Structure & Functions of the Cell

Question 4

What is the main function of the Golgi apparatus?

Answer 4

Protein modification, sorting, and secretion or degradation via the lysosomal pathway.

Question 5

What are the components of the Golgi apparatus?

Answer 5

Membrane-bound compartments (flattened cisternae) interconnected in the perinuclear area.

Question 6

What is the ER lumen?

Answer 6

The cisternal space of the endoplasmic reticulum.

Question 7

What differentiates rough ER from smooth ER?

Answer 7

Rough ER is covered with ribosomes; smooth ER is not.

Question 8

What are vesicles used for?

Answer 8

Transport molecules between different cellular compartments.

Question 9

List the types of vesicles mentioned.

Answer 9

• Clathrin-coated
• Coat protein complex-I-coated
• Endocytotic

Question 10

What are the functions of the cytoskeleton?

Answer 10

• Cellular transport
• Cell growth and division
• Cell differentiation
• Signal transduction
• Gene transcription
• Cell and organelle motility
• Cell shape maintenance

Question 11

What are septin filaments?

Answer 11

Rod-like filaments formed by the polymerization of GTP-binding proteins.

Question 12

What are microtubules?

Answer 12

Dynamic polar hollow cylinders involved in transport, structural support, and chromosome separation during cell division.

Question 13

What are microfilaments composed of?

Answer 13

Solid polar rods made up of globular proteins called actin.

Question 14

What role do intermediate filaments play in the cytoskeleton?

Answer 14

They confer mechanical strength to the cell.

Question 15

What is the structure of the endoplasmic reticulum (ER)?

Answer 15

Dynamic membrane-bound organelle made up of flattened sacs and branching tubules.

Question 16

What is cytosol?

Answer 16

The fluid portion of the cytoplasm.

Question 17

What is the bilipid layer model?

Answer 17

A continuous spherical lipid bilayer formed by molecular forces.

Question 18

Define the fluid mosaic model.

Answer 18

A model describing membranes as fluids with proteins embedded in or attached to the bilipid layer.

Question 19

What are lipid translocators?

Answer 19

Proteins that facilitate the movement of lipids between the inner and outer leaflets of the membrane.

Question 20

What is the dynamic fluid-mosaic model?

Answer 20

A model that emphasizes the nonrandom distribution of membrane proteins and lipids forming microdomains.

Question 21

What are centrioles?

Answer 21

Barrel-shaped cylindrical organelles essential for chromosome movement during cell division.

Question 22

What is the primary function of lysosomes?

Answer 22

Mediating the degradation of extracellular and intracellular particles.

Question 23

What causes lysosomal storage diseases?

Answer 23

Mutations of the gene that codes for lysosomal enzymes.

Question 24

What is the function of peroxisomes?

Answer 24

Perform degradative reactions, including beta oxidation of fatty acids and detoxification of reactive oxygen species.

Question 25

What is the main function of mitochondria?

Answer 25

Converting oxygen and nutrients into energy (ATP synthesis).

Question 26

What is the role of the nucleus?

Answer 26

Houses genetic material and is involved in intermediary metabolism, protein synthesis, and RNA synthesis.

Question 27

What is the nucleolus?

Answer 27

The site of ribosome synthesis within the nucleus.

Question 28

What genetic materials are found in the nucleus?

Answer 28

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).

Question 29

What is transitional ER?

Answer 29

A region of the ER where secretory proteins are exported to the Golgi complex.

Question 30

What are the functions of the ER?

Answer 30

* Quality control of secretory cargo proteins * Protein processing * Lipid metabolism * Intracellular Ca2+ reservoir

Question 31

What is the transitional ER?

Answer 31

A region of the ER where secretory proteins are exported to the Golgi complex.

Question 32

What are the functions of the endoplasmic reticulum (ER)?

Answer 32

* Quality control sites in secretory cargo proteins (transitional ER) * Site of protein processing (rough ER) * Site of lipid metabolism (smooth ER) * Intracellular Ca2+ reservoir.

Question 33

Who introduced the Bilipid Layer Model?

Answer 33

Evert Gorter and François Grendel.

Question 34

What is the orientation of phospholipids in a fluid medium?

Answer 34

The head (polar hydrophilic) is directed towards the fluid medium, while the tail (nonpolar hydrophobic) extends in the opposite direction.

Question 35

What is the glycocalyx?

Answer 35

A carbohydrate-rich layer on the extracellular face of the plasma membrane, comprising glycoproteins, collagen proteins, proteoglycans, and mucopolysaccharides.

Question 36

Define lipidome.

Answer 36

The entire lipid composition of the cells of an organism.

Question 37

What are the three main groups of lipids in the plasma membrane?

Answer 37

* Phospholipids * Glycolipids * Cholesterol.

Question 38

What are lipid rafts?

Answer 38

Small, heterogeneous, highly dynamic domains rich in sterols and sphingolipids that compartmentalize cellular processes.

Question 39

What is the structure of a phospholipid molecule?

Answer 39

Composed of a hydrophilic head with attached hydrophobic acyl chains.

Question 40

What are caveolae?

Answer 40

Flask-shaped membrane invaginations composed of integral and adaptor proteins.

Question 41

What are peripheral membrane proteins?

Answer 41

Proteins associated with one leaflet of the bilayer, involved in signal transduction and anchoring the plasma membrane to the cytoskeleton.

Question 42

True or False: Integral proteins span the membrane and are embedded in the lipid bilayer.

Answer 42

True.

Question 43

What is the role of membrane proteins in signaling?

Answer 43

They translate extra- and intra-cellular cues into meaningful signals.

Question 44

What does the term glycomics refer to?

Answer 44

The study of carbohydrates as information-encoding biological macromolecules.

Question 45

Fill in the blank: The plasma membrane is composed of _______.

Answer 45

[phospholipids, proteins, cholesterol, carbohydrates]

Question 46

What is the function of glycoproteins?

Answer 46

They are proteins conjugated to carbohydrate residues that can play roles in recognition and signaling.

Question 47

What are the functions of membrane lipids?

Answer 47

* Vesicle budding and fusion * Cellular transport * Cell attachment and support * Cellular signaling * Regulation of cellular homeostasis.

Question 48

What is the role of cavins in the plasma membrane?

Answer 48

Involved in membrane remodeling.

Question 49

What is the function of lipid rafts in cellular signaling?

Answer 49

They form scaffolds for signaling molecules and receptors that relay information from the extracellular environment.

Question 50

What are clathrin-coated pits?

Answer 50

Membrane invaginations lined by clathrin protein, involved in the initial processes of endocytosis.

Question 51

What are the main functions of membrane carbohydrates?

Answer 51

They play roles in cell recognition, signaling, and forming the glycocalyx.

Question 52

What are the two types of proteins based on their solubility in membrane fluids?

Answer 52

* Soluble proteins * Insoluble proteins.

Question 53

What are the two structural forms of membrane proteins?

Answer 53

* Fibrous proteins * Globular proteins.