Chapters 7,8,12

Question 1

What is the structure and function of cell membranes?

Answer 1

Cell membranes are fluid mosaics of lipids and proteins.

Question 2

Define selective permeability.

Answer 2

Selective permeability refers to the ability of a membrane to allow certain substances to pass while blocking others.

Question 3

What macromolecules make up membranes?

Answer 3

Membranes are composed of lipids, proteins, and carbohydrates.

Question 4

What does an amphipathic molecule mean?

Answer 4

An amphipathic molecule has both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts.

Question 5

Characterize the fluid mosaic model.

Answer 5

The fluid mosaic model describes membranes as a fluid structure with a mosaic of various proteins embedded in or attached to a double layer of phospholipids.

Question 6

How do membrane lipids and proteins interact?

Answer 6

Membrane lipids and proteins interact through various types of non-covalent interactions, allowing for fluidity and movement.

Question 7

What factors affect membrane fluidity?

Answer 7

Factors include temperature, lipid composition (such as saturation), and the presence of cholesterol.

Question 8

What is the role of cholesterol in membrane fluidity?

Answer 8

Cholesterol helps to maintain membrane fluidity by preventing the fatty acid chains of phospholipids from packing too closely together.

Question 9

How does membrane structure affect the distribution range of organisms?

Answer 9

Membrane structure and composition influence the adaptability of organisms to their environments and their evolutionary fitness.

Question 10

What are glycoproteins and glycolipids?

Answer 10

Glycoproteins are proteins with carbohydrate chains attached, while glycolipids are lipids with carbohydrate chains attached.

Question 11

What is meant by the ‘sidedness’ of membranes?

Answer 11

The ‘sidedness’ of membranes refers to the distinct internal and external faces of the membrane, which have different compositions and functions.

Question 12

Characterize molecule movement across the membrane.

Answer 12

Molecule movement can occur via passive transport, active transport, and bulk transport processes.

Question 13

What is osmoregulation?

Answer 13

Osmoregulation is the process by which cells and organisms regulate water balance and solute concentrations.

Question 14

Define turgidity.

Answer 14

Turgidity is the state of being swollen or firm due to water uptake in plant cells.

Question 15

What does a sodium-potassium pump do?

Answer 15

A sodium-potassium pump moves three sodium ions out of a cell and two potassium ions into a cell while consuming ATP.

Question 16

Which component of the membrane is a peripheral protein?

Answer 16

Peripheral proteins are associated with the membrane surface and do not span the membrane.

Question 17

What is the significance of the mitotic spindle?

Answer 17

The mitotic spindle is crucial for the separation of chromosomes during cell division.

Question 18

Define a genome.

Answer 18

A genome is the complete set of genetic material in an organism.

Question 19

What characterizes the structure of chromosomes?

Answer 19

Chromosomes consist of DNA tightly coiled around histone proteins, forming a structure that is visible during cell division.

Question 20

What is the difference between mitosis and meiosis?

Answer 20

Mitosis results in two genetically identical daughter cells, while meiosis produces four genetically diverse gametes.

Question 21

What are cyclins and their role in the cell cycle?

Answer 21

Cyclins are proteins that regulate the timing of the cell cycle in eukaryotic cells by activating cyclin-dependent kinases.

Question 22

What is the significance of checkpoints in the cell cycle?

Answer 22

Checkpoints are regulatory points that ensure the cell cycle progresses accurately and prevents errors.

Question 23

What is transformation in the context of cancer?

Answer 23

Transformation refers to the process by which normal cells become cancerous.

Question 24

Define exergonic and endergonic reactions.

Answer 24

Exergonic reactions release energy, while endergonic reactions require energy input.

Question 25

What role does ATP play in cellular work?

Answer 25

ATP powers cellular work by coupling exergonic reactions to endergonic reactions.

Question 26

What is the role of enzymes in metabolic reactions?

Answer 26

Enzymes speed up metabolic reactions by lowering the activation energy required for the reaction to occur.

Question 27

How do inhibitors affect enzyme activity?

Answer 27

Inhibitors can prevent enzymes from catalyzing reactions by binding to the enzyme and blocking the active site.

Question 28

What is allosteric regulation?

Answer 28

Allosteric regulation involves the binding of a molecule to an enzyme at a site other than the active site, leading to a change in enzyme activity.

Question 29

What does a cleavage furrow refer to?

Answer 29

A groove in the plasma membrane between daughter nuclei. ## Footnote The cleavage furrow is characteristic of cytokinesis in animal cells.

Question 30

During which phase do you see a cell plate developing across the middle of a cell?

Answer 30

A plant cell in the process of cytokinesis. ## Footnote This indicates that the cell is undergoing cytokinesis, which is typical for plant cells.

Question 31

Which of the following does NOT occur during mitosis?

Answer 31

Replication of the DNA. ## Footnote DNA replication occurs during the S phase of the cell cycle, not during mitosis.

Question 32

The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____

Answer 32

Metaphase. ## Footnote This checkpoint is critical for ensuring proper chromosome segregation.

Question 33

What conclusion can be made if a cultured cell line does not exhibit density-dependent inhibition or anchorage dependence?

Answer 33

The cells show characteristics of tumors. ## Footnote These characteristics are often associated with cancerous cells.

Question 34

Which of the following is an example of potential rather than kinetic energy?

Answer 34

A molecule of glucose. ## Footnote Glucose stores energy that can be converted into kinetic energy during cellular respiration.

Question 35

Anabolic pathways _____

Answer 35

Consume energy to build up polymers from monomers. ## Footnote Anabolic processes are constructive and require energy input.

Question 36

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

Answer 36

The organism ultimately must obtain all of the necessary energy for life from its environment. ## Footnote This emphasizes the need for energy acquisition from external sources.

Question 37

Which of the following is most similar in structure to ATP?

Answer 37

An RNA nucleotide. ## Footnote ATP is an RNA nucleotide with additional phosphate groups.

Question 38

What happens to the heat generated when chemical, transport, or mechanical work is done by an organism?

Answer 38

It is lost to the environment. ## Footnote This reflects the second law of thermodynamics regarding energy dissipation.

Question 39

Which of the following is the most correct interpretation of ATP's role?

Answer 39

ATP is a molecule that acts as an intermediary to store energy for cellular work. ## Footnote ATP functions as the energy currency of the cell.

Question 40

Which of the following is true of enzymes?

Answer 40

Enzymes increase the rate of chemical reaction by lowering activation energy barriers. ## Footnote This is a fundamental principle of enzyme action.

Question 41

The active site of an enzyme is the region that _____

Answer 41

Is involved in the catalytic reaction of the enzyme. ## Footnote This site is critical for substrate binding and catalysis.

Question 42

What would you expect the effect of pH on the function of the enzyme catalase in human cells to look like?

Answer 42

Graph C. ## Footnote Enzyme activity typically varies with pH, showing an optimal range.