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Cell Biology

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Information about Cell Biology

Published on November 28, 2007

Author: cgales

Source: slideshare.net

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Exploring the Cellular Basis of Life

 

Cell Theory: All living things are made of one or more cells Cells are the basic units of structure and function in organisms All cells arise from existing cells

Cell Theory:

All living things are made of one or more cells

Cells are the basic units of structure and function in organisms

All cells arise from existing cells

 

Development of the cell theory: Hooke in 1663, observed cork (plant): named the cell Brown observed and named nucleus Schwann in 1800’s states: all animals are made of cells Schleiden in 1800’s states: all plants are made of cells Pasteur’s work with bacteria ~ 1860 disproved idea of spontaneous generation (living things from nonliving) Virchow observes cells dividing and states all cells come from preexisting cells

Development of the cell theory:

Hooke in 1663, observed cork (plant): named the cell

Brown observed and named nucleus

Schwann in 1800’s states: all animals are made of cells

Schleiden in 1800’s states: all plants are made of cells

Pasteur’s work with bacteria ~ 1860 disproved idea of spontaneous generation (living things from nonliving)

Virchow observes cells dividing and states all cells come from preexisting cells

A cell is the simplest structural and functional unit of life. There are no smaller subdivisions of a cell or organism that, in themselves, are alive. An organism’s structure and all of its functions are ultimately due to the activities of its cells. Cells come only from preexisting cells, not from nonliving matter. All life, therefore, traces its ancestry to the same original cells. Because of this common ancestry, the cells of all species have many fundamental similarities in their chemical composition and metabolic mechanisms. Importance of Cell Theory

A cell is the simplest structural and functional unit of life.

There are no smaller subdivisions of a cell or organism that,

in themselves, are alive.

An organism’s structure and all of its functions are ultimately

due to the activities of its cells.

Cells come only from preexisting cells, not from nonliving

matter. All life, therefore, traces its ancestry to the same

original cells.

Because of this common ancestry, the cells of all species have

many fundamental similarities in their chemical composition

and metabolic mechanisms.

Cells are small

Small cells are more efficient Surface area to volume ratio must remain high

 

Features Common to All Cells

 

Prokaryotic Cell

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Crossing the Membrane Cell Membrane Structure and Transport

Cell Membrane Defines cell boundaries Controls interactions with other cells Controls passage of materials in and out of cell (contributes to homeostasis) Fluid-Mosaic model

Defines cell boundaries

Controls interactions with other cells

Controls passage of materials in and out of cell (contributes to homeostasis)

Fluid-Mosaic model

Fluid Mosaic Model of Membranes

Membrane Proteins

Membrane Fluidity

Membrane Permeability Cell membranes are selectively permeable (semi-permeable) Some solutes cross the membrane freely, some cross with assistance, and others do not cross at all.

Cell membranes are selectively permeable (semi-permeable)

Some solutes cross the membrane freely, some cross with assistance, and others do not cross at all.

 

The diffusion of water molecules through a selectively permeable membrane Osmosis will continue as long as there are more water molecules on one side of the membrane (“osmotic pressure”) Water will continue to diffuse until there are equal numbers of molecules inside and outside the cell (“osmotic balance”) Osmosis

60% H 2 O 90% H 2 O

Water will move out of to the left across the membrane until osmotic balance has been reached

100% H 2 O 80% H 2 O

90% H 2 O 90% H 2 O

75% H 2 O 90% H 2 O Water leaves the cell and it shrinks. This is called plasmolysis in plant cells

 

 

 

 

 

 

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