B2.2 organelles and compartmentalization

Question 1

What is the significance of membrane-bound organelles in a cell?

Answer 1

Membrane-bound organelles allow compartmentalization, enabling unique processes to occur without interference from neighboring chemicals or reactions within the cell.

Question 2

What does cell compartmentalization achieve within a cell?

Answer 2

Cell compartmentalization isolates reactions, enabling cells to work more efficiently by preventing interference among various reactions occurring in close proximity.

Question 3

What purpose do membrane-bound organelles serve in cells?

Answer 3

Membrane-bound organelles facilitate the segregation of cellular processes

Question 4

What is reductionism in cellular research?

Answer 4

Reductionism involves breaking down the cell into its component parts to study each part individually, allowing a better understanding of complex cellular reactions at the molecular level.

Question 5

Why do researchers focus on studying localized parts and reactions within a cell?

Answer 5

By studying localized parts and reactions, researchers can comprehend the intricate overall reactions of the cell, contributing to an understanding of its complexity at a molecular level.

Question 6

What advancements have contributed to our understanding of cells?

Answer 6

Improvements in light microscopes, electron microscopy, and refinements in preparation techniques have significantly advanced our understanding of cells.

Question 6

What is biochemical fractionation in cell research?

Answer 6

Biochemical fractionation is a process that involves the separation and isolation of specific chemicals and structures within cells, allowing detailed research.

Question 7

How does centrifugation aid in cell fractionation?

Answer 7

Centrifugation isolates organelles from cells by spinning a sample at high speeds, separating components by size and shape. Larger and heavier components settle at the bottom of the tube.

Question 8

What is the principle behind chromatography in cell research?

Answer 8

Chromatography separates molecules based on their size and travel speed through a separating medium, effectively isolating pure substances like amino acids, proteins, carbohydrates, and plant pigments.

Question 9

How does gel electrophoresis function in molecular studies?

Answer 9

Gel electrophoresis separates molecules by properties like size and charge by passing them through a gel using an electrical charge, commonly used in studies involving nucleic acids.

Question 10

What are transcription and translation in cell processes?

Answer 10

Transcription involves creating mRNA from a DNA template, while translation uses mRNA to produce proteins through ribosomes.

Question 11

Where does transcription occur in eukaryotic cells?

Answer 11

Transcription occurs in the nucleus of eukaryotic cells.

Question 12

Where does translation take place in eukaryotic cells?

Answer 12

Translation happens in the cytoplasm of eukaryotic cells.

Question 13

How does the separation of transcription and translation benefit eukaryotic cells?

Answer 13

The separation allows post-transcriptional modification of mRNA in the nucleus before translation occurs in the cytoplasm, reducing errors in protein production.

Question 14

How does the process of transcription and translation differ in prokaryotic cells?

Answer 14

In prokaryotic cells, there’s no isolation between transcription and translation, allowing immediate contact between mRNA and ribosomes for translation without prior mRNA modification.

Question 15

What functions are associated with compartments or organelles in eukaryotic cells?

Answer 15

Eukaryotic cell compartments are involved in energy production, metabolism, biosynthesis, and degradation.

Question 16

How does compartmentalization benefit cells in terms of division of labor?

Answer 16

Compartmentalization enables specific tasks to be carried out by individual organelles, keeping enzymes in effective areas and ensuring smooth, controlled, and non-interfering reaction pathways.

Question 17

Why are potentially destructive enzymes isolated in lysosomes?

Answer 17

Lysosomes isolate potentially damaging enzymes involved in the breakdown of wastes and cellular components, preventing severe damage to the cell.

Question 18

What role does phagocytic vacuole formation play in cells?

Answer 18

Phagocytic vacuoles, formed during endocytosis, protect cellular contents from potential damage. They fuse with lysosomes to neutralize and digest threats, aiding in defending cells against invading pathogens.

Question 19

What challenges does compartmentalization pose for cells?

Answer 19

Organelles are connected in functional series, and membrane pumps and carriers facilitate the flow of products between organelles to overcome this challenge and ensure important cell reactions occur.

Question 20

What is cellular respiration, and what does it produce (equation) ?

Answer 20

Cellular respiration converts glucose into ATP, providing energy for cell reactions. Its overall equation is: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy.

Question 20

Where do most of the complex chemical reactions of cellular respiration occur?

Answer 20

Most of the complex chemical reactions of cellular respiration occur in the mitochondrion.

Question 21

How is aerobic respiration defined, and why is it significant?

Answer 21

Aerobic respiration includes oxygen as a reactant and is essential for ATP production in all organisms, representing a fundamental energy-generating process.

Question 22

What are the specific structures within mitochondria?

