Cell Structure and Types Quiz

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Questions and Answers

What is characteristic of each species in terms of chromosomes?

  • All species have the same number of chromosomes
  • Species cannot have different chromosomal arrangements
  • Chromosome number is irrelevant to species classification
  • Each species has a distinct characteristic number of chromosomes (correct)

Where are densely staining granules found in nondividing cells?

  • In the nucleolus (correct)
  • In the endoplasmic reticulum
  • In the cytoplasm
  • In the mitochondria

What role do chromosomal numbers play in the classification of species?

  • They are the primary factor in evolutionary adaptation
  • They help distinguish between different species (correct)
  • They influence the physical appearance of a species
  • They determine the evolutionary history of a species

Which statement about the nucleolus is true?

<p>The nucleolus functions in ribosome production (B)</p> Signup and view all the answers

How does the number of chromosomes vary among species?

<p>It can vary significantly between related species (B)</p> Signup and view all the answers

What is the approximate width of the space separating the two layers?

<p>20-40 nm (B)</p> Signup and view all the answers

What is the diameter of the envelope pores?

<p>100 nm (A)</p> Signup and view all the answers

How do the sizes of the space between the layers and the envelope pores compare?

<p>The space is larger than the pores (D)</p> Signup and view all the answers

Which of the following best describes the relationship between the two layers?

<p>They are separated by a space (D)</p> Signup and view all the answers

What is the role of the protein complex associated with the membrane pores?

<p>To regulate the entry and exit of particles (A)</p> Signup and view all the answers

If the diameter of the envelope pores is 100 nm, what can you infer about their size in relation to the space between the layers?

<p>The pores are smaller than the space's upper limit (A)</p> Signup and view all the answers

Where are the inner and outer membranes continuous?

<p>At the edges where they form pores (D)</p> Signup and view all the answers

Which statement about the membranes is accurate?

<p>Both membranes are continuous at their edges. (B)</p> Signup and view all the answers

What does the term 'pore' refer to in this context?

<p>An opening through which particles can pass (C)</p> Signup and view all the answers

What is NOT a function of the protein complex lining the pores?

<p>To anchor the membranes together (D)</p> Signup and view all the answers

What is the main function of the nuclear lamina?

<p>To maintain the shape of the nucleus (B)</p> Signup and view all the answers

What components make up chromosomes?

<p>Chromatin, which is a complex of DNA and proteins (C)</p> Signup and view all the answers

Which statement about the nuclear matrix is most accurate?

<p>It acts as a framework for chromatin organization (B)</p> Signup and view all the answers

How do histones relate to chromatin?

<p>Histones are basic proteins that help package DNA into chromatin (B)</p> Signup and view all the answers

Which statement is true about the role of the nuclear lamina?

<p>It supports the inner nuclear envelope structure (B)</p> Signup and view all the answers

What is the typical length of a plant cell?

<p>100 µm (C)</p> Signup and view all the answers

Which microscopy technique allows for the observation of structures not visible under a light microscope?

<p>Electron microscopy (C)</p> Signup and view all the answers

Which of the following is a type of electron microscopy?

<p>Scanning electron microscopy (A)</p> Signup and view all the answers

What distinguishes plant cells from other types of cells in terms of structure?

<p>Presence of a cell wall (B)</p> Signup and view all the answers

Which imaging technique is best for observing the surface of a cell?

<p>Scanning electron microscopy (C)</p> Signup and view all the answers

Which microscopy method enhances contrast without staining the sample?

<p>Phase-contrast microscopy (C)</p> Signup and view all the answers

What is NOT a characteristic of plant cells?

<p>Cilia (A)</p> Signup and view all the answers

Which microscopy technique uses fluorescent dyes to visualize samples?

<p>Fluorescence microscopy (B)</p> Signup and view all the answers

Which of the following best describes prokaryotic cells?

<p>They are found in bacteria and cyanobacteria. (C)</p> Signup and view all the answers

What is the primary function of the cytoplasm in eukaryotic cells?

<p>To fill the cell and host metabolic reactions. (A)</p> Signup and view all the answers

Which statement accurately describes the nucleus of eukaryotic cells?

<p>It contains chromatin composed of DNA and proteins. (C)</p> Signup and view all the answers

What is a defining characteristic of eukaryotic cells compared to prokaryotic cells?

<p>They contain membrane-bound organelles. (D)</p> Signup and view all the answers

Which of the following statements about the nuclear envelope is correct?

<p>It contains numerous pores for transport. (D)</p> Signup and view all the answers

How many nucleoli can typically be found in a eukaryotic cell's nucleus?

<p>One or more depending on the cell type. (B)</p> Signup and view all the answers

What size range is typical for a eukaryotic cell nucleus?

<p>5 µm (D)</p> Signup and view all the answers

Which kingdom contains organisms that are classified as prokaryotic?

<p>Prokaryotae (D)</p> Signup and view all the answers

Flashcards

Separation between layers

The distance between two layers.

Envelope pores

Tiny openings in the envelope.

Nanometer (nm)

A unit of measurement for very small things.

What is Biology?

The study of living organisms and their components.

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What are cells?

Microscopic structures that make up all living organisms.

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What is a light microscope?

A microscope that uses light to view objects.

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What is primary cell structure?

Structures within a cell that can be seen using a light microscope.

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What is an electron microscope?

