Biology Unit 2 Cell Biology

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Biology Unit 2 Cell Biology

• Ch 4 Cell Structure and Function
• Ch 5 Homeostasis and Cell Transport
• Ch 6 Photosynthesis
• Ch 7 Cellular Respiration
• Ch 8 Cell Reproduction

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Chapter 4 Cell Structure and Function

• 4-1 The History of Cell Biology
• 4-2 Introduction to Cells
• 4-3 Cell Organelles and Features
• 4-4 Unique Features of Plant Cells

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4-1 The History of Cell Biology

• Name the scientists who first observed living and
  nonliving cells.
• Summarize the research that led to the
  development of the cell theory.
• State the three principles of the cell theory.
• Explain why the cell is considered to be the
  basic unit of life.

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The Discovery of Cells

• Cell the smallest unit of matter that can carry
  on all of the processes of life.
• Discovery of cells was made possible by the
  development of the microscope in the early 17th
  century.

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Robert Hooke (1635 1703)

• English scientist
• 1665 Used light microscope to examine a thin
  slice of cork and observed little boxes he
  named cells after rooms that monks live in.
  (Looked at the remains of dead plant cells)

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• Looked at tree stems, roots, ferns. All had
  similar little boxes.

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Anton van Leeuwenhoek (1632-1723)

• Dutch microscope maker. Precisely ground lenses.
  10 more powerful than Hookes
• First to observe living cells in 1673.
  microscopic organisms.

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• Named the microscopic organisms animalcules
  algae, protists

Algae - Spirogyra
Protist - Vorticella
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Founders of The Cell Theory

• Matthias Schleiden
• Theodor Schwann
• Rudolf Virchow

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Matthias Schleiden (1804 1881)

• German botanist.
• 1838 concluded that all plants are composed of
  cells.

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Theodor Schwann (1810-1882)

• German zoologist
• In 1839 concluded that all animals are made of
  cells.

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Rudolf Virchow (1821-1902)

• Physician, studying how disease affects living
  things.
• In 1855 reasoned that cells come only from other
  cells.

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The Cell Theory

• All living things are composed of 1 or more
  cells.
• Cells are the basic units of structure and
  function in an organism.
• Cells come only from the reproduction of existing
  cells.

Narration Cell Theory
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Developments in Cell Biology

• Fig 4-3 p71. The study of cell biology began with
  the discovery of the cell by Robert Hooke in
  1665. Since then constantly improving technology
  has allowed scientists to unlock the secrets of
  the cell.

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The Cellular Basis of Life

• Microscopes helped biologists clarify our
  definition of life.
• All living things share several basic
  characteristics
• Organized parts
• Obtain energy from their surroundings
• Perform chemical reactions
• Change with time
• Respond to their environment
• Reproduce

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• Living things must also maintain homeostasis
• Separate their relatively stable internal
  environment from an ever changing external
  environment.
• All living things also share a common history.
• All cells share characteristics that indicate
  they are related.

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4-2 Introduction to Cells

• Explain the relationship between cell shape and
  cell function.
• Identify the factor that limits cell size.
• Describe the three basic parts of a cell.
• Compare prokaryotic cells and eukaryotic cells.
• Analyze the relationship among cells, tissues,
  organs, organ systems, and organisms.

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Cell Diversity
Cells have various shapes. A. Nerve cells have
long extensions. B. Skin cells are flat and
plate-like. C. Egg cells are spherical. D. Some
bacteria are rod-shaped. E. Some plant cells are
rectangular.

• Cell shape
• Cell size

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Cell Shape

• Variety of shapes or diversity of form reflects a
  diversity of function (form follows function)

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• At least 200 types to suit diverse functions.

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Cell Size

• Wide diversity in size
• giraffes nerve cell in leg 2 m
• most plants and animal cells 10-50 micrometers
  (Size of period at end of sentence)
• Bacteria .2 micrometers.

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• Limited in size by surface area-to-volume ratio.
• As a cell grows, volume increases more rapidly
  than surface area.
• Nutrients, oxygen, and other materials a cell
  requires must enter through its surface. Wastes
  must exit.
• If cell were to become very large, volume would
  increase much more than the surface area. This
  would not allow materials to pass through quickly
  enough.

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Basic Parts of a Cell

• All cells have an outer boundary, an interior
  substance, and a control region
• Plasma Membrane
• Cytoplasm
• Control Center

Basic Parts Narration
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Plasma Membrane / Cell Membrane

• Covers cells surface and acts as a barrier
  between inside/outside
• All materials enter or exit through plasma
  membrane

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Cytoplasm

• Region of cell within plasma membrane that
  includes the fluid, cytoskeleton, and all of the
  organelles except the nucleus.

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• Gelatin-like aqueous fluid called cytosol
• The part of the cytoplasm that includes molecules
  and small particles such as ribosomes, but not
  membrane-bound organelles. 20 protein.

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Control Center

• Coded info in the form of DNA for regulating cell
  functions and cell reproduction.
• In prokaryotes, DNA floats freely in the cell
• Eukaryotes have a nucleus, membrane-bound
  organelle that contains the cells DNA
• Often most prominent structure
• Maintains its shape with help of protein skeleton
  called nuclear matrix

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Two Basic Types of Cells

• Fossil evidence suggests that the earliest cells
  on Earth were simple, similar to some present day
  bacteria.
• As cells evolved, they differentiated into 2
  major types prokaryotes and eukaryotes.

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Eukaryotes

• Organisms whose cells contain a membrane-bound
  nucleus and membrane-bound organelles.
• Organelle
• Well-defined, intracellular bodies that perform
  specific functions for the cell. (like little
  organs)
• Many are surrounded by a membrane

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Prokaryotes

• Unicellular organisms that lack a membrane-bound
  nucleus and membrane-bound organelles.
• Genetic info (DNA) may be concentrated in one
  area of the cell nucleoid

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A prokaryotic cell lacks a membrane-bound nucleus
and membrane-bound organelles. Most prokaryotic
cells are much smaller than eukaryotic cells.
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• Two domains
• Bacteria similar to first cellular life forms
• Archaea organisms thought to be more closely
  related to eukaryotic cells found in all other
  kingdoms.

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Comparison Narration
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Cellular Organization

• Unicellular one cell carries out all of the
  functions of life
• Colonies / Colonial Organisms collection of
  genetically identical cells that live together in
  a connected group.
• Not truly multicellular because few cell
  activities are coordinated

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Anabaena
Spyrogyra
Volvox an example of a colonial organism
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• True multicellularity
• Cells are specialized
• Cells depend on other cells in the organism for
  their survival. Groups of similar cells and their
  products carry out a specific function.
• Cells ?tissues ? organ ? organ system ? organism