Answer 22

• Outer mitochondrial membrane
• Matrix
• Cristae
• Inner mitochondrial membrane
  -Space between membranes

Question 23

Outer mitochondrial membrane function

Answer 23

Separates mitochondrion contents from the cell.

Question 24

Matrix function

Answer 24

Contains enzymes for initial respiration stages (link reaction, Krebs cycle).

Question 25

Cristae function

Answer 25

Increases surface area for late-stage respiration reactions (oxidative phosphorylation).

Question 26

Inner mitochondrial membrane function

Answer 26

Contains carriers and enzymes for final respiration stages (electron transport chain, chemiosmosis).

Question 27

Space between membranes function

Answer 27

Acts as a reservoir for hydrogen ions (protons), enabling a high proton concentration.

Question 28

How do defects in mitochondrial regions or structures impact ATP production?

Answer 28

Defects in these regions can diminish or eliminate ATP production. Mitochondrial defects in children can lead to muscle weakness and affect mental development due to insufficient energy production.

Question 29

How does the photosynthetic process differ from respiration in terms of location?

Answer 29

Unlike respiration, where some steps occur outside the mitochondrion, all steps of photosynthesis occur within the chloroplast.

Question 30

What is the significance of chloroplasts in the context of photosynthesis?

Answer 30

Chloroplasts are essential for photosynthesis, where they not only house the process but also absorb light crucial for the chemical reactions involved.

Question 31

What evidence supports the theory of endosymbiosis concerning chloroplasts and mitochondria?

Answer 31

Both chloroplasts and mitochondria exhibit characteristics suggesting endosymbiosis: they have an extra outer membrane for protection, possess their own DNA, and are similar in size to typical prokaryotic cells.

Question 32

What is the relationship between chloroplasts and mitochondria?

Answer 32

Carbon dioxide and water serve as the primary raw materials for photosynthesis, with light providing the necessary energy.

Question 33

What is the overall equation for photosynthesis and its implications?

Answer 33

6 CO2 + 12 H2O + light → C6H12O6 + 6 H2O + 6 O2.

It shows that 12 water molecules are consumed, and 6 are produced. Photosynthesis essentially reverses the process of respiration.

Question 34

How does photosynthesis differ from respiration in terms of energy utilization and chemical bonds?

Answer 34

In respiration, energy is released by breaking chemical bonds in glucose to produce ATP. In photosynthesis, chemical bonds are formed to create carbon compounds using light energy.

Question 35

What is the difference between respiration and photosynthesis in terms of catabolism and anabolism?

Answer 35

Respiration is generally a catabolic process, breaking down molecules to release energy, while photosynthesis is an anabolic process, synthesizing molecules using energy.

Question 36

Which organisms primarily undergo photosynthesis, and what term is used to describe them?

Answer 36

Organisms known as autotrophs perform photosynthesis, producing their own food using this process.

Question 37

How does the extensive surface area of thylakoids in chloroplasts relate to their function?

Answer 37

The extensive thylakoid membrane surface area allows for greater absorption of light by photosystems during photosynthesis

Question 38

What role does the small space (lumen) within thylakoids play in chloroplast function?

Answer 38

The small lumen space facilitates the rapid accumulation of protons, creating a concentration gradient crucial for energy production.

Question 39

What is the function of the stroma region in chloroplasts, and how does it relate to the cell?

Answer 39

The stroma, akin to the cell’s cytoplasm or the mitochondrion’s matrix, provides a space for enzymes necessary for the Calvin cycle to function during photosynthesis.

Question 40

How does the double membrane surrounding the chloroplast contribute to its function?

Answer 40

The double membrane isolates the enzymes and working parts of the chloroplast from the surrounding cytoplasm, aiding in efficient photosynthetic processes.

Question 41

What overarching biological concept is demonstrated by the relationship between chloroplast structure and function?

Answer 41

The structure-function correlation is exemplified in chloroplasts, showcasing how their structure, such as membrane surfaces and compartments, directly supports their functions in photosynthesis.

Question 42

What is the function of the nuclear envelope in the cell?

Answer 42

The nuclear envelope, formed by a double membrane, provides a protected area for DNA to carry out its functions without interference from other cellular processes.

Question 43

How do nuclear pores function within the nuclear envelope?

Answer 43

Nuclear pores allow ions, small molecules, mRNA, proteins, and RNA-protein complexes to diffuse between the nucleoplasm and the cytoplasm, controlling the passage of materials into and out of the nucleus.

Question 44

Where are ribosomes produced within the nucleus, and what do they become?

Answer 44

Ribosomes are produced in the nucleolus within the nucleus and often transform into RNA-protein complexes, some of which become ribosomes.

Question 45

What is the relationship between the nuclear envelope and the endoplasmic reticulum (ER)?

Answer 45

The outer membrane of the nuclear envelope is continuous with the ER, shares some functions, and often has ribosomes attached to it.

