Histology LC 1: Introduction to Histology

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Questions and Answers

Which type of molecules predominantly utilize simple diffusion for transport across cell membranes?

Protein complexes

Large charged ions

Small uncharged polar molecules (correct)

Complex carbohydrates

What is the characteristic function of ion channel proteins in membrane transport?

To actively pump ions against their concentration gradient

To bind and transport large macromolecules

To form selective pores allowing ions to pass based on size and charge (correct)

To transport lipophilic molecules through the membrane

What role do carrier proteins play in facilitated diffusion?

They allow for the active transport of molecules

They increase the concentration gradient of molecules

They exclusively transport lipophilic substances

They exhibit specificity for particular molecules being transported (correct)

Why do lipophilic molecules pass through cell membranes more easily than water-soluble molecules?

They dissolve in the lipid bilayer of the membrane Signup and view all the answers

What distinguishes facilitated diffusion from simple diffusion?

Facilitated diffusion uses specific transport proteins Signup and view all the answers

What feature is shared by both ion channels and carrier proteins regarding the transport of molecules?

Both facilitate passive transport mechanisms Signup and view all the answers

Which statement best describes the glyocalyx?

It is a sugar coat that aids in cellular recognition and protection Signup and view all the answers

What type of transport would be required for water molecules to cross cell membranes via aquaporins?

Facilitated diffusion Signup and view all the answers

What is the primary function of ribophorins found in the RER membrane?

To facilitate binding of the large ribosomal subunit Signup and view all the answers

Which characteristic is true about the transitional element of the RER?

It forms vesicles that lack ribosomes Signup and view all the answers

What is the main structural component of the Golgi complex?

Disk-shaped cisternae Signup and view all the answers

In the context of protein synthesis, which cell type would have a highly developed RER?

B lymphocytes producing immunoglobulins Signup and view all the answers

What defines the polarity of the Golgi complex?

Arrangement of cisternae into stacks Signup and view all the answers

What is the approximate size of mitochondria?

0.2 Micrometer wide and 7 Micrometer long Signup and view all the answers

Which type of proteins are synthesized by mitochondria?

Primarily secretory proteins including lysosomal proteins Signup and view all the answers

What role does the RER play in protein management aside from synthesis?

Regulating the degradation of misfolded proteins Signup and view all the answers

What is the primary function of superoxide dismutase (SOD)?

Break down harmful oxygen molecules Signup and view all the answers

What processes generate autophagolysosomes?

Fusion of autophagic vacuoles with lysosomes Signup and view all the answers

Which enzyme is involved in breaking down hydrogen peroxide?

Catalase Signup and view all the answers

What do residual bodies contain after lysosomal degradation?

Undegraded material like lipofuscin Signup and view all the answers

Which of the following accurately describes the formation of multivesicular bodies?

Combination of early endosomes with late endosomes containing endocytic vesicles Signup and view all the answers

What role do autophagic vacuoles play in cellular processes?

They enclose cell components targeted for degradation. Signup and view all the answers

How do lysosomes participate in detoxification?

By containing enzymes that degrade harmful substances like ethanol Signup and view all the answers

Which statement accurately reflects the composition of inclusions in lysosomes?

Inclusions represent undegradable material found in residual bodies. Signup and view all the answers

What is the primary function of glycogen in the body?

To provide a stored energy source that can be degraded to glucose Signup and view all the answers

Which cellular structure is described as containing two centrioles and a cloud of pericentriolar material?

Centrosome Signup and view all the answers

What characteristic distinguishes lipid droplets from other cellular structures?

They vary markedly in size and appearance based on fixation methods Signup and view all the answers

What is lipofuscin primarily associated with in cells?

It represents undigested material that increases with age Signup and view all the answers

How are centrioles arranged within a centrosome?

As a pair oriented at right angles to one another Signup and view all the answers

What is the primary role of peroxisomes in cells?

Degradation of fatty acids and detoxification of harmful substances Signup and view all the answers

What characteristic of glycogen sets it apart from other macromolecules?

It lies close to the smooth endoplasmic reticulum and is not membrane-bound Signup and view all the answers

What structural pattern is observed in each centriole?

