Ch. 3: Cellular Form and Function Practice Flashcards

Comprehensive practice questions covering cell theory, morphology, membrane transport, and organelles based on Chapter 3 lecture notes.

What is the definition of cytology?

Cytology is the study of cells.

According to cell theory, what is the simplest structural and functional unit of life?

Cells.

From where do all cells originate according to cell theory?

Cells come only from preexisting cells.

Which cell shape is described as thin, flat, and scaly?

Squamous.

What name is given to cells that are taller than they are wide?

Columnar.

How is the stellate cell shape described?

Star-like.

Which cell shape is thick in the middle and has tapered ends?

Fusiform (spindle-shaped).

What is the typical diameter of most human cells?

$10-15 μ \text{m}$.

What is the diameter of an egg cell?

$100 μ \text{m}$.

How long can some motor neurons from the spine to the extremities be?

Over $1 \text{meter}$ long.

What are the three main components of the cytoplasm?

Organelles, cytoskeleton, and cytosol (intracellular fluid).

What defines the boundaries of the cell and governs interactions with other cells?

The plasma membrane.

What percentage of membrane molecules are lipids?

$98\% \text{ (75\% phospholipids, 20\% cholesterol, 5\% glycolipids)}$.

In a phospholipid bilayer, which part is hydrophilic and faces the water?

Phosphate heads.

What is the function of cholesterol in the plasma membrane?

It holds phospholipids still and can stiffen the membrane.

What is the fuzzy, external carbohydrate coat of the plasma membrane called?

Glycocalyx.

Which membrane components contribute to the unique identity of the glycocalyx?

Glycoproteins and glycolipids.

What makes up only $2\%$ of the membrane molecules but $50\%$ of its weight?

Membrane proteins.

What is the difference between transmembrane and peripheral proteins?

Transmembrane proteins pass completely through the membrane, while peripheral proteins adhere to only one face.

Which type of membrane protein binds to chemical signals like hormones?

Receptors.

In second-messenger systems, what enzyme does the $G \text{ protein}$ bind to in order to convert $ATP$ to $cAMP$?

Adenylate cyclase.

What is the role of the second messenger $cAMP$ in the cytoplasm?

It activates enzymes called kinases.

What percentage of drugs on the market work through $G \text{ proteins}$ and second messengers?

Up to $60\%$.

What do voltage-gated channels respond to?

Electrical changes (such as $Ca^{2+}$, $K^+$, $Na^{2+}$, or $Cl^-$).

What is the primary function of microvilli?

To increase surface area for absorption ($15-40$ times).

Where can motile cilia be found in the human body?

Respiratory tract, uterine tubes, and ventricles of the brain.

What is the structural arrangement of microtubules in the axoneme of motile cilia?

Two central microtubules surrounded by a ring of nine pairs ($9+2$).

Which protein "crawls" up adjacent microtubules to bend a cilium using $ATP$?

Dynein arms.

What hereditary disease involves the failure to install $Cl^-$ pumps in the plasma membrane?

Cystic fibrosis.

What is the only functional flagellum in humans?

The tail of a sperm.

What are pseudopods used for in cells like macrophages?

Cellular locomotion and capturing foreign particles.

What is the difference between active and passive transport mechanisms?

Passive mechanisms do not require $ATP$ (diffusion), while active mechanisms require $ATP$.

In simple diffusion, how do substances move in relation to their concentration gradient?

Substances diffuse down their concentration gradient (from high to low concentration).

How does increasing temperature affect the rate of diffusion?

Increasing temperature increases the motion of particles and the rate of diffusion.

What defines the specificity of carrier-mediated transport?

Transport proteins are specific for a particular solute that binds to a receptor site.

Which example of carrier-mediated transport moves a solute down its gradient without consuming $ATP$?

Facilitated diffusion (e.g., glucose).

How many $Na^+$ and $K^+$ ions are exchanged in one cycle of the $Na^+/K^+$ pump?

It exports $3 \text{ } Na^+$ and imports $2 \text{ } K^+$.

What percentage of daily calories are used to power the $Na^+/K^+$ pump?

$1/2 \text{ of daily calories}$.

What is an example of secondary active transport mentioned in the notes?

The $Na^+\text{-glucose transporter (SGLT)}$.

What is the vesicular process called that brings large particles into the cell ("cell eating")?

Phagocytosis.

What is "cell drinking" or taking in droplets of ECF called?

Pinocytosis.

During receptor-mediated endocytosis, the plasma membrane sinks inward to form what?

A clathrin-coated pit.

What are the three types of protein filaments in the cytoskeleton?

Microfilaments, intermediate filaments, and microtubules.

What protein makes up microfilaments and forms the terminal web?

Actin.

What is the largest organelle in the cell and what does it contain?

The nucleus; it contains chromatin composed of $DNA$ and protein.

What is the function of the nucleoli?

They are the masses where ribosomes are produced.

What is the difference between Rough and Smooth ER structure?

Rough ER is covered with ribosomes; Smooth ER lacks ribosomes.

Which organelle "reads" coded genetic messages (mRNA) to assemble amino acids into proteins?

Ribosomes.

What system of cisternae synthesizes carbohydrates and finishes protein synthesis?

Golgi complex.

Which organelle is a package of enzymes used for intracellular digestion and works best in acidic environments?

Lysosomes.

Which organelles dispose of surplus proteins tagged with polyubiquitin?

Proteasomes.

What are the folds of the inner mitochondrial membrane called and what is the space between them called?

The folds are cristae; the space is the matrix.