Funbio 6

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Questions and Answers

What is the shape variation of mitochondria and what does it depend on?

Mitochondria can vary in shape from rods to spheres, depending on the specific cell type.

How does the number of mitochondria in a cell vary?

The number of mitochondria in a cell can range from a few to over 1000.

What are the two membranes that bind each mitochondrion?

Each mitochondrion is bound by a smooth outer membrane and an inner membrane.

What are the main byproducts generated during glycolysis?

The main byproducts of glycolysis are pyruvate, ATP, and NADH. Signup and view all the answers

What unique feature do mitochondria possess compared to other organelles?

Mitochondria can reproduce by themselves. Signup and view all the answers

What is the primary role of the Krebs cycle in cellular respiration?

The primary role of the Krebs cycle is to generate NADH for use in the electron transport chain. Signup and view all the answers

What is the role of F1 particles in the mitochondria?

F1 particles play a key role in ATP production during cellular respiration. Signup and view all the answers

What is the significance of extrachromosomal DNA in the mitochondrial matrix?

Extrachromosomal DNA allows mitochondria to produce some of their own proteins independently. Signup and view all the answers

How does NADH function in the electron transport chain?

NADH acts as a coenzyme and carrier molecule, donating electrons and hydrogen ions to the electron transport chain. Signup and view all the answers

What two components make up oxidative phosphorylation?

Oxidative phosphorylation is made up of the electron transport chain and chemiosmosis. Signup and view all the answers

What is the serial symbiotic theory regarding mitochondria?

The serial symbiotic theory suggests that mitochondria originated from free-living prokaryotes that entered into a symbiotic relationship with ancestral eukaryotic cells. Signup and view all the answers

Describe the function of the electrochemical gradient in the electron transport chain.

The electrochemical gradient stores energy that is used to pump hydrogen ions and synthesize ATP during chemiosmosis. Signup and view all the answers

Explain why living mitochondria are described as not static?

Living mitochondria are not static because they move around in the cytoplasm and can aggregate in areas of high metabolic activity. Signup and view all the answers

What is the role of ATP synthase in ATP production?

ATP synthase synthesizes ATP from ADP and inorganic phosphate (Pi) by squeezing them together. Signup and view all the answers

How does the structure of ATP synthase contribute to its function?

ATP synthase has a complex structure with F1 and F0 particles that allow it to form a transmembrane complex for efficient ATP synthesis. Signup and view all the answers

What happens to hydrogen ions during chemiosmosis?

During chemiosmosis, hydrogen ions are pumped from the inner compartment to the outer compartment of the mitochondria. Signup and view all the answers

What is the primary function of the cristae in the mitochondria?

The primary function of the cristae is to provide a large surface area for sequential chemical reactions related to ATP production. Signup and view all the answers

How does the number of cristae relate to cellular activity?

There is a direct correlation between the number of cristae and the activity level of the cell; more cristae indicate higher activity. Signup and view all the answers

What components are contained within the mitochondrial matrix?

The mitochondrial matrix contains mitochondrial ribosomes, non-chromosomal DNA, and enzymes for the Krebs Cycle. Signup and view all the answers

What is the process that converts ADP into ATP in mitochondria?

The process that converts ADP into ATP is known as oxidative phosphorylation. Signup and view all the answers

How does mitochondrial DNA (mtDNA) differ from nuclear DNA?

Mitochondrial DNA is circular, non-chromosomal, and more susceptible to mutations compared to nuclear DNA. Signup and view all the answers

What key cycle is involved in ATP production in the mitochondria?

The key cycle involved in ATP production is the Citric Acid Cycle, also known as the Krebs Cycle. Signup and view all the answers

What role does ATP play in cellular processes?

ATP serves as the primary energy carrier, driving various metabolic processes within the cell. Signup and view all the answers

What are the two main types of membranes found in mitochondria?

The two main types of membranes found in mitochondria are the outer mitochondrial membrane and the inner mitochondrial membrane. Signup and view all the answers

What unique characteristic of mitochondria and chloroplasts supports the theory of endosymbiosis?

They possess their own circular DNA, similar to bacterial DNA. Signup and view all the answers

How do mitochondria and chloroplasts contribute to their own protein synthesis?

They have their own ribosomes which resemble those of bacteria, allowing them to produce their own proteins. Signup and view all the answers

What process allows mitochondria and chloroplasts to replicate independently of the cell?

They undergo binary fission, similar to prokaryotic cell division. Signup and view all the answers

Which specific antibiotics can affect mitochondria and chloroplasts but not eukaryotic cells?

