Transcript The Cell - Mr regh`s science site

Human History Becomes
More a Race Between
Education and Catastrophe
H. G. Wells
A View of the Cell
Discovery of Cells

Robert Hooke- English physicist, used a
microscope to observe many things,
including thin slices of cork (1665)

What he saw, he called “cells” because
they reminded him of small rooms in a
monestary
The Hookemeister
Hooke needed some help



The microscope made it possible for Robert
Hooke to make his observations
The first compound microscope was invented in
about 1590 by a Dutch spectacle maker named
Zacharias Janssen
In the late 1600’s, Anton van Leeuwenhoek
developed a much more powerful compound
microscope (could magnify up to 200 times)

first to see and describe bacteria, yeast, plants, the
teeming life in a drop of water, and the circulation of
blood corpuscles in capillaries
I use Vidal salon products to keep
my hair long and lovely
Cell Theory
Biologists Build a Theory

The invention of the microscope led to
many advances in the study of science.
By the 1830’s, many biologists were using
the microscope as their chief investigative
tool.
Contributors to the cell theory
Mathias Schleiden- botanist, found that
plant parts he examined were made of
cells.
 Made generalization, “all plants are made
of cells”

Contributors to the cell theory
Theodor Schwann- studied animals, his
microscope investigations of animal parts
led him to generalize that all animals are
made of cells.
 He later proposed, “all organisms are
made of cells

Contributors to the cell theory
Rudolf Virchow- German doctor, said that
new plant cells arise only from existing
plant cells and new animal cells arise only
from existing animal cells
 The ideas of these 3 men make up what is
now called the Cell Theory

The Three Principles of the Cell
Theory

Cells are the basic units of all life

All organisms are made of one or more
cells

All cells arise from existing cells
Micro = 0.000001 or millionth
Nano= 0.000000001 or billionth
Most cells are microscopic

The surface area of a cell is important for
carrying out the cell’s functions, such as
acquiring adequate nutrients and oxygen
–
A small cell has more surface area relative to its
cell volume and is more efficient
Large cell has much smaller surface area relative to its volume than smaller
cells
Major characteristics of
Prokaryotic & Eukaryotic Cells
Characteristics
Prokaryotic Cells
Eukaryotic Cells
Plasma Membrane
Yes
Yes
Cytosol w/organelles
Yes
Yes
Ribosomes
Yes
Yes
Nucleus
No
Yes
Size
1 um-10 um
10 um- 100 um
Internal membranes
No
Yes
Types of Cells

Prokaryotes
unicellular organisms
 found in all environments.
 largest group of organisms, mostly due to the
vast array of bacteria which comprise the bulk
of the prokaryote classification


Pro- means “before” and karyon- means
“nucleus”
Prokaryotes Cont.
Characteristics:
 No nuclear membrane (genetic material
dispersed throughout cytoplasm)=no
nucleus (nucleoid)
 No membrane-bound organelles
 Very small and simple internal structure
 Most primitive type of cell
 Have cell membrane and ribosomes

Prokaryote Examples

Staphylococcus
Staphylococcus
aureus

Escherichia coli (E. coli)

Streptococcus
Streptococcus
pneumoniae
Escherichia coli
cells
E. Coli colonies
Types of Cells Cont.

Eukaryotes
generally more advanced than prokaryotes.
 There are many unicellular organisms which
are eukaryotic

 but
all cells in multicellular organisms are
eukaryotic

Eu- means “true” and karyon- means
“nucleus”
Eukaryotes Cont.
Characteristics:
 Nuclear membrane surrounding genetic
material (have a nucleus)
 Numerous membrane-bound organelles
 Complex internal structure
 Appeared approximately one billion years
ago
 Typically larger than prokaryotes

Eukaryotic Examples
Human liver cell
Human breast cancer cell
Centric diatom (protista)
Bread Yeast (Fungus)
Human Red Blood Cells, Platelets, and
T-lymphocytes (from the animalia
kingdom)
Golden colonial alga (protista)
Now it’s time to Cellebrate!!!
Plasma Membrane

Made up of
Phospholipids, proteins, and associated
carbohydrates
 Regulates what gets in and out of cells
 Important for communication

Organelles
An organelle is a small structure that
performs a specialized function within a
cell
 The cytoplasm contains many individual
organelles
 Organelle means “little organ”

Organelles Cont.





