Golgi Apparatus and Ribosomes

Golgi Apparatus

Structure: It is found within the cytoplasm of both plant and animal cells. The Golgi is composed of stacks of membrane-bound structures.

In plant cells, an individual stack is sometimes called a dictyosome.

Function: The creation of lysosomes. Transports lipids around the cell. Packages and labels items and then sends to different parts of

the cell.

Ribosome Structure:

A ribosome is made up of a small subunit and a large one and they come together when the ribosome attaches to messenger RNA to produce a protein in the cytoplasm. The ribosomal subunits of prokaryotes and eukaryotes are quite similar.

Ribosomes exist in the cytosol and bound to the endoplasmic reticulum.

Ribosomes are called either free ribosomes and bound ribosomes, depending on the presence of an ER-targeting signal sequence on the protein being synthesized, so an individual ribosome might be membrane-bound when it is making one protein, but free in the cytosol when it makes another protein.

Ribosome Function:

Ribosomes are need to make large numbers of proteins for the cells and are the sites of protein synthesis where RNA is translated into protein.

Protein synthesis are much needed in the cell and very important so that’s why there’s hundreds or thousands of ribosomes.

In eukaryote cells, 3 of the 4 ribosomal RNA strands are synthesized in the nucleolus. The 4th ribosomal RNA strand is synthesized outside of the nucleolus and then transported into the nucleolus. Ribosomal proteins enter the nucleolus and combine with the 4 ribosomal RNA strands to create the large and small subunits which are the 2 ribosomal structures. The 2 subunits unite outside before the ribosome begins to manufacture proteins.

Prokaryotic cells lack a nucleus or nucleolus which is why ribosomal synthesis takes place in the cytoplasm, without the ribosomes the message would not be read and proteins could not be produced.

Ribosome

In Model A, the proteins are shown in blue and the two RNA strands in orange and yellow. The small patch of green in the center of the subunit is the active site.

Model B, proteins are shown in blue and the single RNA strand in orange.

A B

Compare & Contrast

Compare: Ribosomes make proteins that travel through the

Golgi bodies to the ER which exports them.

Contrast: Golgi Apparatus are only found in most eukaryotic

cells which ribosomes are both in prokaryotes and eukaryotes.

Diseases Golgi Apparatus:

Alzheimer’s disease Inclusion-cell (I-cell) disease

Ribosome: Alzheimer’s disease Gastric cancer Diamond-Blackfan anemia (a ribosomal protein disease) Shwachman-Diamond Syndrome Dyskeratosis Congenita

Alzheimer’s disease

Alzheimer's is a progressive disease that attacks the brain, a type of dementia that causes problems with memory, thinking and behavior (Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks).

Scientists from the University of Kentucky observed that impairment of the function of ribosomes was correlated with a decreased rate of protein synthesis and decreased levels of ribosomal RNA and transfer RNA, the researchers believe that this could be a clear indication that mechanisms that affect protein synthesis are instrumental to the onset and development of Alzheimer's disease.

Studies have indicate that the neuronal Golgi apparatus is a reliable index of activity or degeneration. The results of this study suggest that in AD the Golgi apparatus of a population of neurons without NFTs (neurofibrillary tangles) is involved in the pathogenesis of the disease.

Alzheimer’s disease Symptoms:

Confusion Irritability Aggression Mood swings Trouble with language Long-term memory loss Behavioral problems Forgetting events in your own life history, losing awareness of

who you are Difficulty reading or writing Poor judgment and loss of ability to recognize danger Using the wrong word, mispronouncing words, speaking in

confusing sentences

Alzheimer’s disease There is no cure for this disease, but there are treatments and drugs. Two types of medicine are available:

Donepezil (Aricept), Rivastigmine (Exelon), and Galantamine (Razadyne, formerly called Reminyl) affect the level of a chemical in the brain called acetylcholine. Side effects include indigestion, diarrhea, loss of appetite, nausea, vomiting, muscle cramps, and fatigue.

Memantine (Namenda) is another type of drug approved for treating AD. Possible side effects include agitation or anxiety.

A growing number of herbal remedies, dietary supplements and "medical foods" are promoted as memory enhancers or treatments to delay or prevent Alzheimer’s disease and related disorders: Caprylic acid and coconut oil Coenzyme Q10 Coral calcium Omega-3 fatty acids Phosphatidylserine Tramiprosate

Other medicines may be needed to control aggressive, agitated, or dangerous behaviors. These are usually given in very low doses.