1. Life on a Cellular Level
Mrs. Geist
Biology
Fall

2. Warm-Up 09/08/10 What is a cell?
Does a smaller organism have smaller or fewer cells? Why?
Does a larger organism have larger or a greater number of cells? Why?

3. Standards/Essential Questions
SCOS 2.02 Investigate and describe the structure and function of cells including: cell organelles, cell specialization, communication among cells within an organism.
Essential question(s): - What are the three parts of the cell theory?
What is the relationship between surface area and volume?
Why are there limits on cell size?
Distinguish between prokaryotes and eukaryotes.

4. Cell Size Cell size is limited
Smaller cells are more efficient than larger cells.
Surface area-to-volume ratio decreases as a cell grows larger in size
Harder for larger cells to pass materials in and out of the cell membrane and throughout the cell

5. Surface Area-to-Volume Ratio
To simplify things, we will consider cells to be cuboidal for this exercise.
Surface area = length x width x 6 sides
Volume = length x width x height
Ratio = surface area/volume
Complete the data table

6. Surface Area-to-Volume Ratio
Cell
Dimensions (cm)
Surface Area (cm2)
Volume (cm3)
SA/V Ratio 1
1 x 1 x 1 2
2 x 2 x 2 3
4 x 4 x 4 4
8 x 8 x 8

7. Surface Area-to-Volume Ratio
Cell
Dimensions (cm)
Surface Area (cm2)
Volume (cm3)
SA/V Ratio 1
1 x 1 x 1
= 1 x 1 x 6= 6
= 1 x 1 x 1 = 1
= 6/1 = 6 = 6:1 2
2 x 2 x 2
= 2 x 2 x 6 = 24
= 2 x 2 x 2 = 8
= 24/8 = 3 = 3:1 3
4 x 4 x 4
= 4 x 4 x 6 = 96
= 4 x 4 x 4 = 64
= 96/64 = 1.5 = 3:2 4
8 x 8 x 8
= 8 x 8 x 6 = 384
= 8 x 8 x 8 = 512
= 384/512 = 0.75 = 3:4

8. Why study cells? Cell biology aids in understanding human diseases and the design of therapeutics to treat these diseases.
Duchene muscular
dystrophy
Cystic fibrosis
Sickle cell anemia

9. Multicellular organisms are made up of many different cell types that each carry out a particular function.

10. The Discovery of the Cell
Cells are not visible to the naked eye.
Early Microscopes
In 1665, Robert Hooke used an early compound microscope to look at a thin slice of cork, a plant material.
Cork looked like thousands of tiny, empty chambers.
Hooke called these chambers “cells.”
The cell is the basic unit of life.
Hooke’s Drawing of Cork Cells

11. The Discovery of the Cell
At the same time, Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things.
The microscope revealed a world of tiny living organisms.

12. The History of the Cell
1838- Matthias Schleiden concluded that all plants were made of cells.
1839- Theodor Schwann stated that all animals were made of cells.
1855- Rudolph Virchow concluded that new cells were created only from division of existing cells.
These discoveries led to the cell theory.

13. The Cell Theory All living things are composed of cells.
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells.

14. Cells Cells come in a variety of shapes and sizes. All cells:
are surrounded by a barrier called a cell membrane.
at some point contain DNA.

15. The Nucleus
Cells are classified into two categories, depending on whether they contain a nucleus.
Eukaryotes are cells that contain nuclei.
Prokaryotes are cells that do not contain nuclei.
Nucleus- large membrane-enclosed structure that contains the cell's genetic material (in the form of DNA).
The nucleus controls many of the cell's activities.

16. Nucleus

17. Prokaryotes
Prokaryotic cells have genetic material that is not contained in a nucleus.
do not have membrane-bound organelles.
generally smaller and simpler than eukaryotic cells.
Ex: bacteria

18. Eukaryotes
Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell.
generally larger and more complex than prokaryotic cells.
generally contain dozens of structures and internal membranes.
Many eukaryotic cells are highly specialized.
Ex: Plants, animals, fungi, and protists

19. Rapid Review
09/08/2010
To be completed in class work section of your binder.

20. The cell theory states that new cells are produced from
nonliving material.
existing cells.
cytoplasm.
animals.
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21. The person who first used the term cell was Matthias Schleiden.
Lynn Margulis.
Anton van Leeuwenhoek.
Robert Hooke.
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22. Homework
Define the following terms in your own words: (1) organelle, (2) nucleus, (3) plasma membrane, (4) selective permeability, (5) phospholipid, (6) fluid mosaic model, and (7) transport protein.
Fold your paper in half lengthwise. Terms go on the left-hand side. Definitions go on the right-hand side.
Due tomorrow, Thursday 09/09/10.

