Microbiology Chapter on Bacterial Structures

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Questions and Answers

What is the primary function of plasmids within a bacterial cell?

To serve as the primary site of protein synthesis.

To carry genes that may confer advantages such as antibiotic resistance. (correct)

To store essential nutrients for times of scarcity.

To provide structural support to the cell membrane.

Which of the following best describes the structure of prokaryotic ribosomes?

70S ribosomes made of a 30S and 50S subunit. (correct)

80S ribosomes made of a 30S and 50S subunit.

80S ribosomes made of a 40S and 60S subunit.

70S ribosomes made of a 40S and 30S subunit.

What is the purpose of magnetosomes in some bacteria?

To act as ballast, helping the bacteria to sink to a suitable location. (correct)

To store reserves of inorganic phosphate for ATP production.

To facilitate carbon dioxide fixation.

To help in maintaining buoyancy in aquatic environments.

What is the initial step in the formation of an endospore during sporulation?

The plasma membrane invaginates to isolate the newly replicated DNA. (B) Signup and view all the answers

What is the role of carboxysomes in certain types of bacteria?

They contain enzymes for carbon dioxide fixation. (D) Signup and view all the answers

Which of these is a key difference between prokaryotic and eukaryotic chromosomes?

Prokaryotic chromosomes are not enclosed in a nuclear envelope while eukaryotic chromosomes are. (D) Signup and view all the answers

What is the primary function of metachromatic granules (volutin) in bacterial cells?

They store inorganic phosphate for ATP production. (D) Signup and view all the answers

What characteristic of endospores accounts for their high degree of resistance to environmental stress?

They have a protective structure that is resistant to desiccation, heat, chemicals, and radiation. (A) Signup and view all the answers

What cellular component is NOT a part of a mitochondrion?

Nucleus (C) Signup and view all the answers

Which cell type listed below contains no mitochondria?

Red blood cells (D) Signup and view all the answers

Which scientist first proposed the role of mitochondria in cell respiration based solely on morphological observations?

Benjamin F. Kingsbury (A) Signup and view all the answers

What characteristic is stated to be unique about the mitochondrial genome?

It shows substantial similarity to bacterial genomes (C) Signup and view all the answers

What did David Keilin discover that was crucial to understanding the respiratory chain?

Cytochromes (B) Signup and view all the answers

What was the key finding from the 1939 experiments using minced muscle cells regarding cellular respiration?

One oxygen atom produces two ATP molecules. (B) Signup and view all the answers

Which of these findings was reported in 1898?

Coining of the term 'mitochondria' (B) Signup and view all the answers

In the context of mitochondrial proteins, what is the proteome described to be?

Dynamically regulated (B) Signup and view all the answers

Who is credited with developing the concept of phosphate bonds in ATP as a form of energy in cellular metabolism?

Fritz Albert Lipmann (C) Signup and view all the answers

What did Otto Heinrich Warburg call the particles from guinea-pig liver extracts that he later linked to respiration?

Grana (C) Signup and view all the answers

What significant contribution did Albert Claude make to the study of mitochondria?

Isolated mitochondria through tissue fractionation. (A) Signup and view all the answers

What was discovered about mitochondria in 1967?

They contain ribosomes. (C) Signup and view all the answers

What is primarily responsible for increasing the surface area of the inner mitochondrial membrane?

The deep folds/grooves (B) Signup and view all the answers

Which of the following is NOT a distinct part of a mitochondrion according to the text?

The mitochondrial matrix (A) Signup and view all the answers

Who coined the popular term 'powerhouse of the cell' to describe mitochondria?

Philip Siekevitz (C) Signup and view all the answers

What was one of the key structural findings revealed by the first high-resolution micrographs of the mitochondria (in 1952)?

The existence of two membranes including an inner membrane with folds. (D) Signup and view all the answers

What is the main difference between protoplasts and spheroplasts?

Protoplasts lack peptidoglycan, while spheroplasts lack both the outer membrane and peptidoglycan. (B) Signup and view all the answers

Why are L-forms of bacteria considered unique compared to protoplasts and spheroplasts?

They can revert to a walled state and exhibit variable shapes, unlike protoplasts and spheroplasts. (C) Signup and view all the answers

Why are Gram-negative bacteria less susceptible to penicillin than Gram-positive bacteria?

They have an outer membrane that prevents penicillin from reaching the peptidoglycan. (D) Signup and view all the answers

Which of the following characteristics of phospholipids is critical to plasma membrane structure?

Their amphipathic nature that creates a nonpolar interior of the membrane. (B) Signup and view all the answers

What is the functional significance of Thiomargarita's numerous plasma membrane invaginations?

To increase its surface area relative to its volume, supporting efficient metabolic processes. (A) Signup and view all the answers

According to the fluid mosaic model, which of the following statements regarding membrane structure is true?

Proteins move within the membrane to perform various functions. (A) Signup and view all the answers

What role do integral and transmembrane proteins play in plasma membrane function?

They act as channels allowing materials to move into and out of the cell. (A) Signup and view all the answers

Why does the plasma membrane have selective permeability?

The presence of different integral proteins that allow passage and others that block (D) Signup and view all the answers

Which of the following cell types would contain 80S ribosomes?

Mammalian liver cells (B) Signup and view all the answers

What does the 'S' in 70S and 80S ribosomes stand for?

Svedberg unit (B) Signup and view all the answers

Which of the following accurately describes the chemical composition of ribosomes?

Composed of roughly equal parts of RNA and proteins with no lipids. (C) Signup and view all the answers

How do the sizes of 70S and 80S ribosomes compare?

The 70S ribosomes are smaller than the 80S ribosomes. (B) Signup and view all the answers

What is the approximate molecular weight of 80S ribosomes?

40 x $10^6$ daltons (B) Signup and view all the answers

What is the approximate percentage of RNA in 70S ribosomes found in E.coli?

63% (B) Signup and view all the answers

Which ribosomal RNAs are found in the larger subunit of a 70S ribosome?

23S rRNA and 5S rRNA (C) Signup and view all the answers

What is the approximate number of ribosomes contained in a mammalian cell?

10,000,000 (C) Signup and view all the answers

Which cellular structure's membrane is NOT continuous with the endoplasmic reticulum?

Mitochondrial membrane (D) Signup and view all the answers

What did Palade observe within the cavity of the endoplasmic reticulum that contributes to its rough appearance?

Secretory granules (C) Signup and view all the answers

In which type of cells is a distended rough endoplasmic reticulum often observed due to active protein synthesis?

Acinar cells (A) Signup and view all the answers

Which of the following enzymes is NOT specifically mentioned as being found in the membranes of the endoplasmic reticulum?

DNA Polymerase (A) Signup and view all the answers

Besides phospholipid synthesis, which other process are nucleotide diphosphatases, found in the endoplasmic reticulum, involved in?

Ascorbic acid biosynthesis (C) Signup and view all the answers

Which cell type primarily contains only smooth endoplasmic reticulum, according to the text?

Adrenocortical cells (D) Signup and view all the answers

What is the function of smooth endoplasmic reticulum (SER) in hepatocytes regarding hydrophobic chemicals such as pesticides and carcinogens?

Modifying and detoxifying them into water-soluble products (C) Signup and view all the answers

What is the key distinguishing characteristic of rough endoplasmic reticulum (RER) compared to smooth endoplasmic reticulum (SER)?

Presence of ribosomes on its surface (B) Signup and view all the answers

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Description

Test your knowledge on the functions and structures within bacterial cells with this quiz on microbiology. Questions cover various topics including plasmids, ribosomes, endospores, and cellular components. Ideal for students studying microbiology or related fields.