Nucleus: structure that contains nearly all of the
cell’s DNA
 “control center” of the cell
Nucleolus: spherical body within cell.
 Site where ribosomes are assembled
Nuclear Membrane (AKA-Nuclear envelope):
membrane surrounding the nucleus
Nuclear Pores: controls what may enter or leave
nucleus
Chromatin: complex of DNA and protein stored
in nucleus, which makes up chromosomes

Chromosomes: condensed chromatin
Ribosomes

Ribosomes: protein factories
Composed of rRNA and proteins
 Form ribosomal subunits

 Free
ribosomes: float in cytosol and generally
produce proteins used in cell
 Bound ribosomes: attached to ER, make proteins
for export from cell
Types of Organelles

Endoplasmic Reticulum (ER): network of membranes
within cell that process/transport proteins & other
macromolecules
 Smooth ER: without ribosomes
 Synthesis of lipids
 Metabolism of carbs
 Detoxification of drugs/poisons
 Rough ER: studded with ribosomes
 Produce proteins secreted by cell
 Proteins are packaged into vesicles, bud off ER &
move toward Golgi Apparatus
HEY!!! Wakeup!!!!
Organelles Cont.

Golgi Apparatus: network of membranes in
a cell that, in conjunction with the ER,
process/transport proteins and other
macromolecules
Modification, storage, and shipping
 Contains special enzymes that attach
carbohydrates and lipids to a protein
 Have polarity

 Cis
face receives vesicles, trans face ships
vesicles
Organelles Cont.

Lysosomes- saclike membrane filled with
chemicals and enzymes that can break
down almost any substance within cell


“Clean up crew” for the cell
Vacuoles: saclike structure within cell that
stores material such as proteins, fats, and
carbohydrates in animal cells. In plants,
vacuoles store water & dissolved salts

Provides plants with support (Central vacuole)
Maybe if I sleep, I can learn gooder
Organelles Cont.

Mitochondrion: found in the cells of most
plants and animals that produces energy
from chemical fuel and oxygen
Plural-mitochondria
 “Powerhouse of the cell”
 Outer & inner membrane: inner highly folded
(increase surface area for respiration)
 Inner compartment- fluid filled (mitochondrial
matrix)

Organelles Cont.

Chloroplasts: organelle found in plants and
certain types of algae; harvests the energy
of sunlight


Plastid that stores chlorophyll used in
photosynthesis
Endosymbiotic Theory:
mitochondria/chloroplasts share similar
origin, descended from prokaryotes and
engulfed by ancestors or eukaryotic cells
Both have double membrane
 Both have ribosomes and DNA
 Both reproduce independently within cell

Organelles Cont.


Peroxisomes: single membrane
 Responsible for metabolic functions that involve transfer of H
from compounds to O, making hydrogen peroxide
 Break down fatty acids to be sent to mitochondria
 Detoxify alcohol by transferring H from poison to O
Cytoskeleton- supporting framework of a cell
 Microtubules- protein tubulin, largest, shape & support cell,
organelles can move along, important in cell division, cilia &
flagella
 Microfilaments- protein actin, smaller scale support, involved
w/movement (muscle cells)
 Intermediate filaments- more permanent in cell, maintain shape
of cell and position certain organelles





Centrosomes- near nucleus,
microtubules grow here, contain
centrioles in animal cells
Centriole: small structure in animal
cells that help to organize microtubules
 Used during cell division
Flagella- long and few in #, propel
unicellular organisms
Cilia- shorter and more numerous,
locomotion, move fluids over surface
of tissue (lining of trachea)
ECM (Extracellular Matrix)- just
external to plasma membrane
 Composed of glycoproteins
secreted by cell (collagen)
 Strengthens tissues and serves to
transmit external stimuli into cell



Adjacent cells communicate,
interact, and adhere through
specialized junctions between
them
 Tight junctions prevent
leakage of extracellular
fluid across a layer of
epithelial cells
 Desmosomes fasten cells
together into sheets
 Gap junctions are
channels that allow
molecules to flow between
cells
Plasmodesmata- openings in
plant cell wall that allow
passage of materials
Cell Wall- protects plant and
maintain shape (cellulose)
Look Out!!!
Plant Cell Only
Animal Cells Only
Central Vacuoles
Lysosomes
Chloroplasts
Centrioles
Cell Wall of cellulose
Flagella, cilia
Plasmodesmata
Extracellular matrix
Desmosomes, tight/gap junctions