Untitled Quiz
112 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a major activity of all cells?

The generation of metabolic energy.

What do mitochondria generate energy from?

The breakdown of lipids and carbohydrates.

What does the inner membrane of mitochondria have numerous folds called?

Cristae

Where does glycolysis occur?

<p>The cytosol</p> Signup and view all the answers

What is the name of the process that produces most of the cell's energy?

<p>Oxidative phosphorylation</p> Signup and view all the answers

What do high-energy electrons from NADH and FADH2 transfer through?

<p>A series of carriers in the membrane to molecular oxygen</p> Signup and view all the answers

What is the property of the inner membrane that is critical to maintaining the proton gradient?

<p>The inner membrane is impermeable to most ions and small molecules.</p> Signup and view all the answers

What forms channels that allow the free diffusion of small molecules?

<p>Porins</p> Signup and view all the answers

How do mitochondria often position themselves?

<p>Near locations of high-energy use.</p> Signup and view all the answers

What process allows the exchange of genetic material in mitochondria?

<p>Mitochondrial fusion</p> Signup and view all the answers

What is crucial for the distribution of mitochondria between daughter cells during cell division?

<p>Fission</p> Signup and view all the answers

Mitochondria are thought to have evolved from bacteria living inside larger cells.

<p>True</p> Signup and view all the answers

What type of bacteria have genomes similar to mitochondria?

<p>Free-living α-proteobacteria</p> Signup and view all the answers

What is the intracellular parasite that can reproduce only within eukaryotic cells, like mitochondria?

<p>Rickettsia prowazekii</p> Signup and view all the answers

What type of DNA molecules are mitochondrial genomes typically?

<p>Circular DNA molecules</p> Signup and view all the answers

Besides oxidative phosphorylation, what else do mitochondrial genomes encode?

<p>All the rRNAs and most of the tRNAs needed for translating the protein-coding sequences.</p> Signup and view all the answers

What does the human mitochondrial genome encode?

<p>13 proteins involved in electron transport and oxidative phosphorylation, plus 16S and 12S rRNAs, and 22 tRNAs</p> Signup and view all the answers

The mitochondrial genetic code is the same as the universal code.

<p>False</p> Signup and view all the answers

How many codons are recognized by a single tRNA in the mitochondrial genetic code?

<p>Four codons</p> Signup and view all the answers

Mitochondrial DNA can be altered by mutations.

<p>True</p> Signup and view all the answers

What are almost all the mitochondria of fertilized eggs contributed by?

<p>The oocyte</p> Signup and view all the answers

What disease is caused by mutations in mitochondrial genes that encode components of the electron transport chain?

<p>Leber's hereditary optic neuropathy</p> Signup and view all the answers

How many proteins do mammalian mitochondria genomes encode?

<p>13 proteins</p> Signup and view all the answers

About how many different proteins encoded by the nuclear genome do mammalian mitochondria contain?

<p>1500 different proteins</p> Signup and view all the answers

What are the proteins needed for replication and expression of mitochondrial DNA?

<p>Proteins encoded by nuclear genes include</p> Signup and view all the answers

Which of the following are synthesized on free ribosomes and imported to mitochondria as complete polypeptides?

<p>Most of the proteins</p> Signup and view all the answers

What are the amino-terminal sequences that are removed by proteolytic cleavage after import?

<p>Presequences</p> Signup and view all the answers

What is the name of the protein complex located on the outer mitochondrial membrane that serves as a receptor for presequences?

<p>Tom complex</p> Signup and view all the answers

What is the complex located in the inner mitochondrial membrane that receives proteins after they are transported through the Tom complex?

<p>Tim complex</p> Signup and view all the answers

Protein translocation requires the electrochemical potential established across the inner mitochondrial membrane.

<p>True</p> Signup and view all the answers

Proteins must be folded before being imported into mitochondria.

<p>False</p> Signup and view all the answers

What cleaves presequences after import?

<p>Matrix processing peptidase (MPP)</p> Signup and view all the answers

What binds to and assists in the folding of polypeptides after the presequence is cleaved?

<p>Other Hsp70 chaperones</p> Signup and view all the answers

What happens to proteins with multiple transmembrane domains?

<p>They have internal import signals instead of presequences.</p> Signup and view all the answers

What do Tim9-Tim10 chaperones do in this scenario?

<p>They bring proteins with multiple transmembrane domains to Tim22.</p> Signup and view all the answers

Some inner membrane proteins are encoded by the mitochondrial genome.

<p>True</p> Signup and view all the answers

Where are these proteins synthesized?

<p>On ribosomes in the mitochondrial matrix</p> Signup and view all the answers

Where are these proteins targeted to?

<p>The Oxa1 translocase in the inner membrane.</p> Signup and view all the answers

How do these proteins exit Oxa1 to insert into the inner membrane?

