Download 7-2 Cell Structures

Cell Structure & Function
Cell Organelles (part a)
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Cytoskeleton
Key Concept:
The Cytoskeleton is a network of
protein filaments that helps the cell to
maintain its shape, The Cytoskeleton
is also involved in many forms of cell
movements
Contains:
Microtubules & Microfilaments
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Microtubules
• Hollow tubes of protein about 25
nanometers in diameter
• Maintain cell shape
• Provide “Tracks” along which cell
organelles move
• Especially important during cell
division
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Microtubules-Green
Nucleus
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Microtubules - TEM
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Microtubules & Cell Division
• Separates Chromosomes
Animal
Plant
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Centriole?
Yes
No
Microtubules & Locomotion
Photomicrograph
TEM
Cilia
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Microtubules & Locomotion
Photomicrograph
Flagella
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Microtubules & Locomotion
Photomicrograph
Flagella
Pili
Flagella
E. coli
www.siue.edu/~cbwilso/ Ecoli_flagella.jpg
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Microfilaments
• 7 Nanometers in diameter
• Form Extensive Networks To Support
Cells
• Also used as “Tracks” for organelles
being moved by motor proteins
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Microfilaments - Green
Microtubules
Microfilaments
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Nucleus
First Identified By Robert Brown
in 1831
Key Concept:
The nucleus controls most
cell processes and
contains the hereditary
information of DNA
(deoxyribonucleic acid)
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Nucleus
Frog Blood
Nucleated RBC’s (normal)
Neutrophile
(White Blood Cell)
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Nucleus
Human Cheek
Cells
Nucleus
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Nucleus
Red Blood Cell
Segmented Neutrophile
Band Cell
Human Blood
Smear
Eosinophile
Lymphocyte
Basophile
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Chromatin & Chromosomes
Chromatin
– Granular material within the nucleus which
is a combination of DNA bound to protein
Chromosome
– Condensed Chromatin that forms during
cell division
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Nucleolus
Dense area within
the nucleus which
is where ribosome
formation begins
Nucleolus
Chromatin
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Nuclear Envelope
• Double Membrane
• Surrounds Chromatin
• Contains thousands of Nuclear Pores
which allow the transfer of material in
and out of the Nucleus
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Nuclear Pores
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Nuclear Pore – TEM
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Ribosomes
• Make Proteins
• Made From
r-RNA (ribosomal RNA) +
Protein Subunits (from Nucleolus)
• 0.025 micrometers in diameter
• Translate m-RNA (messenger RNA) into
protein
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Ribosomes
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Ribosome
Amino Acid Being
Added To The
Protein Chain
transfer RNA
tRNA
(We will learn
about later)
messenger RNA
mRNA
(We will learn
about later)
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Endoplasmic Reticulum
Key Concept:
The endoplasmic reticulum is
the organelle in which
components of the cell
membrane are assembled and
some proteins are modified.
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Rough Endoplasmic Reticulum
• Synthesizes Proteins
• Looks rough because of
ribosomes that stud the surface.
– Proteins move from the ribosomes,
directly into the Endoplasmic
Reticulum where the proteins may be
further modified.
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Rough Endoplasmic Reticulum
Nucleus
Rough ER
Smooth ER
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Free Standing Ribosomes
• Manufacture Proteins For Use In The Cell
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Smooth Endoplasmic Reticulum
• This Section Of The ER does not have
any Ribosomes attached.
• Smooth ER typically manufactures
lipids to make membranes
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Golgi Apparatus
• Proteins produced
by the Rough ER
move into the Golgi
Apparatus.
• Consists of a stack
of membranes like
stacks of pita bread
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Golgi Apparatus
Key Concept:
Enzymes in the Golgi apparatus
attach carbohydrates & lipids to
proteins.
Products are then sent to their
final destination.
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Vesicles
Small vacuoles involved in the
transport of substances
within the cell
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