Cell biology

Question 1

what is the largest membrane-bound organelle in the center of most eukaryotic cells. It contains the cell’s genetic code (its DNA). Its function of the nucleus is to direct the cell by storing and transmitting genetic information.

Answer 1

The Nucleus

Question 2

It is a region inside the nucleus where ribosomal RNA (rRNA) is transcribed, and ribosomal subunits are assembled.

Answer 2

The Nucleolus.

Here, rRNA joins together to form the subunits of a complete ribosome. These subunits are then exported to the cytoplasm for final assembly into the complete ribosome used for translation of mRNA into proteins

Question 3

The boundary of the nucleus, made of phospholipid bilayer

Answer 3

Nuclear Envelope

Question 4

What allows certain particles through the nuclear envelope, wo that essential cell processes and communications can occur.

Answer 4

Nuclear pores.

The nuclear pores is subject to change based on the needs of the cell. Through the pores, signal molecules, nucleoplasm proteins, nuclear membrane proteins, lipids, and transcription factors can enter the nucleus, while mRNA, rRNA and ribosomal proteins exit into the cytoplasm.

Question 5

The endomembrane system is a series of intracellular membranes that compartmentalize the cell.

What is the typical pathway through the endomembrane system is?

Answer 5

1. Proteins produced in rough ER (endoplasmic reticulum) and lipids from smooth ER are carried in vesicles to the Golgi apparatus.
2. The Golgi apparatus modifies these products and then sorts and packages them in vesicles that are transported to various cell destinations
3. Secretory vesicles transport products to organelles or to the membrane, where they are secreted via exocytosis
   * Including also lysosomes, peroxisomes, and all the organelles within the cell

Question 6

This unique double membrane organelle is responsible for aerobic respiration which uses oxygen to create ATP

Answer 6

Mitochondria.

The mitochondria is unique in that it has its own genome that is distinct from the genome from within the nucleus, that has its own circular DNA. It also has it own ribosomes

Question 7

What part of the mitochondria that separates the mitochondria from the cytoplasm?

Answer 7

The outer membrane

Question 8

What part of the mitochondria has folds as cristae

Answer 8

Inner membrane

Question 9

This small membrane-bound organelle vesicles are produced by the Golgi apparatus and produces hydrolytic enzymes for the digestion of macromolecules

Answer 9

Lysosomes.

They are especially important in specialized immune cells, which is used to digest invaders. Autodigestion is the process by which lysosomes digest parts of the body’s cells, either to due to disease or trauma or for immune purposes ( e.g. programmed cell death)

Mutations in the genes that encode for lysosomal enzymes cause lysosomal storage disorders. When a mutation renders certain lysosomal enzymes inefficient ( or completely inoperable), waste products accumulate in the cells and cause serious, often incurable complications

Question 10

Continuous with the nuclear envelope and studded with ribosomes, This organelle is where proteins are synthesized, processed and modified.

Answer 10

Rough Endoplasmic Reticulum {R.E.R.)
It synthesizes key membrane components, not just the plasma membrane, but the membrane of the ER, Golgi apparatus, lysosomes, and other organelles before heading to their destination at the plasma membrane-bound organelle

Question 11

It is the site of various synthesis, detoxification and storage processes, such as the synthesize of lipids and steroids, and the metabolism of carbohydrates and other molecules

Answer 11

Smooth ER

Question 12

What are the three key organelles that have a double membrane

Answer 12

Mitochondria- has a double membrane due to their proposed evolution from endosymbiotic prokaryote. It is crucial for creating proton gradient that drives ATP synthesis
Chloroplast- is the site of photosynthesis and ATP synthesis in plant cells

Nucleus- Its organization and compartmentalizing is important for the regulation of gene expression.

