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CELLULAR ORGANELLES
A Spotlight on Research
What are organelles?
 Organelles are membrane-
bound structures inside
cells that carry out specific
functions.
 Today we will learn the
functions of the organelles by
studying real scientific
research.
Scientific Research
Scientists perform experiments to test
hypotheses. Scientific theories
explain phenomena or events in nature.
Theories are based on evidence.
The NUCLEUS:
 The nucleus was the first
organelle discovered. It
was observed by Anton
van Leeuwenhoek in 1719.
 The nucleus is the control
center of the cell, where
genetic information is
stored as DNA.
RIBOSOMES:
 Ribosomes are organelles made from RNA and
proteins.
 They are made in a part of the nucleus called the
nucleolus.
 Ribosomes are important for making proteins
from instructions stored in DNA.
RIBOSOMES:
 While they are represented as dots on many cell
diagrams, ribosomes actually have a very complex
structure.
 3 scientists won the 2009 Nobel Prize in
Chemistry for discovering the structure of
ribosomes. Scientists had been trying to do this
since the 1960’s.
RIBOSOMES:
 Ribosomes are located in 2 places inside the cell:
 Membrane-bound ribosomes are found in the
endoplasmic reticulum.
 Free ribosomes are found in the cytoplasm.
The ENDOPLASMIC RETICULUM (ER)
 Scientists believe that the ER developed from
infoldings of the plasma membrane.
 There are two types of ER:
1) Rough ER contains ribosomes and makes proteins.
2) Smooth ER has no ribosomes and makes lipids.
The GOLGI BODY:
 The Golgi body is
responsible for processing
and packaging proteins.
 Proteins from the Golgi go
on to either the cell
membrane or other
organelles.
The GOLGI BODY:
 Scientists use a protein called Green fluorescent
protein (GFP) to “track” the movement of
proteins through the cell.
The CELL MEMBRANE:
 The cell membrane is composed of a lipid bilayer
with some proteins on its surface
The CELL MEMBRANE:
 Gorter & Grendel performed an experiment that
proved the existence of a bilayer.
 They found the area of red blood cell membranes
was two times the area of the cells themselves.
The CELL MEMBRANE:
 Functions of the cell membrane:
1) Separates the cell from its surroundings
2) Selectively permeable – lets some things in
and keeps other things out
3) Structure
The MITOCHONDRION:
 Mitochondria are the energy producing organelles
in all eukaryotic cells.
 The energy in mitochondria is in the form of
adenosine triphosphate (ATP).
The MITOCHONDRION:
 Research provides evidence for the
endosymbiotic theory, the idea that
mitochondria and some other organelles
originated as prokaryotes that were engulfed b a
eukaryotic cell.
The CHLOROPLAST:
 Found only in plant cells.
 The chlorophyll in chloroplasts provide plants’
green color.
 Chloroplasts absorb energy from the sun to make
glucose (sugars).
 This process is called photosynthesis.
The VACUOLE:
 While they exist in both plant and animal cells,
plants have a large, central vacuole.
 Plant vacuoles can occupy as much as ninety
percent of the cell.
The VACUOLE:
 Three functions:
1) Water storage
2) Contains chemicals that protect the plant
3) Water pressure in the vacuole supports
the cell wall
The CELL WALL:
 Cell walls, found in
plant cells, are located
outside the plasma
membrane.
 The cell wall was the
first structure to be
viewed with a
microscope.
 Robert Hooke’s
observation of cork in
1665.
The CELL WALL:
 Freeze-fracture techniques and electron
microscopy were used to determine how the cell
wall is produced.
Other Important Organelles:
 Lysosomes – Digest waste and cellular debris
 Cytoskeleton – Provide structure and serve as a
transport network for proteins in the cell
 Molecular motors
 Centriole – Specialized organelle used in cell
division
 Cilia & Flagella – Specialized parts of the
cytoskeleton that allow cells to move.