Organelles

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Organelles
Biology 11 E. McIntyre
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Cytoplasm (cytosol) a cell's inner space
Plasma membrane
Cytoskeleton cytosol
Cytosol large fluid-filled space (mostly water
proteins that control most of the cell
metabolisms) glycolysis, transcription factors,
intracellular receptors etc.
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Organelles
Reminder! Membrane-bound organelles are only
found in eukaryotes.

• Nucleus
• Protein production machine the ribosomes
• Mitochondria and Chloroplasts
• Endoplasmic Reticulum and the Golgi apparatus
• Lysosomes and Peroxisomes
• Adapted and/or specialized for carrying out one
  or more vital functions

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Nucleus a cell's center

• Function of the nucleus
• Stores the chromosomes (genetic material) Note
  Two kinds of genetic material
• deoxyribonucleic acid (DNA)
• ribonucleic acid (RNA)
• Keeps the DNA molecules of separated from
  metabolic machinery of cytoplasm.

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...Nucleus a cell's center

• Makes it easier to organize DNA and to copy it
  before parent cells divide into daughter cells
• DNA replication and synthesis of messenger RNA
  (mRNA)

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Nucleolus

• Dense mass of material in nucleus
• Cluster of DNA and proteins
• Subunits must pass through nuclear pores to reach
  cytoplasm
• production of ribosomes in nucleolus

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Nuclear Membrane (Envelope)

• One continuous membrane which spans the ERs
  membrane as well. (lipid bilayers)
• Pores span bilayer and controls what
  enters/leaves nucleus.

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Chromatin

• Cells collection of DNA and associated proteins
• A chromosome is one DNA molecule and its
  associated proteins
• Appearance changes as cell divides

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Ribosomes

• FUNCTION
• assembles proteins (non cytosolic cytosolic
  proteins)
• some are free in cytoplasm (cytoplasmic
  ribosomes), others are attached to the ER (ER
  ribosomes)

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Endoplasmic Reticulum (ER)

• STRUCTURE
• ER is a continuation of the outer nuclear
  membrane.
• Two types Smooth and Rough. (Rough ER has
  ribosomes on it)
• Network of membrane that connects nuclear
  envelope to the cell membrane

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Endoplasmic Reticulum (ER)

• FUNCTION
• Smooth ER (no ribrosomes) responsible for lipid
  and membrane protein modifications)
• Rough ER (has ribosomes on it) responsible for
  the synthesis of other proteins). The ribosomes
  assemble the proteins within the rough ER. Once
  assembled, the proteins pinch off the ER and are
  released in a vesicle.

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Endoplasmic Reticulum (ER)
Endoplasmic Reticulum (ER)
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Golgi Body (Golgi Apparatus)

• FUNCTION
• processes, packages, and, secretes cell products
  (lipids proteins)
• Put finishing touches on proteins and lipids that
  arrive from ER
• Package finished material for shipment to final
  destinations. (Exocytosis)
• Material arrives
• and leaves in vesicles

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Golgi Body (Golgi Apparatus)
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Mitochondria

• STRUCTURE
• Double membrane. Inner membrane is folded for
  greater surface area. Folds are called cristae.
• Interior is called the matrix.
• Contain their own genome (distinct from nuclear
  genome)
• Self-replicating
• FUNCTION
• burns food, i.e. glucose to release energy.
  Energy is used to make ATP. ATP is a high-energy
  molecule that can be directly used by the cell.

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Mitochondria
The powerhouse of the cell
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Lysosomes

• STRUCTURE
• Formed by Golgi bodies
• Bound by a single membrane
• FUNCTIONS
• Digests the food particles inside the cell with
  help of enzymes. These enzymes work at low pH.
• Involved in autolysis (suicide of cell)
• Digest foreign bacteria that invade a cell
• Recycling of membrane components
• Repair damage to plasma membrane

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Peroxisomes

• Made by Golgi
• Surrounded by a single bilipid membrane
• Detoxification of poisonous substances
• Many in the liver/ brain

lysosome
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Cell Wall

• FUNCTION
• maintains the shape of a plant cell
• found in plants, some fungi, some protists
• In plants, cell walls are made of a
  polysaccharide called cellulose.
• Structural component that wraps around the plasma
  membrane

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Cell Wall
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Chloroplasts

• FUNCTION
• Photosynthesis converts sunlight, carbon
  dioxide, and water into sugar (makes food for
  plants)

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Vacuole

• A large membrane bound sac
• FUNCTION
• storage area for proteins and
• water
• Maintain structure in plant cells by means of
  turgor pressure

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Cytoskeleton a cell's scaffold

• very complex and dynamic cell component!
• organizes and maintains the cell's shape (e.g.
  epithelial cells of the gut)
• Allows organelles to remain in place or to move
  throughout cell
• helps during the uptake of external material
  (endocytosis)
• involvement in cell movement
• growth

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...Cytoskeleton
intermediate filaments
microtubules
microfilaments
tubulin
actin
keratin family
All help maintain cell shape
Nuclear lamina Anchorage of nucleus and some
other organelles
Cilia, flagella Chromosome movement Organelle
movement
Cytoplasmic streaming Pseudopodia Cell division
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...Cytoskeleton
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...Cytoskeleton
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Molecular motors
...Cytoskeleton
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...Cytoskeleton
Macrophage attacks bacteria Microfilaments
(actin) allow formation of pseudopods
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...Cytoskeleton
Striated Muscle
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...Cytoskeleton
Centrosome Made up of centriole pairs
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Bibliography

• http//users.ipfw.edu/mustafaa/PQ_B100-02-ppt-Chap
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• http//images.google.ca/imgres?imgurlhttp//biolo
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  5and02/section_2and5_cellimages.htmh768w1024s
  z316tbnidOxmCr18W6AQJtbnh112tbnw149start
  1prev/images3Fq3Dcheek2Bcell26hl3Den26lr3
  D
• www.ops.org/burke/02science/organelles.ppt
• file///C/WINDOWS/Temporary20Internet20Files/Co
  ntent.IE5/UPK3G94Z/266,12,Diffusion
• http//bioweb.wku.edu/courses/biol22000/11Organell
  es/images/F05-43A.JPG
• http//cellbio.utmb.edu/cellbio/nucleus.html
• http//www.cellsalive.com/cells/er.htm
• cellbio.utmb.edu/cellbio/ribosome.htm
• http//cellbio.utmb.edu/cellbio/golgi.htm