Question 13

Flattened sacs that receives transport vesicles from the ER and then may further modify their content before packing the proteins or lipid to be sent in vesicles to its final destination

Answer 13

Golgi apparatus

Question 14

This organelle is involved in catabolism and anabolism of many macromolecules including fatty acids, proteins and carbohydrate

Answer 14

Peroxisomes- it is most abundant in the liver where they are notable for producing bile salts from cholesterol and metabolizing alcohol

Question 15

What does it mean to be Semi-permeable

Answer 15

It means it only allows certain molecules to pass through. A molecule’s ability to diffuse through the plasma membrane depends on the molecule’s size, charge, and polarity. The greater the lipid solubility of the diffusing particle, the more easily it passes through the membrane.
Generally, smaller particles diffuse more rapidly than larger ones, and hydrophobic particles diffuse more rapidly than hydrophilic particles.

Question 16

Enables the movement of molecules across a membrane without the expenditure of energy by the cell

Answer 16

Passive transport

Question 17

The process by which smaller, lipid-soluble molecules freely diffuse through the phospholipid bilayer unassisted.

Answer 17

Simple diffusion

Question 18

What are transport proteins?

Answer 18

Transport proteins move materials into and out of the cell. These include channel proteins and carrier proteins. Channel proteins provide a passageway large, polar or charged molecules that cannot pass through the lipid bilayer without assistance. These proteins facilitate the passive transports molecules, that is, they do not require ATP.
Carrier proteins, however, may facilitate both passive and active transport of molecules. They bind to a specific molecules on one side of the cell membrane and then change conformation to release the molecule on the other side of the membrane.

Question 19

What are adhesive proteins?

Answer 19

They attach cells to neighboring cells for cell-to-cell communication and tissue structure. These proteins generally attach to the cytoskeleton of one

Question 20

What are transport proteins?

Answer 20

Moves materials into and out of the cell. These include channel proteins and carrier proteins. Channel proteins provide a passageway large, polar or charged molecules that cannot pass through the lipid bilayer without assistance. These proteins facilitate the passive transport of molecules, that is, they do not require ATP to operate. Carrier proteins, however may facilitate both passive and active ( energy-requiring) transport of molecules. They bind to specific molecules on one side of the cell membrane and then change conformation to release molecule in the other side of the membrane.

Question 21

What are receptor proteins?

Answer 21

Receptor proteins provide a binding site for hormones, neurotransmitters, and other signaling molecules. Receptor proteins are usually specific in that they bind to a single molecule or certain class of molecules.

Question 22

What are integral membrane proteins?

Answer 22

They are permanently attached to the membrane and thus cannot be removed without disrupting the lipid bilayer. They possess hydrophilic domains which are anchored to hydrophobic lipids. Most integral membrane proteins are transmembrane proteins, spanning the entire membrane

Question 23

What is a solute?

Answer 23

It is the dissolved substances

Question 24

What is a solvent?

Answer 24

It is usually the fluid (usually water) in which substances

Question 25

What is passive transport

Answer 25

Enables the movement of molecules across a membrane without the expenditure of energy by the cell. This method include simple diffusion, osmosis, and facilitated diffusion. Passive transport utilize a concentration gradient, whereby particles diffuse from an area of higher concentration to an area of lower solute concentration

Question 26

This is the process by which smaller, lipid-soluble freely diffuse through the phospholipid bilayer unassisted

Answer 26

Simple diffusion

Question 27

Requires cellular to move solutes against their concentration gradient?

Answer 27

Active transport

Question 28

It is used to transport molecules out of the cell?

Answer 28

Exocytosis. In this process, the cytoplasmic vesicles move to the plasma membrane and fuse with it. The membrane from the vesicles become incorporated in the plasma membrane and the contents of the vesicles are released to the external surroundings of the cell

Question 29

In this process, the plasma membrane sinks inward and forms a vesicle around particles and fluids on the extracellular side of the membrane. The contents are transported to various places into the cytoplasm and may be stored for later use?

Answer 29

Endocytosis

Question 30

What is osmosis

Answer 30

It is diffusion of water across the biological membrane