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Chapter 7 Notes . Cell Structure and Function. Cells and Cell Theory. Cell: the basic unit of all forms of life History Robert Hooke (1665) - described the empty chambers of cork as “cells”. 2. Matthias Schleiden (1838) - all plants are made of cells

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Chapter 7 notes

Chapter 7 Notes

Cell Structure and Function


Cells and cell theory
Cells and Cell Theory

  • Cell: the basic unit of all forms of life

  • History

    • Robert Hooke (1665)

      - described the empty chambers of cork as “cells”


2. Matthias Schleiden (1838)

- all plants are made of cells

3. Theodor Schwann (1839)

- all animals are made of cells

4. Rudolph Virchow (1855)

- all cells come from preexisting cells

** before this, people believed in spontaneous generation


  • Cell Theory

    1. All living things are composed of 1 or more cells

    2. Cells are the basic units of life

    3. All cells come from preexisting cells

    ** exception: viruses?


Ii prokaryotes and eukaryotes
II. Prokaryotes and Eukaryotes

  • Prokaryotic cells do not have nuclei

    - example: all bacteria

  • Eukaryotic cells have nuclei and organelles

    - example: plants, animals, fungi


Iii cell structures
III. Cell Structures

  • Cytoplasm: everything between the membrane and nucleus

    1. Structure

    a. Cytosol: jelly-like mixture consisting of water, proteins, carbohydrates, and other organic compounds


b. Organelles: structures that work like miniature organs, carrying out specific functions in the cell (suspended in the cytosol)

2. Function

a. Biological reactions take place in the cytosol

b. Organelles each have specific jobs within the cell


3. Analogy miniature organs, carrying out specific functions in the cell (suspended in the cytosol)

- like the body of a person

organelles = organs

cytosol = everything surrounding organs


Iv cell shape and size
IV. Cell Shape and Size miniature organs, carrying out specific functions in the cell (suspended in the cytosol)

  • Maintenance of shape

    1. In plants: cell wall

    2. In animals: cytoskeleton

  • Cytoskeleton

    - consists of 2 types of structures

    1. Microtubules: hollow tubes made of tubulin


a. Cilia: short, hair-like projections miniature organs, carrying out specific functions in the cell (suspended in the cytosol)

b. Flagella: long, whip-like projections


2. Microfilaments: NOT hollow – 2 twisted chains of proteins (like a rope)

  • Size of Cells

    - can vary from 1 micrometer (bacteria) to 1 meter (nerve cell)


Movement through the membrane
Movement through the Membrane of proteins (like a rope)

  • The cell membrane is semipermeable

    - only certain molecules can get through

  • Passive transport: no energy required

    1. Diffusion: the movement of molecules from a region of high concentration to a region of low concentration


- continues until equilibrium is reached (equal concentrations on both sides of membrane)


- temperature affects diffusion: concentrations on both sides of membrane)

higher = faster

- size of particles affects diffusion:

smaller = faster


97% water concentrations on both sides of membrane)

100% water

2. Osmosis: the diffusion of water across a membrane from high water concentration to low water concentration

Which way will the water move?


97% water concentrations on both sides of membrane)

90% water

Which way will the water move?


95% water concentrations on both sides of membrane)

95% water

90% water

98% water

This solution is hypertonic

- water diffuses out of the cell

This solution is hypotonic

- water diffuses

into the cell


95% water concentrations on both sides of membrane)

95% water

This solution is isotonic

- no net change


3. Facilitated diffusion: uses protein channels to move molecules from high concentration to low concentration

  • Active Transport: energy required

    1. Carrier proteins may act as pumps

    -example: sodium-potassium pump

    a. Cells continually pump potassium ions into the cell, and sodium ions out


Na move molecules from high concentration to low concentration+

  • Important for muscle contraction and nerve impulse transmission

K+


2. Endocytosis: materials move into cell move molecules from high concentration to low concentration


a. Pinocytosis: membrane encloses a fluid droplet and brings it inside the cell

b. Phagocytosis: membrane encloses a large particle and brings it inside the cell


3. Exocytosis: materials move outside the cell and brings it inside the cell

- wastes and cell products may leave the cell this way


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