The Endomembrane System An adaptation by Thomas Cecelya

The Nucleus
  • The shape of the nucleus is a rounded.
  • It contains all of the cell's genetic material in the form of DNA, as well as the nucleolus (ribosome production center).
  • The nuclear envelope has nuclear pores which allow substances to travel in and out of the nucleus.
  • The nucleus controls all of the cell's functions, holds the genetic information for that cell, and hosts the nucleolus.
  • Only in EUKARYOTIC cells, prokaryotes are left out of the fun :(
  • Thus, nuclei are prolific in eukaryotic cells.
  • Emery-Dreifuss Muscular Dystrophy- Nucleus associated gene mutation that causes difficulty in movement (in other words, issues with muscles and joints).
  • Some organisms, such as slime molds, have multiple nuclei.
Ribosomes
  • Ribosomes are irregularly shaped, but are rounded
  • They comprise of two protein subunits (different depending on eukaryotic ribosome or prokaryotic ribosome).
  • They function in the synthesis of proteins.
  • All organisms (prokaryotic and eukaryotic) contain ribosomes within their cells, although, eukaryotic and prokaryotic cells differ in size and shape.
  • Ribosomes are extremely prolific in all cells, upwards of 10,000 can be present in prokaryotic cells and millions present in eukaryotic cells.
  • Treacher Collins syndrome (linked to ribosomes) causes mutations in ears, eyes, and facial bones.
  • Ribosomes are not reusable! After the formation of a protein, the subunits break apart.
Rough Endoplasmic Reticulum
  • The Rough ER is a continuous membrane (continuing off of the nuclear membrane) with tubules and sacs; it is also "studded" with ribosomes.
  • The Rough ER functions in the synthesizing and transport of proteins, and the increasing of the cell's surface area.
  • Eukaryotic cells contain rough ER, whereas prokaryotic cells do not.
  • Rough ER is prolific in pancreatic cells because it creates enzymes that the pancreas secretes in a great amount.
  • Degenerative diseases such as Alzheimer's can be caused by a malfunction in the ER stress response.
  • All proteins synthesized from the rough ER are exported, not used within the cell.
Smooth Endoplasmic Reticulum
  • The smooth ER is an irregularly shaped tubular system without embedded ribosomes, and is more evenly distributed in the cell.
  • Functions in lipid and steroid production, breaking down of glycogen, and detoxification of the cell.
  • The smooth ER is, like most of these membrane-bound organelles, only present in eukaryotic cells.
  • It is prolific in liver cells because it breaks down harmful chemicals (such as alcohol) and detoxifies the cell, which is what the liver functions in on a larger scale.
  • Diabetes has also been linked to a mutation in the ER stress response, because insulin (an enzyme) isn't produced, glucose builds up in the bloodstream.
  • Alcoholics have more smooth ER in their cells due to the constant processing of alcohol and detoxification of the cells.
The Golgi Apparatus
  • The Golgi apparatus is comprised of flat membranes called cisternae and vesicles.
  • Looks like a stack of pancakes.
  • Processes and packages macromolecules, modifies proteins, and creates lysosomes.
  • The Golgi apparatus is found in all eukaryotic cells, and is not present in prokaryotic cells.
  • Larger and fewer Golgi apparatus in animal cells, smaller and greater amount in plant cells.
  • A mutation in the microtubules of the Golgi apparatus causes Achondrogenesis, which causes cartilage and bone development issues.
  • The Golgi apparatus modifies proteins to create glycoproteins (one such example) which functions in cell to cell recognition.
Mitochondria
  • Rod-shaped organelles that have a double membrane made of phospholipids and proteins.
  • Outer membrane: smooth, freely permeable
  • Inner membrane: Folded (increase surface area), strictly permeable, more complex.
  • Mitochondria contain their own DNA
  • Functions in the production of ATP (energy source), calcium ion concentration maintenance, and apoptosis (cell death), and cellular respiration.
  • They are only found in eukaryotic cells, not in prokaryotic cells.
  • Mitochondria are prolific in liver cells because they aid in the detoxification of ammonia.
  • Mitochondrial myopathy can lead to muscle weakness, hearing loss, balance issues, seizures, learning disabilities.
  • This disease is a result of a mitochondria-linked gene mutation.
  • Mitochondria are believed to have originated from aerobic bacteria, according to the Serial Endosymbiotic Theory (SET).
Chloroplasts
  • Chloroplasts have an elliptical shape
  • Double membrane; inner: embedded with proteins; outer: easily permeable
  • They contain ribosomes
  • The stroma is a semi-fluid matrix within the chloroplast (almost like the cytoplasm of the chloroplast)
  • Lamellae is an internal membrane with stacks (granum) of closed hollow discs (thylakoids)
  • Chloroplasts function in pathogen defense of the cell, production of nutrients through photosynthesis, and generation of energy in the form of ATP.
  • Chloroplasts are only found in plant cells and some photosynthetic protists. The average amount of chloroplasts in plant cells is 50, which is a decent number considering it's role in energy production.
  • A mutation in the DNA in chloroplasts can cause a white phenotype to emerge, which means that there is a lack of chlorophyll in the chloroplast. (sorry, there isn't really a name associated with this, according to my research)
  • There can be as many as half of a million chloroplasts on a 1 square millimeter section of a leaf.
Flagellum
  • Prokaryotic and eukaryotic flagella differ in structure, as well as function.
  • Eukaryotic structure: Whip-like strand with hairs; 9 bundles of microtubules surrounding 2 central microtubules; microtubules made of tubulin; base anchored to cell through basal body.
  • Prokaryotic structure: Helical shape; base attached to basal body; made from protein flagellin.
  • Eukaryotic flagella function in cell motility, serves as a sensory antennae, and in some cases, a secretory organelle.
  • Prokaryotic flagella function in cell motility, sensory/recognition, and it aids in cell immunity by detecting pathogens.
  • Thus, both prokaryotes and eukaryotes have flagella. However, flagella are mainly prolific in sperm cells.
  • Polycystic kidney disease is a disease associated with the flagella that causes cysts to form on the kidney, ultimately resulting in kidney failure.
  • Although the same organelle, flagella differ (slightly) between prokaryotes and eukaryotes in structure and function.
Cilia
  • Slender, microscopic hair-like projections
  • 2 types of cilia
  • Motile: 9 outer microtubules surrounding 2 central microtubules; keeps airways clean from dirt and mucus, helps sperm motility.
  • Primary: Single appendages, lack central pair of microtubules; functions as sensory antennae for cells. In kidneys, sends signals to cells to signal a flow of urine. In eyes, transports molecules from cell to cell.
  • Exists in protists and animal cells, and motile cilia are prolific in the nasal cavity and respiratory tract, whereas primary is found in kidney and eye cells.
  • Polydactyly: defects in primary cilia that causes the hand to grow extra fingers.
  • Cilia are very similar to larger flagella (in structure).
Lysosome
  • Tiny sacs filled with fluid that contains enzymes.
  • Has a single membrane.
  • Processes cell nutrients (digestion) and breaks down cell after death.
  • Common in animal cells (constant processing and digestion of materials), but not as common in plant cells, due to the cell wall not allowing for the easy passing of materials in and out of the cell.
  • A disease associated with lysosomes is Tay-Sachs disease which is the progressive deterioration of the nerve cells in the brain and spinal cord.
  • Lysosomes contain about 50 different enzymes to be able to break down all the macromolecules it processes.
Food Vacuole
  • Membrane-bound sac.
  • Larger version of a vesicle.
  • Forms by pinching from the plasma membrane.
  • Functions in phagocytosis by fusing with the lysosome which contains enzymes that can break down the food particles within the food vacuole.
  • Present in animal cells and protists, and common in both as both organisms are constantly breaking down nutrients.
  • Cardiomyopathy is a disease associated with defects in the food vacuole that causes weakening of the heart muscles, and learning disabilities.
Central Vacuole
  • Membrane-bound sacs in the cytoplasm.
  • Larger than food vacuoles
  • The cell sap within the vacuole differs in composition from the cytoplasm.
  • The central vacuole is a container for plant waste, functions in protein storage for developing seed cells, aids in plant growth, and controls the turgor pressure of the cell.
  • The central vacuole is only found in plant cells, and there is only one, large central vacuole in a plant cell.
  • Vacuoles in general are susceptible to yielding Danon's disease in the event of mutation, which affects the heart, and limits intellectual abilities, and is more prominent and severe in males.
  • Without the central vacuole, the entire cell will fall apart.

