Microvilli and Cilia Structure and Function

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Questions and Answers

What is the primary role of motile cilia in the human respiratory tract?

Moving mucus toward the mouth (correct)

Conduction of cerebrospinal fluid

Sensing extracellular signals

Transporting the ovum to the uterus

Which proteins are involved in the structure of microvilli?

Actin, tubulin, and villin

Actin, fimbrin, and calmodulin (correct)

Calmodulin, catenin, and fibrin

Myosin, dynein, and actin

What distinguishes primary cilia from motile cilia?

Motile cilia are found on every cell in humans.

Motile cilia do not have a structural base.

Primary cilia serve as sensors for extracellular signals. (correct)

Primary cilia are responsible for movement.

Which of the following is NOT a function of motile cilia?

Sensing light and odorants Signup and view all the answers

What type of cilia are responsible for sperm motility in humans?

Motile cilia Signup and view all the answers

Which protein attaches actin filaments to the plasma membrane in microvilli?

Myosin I Signup and view all the answers

What is the primary purpose of isoelectric focusing in protein analysis?

To separate proteins based on their isoelectric points Signup and view all the answers

Where can primary cilia typically be found in human cells?

On almost every animal cell Signup and view all the answers

What is the main type of projection that cilia and flagella originate from?

Microtubule structure Signup and view all the answers

In the second step of isoelectric focusing, what is the purpose of adding SDS?

To separate proteins based on their size Signup and view all the answers

What distinguishes the resolving power of isoelectric focusing?

Ability to identify proteins with minimal size differences Signup and view all the answers

Which component is essential for electrophoresis in isoelectric focusing?

Polyacrylamide gel Signup and view all the answers

What chemical bond is formed by the transfer of electrons from one atom to another?

Ionic bond Signup and view all the answers

What is a key feature of the octet rule in chemical bonding?

Atoms seek to achieve a total of eight electrons in their valence shell Signup and view all the answers

Which structural representation demonstrates the connectivity of atoms in a molecule?

Lewis structures Signup and view all the answers

When writing resonant structures, which rule must be followed?

The overall charge must remain constant Signup and view all the answers

What is the primary reason that atoms form covalent bonds?

To achieve the electronic configuration of a noble gas Signup and view all the answers

What does the octet rule refer to?

The configuration of noble gases being stable with eight electrons in the valence shell Signup and view all the answers

What is an ionic bond?

An attractive force between oppositely charged ions Signup and view all the answers

Which factor primarily influences the formation of ionic bonds?

The electronegativity difference between atoms Signup and view all the answers

How are molecules that are predominantly formed by covalent bonds typically represented?

Using electron-dot formulas and dash structural formulas Signup and view all the answers

Which unique property does hydrogen exhibit in terms of bonding?

It has one valence electron and belongs to group IA Signup and view all the answers

Which statement is true regarding electronegativity?

It reflects the ability of an atom to attract electrons Signup and view all the answers

What is the effect of achieving an octet in an atom's valence shell?

It stabilizes the atom and reduces its tendency to react Signup and view all the answers

What is the purpose of resonance structures in chemistry?

They facilitate the understanding of molecules where a single Lewis structure is insufficient. Signup and view all the answers

Which characteristic is specific to dash structural formulas?

They visually represent bonding electron pairs with lines. Signup and view all the answers

What is typically included in a condensed structural formula?

Hydrogen atoms are appended directly after each carbon they are bonded to. Signup and view all the answers

Which of the following statements about formal charges is correct?

Formal charges can help in evaluating the stability of a molecule. Signup and view all the answers

Which of the following is a limitation of resonance structures?

They do not reflect the actual physical existence of molecules. Signup and view all the answers

How can isopropyl alcohol be represented in condensed structural formulas?

In multiple ways, each depicting the same molecular composition. Signup and view all the answers

What is incorrect about the depiction of atoms in dash structural formulas?

They represent only the central carbon atoms. Signup and view all the answers

What is a primary reason for using condensed structural formulas?

To simplify the representation of large organic molecules. Signup and view all the answers

What are essential amino acids in cell culture?

Amino acids that must be obtained from the diet Signup and view all the answers

Which statement accurately describes a primary cell culture?

They are derived from living tissue. Signup and view all the answers

What is a crucial characteristic of mammalian cell culture media?

It should have a regulated physico-chemical environment. Signup and view all the answers

Why is aseptic technique important in cell culture?

To avoid contamination. Signup and view all the answers

Which component is NOT typically found in a mammalian cell culture medium?

Toxic chemicals Signup and view all the answers

What is a unique feature of cell lines compared to primary cell cultures?

They can proliferate indefinitely. Signup and view all the answers

At what temperature should mammalian cell cultures typically be maintained?

37 ºC Signup and view all the answers

What is a reason for changing the culture medium frequently?

To provide fresh nutrients and remove toxic metabolites. Signup and view all the answers

Study Notes

Microvilli Structure

Microvilli are made up of five main proteins: actin, fimbrin, villin, myosin (Myo1A), and calmodulin.
Actin filaments are cross-linked into closely packed bundles by actin bundling proteins, particularly fimbrin and villin.
Actin filaments attach to the plasma membrane by lateral arms consisting of myosin I and calmodulin.

Cilia and Flagella

Cilia and flagella are microtubule-based plasma membrane projections.
Cilia act as antennae, sensing extracellular signals and facilitating movement.
There are two types of eukaryotic cilia: primary (non-motile) cilia and motile cilia.
Primary cilia are found on most animal cells and are involved in sensing extracellular signals, including movement, odorants, and light.
Motile cilia are responsible for cell movement.

Motile Cilia

Found on the surface of epithelial cells in the upper respiratory tract, uterine tubes (oviducts), and efferent ducts.
Their functions include moving mucus over epithelial surfaces in respiratory epithelium (clearing dust particles, dead cells, and bacteria from respiratory passages) and transporting the ovum toward the uterus in the uterine tubes.

Cell Culture

Living cells can be suspended in an appropriate liquid for examination under a light microscope, but they will soon die.
Prolonged study of living cells can be achieved by cultivating them in solutions containing necessary nutrients to keep them alive.

Cell Culture Conditions

Cell culture requires a medium that supplies essential nutrients (amino acids, carbohydrates, vitamins, minerals), growth factors, hormones, gases (O2, CO2), and a regulated physicochemical environment (pH, osmotic pressure, temperature).
Most cells are anchorage-dependent and must be cultured while attached to a solid or semi-solid substrate.

Mammalian Cell Culture Medium

Rich media are required and contain essential nutrients like amino acids (including 10 essential amino acids that cannot be synthesized by vertebrates and must be obtained from the diet), vitamins, various salts, glucose, and serum (containing factors needed for cell proliferation, including growth factors).
Most animal cells can only grow on special solid surfaces like treated plastics and glass.
The medium should be changed frequently.
Aseptic technique is necessary to avoid contamination (antibiotics are employed).
Cell culture is typically performed in laminar-flow hoods at a temperature of 37°C and pH 7.4 (phenol red is used as an indicator dye).

Primary Cell Culture vs Cell Lines

Primary cell culture is derived from living tissue or organs, with cells isolated directly from human or animal tissue using enzymatic or mechanical methods. It has a limited lifespan.
Cell lines are widely used for experiments and consist of eukaryotic cells that have acquired the ability to proliferate indefinitely through genetic mutations or artificial modifications. They are immortalized or continuous cell lines.

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Description

This quiz covers the structure and functions of microvilli, cilia, and flagella. Learn about the proteins involved in microvilli and how cilia serve as sensory and motile structures in eukaryotic cells. Test your understanding of these vital cellular components.