Cell Structure and Function: Organelles

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Questions and Answers

What is the general shape of mitochondria?

Square-shaped

Circular

Rod-shaped or oval (correct)

Triangular

What surrounds the mitochondria?

No membrane

Single membrane

Triple membrane

Double membrane (correct)

What structures project into the inner cavity of mitochondria?

Ribosomes

Matrix

Membranes

Cristae (correct)

What is the gel-like solution inside the mitochondria called?

Matrix Signup and view all the answers

What role does the mitochondria play in skeletal muscle cells?

Energy production Signup and view all the answers

Which of the following best describes the inner membrane of mitochondria?

Highly folded with cristae Signup and view all the answers

What is the primary role of Na+ and K+ concentration gradients across the plasma membrane?

To provide energy for secondary active transport Signup and view all the answers

Where are dissolved enzymes primarily found in mitochondria?

In the matrix Signup and view all the answers

How does secondary active transport differ from primary active transport?

It relies on concentration gradients of ions Signup and view all the answers

What is the primary function of mitochondria?

Production of usable energy Signup and view all the answers

In which type of cells is glucose actively transported from low to high concentration using secondary active transport?

Intestinal and kidney cells Signup and view all the answers

What role does the concentration gradient of Na+ play in the transport of glucose into intestinal cells?

It provides energy for glucose transport Signup and view all the answers

What happens to glucose in the kidney cells during transport?

It is concentrated in the blood Signup and view all the answers

What is the primary function of peroxisomes in the cell?

Detoxify various wastes Signup and view all the answers

Which of the following best describes lysosomes?

Organelles containing hydrolytic enzymes Signup and view all the answers

Which type of enzymes are found in peroxisomes?

Oxidative enzymes Signup and view all the answers

How do lysosomes contribute to cellular function?

By breaking down waste materials Signup and view all the answers

What is the result of the action of oxidative enzymes found in peroxisomes?

Detoxification of harmful substances Signup and view all the answers

Which of the following activities do peroxisomes NOT perform?

Producing hydrolytic enzymes Signup and view all the answers

What type of cellular structure involves the binding of a specific molecule to the surface membrane?

Receptor-mediated endocytosis Signup and view all the answers

What process enables cells to internalize foreign toxic compounds from their environment?

Endocytosis Signup and view all the answers

What primary role do microtubules serve in the cell?

Maintaining cell shape and transporting materials Signup and view all the answers

Which structure is composed of tubulin molecules?

Microtubules Signup and view all the answers

What is the main structural component of cilia and flagella?

Microtubules Signup and view all the answers

What are the three components of the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments Signup and view all the answers

Which of the following pathways is crucial for producing energy in cellular respiration?

All of the above Signup and view all the answers

What is the primary function of the cytosol?

Medium for chemical reactions within the cell Signup and view all the answers

Which organelles are primarily positioned by the cytoskeleton?

Mitochondria and lysosomes Signup and view all the answers

What is a major function of actin filaments?

Muscle contraction and cell movement Signup and view all the answers

What characterizes exocytosis in terms of vesicle docking?

Involves ‘lock-and-key’ matching of v-SNARE and t-SNARE Signup and view all the answers

How does the process of simple diffusion continue?

Until the concentration gradient is abolished Signup and view all the answers

What type of molecules does osmosis specifically involve?

Water molecules only Signup and view all the answers

Which of the following is true about facilitated diffusion?

Can reach a transport maximum (Tm) Signup and view all the answers

What drives secondary active transport?

Ion gradient established by primary active transport Signup and view all the answers

Which process is classified as active transport and requires ATP?

Primary active transport Signup and view all the answers

What happens to the membrane surface area during balanced endocytosis and exocytosis?

It remains constant Signup and view all the answers

What is a key characteristic of diffusion through protein channels?

Passively moves specific small ions Signup and view all the answers

What typically limits the rate of carrier-mediated transport?

Saturation of the carrier protein Signup and view all the answers

Which type of transport does not require energy input?

Facilitated diffusion Signup and view all the answers

Study Notes

Organelles: Lysosomes and Peroxisomes

Lysosomes are membrane-bound organelles containing hydrolytic enzymes for breaking down waste materials and cellular debris.
Peroxisomes contain oxidative enzymes that detoxify various wastes produced within the cell and neutralize foreign toxic compounds.

Mitochondria

Rod-shaped or oval structures, similar in size to bacteria, encased in a double membrane.
Inner membrane folds into cristae, increasing surface area for energy production.
The matrix is a gel-like solution where metabolic processes occur, contributing to ATP synthesis.

Cytoskeleton

Composed of three main components: microtubules, microfilaments, and intermediate filaments.
Microtubules are hollow tubes made from tubulin, providing structural support and enabling transport within cells.
Responsible for positioning organelles and forming the mitotic spindle for cell division.

Membrane Transport Mechanisms

Secondary Active Transport: Utilizes ion gradients to transport molecules against their concentration gradient, specifically through symport (co-transport) mechanisms involving sodium ions and glucose.
Exocytosis: Involves secretory vesicles docking at the plasma membrane through specific protein interactions (v-SNARE and t-SNARE), allowing materials to exit the cell.

Membrane Balance

Endocytosis and Exocytosis: These processes regulate membrane surface area and cell volume, maintaining homeostasis.
Membrane components are continuously recycled and restructured to accommodate internalized materials.

Membrane Transport Methods Summary

Simple Diffusion: Passive transport of nonpolar molecules down their concentration gradient until equilibrium is reached.
Facilitated Diffusion: Specific polar molecules transport through protein channels, obeying concentration gradients, but saturated at maximum capacity.
Osmosis: Water moves passively from areas of low solute concentration to high until equilibrium or opposing pressure is met.
Carrier-Mediated Transport:
- Primary Active Transport: Moves ions against their gradients using ATP; rate is limited by carrier saturation.
- Secondary Active Transport: Driven by existing ion gradients from primary transport, also displays saturation limits.

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Description

Explore the intricacies of cell organelles including lysosomes and peroxisomes. This quiz delves into their functions, structures, and the role of hydrolytic enzymes. Test your knowledge on these essential components of cell biology.