23. Warm-up 09/09/10 Describe why oil and water do not mix.
What kinds of substances might need to enter a cell?
What kinds of substances might need to leave a cell?

24. Eukaryotic Cell Structures
Structures within a eukaryotic cell that perform important cellular functions are known as organelles.
Cell biologists divide the eukaryotic cell into two major parts:
Nucleus
The nucleus is the control center of the cell.
Contains nearly all the cell's DNA, which is the coded instructions for making proteins and other important molecules.
Cytoplasm
The cytoplasm is the portion of the cell outside the nucleus.

25. Plant Cell Nucleolus Nucleus Smooth endoplasmic reticulum
Nuclear envelope
Ribosome (free)
Rough endoplasmic reticulum
Ribosome (attached)
Cell wall
Golgi apparatus
Cell membrane
Chloroplast
Mitochondrion
Vacuole
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26. Animal Cell Smooth endoplasmic reticulum Nucleolus Nucleus
Ribosome (free)
Nuclear envelope
Cell membrane
Rough endoplasmic reticulum
Ribosome (attached)
Centrioles
Golgi apparatus
Mitochondrion
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27. The Structure of the Nucleus
Chromatin
Nuclear envelope
Nucleolus
The nucleus controls most cell processes and contains the hereditary information of DNA. The DNA combines with protein to form chromatin, which is found throughout the nucleus. The small, dense region in the nucleus is the nucleolus.
Nuclear pores
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28. The Structure of the Nucleus
The nucleus is surrounded by a nuclear envelope composed of two membranes.
The envelope is dotted with nuclear pores
Nuclear pores allow material to move in and out of the nucleus.
Nuclear envelope
Nuclear pores
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29. Chromatin
The granular material in the nucleus is called chromatin.
Chromatin consists of DNA bound to protein.
Chromatin
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30. Chromosomes
When a cell divides, chromatin condenses to form chromosomes.
Chromosomes contain the genetic information that is passed from one generation of cells to the next.
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31. Nucleolus Nucleolus Most nuclei also contain a nucleolus.
The nucleolus is where the assembly of ribosomes begins.
Nucleolus
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32. Ribosomes
One of the most important jobs carried out in the cell is making proteins.
Proteins are assembled on ribosomes.
Ribosomes are small particles of RNA and protein found throughout the cytoplasm.

33. Ribosomes
Ribosomes produce proteins by following coded instructions that come from the nucleus. Cells that are active in protein synthesis are often packed with ribosomes.
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34. Endoplasmic Reticulum
Eukaryotic cells contain an internal membrane system called the endoplasmic reticulum, or ER.
The endoplasmic reticulum is where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell.
2 types of Endoplasmic Reticulum
Smooth ER
Rough ER

