New Video Posted: The Golgi Apparatus and Protein Processing

In the video - The Golgi Apparatus and Protein Processing - I look at the role of the Golgi in processing proteins.

The Golgi apparatus (possibly my favourite organelle) was discovered by Camillo Golgi in 1898 and confirmed in the 1950s.

Structurally, the Golgi resembles a stack of plates, and it has three distinct regions: the cis face (closest to the ER), the medial Golgi, and the trans face (furthest from the ER). The primary function of the Golgi is to process and sort proteins received from the ER, directing them to lysosomes, endosomes, or the plasma membrane.

There are two main theories for how the Golgi operates:

• Vesicle Transport Model - proteins move to the machinery.
• Cisternal Maturation Model - machinery moves to the proteins.

Evidence, such as vesicular tubular clusters and vesicles' size constraints, supports the Cisternal Maturation Model. In this model, the Golgi's cisternae mature over time, recycling enzymes via COPI vesicles.

Upon leaving the Golgi, proteins can enter one of two pathways:

• Constitutive secretory pathway - direct to the cell surface)
• Regulated secretory pathway - via secretory vesicles and requires a signal for the vesicles to traffic further.

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

New Video Posted: Understanding the Endoplasmic Reticulum: Rough vs Smooth ER and Protein Import

In the video Understanding the Endoplasmic Reticulum: Rough vs Smooth ER and Protein Import, I look at the smooth and rough Endoplasmic Reticulum (ER), and discuss how proteins are targeted to and imported into the ER.

The ER is a vital cellular structure with two types: rough ER (RER) and smooth ER (SER). The RER is covered in ribosomes and is essential for protein production. Proteins are synthesised and threaded into the ER lumen via a process involving signal recognition particles (SRP) and the Sec61 complex. 

Membrane-spanning proteins are produced at the RER by using various signal sequences that direct their insertion into or through the membrane. The ER also plays a role in N-linked glycosylation, adding N-linked oligosaccharides to proteins and in quality control, ensuring proteins are correctly folded and functional. 

In contrast, the SER lacks ribosomes, synthesises lipids, and forms vesicles for transporting proteins and lipids to the Golgi apparatus.

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

New Video Posted: Exploring the Endoplasmic Reticulum: Functions, Vesicle Trafficking, and Quality Control

In the video Exploring the Endoplasmic Reticulum: Functions, Vesicle Trafficking, and Quality Control, I look at the important role played in the cell by the Endoplasmic Reticulum (ER).

The endoplasmic reticulum (ER) is involved in a number of key processes in the cell connected with protein production, including:

• Disulphide Bond Formation: Occurs as proteins are imported into the ER, crucial for protein stability and function.
• Protein Glycosylation: Starts in the ER and finishes in the Golgi, important for protein folding and interactions.
• Quality Control: Marks incorrectly folded proteins for destruction, though it may sometimes incorrectly target properly folded proteins.

The newly made proteins are trafficked from the ER to the Golgi in COPII Vesicles. 

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

The Biosciences Glossary

When I was a student, one of my go-to books was a glossary of terms for bioscientists. I used the glossary when I was learning new material to look up things I didn’t understand and remind myself of what I had previously learned. I found it an invaluable learning and revision tool.

Sadly, the book is no longer in print, so I decided to write my own and I have just published The Biosciences Glossary on the Google Play Book Store.

The Biosciences Glossary

The book defines over 2,000 words, phrases, terms, and abbreviations used in the biosciences. It also includes 80+ chemical structures with links to additional information and to my videos on YouTube.

If you go to The Biosciences Glossary on the Google Play Book Store, you can review 20% of the book for free and decide if it would help you in your studies.

The book is available as a PDF and an ePub.

New Video Posted: How Proteins Get Into Peroxisomes | Biology Explained

In the video - How Proteins Get Into Peroxisomes | Biology Explained - I look at how the cell targets proteins to the peroxisomes.

Peroxisomes are involved in fatty acid oxidation and detoxification. The import of proteins into the peroxisomes relies on a short SKL motif at the C-terminal of the protein, which acts as an address. 

The SKL motif binds to the PTS1R receptor in the cytosol, which then interacts with the Pex14P receptor on the peroxisome membrane. The protein can either be imported with or without the receptor entering the peroxisome.

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

New video posted: Organelles: Targeting Proteins to the Mitochondria

In this video, Organelles: Targeting Proteins to the Mitochondria, I look at how the cell targets proteins to the mitochondria.

Proteins destined for the mitochondria begin their journey in the cell's cytosol, guided by a signal peptide that acts like a "postcode." This signal, located at the N-terminal of the precursor protein, directs the protein to the mitochondria.

The video looks at the role of the Translocase of the Outer Membrane (TOM) and the Translocase of the Inner Membrane (TIM), along with the OXA complex, during the import process and discusses how proteins are targeted to the outer and inner membranes, the intermembrane space and the matrix of the mitochondria.

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.

New Video Posted: Understanding Vesicle Trafficking and the SNARE Hypothesis

In this video, Understanding Vesicle Trafficking and the SNARE Hypothesis, I look at the SNARE hypothesis and how it helps the targetting of vesicles to the correct membrane.

 

Vesicle trafficking is a crucial cellular process where vesicles transport materials to specific organelles or membranes. This process involves the SNARE hypothesis, where vesicles have vesicle SNAREs (vSNAREs) and target membranes have target SNAREs (tSNAREs). The vSNAREs and tSNAREs recognise each other, ensuring that vesicles dock at the correct membranes.

However, the SNARE proteins are promiscuous and can bind with multiple partners, posing challenges for precise docking. To address this, cells use Tether proteins, which operate over greater distances and add an additional layer of specificity. Tether proteins help vesicles recognise their target membranes, while SNAREs facilitate the fusion process.

This combined mechanism ensures accurate vesicle targeting and fusion, which is regulated by a GTP timer that coordinates the events. 

If you would like to say thanks for the video, then please feel free to buy me a coffee at https://www.buymeacoffee.com/drnickm

Blog Bonus: Free information sheet summarising the video and defining the key terms - download.