Cell Fractionation and Ultracentrifugation

Flashcards covering key concepts from the lecture on cell fractionation and ultracentrifugation.

What is cell fractionation used for?

To break open cells in order to isolate different organelles and examine their structure and function.

What are the three essential characteristics of the solution used in cell fractionation?

The solution must be cold, isotonic, and buffered.

Why must the solution be cold during cell fractionation?

To reduce enzyme activity that could damage organelles.

What does 'isotonic' mean in the context of cell fractionation?

The water potential of the solution is the same as the organelles to prevent osmosis.

What could happen if the solution was not isotonic?

Organelles could shrivel or burst due to osmotic pressure.

Why is the solution buffered during cell fractionation?

To prevent sudden changes in pH that could damage the organelles.

What are the two steps involved in cell fractionation?

Homogenization and ultracentrifugation.

How are cells homogenized in cell fractionation?

By using a blender to break open the cells.

What is the purpose of filtering the solution after homogenization?

To remove large cell debris and leave a filtrate containing organelles.

What happens during ultracentrifugation?

The filtrate is spun at high speeds to separate organelles based on density.

What are centrifugal forces?

Forces created by spinning at high speeds that cause denser organelles to move to the bottom.

What is a pellet in the context of ultracentrifugation?

The solid part that collects at the bottom of the centrifuge tube, containing dense organelles.

What is the supernatant in ultracentrifugation?

The liquid above the pellet that contains less dense organelles.

What does differential centrifugation mean?

Spinning the solution at increasing speeds to isolate organelles based on their density.

Which organelle is typically separated first during ultracentrifugation?

Nuclei, as they are the most dense.

What is the second pellet expected to contain after ultracentrifugation?

Chloroplasts and mitochondria.

What is the third pellet expected to contain?

Lysosomes and the endoplasmic reticulum.

What is the fourth pellet expected to contain?

Ribosomes.

What should you know for exam questions regarding organelle isolation?

The order of separation based on density and the increased speeds used.

Why can understanding cell fractionation help in studying cells?

It allows for the isolation of organelles to study their individual structure and function.

Which type of cells are typically examined using cell fractionation?

Eukaryotic and prokaryotic cells.

What is the importance of the microscope in studying cells?

It allows for the visualization of cell structures and organelles.

What would happen if enzymes released during cell homogenization were not controlled?

They could damage organelles, complicating their study.

Why is it a mistake to say cells can shrivel or burst in isotonic solutions during cell fractionation?

The cells have already been broken open; the focus should be on preventing organelles from shrinking or bursting.

How does increasing the speed in centrifugation help isolate organelles?

Faster speeds are needed to sediment less dense organelles out of solution.

What does a successful cell fractionation allow scientists to do?

Isolate large numbers of organelles for study.

What type of preparation is required for organelles before ultracentrifugation?

Preparation in a cold, isotonic, and buffered solution.

How does differential ultracentrifugation aid studies in biology?

By separating organelles based on their density, allowing for detailed study of each organelle.

What practical application of cell fractionation was mentioned in the lecture?

Isolating organelles from spinach cells.

What is the main benefit of using a blender in homogenization?

To efficiently break open cells and prepare the solution for centrifugation.

What role does filtration play after homogenization?

Removes debris and allows only organelles to remain in the solution.

Why is it important to know the order organelles are separated?

It is crucial for practical lab applications and answering exam questions.

What type of changes in pH does buffering prevent?

Sudden shifts that could be too acidic or too alkaline.

What happens to organelles during osmotic pressure if the solution isn't isotonic?

They could either shrivel or burst.

What can negatively affect the study of organelles?

Damage from enzymes or improper solution conditions.

In what context was spinach mentioned during the lecture?

As an example of plant tissue for organelle isolation.

How long might centrifugation cycles last before changing speeds?

Typically short periods, enough to allow organelles to settle.

How does the knowledge from cell fractionation tie into cell biology concepts?

It enhances understanding of organelle functions and interactions.

What is emphasized about studying organelles?

Understanding their structure and function through isolation and examination.

What visual aid did the lecturer suggest for understanding previous videos?

Links to previous videos on microscopes and related topics.

How should students approach practicing for the exam based on this lecture?

By reviewing questions related to cell fractionation and organelles.

What aspect of the lesson encourages active participation from students?

The invitation to take notes and reflect on the questions posed.