Cell Biology: Endomembrane System & ER

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Questions and Answers

What is the primary function of the Rough ER in the endomembrane system?

Storage of energy molecules

Transport of electrons

Translation of mRNA to protein (correct)

Waste recycling

Which part of the Golgi apparatus is primarily responsible for receiving incoming vesicles?

Trans face

Cis face (correct)

Lumen

Periphery

What role do lysosomes play in the cell?

Store genetic material

Synthesize energy

Regulate protein synthesis

Degrade biomolecules (correct)

What structural feature distinguishes the Smooth ER from the Rough ER?

Presence of ribosomes Signup and view all the answers

How does the Golgi apparatus modify proteins?

By adding sugar chains Signup and view all the answers

What is the primary function of mitochondria within a cell?

Chemical energy conversion Signup and view all the answers

Which structure is involved in the transformation of light energy into chemical energy?

Chloroplasts Signup and view all the answers

What unique features support the endosymbiont hypothesis regarding mitochondria and chloroplasts?

Double membranes and independent genomes Signup and view all the answers

What is the subunit that makes up microtubules in the cytoskeleton?

Tubulin Signup and view all the answers

Which structure in animal cells is responsible for providing cell-cell communication?

Gap junctions Signup and view all the answers

What is one of the primary functions of the actin filaments in the cytoskeleton?

Muscle contraction Signup and view all the answers

Which statement accurately describes peroxisomes?

Involved in alcohol detoxification Signup and view all the answers

What process do vacuoles mainly facilitate in damaged materials?

Autophagy Signup and view all the answers

Which component of the extracellular matrix provides structural support?

Collagen Signup and view all the answers

Which type of cytoskeletal filament is primarily involved in chromosome movement during cell division?

Microtubules Signup and view all the answers

What is the primary function of the Smooth ER within the endomembrane system?

Detoxification and lipid metabolism Signup and view all the answers

Which statement accurately describes the structure of the Golgi apparatus?

It is comprised of pancake-like chambers known as cisternae. Signup and view all the answers

What is the role of ribosomes on the Rough ER?

To facilitate protein translation for secretion Signup and view all the answers

What key process occurs within lysosomes?

Degradation of biomolecules via hydrolytic enzymes Signup and view all the answers

In what manner do vesicles function within the Golgi apparatus?

By budding off and transporting between cisternae Signup and view all the answers

What is the function of chlorophyll in chloroplasts?

To capture light energy Signup and view all the answers

What distinguishes the inner membrane of mitochondria?

It contains structures for ATP production Signup and view all the answers

Which type of cytoskeletal filament is primarily responsible for maintaining cell shape?

Microtubules Signup and view all the answers

What is a major function of desmosomes in animal cells?

Bonding cells together via intermediate filaments Signup and view all the answers

Which evidence supports the endosymbiont hypothesis regarding organelles?

Independent genetic material Signup and view all the answers

What is the role of the extracellular matrix in animal cells?

To provide a rigid meshwork for cellular structure Signup and view all the answers

What is the primary role of cristae in mitochondria?

Increasing surface area for enzymatic reactions Signup and view all the answers

What are the monomers that compose actin filaments?

Actins Signup and view all the answers

What is the main function of peroxisomes within a cell?

Chemical oxidations and detoxifying substances Signup and view all the answers

Which of the following structures is involved in inter-cell exchange and communication?

Gap junctions Signup and view all the answers

Study Notes

Tour of the Cell 2

The lecture covers the endomembrane system, protein trafficking, and metabolic functions within cells.
The endomembrane system is like a cellular factory.
The endoplasmic reticulum (ER) is responsible for production, biosynthesis and other functions.
The rough ER has ribosomes attached, making proteins for secretion, and often glycosylating them.
The smooth ER lacks ribosomes and produces lipids and hormones.
The Golgi apparatus processes and packages proteins, and adds sugar chains to them, before, often exporting them to lysosomes.
Vesicles transport materials within the cell.

Endoplasmic Reticulum (ER)

The ER is a network of membranes within the cytoplasm.
It has a large surface area, with a convoluted structure.
The inside of the ER is called the lumen.
The ER has specialized environments to control specific processes.
ERs are of two types: smooth ER and rough ER.
The rough ER is studded with ribosomes, aiding protein production.
The smooth ER is responsible for lipid production, and lacks ribosomes.

