Cells And Subcellular Structures

Question 1

What is the cell theory?

Answer 1

All living organisms are made up of one or more cells, the cell is the basic unit of life, cells arise from existing cells by division.

Question 2

What are the two main types of cells?

Answer 2

• Prokaryotes
• Eukaryotes

Question 3

Define prokaryotes.

Answer 3

No nucleus, always single-cellular.

Question 4

Define eukaryotes.

Answer 4

Have a nucleus, can be single or multicellular.

Question 5

List the types of eukaryotic organisms.

Answer 5

• Animals
• Plants
• Fungi
• Protozoans

Question 6

What is the evolutionary origin of cells?

Answer 6

Ancestral prokaryotes evolved into bacteria, anaerobic ancestral eukaryotes, and archaea over billions of years.

Question 7

What is the structure of the cell (plasma) membrane?

Answer 7

Bilayer of phospholipids, cholesterol, and embedded transmembrane proteins with lipid rafts.

Question 8

What are phospholipids?

Answer 8

Amphipathic molecules with a hydrophilic phosphate group and hydrophobic lipid tails.

Question 9

What are the main roles of the cell membrane?

Answer 9

• Barrier
• Communication
• Import and export
• Electrical capacitor

Question 10

What is the cytoskeleton?

Answer 10

A network of protein fibers.

Question 11

List the components of the cytoskeleton.

Answer 11

• Actin filaments
• Intermediate filaments
• Microtubules

Question 12

What are the main roles of the cytoskeleton?

Answer 12

• Maintenance of shape and stability
• Adaptation of shape to change
• Cell division
• Motility
• Movement of particles within cells

Question 13

What does the cytoplasm (cytosol) contain?

Answer 13

Aqueous solution of defined pH (7.2) and ion composition, high concentration of proteins (20-30% metabolic enzymes, messengers).

Question 14

What surrounds the nucleus?

Answer 14

Two lipid double layers.

Question 15

What is chromosomal DNA?

Answer 15

DNA packed with histones and gene regulatory proteins.

Question 16

What is the nucleolus?

Answer 16

Site of ribosome synthesis and can capture gene regulatory proteins.

Question 17

What is the function of the rough endoplasmic reticulum (RER)?

Answer 17

Synthesis of secreted and transmembrane proteins.

Question 18

What is the function of the smooth endoplasmic reticulum (SER)?

Answer 18

• Synthesis of lipids and steroid hormones
• Detoxification
• Release of glucose from the liver

Question 19

What are mitochondria?

Answer 19

Double membrane organelles folded into cristae.

Question 20

What processes occur in the mitochondria?

Answer 20

• Oxidative phosphorylation
• Citric acid (Krebs) cycle
• Heat production
• Ca2+ storage
• Programmed cell death (apoptosis)

Question 21

What are lysosomes?

Answer 21

Membrane-bound organelles in animal cells that degrade unwanted proteins, membranes, and organelles.

Question 22

What is the optimal pH for lysosomal enzymes?

Answer 22

pH 4.8-5.

Question 23

What are peroxisomes?

Answer 23

Organelles involved in fatty acid oxidation that produces hydrogen peroxide.

Question 24

What enzyme neutralizes hydrogen peroxide in peroxisomes?

Answer 24

Catalase.

Question 25

Fill in the blank: The cytosol has a defined pH of _______.

Answer 25

7.2

Question 26

True or False: Eukaryotic cells always have a nucleus.

Answer 26

True