Question 46

How does the nuclear envelope participate in cell division processes like mitosis and meiosis?

Answer 46

During mitosis and meiosis, the nuclear envelope breaks down early in the processes to allow movement of DNA structures. Later, vesicles derived from the nuclear envelope reform around the DNA, reconstructing the nuclear envelope once DNA positioning is complete.

Question 47

What are ribosomes composed of, and what are their subunits?

Answer 47

Ribosomes are composed of proteins and ribosomal RNA (rRNA). They consist of two subunits: a large ribosomal subunit and a small ribosomal subunit.

Question 48

What distinguishes eukaryotic ribosomes from prokaryotic ribosomes?

Answer 48

Eukaryotic ribosomes are slightly larger than prokaryotic ribosomes, and they are responsible for protein synthesis in eukaryotic cells.

Question 49

Where can ribosomes be found within cells, and what distinguishes rough ER from free ribosomes?

Answer 49

Ribosomes can be attached to the endoplasmic reticulum (ER) or free in the cytoplasm. Rough ER (rER) refers to ER with ribosomes attached. Free ribosomes produce proteins used within the cell or in organelles, while membrane-bound ribosomes produce proteins exported from the cell.

Question 50

What types of proteins do free ribosomes produce, and where are these proteins utilized?

Answer 50

Free ribosomes produce proteins used within the cell, such as those in the cytoskeleton, nucleus, mitochondria, and other organelles not derived from the cell’s inner membrane system.

Question 51

What is the role of membrane-bound ribosomes, and what kind of proteins do they produce?

Answer 51

Membrane-bound ribosomes produce proteins that are transported through the ER and are often exported from the cell. These secretory proteins are sent to the Golgi apparatus for packaging before cellular exit. Examples include hormones and enzymes.

Question 52

What is the structure of the Golgi apparatus, and how does its quantity vary among cells?

Answer 52

The Golgi apparatus consists of flattened sacs called cisternae. Its quantity varies, with some cells having as few as one and others having over 20, especially in cells engaged in producing and secreting substances.

Question 53

What is the significance of the Golgi apparatus’ position in a cell, and what are its two distinct sides called?

Answer 53

One side of the Golgi stack, called the cis side, is near the endoplasmic reticulum (ER), while the other side, the trans side, faces the plasma membrane. This positioning correlates with the Golgi’s function in cellular transport.

Question 54

How do proteins or lipids move through the Golgi apparatus, and what happens to them as they pass through?

Answer 54

Transport vesicles filled with proteins or lipids arrive at the cis side from the ER. As they move through the cisternae, they undergo modifications to enable their specific functions. Finally, they are packaged into vesicles on the trans side.

Question 55

What occurs during the modification of substances within the Golgi apparatus?

Answer 55

Substances are modified within the Golgi apparatus, often involving the attachment of signal chemicals that direct the final product to its destination, which could include lysosomes, return to the ER, fusion with the plasma membrane, or exocytosis for secretion.

Question 56

How does the Golgi apparatus contribute to cellular secretion, and what happens to the substances after processing?

Answer 56

Many processed substances combine with the plasma membrane and undergo exocytosis, leading to their secretion out of the cell. Some vesicles may become lysosomes or return to the ER after Golgi processing.

Question 57

What distinguishes vesicles from vacuoles

Answer 57

Vesicles are smaller membrane-bound sacs used for transport or storage in the cell, unlike larger vacuoles.

Question 58

what are some examples of vesicles?

Answer 58

Examples include
- peroxisomes (for fatty acid breakdown),
- lysosomes (for cellular digestion),
- transport vesicles (for intracellular molecule movement),
- secretory vesicles (for excreting materials).

Question 59

What are lysosomes and peroxisomes, and what functions do they serve in the cell?

Answer 59

Lysosomes contain enzymes for cellular digestion and removing damaged organelles, while peroxisomes contain enzymes for breaking down fatty acids.

Question 60

How do secretory vesicles and transport vesicles differ in their functions?

Answer 60

Secretory vesicles contain materials for excretion from the cell, such as neurotransmitters and hormones, while transport vesicles move molecules within the cell.

Question 61

What are clathrins, and what role do they play in receptor-mediated endocytosis?

Answer 61

Clathrins are proteins on the cell membrane that anchor specific proteins, especially in receptor-mediated endocytosis. They line coated pits, allowing receptors to bind to specific molecules, leading to vesicle formation.

Question 62

What is the advantage of receptor-mediated endocytosis over ordinary endocytosis?

Answer 62

Receptor-mediated endocytosis is highly selective and efficient, driven by specific receptors on cell surfaces, allowing cells to take in specific molecules rapidly and with high specificity compared to ordinary endocytosis.