Bacterial antibiotics that target prokaryotic ribosomes can poison these organelles. Signup and view all the answers

What is the established theory regarding the origin of mitochondria?

Mitochondria arise from pre-existing mitochondria through a process of division. Signup and view all the answers

How many genes are encoded in mitochondrial DNA, and why are they essential?

Mitochondrial DNA encodes 37 genes, 13 of which are crucial for oxidative phosphorylation. Signup and view all the answers

Describe the process by which mitochondria replicate.

Mitochondria replicate by dividing in two, using a process called fission. Signup and view all the answers

Identify the two types of bacteria that evolved into mitochondria and chloroplasts.

Mitochondria evolved from aerobic bacteria, while chloroplasts evolved from photosynthetic bacteria. Signup and view all the answers

What structural feature do mitochondria and chloroplasts possess that is similar to prokaryotic cells?

They have multiple invaginations of their inner membranes. Signup and view all the answers

What does the Serial Endosymbiotic Theory (SET) propose about the evolution of mitochondria?

SET proposes that aerobic bacteria evolved into mitochondria through symbiosis with an ancestral eukaryotic host. Signup and view all the answers

How did aerobic bacteria contribute to eukaryotic cells according to SET?

Aerobic bacteria provided energy to anaerobic host cells, leading to a mutualistic relationship. Signup and view all the answers

How does the presence of their own DNA in mitochondria and chloroplasts support their function?

It enables them to produce enzymes necessary for their metabolic functions without relying solely on the nuclear genome. Signup and view all the answers

What role do photosynthetic bacteria play in the context of SET?

Photosynthetic bacteria are theorized to have become chloroplasts in plant cells through a similar endosymbiotic process. Signup and view all the answers

What historical evidence supports the Serial Endosymbiotic Theory?

Evidence includes the presence of bacterial-like DNA in mitochondria and the similarities in division processes. Signup and view all the answers

In SET, what is implied about the origin of the endoplasmic reticulum and nuclear envelope?

The endoplasmic reticulum and nuclear envelope are thought to have formed from invaginations of the plasma membrane. Signup and view all the answers

Which types of cells rely on the outcomes of SET for their energy needs?

Eukaryotic cells, including animals, fungi, and some protists, benefit from this evolutionary process. Signup and view all the answers

What role do electrons play in the electron transport chain?

Electrons from the Krebs cycle transfer energy through the electron transport chain, ultimately leading to the pumping of protons into the intermembrane space. Signup and view all the answers

How do protons contribute to ATP synthesis in mitochondria?

Protons are pumped into the intermembrane space and flow back through ATP synthase, providing the energy to convert ADP and inorganic phosphate into ATP. Signup and view all the answers

What is the function of Complex IV in the electron transport chain?

Complex IV reduces molecular oxygen to water using electrons and hydrogen ions. Signup and view all the answers

Describe how mitochondria reproduce during cell division.

During cell division, mitochondria are distributed equally between the daughter cells, and their numbers increase to ensure proper cell function. Signup and view all the answers

What role does ATP synthase play in mitochondrial function?

ATP synthase synthesizes ATP from ADP and inorganic phosphate using the energy from the flow of protons back into the mitochondrial matrix. Signup and view all the answers

What process generates the protons that are pumped into the intermembrane space?

The energy released during the transfer of electrons through the electron transport chain generates the protons pumped into the intermembrane space. Signup and view all the answers

Explain the significance of the proton gradient in mitochondria.

The proton gradient created by the electron transport chain is critical for driving ATP synthesis as protons flow through ATP synthase. Signup and view all the answers

How do newly formed mitochondria increase their numbers after cell division?

Newly formed mitochondria increase their numbers through processes like fission, allowing for adequate energy supply for cell function. Signup and view all the answers

Study Notes

Mitochondrial Structure

Mitochondria are the second most prominent cellular organelles.
They are visible with a light microscope.
Detailed structure requires an electron microscope.
Singular form: mitochondrion.
From the Greek, mitos (thread) and chondrios (granule).
Found in all eukaryotic cells (plant and animal).
Number varies from a few to >1000 per cell.
Shape varies, ranging from rods to spheres.
Shape is characteristic of a particular cell type.
Mitochondria are dynamic and move around the cytoplasm.
They aggregate in areas of high metabolic activity.
Variable size: 0.5-1.0 μm diameter, 5-10 μm long.
Each mitochondrion is bound by two membranes.
- Smooth outer membrane.
- Inner membrane, folded into thin plates called cristae.
  - Cristae increase surface area for chemical reactions.