Works Cited:

Davidson, Michael W. "Molecular Expressions Cell Biology: The Cell Nucleus." Molecular Expressions Cell Biology: The Cell Nucleus. N.p., 1 Oct. 2000. Web. 28 Nov. 2016.

Nizami, Zehra, and Svetlana Deryusheva And. "Zehra Nizami." Cold Spring Harbor Perspectives in Biology. N.p., 1970. Web. 28 Nov. 2016.

"Nucleus." Nucleus | Function of Nucleus | Nucleus Structure | Biology@TutorVista.com. N.p., 2016. Web. 28 Nov. 2016.

Studio7designs.com, Fullahead.org -. "PAGE LINKS." The Nucleus Tutorial - Diseases. N.p., n.d. Web. 28 Nov. 2016.

Worman, Howard J., Cecelia Östlund, and Yuexia Wang. "Diseases of the Nuclear Envelope." Cold Spring Harbor Perspectives in Biology. N.p., 1970. Web. 28 Nov. 2016.

Arnold, Paul. "5 Interesting Facts About the Cell Nucleus: Who Discovered the Cell Nucleus? and More." Bright Hub. N.p., 2009. Web. 28 Nov. 2016.

"Emery-Dreifuss Muscular Dystrophy - Genetics Home Reference." U.S National Library of Medicine. U.S. National Library of Medicine, 22 Nov. 2016. Web. 28 Nov. 2016.

@questionstudy. "What Is Endomembrane System? - Question Study." Question Study. N.p., 2016. Web. 28 Nov. 2016.

Davidson, Michael W. "Molecular Expressions Cell Biology: Plant Cell Structure - Nucleus." Molecular Expressions Cell Biology: Plant Cell Structure - Nucleus. N.p., n.d. Web. 28 Nov. 2016.

Created By
Thomas Cecelya
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