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Bio > Textbook ch. 6.5 (Mwitachondria), > Flashcards

Textbook ch. 6.5 (Mwitachondria), Flashcards

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1
Q

What is the primary function of mitochondria in eukaryotic cells?

A

Mitochondria are the sites of cellular respiration, a metabolic process that uses oxygen to generate ATP by extracting energy from sugars, fats, and other fuels.

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2
Q

What role do chloroplasts play in plant and algal cells?

A

Chloroplasts are the sites of photosynthesis, converting solar energy to chemical energy by synthesizing sugars from carbon dioxide and water.

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3
Q

What theory explains the evolutionary origin of mitochondria and chloroplasts?

A

The endosymbiont theory, which suggests that an early ancestor of eukaryotic cells engulfed a prokaryotic cell, leading to a symbiotic relationship and eventually to mitochondria and chloroplasts in modern eukaryotes.

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4
Q

What structural features of mitochondria and chloroplasts support the endosymbiont theory?

A

Both have double membranes, contain ribosomes, have circular DNA, and reproduce somewhat independently within the cell.

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5
Q

Describe the structure of the mitochondrial membranes.

A

Mitochondria have an outer smooth membrane and an inner membrane with infoldings called cristae, which divide the mitochondrion into two compartments: the intermembrane space and the mitochondrial matrix.

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6
Q

How does the structure of the inner mitochondrial membrane enhance cellular respiration?

A

The cristae provide a large surface area, facilitating more efficient ATP production during cellular respiration.

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7
Q

What is the function of chlorophyll in chloroplasts?

A

Chlorophyll, the green pigment in chloroplasts, captures light energy to drive the photosynthesis process.

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8
Q

What are thylakoids, and where are they located?

A

Thylakoids are flattened, interconnected sacs within the chloroplast; in some regions, they form stacks called grana.

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9
Q

What is the purpose of the stroma in chloroplasts?

A

The stroma is the fluid surrounding the thylakoids that contains chloroplast DNA, ribosomes, and enzymes necessary for the photosynthetic production of sugars.

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10
Q

What are plastids, and what are two examples of them?

A

Plastids are a family of closely related organelles in plants, including amyloplasts (store starch) and chromoplasts (give fruits and flowers their colors).

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11
Q

What is the primary function of peroxisomes?

A

Peroxisomes contain enzymes that transfer hydrogen atoms to oxygen, producing hydrogen peroxide, which is then converted to water, helping with the breakdown of fatty acids and detoxification.

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12
Q

How do peroxisomes aid in cellular detoxification?

A

They detoxify harmful compounds (e.g., alcohol in the liver) by transferring hydrogen from the toxins to oxygen.

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13
Q

Why are peroxisomes essential in plant seeds?

A

Specialized peroxisomes, called glyoxysomes, convert fatty acids to sugars, providing energy for the seedling until it can photosynthesize.

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14
Q

What is the evolutionary debate surrounding peroxisomes?

A

Some scientists suggest peroxisomes may have an endosymbiotic origin, while others argue against this due to their unique growth process and single membrane.

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15
Q

How do mitochondria move within a cell, and why is this movement significant?

A

Mitochondria move, change shape, and can divide or fuse within the cell, forming a dynamic network that adapts to the cell’s energy needs.

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16
Q

What determines the number of mitochondria in a cell?

A

The number of mitochondria in a cell correlates with the cell’s level of metabolic activity, with more active cells containing more mitochondria.

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17
Q

What is the mitochondrial matrix, and what does it contain?

A

The mitochondrial matrix is the compartment inside the inner membrane containing enzymes, mitochondrial DNA, and ribosomes, crucial for cellular respiration.

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18
Q

Why do mitochondria and chloroplasts contain their own DNA?

A

They have their own DNA, similar to prokaryotic cells, which allows them to produce some of their own proteins and supports the endosymbiont theory of their origin.

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19
Q

What is the main pigment involved in photosynthesis, and why is it important?

A

Chlorophyll is the main pigment in chloroplasts, capturing light energy necessary for converting carbon dioxide and water into sugars.

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20
Q

What is the role of the intermembrane space in mitochondria?

A

The intermembrane space, located between the inner and outer membranes, plays a role in creating a proton gradient necessary for ATP synthesis.

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21
Q

How do cristae support cellular respiration in mitochondria?

A

Cristae increase the inner membrane’s surface area, enabling more proteins and enzymes to support efficient ATP production.

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22
Q

Explain the compartmental organization within chloroplasts and its significance.

A

Chloroplasts have three compartments—intermembrane space, stroma, and thylakoid space—each supporting different steps in the photosynthetic process.

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23
Q

What is a granum, and where is it found?

A

A granum is a stack of thylakoids within chloroplasts that facilitates light absorption in photosynthesis.

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24
Q

How do the cytoskeleton and chloroplasts interact within a cell?

A

Chloroplasts are mobile and move along the cell’s cytoskeleton, enabling efficient positioning for light capture.