A microscope that uses electrons to view objects.

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What is ultrastructure?

Structures within a cell that can be seen using an electron microscope.

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What are prokaryotic cells?

Cells that lack a nucleus and other membrane-bound organelles.

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What are eukaryotic cells?

Cells that have a nucleus and other membrane-bound organelles.

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Membrane

The boundary surface between two different cellular compartments. Examples include the cell membrane, the nuclear envelope, and the membranes surrounding organelles like the mitochondria.

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Pore

A protein complex that spans the width of the cell membrane and regulates the passage of molecules and ions.

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Outer Membrane

The outer layer of the cell membrane, in direct contact with the external environment.

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Inner Membrane

The inner layer of the cell membrane, facing the interior of the cell.

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Entry and Exit of Particles

The process by which molecules and ions move across the cell membrane, controlled by pores and other membrane proteins.

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Cytoplasm

The fluid matrix that fills the cell, containing organelles, internal membrane systems and various structures.

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Site of Metabolism (Cytoplasm)

All chemical reactions associated with life processes take place here, making it a vital part of the cell's function.

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Nucleus

Contains DNA and proteins organized into chromosomes, the genetic material of the cell.

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Nuclear Envelope

Double membrane surrounding the nucleus, with pores that allow communication and transport between the nucleus and cytoplasm.

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Nucleolus

Tiny structures within the nucleus, involved in the production of ribosomes, which are essential for protein synthesis.

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Ribosomes

These are involved in the production of proteins, which are essential for cell growth, repair and function.

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Genetic Material

The genetic material in the form of DNA, housed in the nucleus and responsible for directing the cell's activities.

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Proteins (in Nucleus)

They help to maintain the shape of the cell and provide structural support for internal organelles.

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Nuclear Lamina

A network of protein filaments inside the nucleus that helps maintain the shape of the nucleus.

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Chromatin

A complex of DNA and proteins (histones) that makes up chromosomes.

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Histones

The basic proteins that help package and organize DNA into chromosomes.

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Chromosomes

Structures within the nucleus that contain genetic information in the form of DNA.

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Nuclear Matrix

A complex network of protein fibers within the nucleus that provides structural support and helps organize DNA.

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Chromosome number in species

Every species has a unique set of chromosomes, like a fingerprint. It's like having a specific number of books in a library for each species.

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Chromosome number in species

The number of chromosomes in a species is usually a constant, though variation may occur.

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What is the function of the nucleolus?

The nucleolus plays a vital role in ribosome synthesis and is a part of the nuclear structure.

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What is a chromosome and its function?

Chromosomes are the structure that carry genetic information in the nucleus. Each chromosome has a number of genes.

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Study Notes

Cell Structure

  • A cell is a fundamental membrane-bound unit that makes up all living things.
  • Cell size is measured in micrometres (µm).
  • 1 µm = 10⁻³ mm
  • A typical bacterium is 10 µm long.
  • A typical animal cell is 40 µm in diameter.
  • A typical plant cell is 100 µm long.
  • Different types of cells use different techniques for visualization such as brightfield (stained), phase-contrast, differential interference contrast, and fluorescence.

Types of Cells

  • Two types of cells exist: prokaryotic and eukaryotic.
  • Prokaryotic cells are found in bacteria and cyanobacteria.
  • Eukaryotic cells are found in all other organisms, including protoctista, fungi, plantae, and animalia.

Primary Cell Structure

  • Primary cell structure is what can be seen using a light microscope.
  • This includes the cell wall, cytoplasm, and nucleus.

Ultrastructure

  • Ultrastructure refers to the structures that are visible through an electron microscope.
  • Methods of electron microscopy include scanning (SEM) and transmission (TEM).

Specimen Preparation for TEM

  • Specimens are prepared carefully for transmission electron microscopy.
  • Steps include specimen acquisition, trimming and concentration, fixation, dehydration, infiltration with transitional solvent, infiltration with resin, and embedding and curing.

Cytoplasm

  • The cytoplasm is the fluid matrix filling the cell.
  • It is the site of all chemical reactions vital for life processes.
  • Its ultrastructure is dynamic and complex, containing organelles and internal membrane systems.

Nucleus

  • The nucleus contains genetic material.
  • It can be spherical.
  • It is usually surrounded by a double membrane (the nuclear envelope).
  • The nuclear envelope has pores allowing for material exchange.
  • It is usually 5 µm in diameter.
  • A single nucleus is typically within the cell.
  • The nucleus contains DNA and proteins that form chromosomes.
  • One or more nucleoli are also contained in the nucleus.
  • The nuclear envelope is a double membrane composed of layers separated by a small space (20-40nm)
  • Nuclear pores are around 100nm in diameter.
  • Protein complexes regulate the entry and exit of particles through the nuclear pores.
  • The nuclear side of the membrane is lined with a network of protein filaments called the nuclear lamina maintaining the shape of the nucleus.
  • Chromatin is a complex of DNA and proteins (histones), and appears as a diffuse mass in non-dividing/resting cells.
  • Chromosomes contain genes that control the cell's activities by regulating protein synthesis in the cytoplasm.

Nucleolus

  • The nucleolus is a densely staining granule within the nucleus, visible in non-dividing cells.
  • Each cell has one or more nucleoli.
  • The nucleolus is the site of ribosome production.

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