Lecture 5 easy

Questions and Answers

What is a primary function of the smooth endoplasmic reticulum?

Cellular respiration

Ribosome storage

Production of proteins

Synthesis of lipids (correct)

What is the special name of the smooth ER found in muscle cells?

Cytosolic reticulum

Chloroplast

Sarcoplasmic reticulum (correct)

Granular ER

Which of the following is NOT a function of the smooth endoplasmic reticulum?

Detoxification of harmful substances

Production of enzymes for liver metabolism

Synthesis of steroid hormones

Storage of ATP molecules (correct)

Where is the smooth endoplasmic reticulum primarily located within the cell?

Cell periphery Signup and view all the answers

Which of the following statements about the smooth ER is true?

It synthesizes phospholipids and steroids. Signup and view all the answers

What is the primary function of heterophagia?

Breakdown of foreign substances absorbed by endocytosis Signup and view all the answers

What are primary lysosomes primarily responsible for?

Carrying inactive enzymes known as hydrolases Signup and view all the answers

What characterizes secondary lysosomes?

They merge with vesicles formed during endocytosis. Signup and view all the answers

During autophagy, what happens to unnecessary or damaged cellular components?

They are wrapped in a membrane and then digested by lysosomes. Signup and view all the answers

What is the final outcome for indigestible molecules in secondary lysosomes?

They form residual bodies that remain in the cell. Signup and view all the answers

What is one key function of the endoplasmic reticulum?

Production of proteins Signup and view all the answers

What distinguishes rough ER from smooth ER?

Rough ER has membrane-bound ribosomes Signup and view all the answers

Which of the following correctly describes the structure of the endoplasmic reticulum?

A network of interconnected flattened sheets and tubules Signup and view all the answers

Which substance is stored by the endoplasmic reticulum?

Calcium Signup and view all the answers

What happens in the lumen of rough ER?

Protein synthesis and modification take place Signup and view all the answers

What process do lysosomes facilitate to remove damaged cellular components?

Autophagy Signup and view all the answers

What role do lysosomes play in cellular repair?

They regulate the immune response. Signup and view all the answers

What occurs during the autolysis of a cell?

Lysosomes explode to release enzymes. Signup and view all the answers

Which of the following materials are lysosomes capable of breaking down?

Pathogens Signup and view all the answers

What is the primary function of the Golgi network?

Transporting, modifying, and packaging proteins and lipids Signup and view all the answers

Which network of the Golgi is closest to the endoplasmic reticulum (ER)?

Cis-Golgi network Signup and view all the answers

Which process describes the recycling of broken down molecules into new cellular products?

Autophagy Signup and view all the answers

What is the primary function of lysosomes in a cell?

Waste degradation and recycling Signup and view all the answers

How are lysosomes formed within the cell?

From the Golgi apparatus Signup and view all the answers

What occurs to proteins and lipids when they enter the Golgi?

They are modified and packaged Signup and view all the answers

What is the internal pH of lysosomes, which is necessary for their function?

4.5 to 5.5 Signup and view all the answers

What type of vesicles leave the Golgi after processing?

Secretory vesicles Signup and view all the answers

Which of the following is NOT produced by the Golgi network?

Amino acids Signup and view all the answers

What type of enzymes do lysosomes contain to degrade molecules?

Hydrolases Signup and view all the answers

What process allows external materials to enter the cell and be delivered to lysosomes?

Endocytosis Signup and view all the answers

What is the primary role of protein trafficking in a cell?

It refers to the movement of newly synthesized proteins. Signup and view all the answers

Which component of the Golgi apparatus is farthest from the endoplasmic reticulum?

Trans face Signup and view all the answers

What does the endoplasmic reticulum - Golgi intermediate compartment (ERGIC) facilitate?

Transport between the ER and Golgi apparatus. Signup and view all the answers

How are the cisternae in the Golgi apparatus structured?

Stacked in groups of 4-8. Signup and view all the answers

What are the three components of the Golgi apparatus named for?

Their proximity to the endoplasmic reticulum. Signup and view all the answers

What is the role of ribosomes in a cell?

They help the cell make the proteins it needs to function. Signup and view all the answers

What happens during the elongation step of protein synthesis?

The peptide chain keeps growing as more amino acids are added. Signup and view all the answers

Where are ribosomes primarily made within a cell?

In the nucleolus of the nucleus. Signup and view all the answers

Which of the following best describes the structure of a ribosome during protein production?

A complex of mRNA, a large subunit, and a small subunit. Signup and view all the answers

What occurs during the termination step of protein synthesis?