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25
Describe the double-membrane structure of mitochondria and chloroplasts.
Both mitochondria and chloroplasts have an outer and inner membrane, likely derived from an ancestral prokaryote's two membranes, aligning with the endosymbiont theory.
26
What is the function of ribosomes in mitochondria and chloroplasts?
Ribosomes within these organelles synthesize proteins needed for their function, further supporting their semi-autonomous nature.
27
How do glyoxysomes benefit germinating plant seeds?
Glyoxysomes convert stored fatty acids into sugars, providing the necessary energy for seedling growth until it can perform photosynthesis.
28
What is hydrogen peroxide’s role in peroxisomes, and how is it managed?
Peroxisomes produce hydrogen peroxide as a by-product of fatty acid breakdown, which is then converted to water by catalase, preventing cellular damage.
29
Why are peroxisomes considered autonomous yet debated for endosymbiotic origin?
While they contain unique enzymes and grow by incorporating cytosolic proteins, their lack of DNA and singular membrane challenge a strict endosymbiotic origin.
30
What does the dynamic behavior of mitochondria and chloroplasts suggest about their function?
Their ability to change shape, divide, and move within the cell indicates a highly adaptable structure that meets cellular energy demands.
31
What evidence supports the endosymbiont theory for the origin of mitochondria and chloroplasts?
They both have double membranes, their own circular DNA, ribosomes, and can reproduce independently within the cell, similar to prokaryotic cells.
32
How do mitochondria generate ATP during cellular respiration?
Mitochondria use enzymes in the matrix and proteins in the inner membrane to extract energy from fuels like glucose, transferring it to ATP.
33
Why are mitochondria particularly abundant in muscle cells?
Muscle cells have high energy demands for movement and contraction, requiring a large number of mitochondria to generate ATP.
34
How do chloroplasts contribute to the process of photosynthesis?
Chloroplasts absorb sunlight, which powers the conversion of CO₂ and water into sugars, releasing oxygen as a byproduct.
35
Why do chloroplasts contain a third membrane system, the thylakoids?
The thylakoids provide a large surface area for light-dependent reactions in photosynthesis, which occur within this membrane system.
36
What role does the enzyme ATP synthase play in mitochondria?
ATP synthase, located in the inner membrane, synthesizes ATP from ADP and inorganic phosphate, powered by the proton gradient established across the membrane.
37
How is compartmentalization important in mitochondria and chloroplasts?
Compartmentalization allows separation of various processes, enhancing efficiency by isolating specific enzymes and conditions for reactions.
38
Describe the relationship between mitochondria and energy demand in cells.
Cells with higher energy requirements, like those in the heart and muscles, have more mitochondria to meet their greater demand for ATP.
39
How do peroxisomes differ from mitochondria and chloroplasts in terms of membranes?
Peroxisomes are bounded by a single membrane, unlike the double-membraned mitochondria and chloroplasts.
40
How do peroxisomes help in lipid metabolism?
Peroxisomes break down fatty acids into smaller molecules that mitochondria can use for cellular respiration.
41
What is catalase, and why is it crucial within peroxisomes?
Catalase is an enzyme that converts toxic hydrogen peroxide (H₂O₂) into water, protecting the cell from oxidative damage.
42
What function do chromoplasts serve in plants?
Chromoplasts contain pigments that give fruits and flowers vibrant colors, which can attract pollinators or aid in seed dispersal.
43
How do amyloplasts function in plants?
Amyloplasts store starch, particularly in non-photosynthetic tissues like roots and tubers, providing an energy reserve.
44
What is the significance of mitochondrial DNA in inheritance?
Mitochondrial DNA is maternally inherited, as mitochondria in sperm are typically not passed to the offspring.
45
How does the mitochondrial inner membrane contribute to ATP production?
The inner membrane's cristae create a large surface area for electron transport chain proteins and ATP synthase, essential for efficient ATP production.
46
What evolutionary evidence suggests that mitochondria and chloroplasts were once free-living bacteria?
Their ribosomes and circular DNA resemble those of bacteria, and their double membranes hint at an engulfing process by an early eukaryotic ancestor.
47
Why do chloroplasts exhibit mobility within the cell?
Chloroplasts move along the cytoskeleton to optimize light absorption, aiding in efficient photosynthesis.
48
In what way are mitochondria considered semi-autonomous organelles?
They have their own DNA, ribosomes, and the ability to replicate independently within the cell.
49
What is the thylakoid space, and why is it important?
The thylakoid space is the internal area within the thylakoids where protons accumulate, creating a gradient essential for ATP synthesis during photosynthesis.
50
How does the compartmentalization within chloroplasts aid photosynthesis?
The separate spaces (intermembrane, stroma, and thylakoid space) allow for distinct environments, optimizing the light-dependent and light-independent reactions.
51
What cellular process occurs in mitochondria, and why is it important?
Cellular respiration occurs in mitochondria, allowing the cell to produce ATP by using oxygen to break down sugars, fats, and other fuels.
52
How does chloroplast structure support photosynthesis?
