Endomembrane System in Eukaryotic Cells

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Which statement best describes the endomembrane system?

It is found only in prokaryotic cells.

It is present only in eukaryotic cells and is made up of compartments like the endoplasmic reticulum and Golgi apparatus. (correct)

It consists of cytoplasmic cavities bounded by membranes that do not intercommunicate.

It contains the nucleus and mitochondria.

Which organelle is linked to the nuclear envelope?

Endoplasmic reticulum (correct)

Golgi apparatus

Lysosomes

Phagosomes

What is the chemical composition of the endoplasmic reticulum?

It contains the plant vacuole.

It is not composed of membranes.

It is composed of rough microsomes.

It may be isolated from the 3rd pellet of the UCD in the form of rough or smooth microsomes. (correct)

What distinguishes the smooth endoplasmic reticulum (SER) from the rough endoplasmic reticulum (RER)?

Presence of ribosomes on the membrane Signup and view all the answers

What is the ultrastucture of ER membrane as seen in TEM?

Trilamellar and thinner than plasma membrane Signup and view all the answers

What is used to separate rough from smooth microsomes?

Centrifugation in a sucrose density gradient Signup and view all the answers

What type of fatty acids are present in the phospholipid bilayer of the smooth microsome membrane?

High percentage of unsaturated fatty acids Signup and view all the answers

What is the main purpose of centrifugation of the smooth microsomes in a sucrose concentration gradient?

To separate microsomes based on their density and origin Signup and view all the answers

What is the approximate protein content in the membrane of the smooth microsomes?

70% Signup and view all the answers

Where are carbohydrates found in relation to proteins and lipids in the smooth microsome membrane?

Towards the luminal surface Signup and view all the answers

What is the specific content of the cavity in the smooth endoplasmic reticulum (SER) dependent on?

Cell type Signup and view all the answers

Where does protein synthesis for luminal proteins in the rough endoplasmic reticulum (RER) begin?

Cytosol Signup and view all the answers

What is the function of the signal sequence in protein synthesis for luminal proteins in the RER?

Enables the protein to be addressed for translocation Signup and view all the answers

What is the role of Signal Recognition Particle (SRP) in protein synthesis for luminal proteins in the RER?

Binds to the signal sequence and causes a temporary halt in translation Signup and view all the answers

What happens after the protein enters the lumen of the RER during protein synthesis for luminal proteins?

'The protein is taken up by chaperone proteins involved in translocation and post-translational modifications' Signup and view all the answers

What types of proteins can be synthesized in the rough endoplasmic reticulum (RER)?

Soluble or luminal proteins and hydrophobic proteins Signup and view all the answers

What represents 50 to 60% of the cell volume and is the fundamental substance of the cell in which organelles are immersed?

Hyaloplasm Signup and view all the answers

What comprises a network of protein filaments and a complex aqueous solution within the cell?

Hyaloplasm Signup and view all the answers

What is the pH range of hyaloplasm in plant cells?

pH 5.5 to 6 Signup and view all the answers

In which cell part can hyaloplasm be found in the form of a gel or fluid?

Hyaloplasm itself Signup and view all the answers

Which part of the cell is specifically criss-crossed by fibrous or tubular structures contributing to its architecture and dynamics?

Cytoskeleton Signup and view all the answers

Which organelle is linked to the nuclear envelope and plays a role in the architecture and dynamics of the cell?

Cytoskeleton Signup and view all the answers

What is the main component of microtubules?

Globular protein of 50 kDa Signup and view all the answers

What is the diameter of the microtubules?

25 nm Signup and view all the answers

What stabilizes the structure of microtubules?

Microtubule-associated proteins (MAPs) Signup and view all the answers

What are the permanent cellular elements made up of stable microtubules?

Centrioles and cilia/flagella Signup and view all the answers

What are centrioles composed of?

9 parallel triplets of short microtubules Signup and view all the answers

What are the characteristics of cilia and flagella?

Fine digitiform structures carried by the cell surface Signup and view all the answers

What types of microtubules are preserved regardless of the fixative and fixation temperature?

Stable microtubules Signup and view all the answers

What proteins are associated with the transport of vesicles along microtubules?

Kinesin and dynein Signup and view all the answers

What is the specific structure that makes up centrioles?