35. Endoplasmic Reticulum
Ribosomes
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36. 2 Types of Endoplasmic Reticulum
Rough Endoplasmic Reticulum
Involved in protein synthesis
Ribosomes are found on the surface of the Rough (ER)
Abundant in cells that produce large amounts of protein for export.
Proteins produced in the Rough ER move into the Golgi apparatus.
Smooth Endoplasmic Reticulum
Does not have ribosomes on its surface.
Contains enzymes that perform specialized tasks
Synthesis of membrane lipids
detoxification of drugs.
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37. Golgi Apparatus
The Golgi apparatus modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell.
From the Golgi apparatus, proteins are then “shipped” to their final destinations throughout the cell or outside of the cell.
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38. Golgi Apparatus
The Golgi apparatus modifies, sorts, and packages proteins.
Notice the stacklike membranes that make up the Golgi apparatus.
The Golgi apparatus modifies, sorts, and packages proteins. Notice the stacklike membranes that make up the Golgi apparatus.
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39. Lysosomes Lysosomes are small organelles filled with enzymes.
Lysosomes break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell.
Lysosomes also break down organelles that have outlived their usefulness.
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40. Vacuoles
Some cells contain saclike structures called vacuoles that store materials such as water, salts, proteins, and carbohydrates.
In many plant cells there is a single, large central vacuole filled with liquid.
The pressure of the central vacuole allows plants to support heavy structures such as leaves and flowers.
Vacuole
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41. Vacuoles
Contractile vacuole
Vacuoles are also found in some unicellular organisms and in some animals.
The paramecium contains a contractile vacuole that pumps excess water out of the cell.
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42. Mitochondria Nearly all eukaryotic cells contain mitochondria.
Mitochondria convert the chemical energy stored in food into compounds that are more convenient for the cell to use.
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43. Mitochondria Mitochondria are enclosed by two membranes outer membrane
inner membrane.
The inner membrane is folded up inside the organelle.
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44. Chloroplasts Plants and some other organisms contain chloroplasts.
Plants and some other organisms contain chloroplasts.
Chloroplasts capture energy from sunlight and convert it into chemical energy in a process called photosynthesis.
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45. Chloroplasts Chloroplasts are surrounded by two membranes.
Chloroplasts contain the green pigment chlorophyll.
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46. Cytoskeleton
Eukaryotic cells are given their shape and internal organization by the cytoskeleton.
The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape.
The cytoskeleton is also involved in movement.
The cytoskeleton is made up of:
microfilaments
microtubules
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47. Cytoskeleton Cell membrane Endoplasmic reticulum Microtubule
The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape and is involved in many forms of cell movement. Microtubules are part of the cytoskeleton that help maintain cell shape.
Microfilament
Ribosomes
Mitochondrion
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48. Cytoskeleton  Microfilaments
are threadlike structures made up of the protein actin.
form extensive networks in some cells.
produce a tough, flexible framework that supports the cell.
help some cells move.
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49. Cytoskeleton  Microtubules
Microtubules are hollow structures made up of proteins known as tubulins.
Microtubules:
maintain cell shape.
are important in cell division.
build projections from the cell surface—cilia and flagella—that enable some cells to swim rapidly through liquids.
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50. Cytoskeleton  Centrioles
In animal cells, structures known as centrioles are formed from tubulin.
Centrioles are located near the nucleus and help to organize cell division.
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51. 7-2 In the nucleus of a cell, the DNA is usually visible as
a dense region called the nucleolus.
the nuclear envelope.
granular material called chromatin.
condensed bodies called chloroplasts.
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52. 7-2 Two functions of vacuoles are storing materials and helping to
break down organelles.
assemble proteins.
maintain homeostasis.
make new organelles.
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53. 7-2 Chloroplasts are found in the cells of plants only.
plants and some other organisms.
all eukaryotes.
most prokaryotes.
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54. 7-2 Which of the following is NOT a function of the Golgi apparatus?
synthesize proteins
modify proteins
sort proteins
package proteins
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55. 7-2 Which of the following is a function of the cytoskeleton?
manufactures new cell organelles
assists in movement of some cells from one place to another
releases energy in cells
modifies, sorts, and packages proteins
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56. 7-2 Which of the following is a function of the cytoskeleton?
manufactures new cell organelles
assists in movement of some cells from one place to another
releases energy in cells
modifies, sorts, and packages proteins
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57. Microscopy

58. How do we study cells?
The invention of the microscope led to the discovery of the cell.
Light microscopes can magnify images up to 1,000 times the actual size.
At higher magnifications, the image blurs and more efficient microscopes are necessary.

59. Microscopes Microscopes vary in magnification and resolving power.
Magnification is the ratio of an object’s image to its real size.
Resolution is the ability to distinguish between 2 points.
Resolution is limited by the wavelength of light.

60. An visual example of how big a cell and its parts are
Magnified by a factor of 10
01_09_Scale.jpg

61. Electron Microscopes
Electron microscopes reveal details times smaller than those visible in light microscopes.
Electron microscopy can be used to visualize only nonliving, preserved cells and tissues.
Transmission electron microscopes (TEMs)
Used to study cell structures and large protein molecules
Specimens must be cut into ultra-thin slices

62. Electron Microscopes Scanning electron microscopes (SEMs)
Produce three-dimensional images of cells
Specimens do not have to be cut into thin slices

63. Scanning Electron micrograph of neurons

64. Confocal Light Microscopes
Confocal Light Microscopes scan cells with a laser beam.
This makes it possible to build 3-D images of cells and their parts.
Confocal Light Micrograph of HeLa Cells

65. Scanning Probe Microscopes
Scanning Probe Microscopes allow us to observe single atoms.
Images are produced by tracing surfaces of samples with a fine probe.
Scanning Probe Micrograph of DNA

66. electron microscopes can be used with live organisms.
Electron microscopes are capable of revealing more details than light microscopes because
electron microscopes can be used with live organisms.
light microscopes cannot be used to examine thin tissues.
the wavelengths of electrons are longer than those of light.
the wavelengths of electrons are shorter than those of light.
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67. Which organism listed is a prokaryote? protist bacterium fungus plant
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68. One way prokaryotes differ from eukaryotes is that they
contain DNA, which carries biological information.
have a surrounding barrier called a cell membrane.
do not have a membrane separating DNA from the rest of the cell.
are usually larger and more complex.
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