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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”

slide3
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

slide4
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

slide7
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

slide8
3. Analogy

- like the body of a person

organelles = organs

cytosol = everything surrounding organs

iv cell shape and size
IV. Cell Shape and Size
  • 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

slide10
a. Cilia: short, hair-like projections

b. Flagella: long, whip-like projections

slide11
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
  • 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

slide13
- continues until equilibrium is reached (equal concentrations on both sides of membrane)
slide14
- temperature affects diffusion:

higher = faster

- size of particles affects diffusion:

smaller = faster

slide15

97% water

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?

slide16

97% water

90% water

Which way will the water move?

slide17

95% water

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

slide18

95% water

95% water

This solution is isotonic

- no net change

slide19
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

slide20

Na+

  • Important for muscle contraction and nerve impulse transmission

K+

slide22
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

slide23
3. Exocytosis: materials move outside the cell

- wastes and cell products may leave the cell this way

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