Rough ER

Ribosomes are attached to the rough ER.
Ribosomes translate mRNA into proteins.
Proteins produced by rough ER are often secreted out of the cell or are transported to other parts of the cell.
Many proteins produced on the rough ER are glycosylated , which is adding sugars.
Proteins are processed within the membrane of the rough ER.
Leader signal polypeptides can target proteins to the ER.
Proteins are integrated into the ER interior, where they are processed.

Golgi Apparatus

The Golgi apparatus is a series of flattened sacs.
It has a cis (receiving end) and trans (shipping end).
Materials move from cis to trans within the Golgi.
Sugars are added to proteins in the Golgi.
Proteins are exported or directed to lysosomes.
It is like a sorting and modification center for proteins in cells.

Lysosomes

Lysosomes are sacs filled with hydrolytic enzymes.
They are produced by the Golgi and involved in waste recycling.
They degrade biomolecules and damaged materials.
The enzymes in lysosomes are ready to degrade biomolecules.
Lysosomes merge with vesicles from the outer (cell) membrane to digest material in phagocytosis.
Lysosomes merge with vacuoles containing damaged materials in autophagy.

Energy Organelles - Mitochondria

Mitochondria convert chemical energy into ATP.
They have two membranes. The outer membrane is smooth, and the inner membrane is folded (cristae) to increase surface area.
They contain their own DNA and ribosomes.
Processes like respiration produce ATP, the cells' energy currency.

Energy Organelles - Chloroplasts

Chloroplasts convert light energy into chemical energy (sugars).
They have two membranes and thylakoids (internal membrane stacks).
Thylakoids contain chlorophyll for photosynthesis.
Chloroplasts contain their own DNA and ribosomes.

Energy Organelles - Peroxisomes

Peroxisomes contain enzymes for chemical oxidation.
They protect cells from toxic substances like hydrogen peroxide (H₂O₂).
Peroxisomes are involved in alcohol detoxification.

Endosymbiotic Hypothesis

Mitochondria and chloroplasts were once free-living prokaryotes (bacteria) that formed relationships with early eukaryotic cells.
This theory explains why they have double membranes, their own DNA, and their unique ribosomes.

Mitochondria (detailed)

Mitochondria have two membranes.
The outer membrane is smooth.
The inner membrane is folded into cristae to increase surface area.
The spaces within are the intermembrane space and the matrix.
Mitochondrial processes happen in these two spaces.

Chloroplasts (detailed)

Chloroplasts also have two membranes.
The thylakoids are inside, interconnected sacs.
Grana are stacks of thylakoids.
The stroma is the fluid around the thylakoids.
The sites of photosynthesis are primarily in the stroma, thylakoid membranes contain chlorophyll.

Cytoskeleton

The cytoskeleton maintains cell shape and enables cell movement.
There are three types of cytoskeleton filaments: Microtubules, Actin filaments, and Intermediate filaments.
Microtubules are hollow tubes, help maintain cell shape, are involved in cell division and cell motility.
Actin filaments are solid rods, also helpful in cell shape, cell contraction and motility .
Intermediate filaments are more diverse and also assist in cell structure, helping to withstand tension in anchoring structures.
A variety of proteins interact with the cytoskeleton to direct the movement and actions of cell components.

Extracellular Connections

Extracellular matrix is a complex of glycoproteins, carbs, and fibrous proteins.
It provides structure and support for animal cells.
Collagen, one major protein in the extracellular matrix, is a major part of the human protein matrix, making up nearly 40%.
Integrins are cell surface proteins that connect cells to the extracellular matrix.
Junctions between animal cells include tight junctions, desmosomes, and gap junctions.
Tight junctions prevent leakage between cells.
Desmosomes provide strong adhesion between cells.
Gap junctions allow for intercellular communication.

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Description

This quiz explores the intricacies of the endomembrane system, focusing on structures like the endoplasmic reticulum (both smooth and rough) and the Golgi apparatus. Understand how proteins are synthesized, processed, and transported within the cell. Ideal for students delving into cellular biology.