Mitochondrial Structure - Cristae

Cristae are infolds of the inner plasma membrane.
They may extend from wall to wall or only part of the way.
Cristae may be tubular or have other shapes.
Cristae function in providing a large surface area for sequential chemical reactions.
A direct correlation exists between the number of cristae and the activity of the cell.

Mitochondrial Structure - Matrix

The interior of the mitochondrion is called the matrix.
Contains mitochondrial ribosomes and non-chromosomal DNA.
Contains 5-10 identical circular DNA molecules, 2-3 nm in diameter.
Mitochondria manufacture their own proteins, which can also use proteins from the nucleus.
The number of proteins produced by mitochondrial DNA (mtDNA) is small.
Contains Kreb's/Citric acid cycle enzymes, which convert chemical energy in food into ATP energy.

Mitochondrial Function

Mitochondria are the "Powerhouse of the Cell".
They are eukaryotic organelles that generate chemical energy via aerobic cellular respiration.
ATP production via oxidative phosphorylation.
The oxidative process uses O₂ to convert Adenosine diphosphate (ADP) into Adenosine Triphosphate (ATP).
ATP contains a high-energy bond used to drive metabolic processes in the cell.
The central set of reactions, involved in ATP production, are collectively known as the Citric Acid Cycle/Krebs Cycle. (aerobic respiration)

Aerobic Respiration Recap

Glucose breakdown (Glycolysis) occurs in the cytoplasm, producing pyruvate, ATP, and NADH.
The Krebs/Citric Acid Cycle takes place in mitochondria, producing NADH for use in the electron transport chain.
In mitochondria, NADH is a coenzyme/carrier molecule, donating electrons and hydrogen ions to the Electron Transport Chain.
The total ATP production is approximately 36.

Oxidative Phosphorylation

Oxidative phosphorylation is the final stage of cellular respiration.
It consists of two parts: the electron transport chain and chemiosmosis.
In the electron transport chain, electrons are passed along molecules, releasing energy to create an electrochemical gradient.
Chemiosmosis uses the energy in the electrochemical gradient to produce ATP.
This involves pumping hydrogen ions through channels in the mitochondrial membranes from the inner to the outer compartment.

Mitochondrial Structure/Function - F₁Fo Particles

Mitochondrial inner membrane is studded with round particles called F₁ particles which protrude from the membrane.
The Fo base is embedded in the membrane.
ATP Synthase (F₁-F₀ particle) acts as an enzyme (ATPase).
It's part of a respiratory assembly in the electron transport chain.
Forms a transmembrane complex of 9 different polypeptides on the inner mitochondrial membrane.
The F₁ portion synthesizes ATP from ADP + Pi, while the F₀ portion uses the movement of protons to drive this synthesis.

Respiratory Assembly (Electron Transport Chain)

Energy obtained through electron transfer.
Protons are pumped from the mitochondrial matrix to the intermembrane space.
ATP synthase uses the H⁺ flow to generate ATP from ADP and inorganic phosphate (P₁).
Electrons from the Krebs cycle (NADH) are passed along carrier molecules.
Complex IV uses electrons and hydrogen ions to reduce molecular oxygen to water.

Mitochondrial Reproduction and Origin

Mitochondria are distributed equally to daughter cells when a cell divides.
Mitochondria increase in number to maintain sufficient function after division.
Mitochondria arise from pre-existing mitochondria via division.
The division process is similar to asexual bacterial division (fission).

Serial Endosymbiotic Theory (SET)

Symbiotic prokaryotic origin taking up residence in anaerobic cells to become mitochondria and provide energy.
More likely explanation for mitochondrial evolution.
Evidence: Mitochondria and chloroplasts have their own circular DNA (mtDNA).
Produce their own proteins.
Can replicate independently within the cell.
Ribosomes resemble bacterial ribosomes.
Susceptible to antibiotics that don't affect eukaryotic cells.

Mitochondrial Component - Evidence

Some organelles have double membranes (outer membrane potentially having a vesicular origin).
Susceptible to antibiotics like chloramphenicol (indicates possible bacterial origin).
Reproduction occurs via a fission-like process.
mtDNA, similar to prokaryotic DNA, is naked and circular.
Ribosomes are 70S, matching the size of prokaryotic ribosomes.
37 genes in mtDNA, crucial for normal mitochondrial function.
13 of these genes provide instructions for enzymes of oxidative phosphorylation.

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Description

Explore the fascinating world of mitochondria, the powerhouse of the cell. This quiz covers their structure, including the unique cristae, and their dynamic roles within eukaryotic cells. Test your knowledge on how mitochondria vary in number and shape based on cell type.