Transcript The Cell Theory - s3.amazonaws.com

Anton Van Leeuwenhoek – 1600’s
Dutch merchant
used magnifying
glass to view cloth
 Developed first
usable microscope.
 First person to view
small organisms in
pond water.

Leeuwenhoek first to view bacteria
Leeuwenhoek took
samples of pond water
and view them
through his
microscope.
 Spirochetes
 Algae
 Protists
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Robert Hooke develops simple
microscope- 1665
English physicist,
developed first simple
compound microscope
 View cork under
microscope, saw tiny box
like structures
 Called these structures
cellulae(monks chamber)

Hooke first to use the term cell

Hooke had discovered
plant cells -- more
precisely, what Hooke saw
were the cell walls in cork
tissue. In fact, it was
Hooke who coined the
term "cells": the boxlike
cells of cork reminded him
of the cells of a
monastery.
Schleiden and Schwann develop Cell
Theory- 1838
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The Cell Theory When
Schleiden and Schwann
proposed the cell theory
in 1838, cell biology
research was forever
changed. The cell
theory states that:
All life forms are made
from one or more cells.
The cell is the smallest
form of life.
Virchow modifies Cell Theory
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Twenty years later in
1855 Rudolf Virchow
proposed an important
extension of cell theory
that "All living cells
arise from preexisting cells".
("Omnis cellula e
celula") This statement
has become what is
known as the "Biogenic
law".
Basic Cell Structure
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Cells range in size from
0.2um to 7 ft.
All cells have certain
basic structures.
Cell Membrane – thin
flexible layer,usually a
bi-layer of phospholipids
Cytoplasm – colloidal
material, acts as
cushion
Two basic types of cells
Prokaryotic cells – “pre-kernel” most
likely first type of cell. Capable of
carrying out all requirements of life.
Unicellular organisms only
 Eukaryotic cells- “true-kernel” most
abundant type of cells. Both unicellular
and multicellular organisms.

Prokaryotic Cells – Bacteria cells only
No membrane
bound organelles.
 No nucleus
 Simpler of the two
types.
 Bacteria cells only
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Eubacteria
Archeabacteria
Eukaryotic Cells- Protista, Fungi,
Plants, and Animals
Membrane bound
organelles present
 Nucleus present
 Most complex of the
two types of cells

Cell Structures
Cell Membrane – all
cells have a cell
membrane
 composed of a bi-layer
of phospholipids.
 Hydrophilic – water
loving
 Hydrophobic – water
fearing
 selectively permeable.
 flexible, but strong

Hydrophobic
Inside of cell
Hydrophilic
Outside of Cell
Plant cells and certain prokaryotic
cells have cell walls
Function
 Provides support
and protection for
cell.
 Composed of
cellulose and pectin.
 NOT FOUND IN
ANIMALS
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NUCLEUS
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First identified by Robert
Brown,1831
Nucleus functions as the
control center for cell.
Contains:
Chromatin –appears as
a granular material,
consists of DNA and
proteins
Nucleolus – assembles
ribosomes
Nuclear envelope –
surrounds nucleus
CYTOSKELETON
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Gives cell shape,
support, movement
and is used during
mitosis to aids in cell
division.
Composed of two
primary filaments.
Microtubules –
hollow tubes of
protein, used to
maintain shape, aid
in movement and
especially important
in cell division.
CYTOSKELETON
Microfilaments – also known as actin
filaments, small actin protein filaments.
 Provides support for cell, and aids in the
movement of organelles with in the
cells
 Certain cytoskeleton proteins will
become cilia or flagellum.
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Organelles in the cytoplasm
Ribosomes can be
considered the
matchmakers of the
protein making
process.
 Ribosomes are either
free floating in the
cytoplasm of a cell or
attached to
endoplasmic
reticulum in a cell.

Organelles
Endoplasmic reticulum
(ER)
 Two types, smooth no
ribosomes attached,
rough ribosomes are
attached.
 ER assembles
components for cell
membrane.Helps to
modify certain proteins

Organelles
Golgi Apparatus –
consists of many
folded and stacked
membranes
 Packages and moves
proteins to their
final destination.
 Attaches
carbohydrates and
lipids to proteins.
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Organelles
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Lysosomes – enzyme
containing sacks.
Releases enzymes to
break down lipids,
carbohydrates and
proteins.
 Breaks down old
organelles, removes
debris and recycles
it.
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Organelles
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Vacuole- stores materials
such as water, salt and
carbohydrates.
Saclike structure, most
plants will have a large
single vacuole. The
pressure in this large
vacuole helps give support
to heavy structure in
plants. Animals will have
several small vacuoles also
called vesicles.
Vacuole
Organelles
Mitochondria – powerhouse
of the cell. Take glucose
and converts it to energy
that the cell can use (ATP).
 Double folded membrane
found in over 97% of all
eukaryotic cells, including
plant cells.
 Once believed to be its own
organism.
 Has its own DNA
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Organelles – special to plants
Chloroplasts – used in
photosynthesis.
Converts light energy
to chemical energy.
 Found in plants and
certain protists. NEVER
in ANIMAL CELLS.
 Contains chlorophyll
and other pigments.
 Has its own DNA

Origin of the Cell
First cells believed to be a prokaryotic.
 Built in mechanisms for survival.
 Eukaryotic cells believed to have formed
a symbiotic relationship with prokaryotic
organisms.
 Mitochondria and Chloroplasts believed
to have been separate prokaryotic
organisms at one time. DNA in these
organelles come from mother only.
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The primordial Earth was a very different place than
today, with greater amounts of energy, stronger storms,
etc. The oceans were a "soup" of organic compounds
that formed by inorganic processes (although this soup
would not taste umm ummm good). Miller's (and
subsequent) experiments have not proven life
originated in this way, only that conditions thought to
have existed over 3 billion years ago were such that
the spontaneous (inorganic) formation of organic
macromolecules could have taken place.
Getting things into the cell
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The cell membrane is a
selectively permeable
membrane, but things must
get into the cell.
Water can enter the cell
through a process called
Osmosis.
Glucose will enter the cell
through facilitated diffusion
Large protein move into the
cell by endocytosis
Diffusion
Diffusion is the movement of molecules
from a region in which they are highly
concentrated to a region in which they
are less concentrated.
 Does not require any energy (passive).
 Allows particles to reach lowest state of
energy.
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Diffusion Across Cell
Membrane
Molecules such as:
 Oxygen
 Carbon dioxide
 Nitrogen
 Important to allow cell to function when
energy is not available
 Allows for respiration to occur
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Osmosis
Movement of water from an area of low
solute to an area of higher solute.
 No energy required (passive)
 Only water moves
 Major method of getting water into the
cell.
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Osmosis
Osmosis
Solutions and Concentrations
Hypertonic solutions contain higher concentrations of solutes than those
in surrounding cells resulting in the cell shrinking in size.
Hypotonic solutions contain lower concentrations of solutes than those
in surrounding cells resulting in the cell swelling.
Isotonic solutions contain equal concentrations of solutes than those in
surrounding cells and the cell volume remains unchanged .