<p>Laterally</p> Signup and view all the answers

What do proteins destined for the outer membrane or intermembrane space pass through?

<p>The Tom complex</p> Signup and view all the answers

How are proteins with single transmembrane domains inserted into the outer membrane?

<p>Via the outer membrane protein Mim1</p> Signup and view all the answers

What is the name of the translocon that β-barrel proteins are carried to?

<p>SAM (sorting and assembly machinery)</p> Signup and view all the answers

Lipids are imported from the cytosol into mitochondria.

<p>True</p> Signup and view all the answers

What phospholipid do mitochondria catalyze the synthesis of?

<p>Cardiolipin</p> Signup and view all the answers

What does cardiolipin do to improve the efficiency of oxidative phosphorylation?

<p>It restricts proton flow across the membrane.</p> Signup and view all the answers

What mediates lipid transfer between the ER and mitochondria?

<p>Phospholipid transfer proteins</p> Signup and view all the answers

What energy source does the electrochemical gradient generated by proton pumping during oxidative phosphorylation provide?

<p>Energy is provided by the electrochemical gradient for the movement of small molecules in and out of mitochondria.</p> Signup and view all the answers

The transport of ATP and ADP across the mitochondrial inner membrane is mediated by an integral membrane protein called the adenine nucleotide translocator.

<p>True</p> Signup and view all the answers

What is the exchange of one molecule of ATP for one molecule of ADP across the mitochondrial inner membrane driven by?

<p>The voltage component of the electrochemical gradient</p> Signup and view all the answers

What is brought into mitochondria as phosphate in exchange for hydroxyl ions?

<p>Pi</p> Signup and view all the answers

If you were to compare chloroplasts to mitochondria, how are they similar?

<p>Both generate metabolic energy, both evolved by endosymbiosis, both contain their own genetic systems, and both replicate by division.</p> Signup and view all the answers

What is the primary difference in size and complexity between mitochondria and chloroplasts?

<p>Chloroplasts are larger and more complex.</p> Signup and view all the answers

What do chloroplasts convert carbon dioxide to?

<p>Carbohydrates</p> Signup and view all the answers

Chloroplasts contain their own DNA molecules.

<p>True</p> Signup and view all the answers

What is the name of the double membrane that surrounds chloroplasts?

<p>The chloroplast envelope</p> Signup and view all the answers

What does the thylakoid membrane form within chloroplasts?

<p>A network of flattened discs called thylakoids.</p> Signup and view all the answers

What are the three internal compartments of chloroplasts?

<p>The intermembrane space, the stroma, and the thylakoid lumen.</p> Signup and view all the answers

What is the inner membrane of chloroplasts impermeable to?

<p>Ions and metabolites.</p> Signup and view all the answers

What does the stroma contain?

<p>The genetic system and metabolic enzymes, including those needed to convert CO2 to carbohydrates.</p> Signup and view all the answers

Where does electron transport and ATP generation take place in chloroplasts?

<p>The thylakoid membrane.</p> Signup and view all the answers

What are pumped across the thylakoid membrane during photosynthesis?

<p>Protons.</p> Signup and view all the answers

What is the thylakoid membrane equivalent to in mitochondria?

<p>The inner membrane of mitochondria.</p> Signup and view all the answers

Chloroplast genomes are larger and more complex than those of mitochondria.

<p>True</p> Signup and view all the answers

What do chloroplast genetic systems reflect?

<p>Their evolutionary origin from photosynthetic bacteria.</p> Signup and view all the answers

Chloroplast tRNAs are sufficient to translate all mRNA codons using the universal genetic code.

<p>True</p> Signup and view all the answers

What enzyme does one subunit of rubisco is encoded by?

<p>Chloroplast DNA</p> Signup and view all the answers

What is the name of the cycle where rubisco catalyzes the addition of CO2 to ribulose-1,5-bisphosphate?

<p>The Calvin cycle</p> Signup and view all the answers

Rubisco is critical for photosynthesis.

<p>True</p> Signup and view all the answers

Where are other proteins synthesized and then imported into chloroplasts?

<p>On free ribosomes</p> Signup and view all the answers

What are the N-terminal sequences that direct translocation across the two membranes of the envelope and are removed by proteolytic cleavage?

<p>Transit peptides</p> Signup and view all the answers

What does the Toc complex translocate?

<p>Transit peptides direct proteins to the translocase of the chloroplast outer member.</p> Signup and view all the answers

What keeps polypeptides in an unfolded state during import into chloroplasts?

<p>Hsp70 molecules</p> Signup and view all the answers

What do some Hsp70 molecules hydrolyze to provide energy during the translocation process?

<p>GTP</p> Signup and view all the answers

What complex do proteins enter on the inner chloroplast membrane?

<p>The Tic complex</p> Signup and view all the answers

What does the Tic complex transport proteins to?

<p>The stroma.</p> Signup and view all the answers

What cleaves the transit peptide in the stroma?

