilia and flagella!

54. Cell Specialization
Cells in a multi-cellular organism become specialized by turning different genes on and off
This is known as DIFFERENTIATION
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55. Specialized Animal Cells
Muscle cells
Red blood cells
Cheek cells
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56. Specialized Plant cells
Pollen
Xylem cells
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57. What is unique about Plant Cells?
Plant cells are generally larger than animal cells.
Plant cells have cell walls that help to support the cells.
Plant cells have chloroplasts that make the cell’s food.
Plant cells have one large vacuole.