Chloroplasts contain chlorophyll, thylakoids, and a stroma, enabling the capture of light energy and conversion into chemical energy stored in organic molecules.
53
What specific evolutionary origin theory explains the presence of mitochondria and chloroplasts in eukaryotic cells?
The endosymbiont theory suggests that a eukaryotic ancestor engulfed prokaryotes, which eventually evolved into mitochondria and chloroplasts, forming a symbiotic relationship.
54
Why are mitochondria and chloroplasts not part of the endomembrane system despite having membranes?
They have distinct double membranes from their prokaryotic ancestry, and they function independently within the cell, unlike other organelles of the endomembrane system.
55
What type of DNA do mitochondria and chloroplasts contain, and where is it located?
Both organelles contain circular DNA molecules attached to their inner membranes, similar to bacterial DNA, which is involved in coding for their own proteins.
56
Describe the difference between the outer and inner mitochondrial membranes.
The outer membrane is smooth and protective, while the inner membrane has folds (cristae) that increase the surface area for ATP-generating enzymes.
57
What are cristae, and what role do they play in cellular respiration?
Cristae are folds in the inner mitochondrial membrane that provide additional surface area for ATP synthesis, maximizing energy production efficiency.
58
What evidence from ribosomes supports the theory that mitochondria and chloroplasts evolved from bacteria?
Mitochondria and chloroplasts contain their own ribosomes, which resemble those found in bacteria, suggesting they once existed as independent prokaryotic cells.
59
How does the dynamic nature of mitochondria and chloroplasts affect their function?
Their ability to move, divide, and change shape allows them to adapt to cellular needs and distribute energy efficiently where required.
60
What is the role of the mitochondrial matrix in cellular respiration?
The matrix contains enzymes that catalyze the citric acid cycle, part of cellular respiration, releasing energy for ATP production.
61
How does the structure of chloroplast thylakoids facilitate light-dependent reactions in photosynthesis?
Thylakoids provide a large surface area with pigments and proteins essential for capturing light energy and producing ATP and NADPH.
62
What is the stroma in a chloroplast, and what does it contain?
The stroma is the fluid-filled area outside the thylakoids that contains chloroplast DNA, ribosomes, and enzymes necessary for the Calvin cycle (light-independent reactions).
63
Explain the role of the cytoskeleton in the movement of chloroplasts and mitochondria.
The cytoskeleton provides tracks that allow chloroplasts and mitochondria to move, ensuring optimal positioning and distribution for energy production and photosynthesis.
64
What are plastids, and how are they related to chloroplasts?
Plastids are a family of plant organelles that include chloroplasts, amyloplasts (for starch storage), and chromoplasts (for pigments), each with specialized functions.
65
Describe the compartmentalization within chloroplasts and its relevance to photosynthesis.
Chloroplasts have intermembrane, thylakoid, and stroma spaces, which help organize photosynthetic reactions, isolating specific enzymes and processes.
66
How do peroxisomes differ from other organelles in their evolutionary origin and function?
Unlike mitochondria and chloroplasts, peroxisomes do not contain DNA and have a debated evolutionary origin; they function primarily in oxidation and detoxification.
67
What reactions occur within peroxisomes, and what by-product is generated?
Peroxisomes catalyze reactions that transfer hydrogen to oxygen, creating hydrogen peroxide (H₂O₂) as a by-product, which is then broken down to avoid cell damage.
68
How do liver cell peroxisomes contribute to detoxification?
Liver peroxisomes remove hydrogen atoms from toxins like alcohol, producing hydrogen peroxide, which they then convert to water, aiding in cellular detox.
69
What unique role do glyoxysomes play in plant seeds?
Glyoxysomes in seeds convert stored fats into sugars, supplying energy for seedling growth until photosynthesis can occur.
70
Explain how the compartmentalized structure of peroxisomes prevents cellular damage.
By isolating enzymes that produce and neutralize hydrogen peroxide, peroxisomes protect the cell from oxidative damage.
71
What argument exists against an endosymbiotic origin for peroxisomes?
Unlike mitochondria and chloroplasts, peroxisomes lack their own DNA and reproduce by dividing or incorporating proteins from the cytosol, leading some to argue against an endosymbiotic origin.
72
What happens to the number of peroxisomes when they reach a certain size?
Peroxisomes may divide to increase their number, especially when the cell needs more capacity for fatty acid breakdown and detoxification.
73
How does the endosymbiont theory explain the double membranes of mitochondria and chloroplasts?
It suggests that the original prokaryotic cell was engulfed by an ancestral eukaryote, resulting in the double membranes seen in these organelles.
74
What structural features in mitochondria and chloroplasts support their semi-autonomous nature?
Their own DNA, ribosomes, and ability to replicate independently enable them to produce proteins and function semi-autonomously within the cell.
75
How does the structure-function relationship in cristae demonstrate cellular efficiency?
The cristae's folded surfaces maximize the space available for enzymes that generate ATP, increasing the cell’s capacity for energy production.

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