The ribosomal subunits break apart and release the new protein. Signup and view all the answers

What happens to vesicles as they move through the Golgi apparatus?

They undergo various modifications by enzymes. Signup and view all the answers

What is the role of the trans face of the Golgi apparatus?

To sort and package molecules for their destinations. Signup and view all the answers

Which modification is NOT mentioned as occurring to proteins and lipids in the Golgi apparatus?

Phosphorylation of amino acids. Signup and view all the answers

What structure in the Golgi apparatus is responsible for receiving incoming vesicles?

Cis face. Signup and view all the answers

Which of the following is a final destination for molecules processed in the Golgi apparatus?

Various locations depending on the sorting. Signup and view all the answers

Study Notes

Smooth ER

Located near the cell periphery, the smooth endoplasmic reticulum (SER) lacks ribosomes, distinguishing it from rough ER.
Functions include lipid, steroid, and carbohydrate synthesis, along with metabolizing drugs and toxins.
The type of cell influences the specific functions of the SER.
In muscle cells, it's known as the sarcoplasmic reticulum, regulating calcium ion concentrations during muscle contraction and relaxation.
In adrenal glands, SER secretes cholesterol, a precursor to steroid hormones.
In liver cells, SER synthesizes and stores detoxifying enzymes to process harmful substances like alcohol and drugs.

Functions of ER

Rough ER (RER) is primarily responsible for protein production, while SER synthesizes phospholipids and steroids.
The ER detoxifies harmful exogenous molecules and regulates calcium ion sequestration and release.

Lysosomes

Heterophagia involves breaking down foreign substances absorbed via endocytosis.
Autophagy is the process of degrading internal materials, including nutrients and dysfunctional organelles.
Autolysis occurs when lysosomes rupture, digesting the cell due to pathology or aging.
Primary lysosomes form from the Golgi apparatus and contain inactive hydrolases for degrading large molecules.
Secondary lysosomes form when primary lysosomes merge with endocytic vesicles, digesting various materials and recycling products to the cytoplasm.

Endoplasmic Reticulum Structure and Function

The endoplasmic reticulum (ER) produces, processes, and secretes proteins, playing a vital role in every cell of humans and other organisms.
Its structure consists of interconnected flattened sheets (cisternae) and tubules, facilitating efficient function.
Rough ER is studded with ribosomes, while the smooth ER lacks them.

Rough ER

Lumen of rough ER is narrower than that of smooth ER.
Central to protein synthesis as ribosomes translate mRNA into proteins, which are then modified and transported.

Golgi Network

Composed of two networks: cis and trans Golgi networks, each made of multiple cisternae.
The cis Golgi network is adjacent to the ER, while the trans Golgi network is the farthest.
The Golgi modifies proteins and lipids received from the ER, packaging them into vesicles for transport.

Protein Trafficking

Newly synthesized proteins are transported from the ER to the Golgi for modification and sorting to their destinations.
The Golgi creates polysaccharides and packages proteins and lipids within vesicles for secretion or internal use.

Lysosome Functionality

Lysosomes are membrane-bound organelles responsible for cellular waste degradation and recycling.
Their acidic internal environment (pH 4.5-5.5) contains hydrolytic enzymes, facilitating the breakdown of internal and external materials.
They play a role in autophagy, cellular repair, and can trigger autolysis when a cell is irreparably damaged.

Ribosome Structure and Function

Ribosomes are essential for protein synthesis, directing what type of proteins are produced based on location.
Composed of two subunits (large and small), they come together to facilitate protein production when needed.
The ribosomal process involves initiation, elongation, and termination of protein synthesis.

Golgi Apparatus Structure

The Golgi apparatus, made up of stacked pouches called cisternae, operates closely with the ER.
Composed of the cis face (closest to the ER), trans face (farthest from the ER), and medial section, it processes proteins and lipids.
The endoplasmic reticulum-Golgi intermediate compartment (ERGIC) facilitates transport between the ER and Golgi.

Golgi Processing Steps

Proteins or lipids leave the ER as vesicles, enter the Golgi at the cis face, and are modified as they move through its lumen.
Modifications may include sugar replacements or the addition of fatty acids or phosphates.
At the trans face, molecules are sorted and packaged into vesicles for delivery to specific cellular locations.

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Description

This quiz focuses on the smooth endoplasmic reticulum (ER), its structure, and its various functions. Learn about lipid synthesis, metabolism of toxins, and the special characteristics of smooth ER in different cell types, including muscle cells. Test your knowledge on this essential cellular component.