Cell Biology: Organelles and Functions

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Questions and Answers

What is the primary function of lysosomes in a cell?

To synthesize proteins

To store genetic information

To break down ingested food and recycle components (correct)

To promote cell mobility

Which of the following best describes the role of peroxisomes?

They provide structural support to the cell.

They synthesize glycoproteins for the extracellular matrix.

They neutralize hydrogen peroxide to prevent cellular damage. (correct)

They absorb nutrients and build cellular structures.

What are ribosomes primarily composed of?

DNA and protein

Peptides and nucleotides

Lipids and carbohydrates

RNA and protein (correct)

Which component of the cytoskeleton is made of tubulin?

Microtubules Signup and view all the answers

What is the smallest class of filaments in the cytoskeleton?

Microfilaments Signup and view all the answers

What role do intermediate filaments play in the cell?

They help maintain the cell's shape. Signup and view all the answers

Which statement is true regarding non-membrane-bound organelles?

They consist of solid structures without membranes. Signup and view all the answers

During cytokinesis, which cytoskeletal filament is particularly important?

Microfilaments Signup and view all the answers

What major activity occurs during the G1 phase of the cell cycle?

Protein synthesis and metabolic activities Signup and view all the answers

What is the outcome of the S phase of the cell cycle?

DNA is replicated, resulting in twice the actual DNA. Signup and view all the answers

Which of the following processes is not directly associated with the G2 phase?

DNA replication Signup and view all the answers

What is the primary purpose of mitosis?

To produce two genetically identical daughter cells Signup and view all the answers

Which of the following stages is not part of mitosis?

G1 phase Signup and view all the answers

During which stage do the chromosomes first become visible as short and thick rods?

Prophase Signup and view all the answers

What occurs during the metaphase of mitosis?

Chromosomes align at the metaphase plate. Signup and view all the answers

Which organelle is replicated during the G2 phase to facilitate cell division?

Centriole Signup and view all the answers

What is the primary mechanism by which oxygen (O2) enters a cell?

Simple diffusion Signup and view all the answers

What causes carbon dioxide (CO2) to diffuse out of the cell?

It diffuses due to a concentration gradient. Signup and view all the answers

What is the result when cells are placed in a hypertonic solution?

They shrivel as water exits. Signup and view all the answers

What term is used to describe solutions that have equal concentrations of solutes inside and outside the cell?

Isotonic Signup and view all the answers

How does water primarily move across the cell membrane?

Through protein channels and lipid bilayer Signup and view all the answers

What defines a solution that is hypertonic?

Higher concentration of solutes than another solution Signup and view all the answers

What occurs during osmosis?

Water diffuses through a semipermeable membrane Signup and view all the answers

In what condition can osmotic balance be disrupted?

When there is an unequal concentration of solutes Signup and view all the answers

What is the primary reason that causes the movement of molecules in a solution?

Random motion due to energy in individual molecules Signup and view all the answers

Which factor does NOT affect the rate of diffusion?

Color of the solution Signup and view all the answers

In which scenario would diffusion generally occur most quickly?

In a hot, crowded environment Signup and view all the answers

How does an increase in temperature affect molecular movement?

It causes molecules to move faster and collide more often Signup and view all the answers

What happens to molecules once they are evenly distributed in a solution?

There is no net movement but molecular motion continues Signup and view all the answers

How does a concentration gradient influence molecular diffusion?

Molecules diffuse toward lower concentration areas Signup and view all the answers

Which statement best describes the role of charge in diffusion?

Charged particles can influence the rate and direction of diffusion Signup and view all the answers

What effect does an increase in pressure have on diffusion?

It speeds up diffusion by increasing molecular collisions Signup and view all the answers

What is the primary energy source for passive transport mechanisms in cells?

Heat energy from the cellular environment Signup and view all the answers

Which of the following best describes simple diffusion?

Movement of molecules down their concentration gradient Signup and view all the answers

Active transport differs from passive transport in that it requires ____.

Cellular energy reserves Signup and view all the answers

Which transport mechanism requires the cell to do work?

Active transport Signup and view all the answers

Exocytosis and endocytosis are processes involved in ____.

Movement of large molecules across the cell membrane Signup and view all the answers

What characterizes facilitated transport compared to simple diffusion?

Involves specialized transport proteins Signup and view all the answers

Which of the following statements about passive transport is accurate?

It does not require cellular energy. Signup and view all the answers

The purpose of the cell membrane functioning as a 'gatekeeper' is to ____.

Control the internal environment of the cell Signup and view all the answers

Study Notes

Cellular Structures and Functions

Digested food and recycled components are released into the cytosol for cell use.
Indigestible food remains in lysosomes, forming residual bodies for elimination via exocytosis.

Peroxisomes

Peroxisomes are vital for cellular metabolism; they absorb nutrients and contain digestive enzymes.
They neutralize hydrogen peroxide, preventing DNA and membrane damage, promoting long-term cell health.

Non-Membrane-Bound Organelles

Ribosomes: Composed of RNA and protein, ribosomes can be free, attached to the endoplasmic reticulum, or form polyribosomes, playing a crucial role in protein synthesis.
Cytoskeleton: Made of structural proteins, maintaining cell shape and enabling mobility with three main filament types:
- Microtubules: Largest filaments, made of tubulin, crucial for cell shape and motility.
- Intermediate filaments: Medium-sized, composed of keratin, support cell shape.
- Microfilaments: Smallest, made of actin, important for cytokinesis and cellular mobility.

Cell Cycle Phases

G1 Phase: Cells perform metabolic activities, synthesizing mRNA and proteins, and enlarging in volume.
S Phase: DNA replication occurs, doubling genetic material; chromosomes consist of two chromatids.
G2 Phase: Rapid cell growth and preparation for division; synthesis of essential organelles, including centrioles for cell division.

Mitosis

Mitosis involves division of somatic and germ cells, producing two genetically identical daughter cells.
Stages of mitosis:
- Prophase: Chromosomes condense, centrosomes move apart, nuclear envelope disassembles.
- Metaphase: Chromosomes align at the metaphase plate, preparing for separation.

Membrane Structure and Function

The cell membrane is referred to as the "gatekeeper," controlling substance movement into and out of cells.

Transport Mechanisms

Two categories of transport: passive (no energy required) and active (energy expended by the cell).
Passive Transport: Includes simple diffusion and osmosis; relies on concentration gradients.
- Simple Diffusion: Molecules move from high to low concentration until distributed equally; affected by size, temperature, concentration, charge, and pressure.
- Osmosis: Specific to water movement, occurs through semipermeable membranes; can result in isotonic (equal concentrations) or hypertonic solutions (causing cell shrinkage).

Key Transport Concepts

Isotonic solutions maintain normal cell shape; hypertonic solutions lead to cell shrinkage through water loss.
Active transport requires cellular energy to move substances against concentration gradients, crucial for nutrient and ion uptake.

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Description

This quiz covers essential cellular structures, including lysosomes, peroxisomes, and ribosomes. Explore how these organelles contribute to metabolism, protein synthesis, and cell structure in both eukaryotic and prokaryotic cells. Test your knowledge on the functions and importance of these cellular components.