Cell Biology Quiz: Nucleus and Organelles

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Questions and Answers

What is the primary function of the nucleus in a cell?

Protein digestion

Genetic control center (correct)

Energy production

Photosynthesis

Which organelle is responsible for the synthesis of ribosomal RNA?

Peroxisome

Centrosome

Endoplasmic reticulum

Nucleus (correct)

What function do peroxisomes serve in the cell?

DNA replication

Synthesis of chlorophyll

Production and conversion of hydrogen peroxide (correct)

Transport of nutrients

What is the role of the centrosome in a cell?

Microtubule-organizing center Signup and view all the answers

Which structure provides structural support and motility within the cell?

Cytoskeleton Signup and view all the answers

How are microfilaments involved in cellular motility?

Through the interaction with motor proteins Signup and view all the answers

What characterizes the nuclear envelope?

Pores that allow material flow Signup and view all the answers

Which of the following structures are centrioles composed of?

Nine triplets of microtubules in a ring Signup and view all the answers

What role do intermediate filaments play in muscle cells?

They reinforce cell shape and anchor organelles Signup and view all the answers

What is the structural arrangement of microtubules in cilia and flagella called?

9 + 2 pattern Signup and view all the answers

Which of the following statements about the extracellular matrix (ECM) is true?

The ECM helps hold cells together in tissues Signup and view all the answers

What type of protein is associated with bending the microtubules in cilia and flagella?

Dynein Signup and view all the answers

How do integrins function in relation to the extracellular matrix?

They connect the ECM to microfilaments in the cytoskeleton Signup and view all the answers

What is the diameter of actin filaments in muscle cells?

7 nm Signup and view all the answers

What is one primary function of microtubules in muscle cells?

Providing rigidity and tracks for organelle movement Signup and view all the answers

Which of the following correctly describes the size comparison of actin, intermediate filaments, and microtubules?

Microtubules are the largest, followed by intermediate filaments then actin Signup and view all the answers

What type of cell junction prevents leakage of extracellular fluid across epithelial cells?

Tight junctions Signup and view all the answers

What is the primary function of anchoring junctions in animal tissues?

Connect to the extracellular matrix Signup and view all the answers

Which of the following statements about gap junctions is accurate?

They facilitate rapid intercellular communication. Signup and view all the answers

In cell fractionation, what process follows homogenization?

Differential centrifugation Signup and view all the answers

What is the role of microfilaments in the cytoskeleton?

Structural support and motility Signup and view all the answers

Which type of junction is likely found in tissues that experience constant mechanical stress, such as the skin and heart?

Desmosomes Signup and view all the answers

How does centrifugation assist in the study of cell organelles?

It enables separation of organelles based on size and density. Signup and view all the answers

Which cellular structure is rich in mitochondria after centrifugation at high speeds?

Pellet Signup and view all the answers

What is cell fractionation primarily used for in scientific research?

Separating and analyzing organelles Signup and view all the answers

What role does the extracellular matrix perform in relation to cells?

Connects cells and supports tissue integrity Signup and view all the answers

Study Notes

Cellular Organelles

Cells contain various organelles, including the nucleus, peroxisomes, and the endomembrane system.

The Nucleus

The nucleus is the control center of the cell.
It contains most of the cell's DNA.
DNA directs protein synthesis by producing mRNA.
Chromosomes are structures composed of DNA and proteins. Each chromosome contains a single DNA molecule.
The nuclear envelope is a double membrane with pores that allow materials to move in and out of the nucleus.
The nuclear envelope is connected to the endoplasmic reticulum.
The nucleolus is a prominent structure within the nucleus, responsible for rRNA synthesis.

Peroxisomes

Peroxisomes are metabolic compartments.
Bounded by a single membrane.
Produce hydrogen peroxide.
Convert hydrogen peroxide to water.
Perform various reactions with many different functions.

Centrosomes and Centrioles

Microtubules grow out from a centrosome near the nucleus.
The centrosome is a microtubule-organizing center.
Animal cells have a centrosome with a pair of centrioles.
Each centriole has nine triplets of microtubules arranged in a ring.

The Cytoskeleton

The cytoskeleton is a network of protein fibers that organizes the cell's structure and activities.
It provides structural support and motility, with interactions between the cytoskeleton's proteins and motor proteins driving many cellular functions.
Composed of three main types of fibers: microfilaments, intermediate filaments, and microtubules.
Microfilaments (actin filaments): support cell shape and are involved in motility. Contain myosin in addition to actin, and in muscle cells, thousands of actin filaments are arranged parallel to each other.
Intermediate filaments: reinforce cell shape and anchor organelles.
Microtubules (tubulin): give the cell rigidity and act as tracks for organelle movement.
- Microtubules have a 9+2 pattern, and are anchored to centrioles/basal bodies.
Cilia and flagella are made from microtubules, and are surrounded by plasma membrane.

Cilia and Flagella

Cilia and flagella move by bending microtubules.
Some protists use them for locomotion.
Multicellular organisms use them for different purposes (eg. cilia sweep mucus in lungs, flagella move sperm).
Both are made of microtubules wrapped in plasma membrane with a 9+2 structure.
Move through bending of motor proteins called dynein feet.

The Extracellular Matrix (ECM)

Animal cells synthesize and secrete an extracellular matrix (ECM).
The ECM helps hold cells together in tissues and protects and supports the plasma membrane.
The ECM attaches to cells through glycoproteins
Integrins span the plasma membrane and connect to the microfilaments of the cytoskeleton.

Cell Junctions

Adjacent cells communicate, interact, and adhere via specialized junctions.
Tight junctions prevent leakage of extracellular fluid across layers of epithelial cells.
Anchoring junctions hold cells together and attach them to components of the extracellular matrix, and are found in tissues prone to mechanical stress.
Gap junctions form channels connecting adjacent cells to mediate the rapid exchange of molecules in many bodily systems and are associated with normal physiological function.

Cell Fractionation

Cell fractionation separates major organelles from one another.
Centrifuges are used to fractionate cells into their component parts.
Enables scientists to determine functions of organelles.
Biochemistry and cytology help relate cell function with structure.

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Description

Test your knowledge on the primary functions of cellular components, including the nucleus, ribosomes, and peroxisomes. This quiz explores various organelles and their roles in maintaining cell structure and function. Perfect for students studying cell biology or related subjects.