Nine triplets of microtubules arranged radially Signup and view all the answers

What is the primary function of the nucleolus?

Synthesis of rRNA and assembly into ribosomal precursors Signup and view all the answers

Which structure is characterized as clusters of irregularly distributed particles containing RNP?

Interchromatin granules Signup and view all the answers

What is the approximate diameter of perichromatin granules?

30-50 nm Signup and view all the answers

What do hnRNP particles consist of?

Precursor mRNA and proteins Signup and view all the answers

Which type of granules contain 4.7S RNA and peptides similar to those found in hnRNPs?

Perichromatin granules Signup and view all the answers

What role does heterochromatin play in relation to interchromosomal interactions?

Facilitates chromosomal segregation during meiosis Signup and view all the answers

Under which condition might the number of interchromatin granules increase?

Exposure to carcinogens or high temperatures Signup and view all the answers

Which function, although transcriptionally inactive, is associated with the nucleolus?

Sequestration of regulatory proteins Signup and view all the answers

Study Notes

Cell Transport Mechanisms

Simple diffusion transports small non-polar molecules (O2, N2) and small uncharged polar molecules (H2O, CO2, glycerol).
Diffusion rate is proportional to the concentration gradient and shows little specificity.
Lipophilic (fat-soluble) molecules pass easily through membranes, while water-soluble molecules diffuse slowly.
Facilitated diffusion involves ion channels and carrier proteins, which have specificity for the transported molecules.

Membrane Proteins

Ion Channels

Multi-pass transmembrane proteins create aqueous pores for specific small water-soluble molecules and ions.
Passive transport occurs down electrochemical gradients, aided by proteins like aquaporins for water.

Carrier Proteins

Carrier proteins assist in the transport of larger molecules across membranes.

Glycocalyx

A sugar coat on the plasmalemma's outer surface, aiding cell recognition and interaction.

Rough Endoplasmic Reticulum (RER)

Contains ribophorins for the binding of large ribosomal subunits.
Abundant in secretory protein-synthesizing cells, organized into parallel arrays.
Transitional elements form vesicles free of ribosomes, connected to the Golgi apparatus.

Mitochondria

Rod-shaped organelles (0.2 µm wide, 7 µm long) synthesize membrane-bound proteins, lysosomal proteins, and secretory proteins.

Golgi Complex

Composed of membrane-bounded cisternae (saccules) arranged in a stack, held by microtubules.
Has distinct polarity with varying functions across regions.
Contains enzymes for oxidizing fatty acids, synthesizing cholesterol, and detoxifying substances.

Lysosomes

Types include multivesicular bodies formed by the fusion of endosomes, phagolysosomes fused with phagocytic vacuoles, and autophagolysosomes from autophagic vacuoles.
Residual bodies are lysosomes expanded with undegraded material, often excreted from the cell.
Examples of lysosomal enzymes include superoxide dismutase (SOD), glutathione oxidase, and catalase.

Peroxisomes

Also known as microbodies, these spherical organelles are involved in oxidative reactions and contain catalase.

Glycogen and Lipid Droplets

Glycogen appears as clusters in hepatocytes, serves as a glucose source for the bloodstream.
Lipid droplets are storage forms of triglycerides and cholesterol, vary in size based on fixation methods.

Lipofuscin

Membrane-bound, electron-dense material that accumulates with age in non-dividing cells, considered an "age pigment."

Centrosome

Near the nucleus, consists of two centrioles and pericentriolar material.
Centrioles are cylindrical (0.2 µm wide, 0.5 µm long) and composed of nine triplets of microtubules.

Nucleolus

Involved in rRNA synthesis and ribosome assembly, has various particles including interchromatin and perichromatin granules.
Sequesters nucleolar proteins for cell-cycle checkpoint signaling; regulator proteins are released when needed.

Nuclear Matrix

Contains maturing ribosomal precursor particles, implicated in RNA processing and chromosomal interactions.

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Description

This quiz focuses on the basic principles of histology, particularly small molecule transport mechanisms such as simple diffusion. Understanding how non-polar and polar molecules move across cell membranes is crucial in the study of histology. Prepare to test your knowledge with questions on these foundational concepts.