Chapter 1: The Cell

Question 1

What is are 4 basic tenets of cell theory?

Answer 1

1. All living things are composed of cells.
2. The cell is the basic functional unit of life.
3. Cells arise only from preexisting cells.
4. Cells carry genetic information in the form of deoxyribonucleic acid (DNA). This genetic material is passed on from parent to daughter cell.

Question 2

Name differences between a prokaryotic and eukaryotic cell.

Answer 2

• prokaryotic organisms are always single-celled
• eukaryotic organisms can be unicellular or multicellular
• eukaryotic cells contain a true nucleus enclosed in a membrane
• prokaryotic cells do not contain a nucleus

Question 3

Why the nuclear envelope important?

Answer 3

Because it creates two distinct environments within the cell (separates the nucleus from the cytoplasm). This allows for the compartmentalization of transcription.

Question 4

Discuss the outer and inner membranes of the mitochondria.

Answer 4

outer membrane - serves as a barrier between the cytosol and the inner environment of the mitochondrion.

inner membrane - is arranged into numerous inholdings called cristae and it contains molecules and enzymes of the ETC.

Question 5

Define cristae

Answer 5

the inner membrane of the mitochondria which is arranged into numerous inholdings is called the cristae, and contains molecules and enzymes of the electron transport chain.

Question 6

What is the space between the inner and outer membrane called in the mitochondria?

Answer 6

the space between the inner and outer membrane is called the intermembrane space.

Question 7

What is the space inside the inner membrane called? (mitochondria)

Answer 7

the space inside the inner membrane is called the mitochondrial matrix.

Question 8

How is the mitochondria semi-autonomous? What is this an example of?

Answer 8

Mitochondria are semi-autonomous in that they contain some of their own genes and replicate independently of the nucleus VIA binary fission.

This is an example of cytoplasmic or extranuclear inheritance - the transmission of genetic material independent of the nucleus.

Question 9

What is the thought of how mitochondria originated?

Answer 9

mitochondria are thought to have originated when the engulfing of an aerobic prokaryote by an anaerobic prokaryotic resulted in a symbiotic relationship.

Question 10

What are lysosomes?

Answer 10

lysosomes are membrane-bound structures containing hydrolytic enzymes that are capable of breaking down many different substrates.

Question 11

What are endosomes?

Answer 11

endoscopes transport, package, and sort cell material travelling to and from the membrane.

Question 12

What is the endoplasmic reticulum?

Answer 12

the ER is a series of interconnected membranes that are actually contiguous with the nuclear envelope.

Question 13

Describe the structure of the ER.

Answer 13

the double membrane of the ER is folded into numerous invaginations, creating complex structures with a central lumen.

Question 14

What is the difference between the rough ER (RER) and the smooth ER (SER)?

Answer 14

• the RER is studded with ribosomes, which permit the translation of proteins destined for section directly into its lumen.
• the SER lacks ribosomes and is utilized primarily for lipid synthesis (such as phospholipids in the cell membrane) and the detoxification of certain drugs and poisons. also transports proteins from the RER to the Golgi apparatus.

Question 15

What is the function of the Golgi apparatus?

Answer 15

• cellular products may be modified by the addition of groups like carbohydrates, phosphates, and sulphates.
• Golgi apparatus may also modify cellular products through the introduction of signal sequences which direct the delivery of the product to a specific cellular location.

Question 16

What is peroxisomes and what is it’s function?

Answer 16

Peroxisomes contain hydrogen peroxide.

One of the primary functions of peroxisomes is the breakdown of very long chain fatty acids VIA β-oxidation.

Question 17

What is the cytoskeleton?

Answer 17

the cytoskeleton provides structure to the cell and helps it to maintain its shape and provides a conduit for the transport of materials around the cell.

Question 18

What are microfilaments composed of and what is its function?

Answer 18

microfilaments are made up of solid polymerized rods of actin.

microfilament are resistant to both compression and fracture, providing protecting for the cell.

Question 19

What is the role of microfilaments in cytokinesis?

Answer 19

during mitosis, the cleavage furrow is formed from microfilaments, which organize as a ring at the site of division between the two new daughter cells. as the actin filaments within this ring contract, the ring becomes smaller, eventually pinching off the connection between the two daughter cells.

Question 20

What are microtubules composed of and what is its function?

Answer 20

microtubules are hollow polymers of tubular proteins.

microtubules radiate through the cell providing the primary pathways along which motor pathways like kinesin and dynein carry vesicles.

Question 21

What is 9+2 structure? Where is it found? What are some examples of a 9+2 structure?

Answer 21

a 9+2 structure is composed of nine pairs of microtubules forming an outer ring, with two microtubules in the centre.

a 9+2 structure is seen only in eukaryotic organelles of MOTILITY.

cilia and flagella are motile structures composed of microtubules in the 9+2 structure.

Question 22

What are centrioles and what is its function?

Answer 22

centrioles are found in region of the cell called the centrosomes. they are the organizing centres for microtubules.

Question 23

What is kinetochores and what is its function?

Answer 23

the microtubules emanating from the centrioles attach to the chromes VIA complexes called kinetochores and exert force on the sister chromatid, pulling them apart.

Question 24

What are intermediate filaments, and what is their function?

Answer 24

intermediate filaments are a diverse group of filamentous proteins, which includes keratin, design, vimentin and laming.

many intermediate filaments are involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton.

Question 25

Where can you find epithelial tissue? and what is its function?

Answer 25

Epithelial tissue covers the body and lines its cavities, proving a means for protection against pathogen invasion and desiccation.

Question 26

How do epithelial tissue stay as one cohesive tissue?

Answer 26

to stay as one cohesive unit, epithelial cells are tightly joined to each other and to an underlying layer of connective tissue know as the basement membrane.

Question 27

In most organs, epithelial cells constitute the? give an example of this.

Answer 27

parenchyma- or the functional parts of an organ as compared to the connecting or supportive tissue.

ie: nephrons in the kidneys are composed of epithelial cells, and acid producing cells of the stomach are epithelial cells.

(for future me: it basically means the cells have a function)

Question 28

Epithelial cells are often polarized. What does this mean?

Answer 28

this means that one side faces a lumen (the hollow inside of an organ or tube) or the outside world, while the other side interacts with underlying blood vessels and structural walls.

Question 29

How do we classify different epithelia? Describe the different types of epithelia.

Answer 29

we can classify epithelia according to the number of layers they have and the shape of their cells.

• simple epithelia have one layer of cells
• stratified epithelia have multiple layers
• pseudo stratified epithelia appear to have multiple layers due to differences in cell height but are, in reality, only one layer.

Question 30

What are the different possible shapes of epithelial cells?

Answer 30

cuboidal - cells are cube-shaped
columnar - cells are long and thin
squamous - cells are flat and scalelike