<p>Stromal processing peptidase (SPP)</p> Signup and view all the answers

What do proteins that must cross the thylakoid membrane have?

<p>A second signal sequence.</p> Signup and view all the answers

What are the two pathways that proteins can take to be translocated into the thylakoid lumen?

<p>The Sec pathway and the Tat pathway.</p> Signup and view all the answers

What does the Sec pathway require?

<p>ATP-dependent; signal sequence is recognized by SecA protein.</p> Signup and view all the answers

What pathway does the Tat pathway use to gain energy?

<p>The proton gradient.</p> Signup and view all the answers

What does the Tat pathway allow proteins to be transported as?

<p>In their fully folded state.</p> Signup and view all the answers

What cleaves the signal sequences in the Tat pathway?

<p>Thylakoid processing protease (TPP).</p> Signup and view all the answers

What do proteins with a transmembrane sequence exit the Sec translocon laterally?

<p>The Sec pathway.</p> Signup and view all the answers

What recognizes proteins in the SRP pathway for chloroplasts and inserts them into the thylakoid membrane?

<p>The chloroplast signal recognition particle (cpSRP).</p> Signup and view all the answers

The insertion of proteins into the thylakoid membrane can occur by a mechanism that does not involve any known transport machinery.

<p>True</p> Signup and view all the answers

What are chloroplasts a type of?

<p>Plastid.</p> Signup and view all the answers

What do plastids share with chloroplasts but differ in?

<p>The same genome as chloroplasts, but differ in structure and function.</p> Signup and view all the answers

What are chloroplasts specialized for?

<p>Photosynthesis.</p> Signup and view all the answers

What are the other types of plastids involved in?

<p>Other aspects of plant metabolism.</p> Signup and view all the answers

What is the name of plastids that contain carotenoids?

<p>Chromoplasts.</p> Signup and view all the answers

What are plastids that are nonpigmented called?

<p>Leucoplasts.</p> Signup and view all the answers

What do amyloplasts store?

<p>Starch.</p> Signup and view all the answers

What do elaioplasts store?

<p>Lipids.</p> Signup and view all the answers

What do all plastids develop from?

<p>Proplastids.</p> Signup and view all the answers

Mature plastids can change from one type to another.

<p>True</p> Signup and view all the answers

What do chromoplasts develop from?

<p>Chloroplasts.</p> Signup and view all the answers

What are the single-membrane organelles containing enzymes involved in many metabolic reactions called?

<p>Peroxisomes.</p> Signup and view all the answers

Peroxisomes have their own genomes.

<p>False</p> Signup and view all the answers

Where are most peroxisomal proteins synthesized?

<p>On free ribosomes and imported as completed polypeptides.</p> Signup and view all the answers

Peroxisomes can replicate by division but can also regenerate even if they're completely lost.

<p>True</p> Signup and view all the answers

What are peroxisomal proteins typically?

<p>Typical eukaryotic proteins.</p> Signup and view all the answers

What kind of reactions do peroxisomes use to break down many substrates?

<p>Oxidative reactions.</p> Signup and view all the answers

What converts hydrogen peroxide to water or oxidizes another organic compound?

<p>Catalase.</p> Signup and view all the answers

Peroxisomes are involved in the synthesis of lipids.

<p>True</p> Signup and view all the answers

What are the phospholipids with one hydrocarbon chain joined to glycerol by an ether bond rather than an ester bond called?

<p>Plasmalogens.</p> Signup and view all the answers

Where in animal cells are cholesterol and dolichol synthesized?

<p>In peroxisomes and the ER.</p> Signup and view all the answers

What are peroxisomes in the liver involved in the synthesis of?

<p>Bile acids.</p> Signup and view all the answers

What is the name of the cycle that peroxisomes in seeds use to convert fatty acids into carbohydrates?

<p>The glyoxylate cycle.</p> Signup and view all the answers

What is the name of the cycle that the glyoxylate cycle is a variant of?

<p>The citric acid cycle.</p> Signup and view all the answers

What does the glyoxylate cycle provide for the germinating plant?

<p>Energy and raw materials.</p> Signup and view all the answers

What are the peroxisomes sometimes referred to as?

<p>Glyoxysomes.</p> Signup and view all the answers

What are peroxisomes in leaves involved in?

<p>Photorespiration.</p> Signup and view all the answers

More Like This

Untitled Quiz
6 questions

Untitled Quiz

AdoredHealing avatar
AdoredHealing
Untitled Quiz
55 questions

Untitled Quiz

StatuesquePrimrose avatar
StatuesquePrimrose
Untitled Quiz
18 questions

Untitled Quiz

RighteousIguana avatar
RighteousIguana
Untitled Quiz
50 questions

Untitled Quiz

JoyousSulfur avatar
JoyousSulfur
Use Quizgecko on...
Browser
Browser