Cellular Respiration and Photosynthesis

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Questions and Answers

What is the process by which ATP is synthesized during respiration?

Oxidative phosphorylation (correct)

Photophorylation

Electron transport

Proton consumption

What is the main function of fimbriae in Gram-negative bacteria?

Respiration

Adherence to surfaces (correct)

ATP synthesis

Bacterial movement

What is the term used to describe the hair-like structures on the surfaces of procaryotic cells?

Cilia

Pili (correct)

Fimbriae (correct)

Flagella

What is the role of the F or sex pilus in E. coli?

Stabilizing mating bacteria during conjugation Signup and view all the answers

What is the main function of common pili in bacteria?

Specific adherence to surfaces Signup and view all the answers

What is the role of fimbriae in pathogenic Neisseria gonorrhoeae?

Adherence to human epithelium Signup and view all the answers

What is the term used to describe the process by which ATP is synthesized during photosynthesis?

Photophorylation Signup and view all the answers

What is the role of fimbriae in bacterial virulence?

Resisting attack by phagocytic white blood cells Signup and view all the answers

What is the purpose of Gram staining in bacterial cell identification?

To distinguish between Gram positive and Gram negative cells Signup and view all the answers

What is the function of murF in peptidoglycan precursor biosynthesis?

Catalyzes the first committed membrane-bound step of bacterial peptidoglycan synthesis leading to the formation of lipid I Signup and view all the answers

What is the function of uppS in cell wall biosynthesis?

Provides the precursor for the carrier lipid, undecaprenyl phosphate (C55-P) Signup and view all the answers

What is the composition of the peptidoglycan layer in bacterial cell walls?

Linear chains of two alternating amino sugars Signup and view all the answers

What is the function of murG in peptidoglycan precursor biosynthesis?

Catalyzes the conversion of lipid I to lipid II Signup and view all the answers

What is the function of the peptidoglycan layer in bacterial cell walls?

To protect the cell from lysis caused by turgor pressure Signup and view all the answers

What is the name of the enzyme responsible for cross-linking between amino acids in different linear amino sugar chains?

DD-transpeptidase Signup and view all the answers

What is the function of bacA in biosynthesis?

Involved in the biosynthesis of the antibiotic bacilysin Signup and view all the answers

Which of the following bacterial species has a peptidoglycan layer containing L-alanine, D-glutamine, L-lysine, and D-alanine with a 5-glycine interbridge between tetrapeptides?

Staphylococcus aureus Signup and view all the answers

What is the function of Alash?

Not mentioned Signup and view all the answers

What is the result of cross-linking between amino acids in different linear amino sugar chains?

A 3-dimensional structure that is strong and rigid Signup and view all the answers

What is the function of Flippase?

Transmembrane lipid transporter proteins Signup and view all the answers

Which of the following groups of microorganisms does not contain peptidoglycan?

Archaea Signup and view all the answers

What is the family of proteins that Flippases belong to?

P4-type ATPase and ABC transporter families Signup and view all the answers

What is the function of mraY in peptidoglycan precursor biosynthesis?

Catalyzes the first committed membrane-bound step of bacterial peptidoglycan synthesis leading to the formation of lipid I Signup and view all the answers

What is the shape of the freshly added septal material of synthesis in bacterial cell walls?

Hemispherical Signup and view all the answers

What is the primary function of GTase (EC 2.4.1.129 Enzyme)?

To synthesize peptidoglycan glycosyltransferase Signup and view all the answers

What is the function of Tpase (EC 3.4.16.4 Enzyme)?

To act as a serine-type D-Ala-D-Ala carboxypeptidase Signup and view all the answers

What are teichoic acids composed of?

Glycerol phosphate or ribitol phosphate and carbohydrates linked via phosphodiester bonds Signup and view all the answers

Where are teichoic acids typically found?

In the cell wall of Gram-positive bacteria Signup and view all the answers

What is the function of lipoteichoic acids?

To anchor to the lipid membrane Signup and view all the answers

What is the difference between lipoteichoic acids and wall teichoic acids?

Lipoteichoic acids are anchored in the lipid membrane, while wall teichoic acids are covalently linked to peptidoglycan Signup and view all the answers

What is the process by which phospholipid molecules move between the two leaflets of a cell's membrane?

Transverse diffusion Signup and view all the answers

What is the term for the movement of phospholipid molecules between the two leaflets of a cell's membrane?

Flip-flop transition Signup and view all the answers

What is the function of Lipopolysaccharide (LPS)?

Permeability barrier, endotoxin, serotyping of gram negative bacteria Signup and view all the answers

What is the function of Mg++ bridges?

Stabilizes LPS and is essential for its permeability characteristics Signup and view all the answers

What is the function of Braun lipoprotein?

Anchors the outer membrane to peptidoglycan (murein) sheet Signup and view all the answers

What is the function of Omp C and Omp F proteins?

Forms pores for hydrophilic molecules Signup and view all the answers

What is the function of Omp A protein?

Provides receptor for viruses and bacteriocins Signup and view all the answers

What is the composition of S-layers?

A monomolecular layer composed of only one (or, in a few cases, two) identical proteins or glycoproteins Signup and view all the answers

Where are S-layers typically located in Gram-negative bacteria?

Associated with lipopolysaccharides Signup and view all the answers

What is the thickness range of S-layers?

5-25 nm Signup and view all the answers

Study Notes

ATP Synthesis

ATP can be synthesized by the membrane-bound ATPase enzyme, which consumes protons during ATP synthesis from ADP and phosphate.
The connection between electron transport, establishment of proton motive force (pmf), and ATP synthesis during respiration is known as oxidative phosphorylation, and during photosynthesis, it is called photophorylation.

Fimbriae and Pili

Fimbriae and pili are interchangeable terms used to describe short, hair-like structures on the surface of procaryotic cells.
They are composed of protein, shorter and stiffer than flagella, and slightly smaller in diameter.
Fimbriae are generally involved in adherence of bacteria to surfaces, substrates, and other cells or tissues in nature, rather than bacterial movement.
In E. coli, a specialized type of pilus, the F or sex pilus, stabilizes mating bacteria during conjugation, but the function of smaller, more numerous common pili is different.

Gram Staining

Gram staining is a procedure used to stain bacteria, developed by Hans Christian Gram in 1884.
Gram-positive cells stain purple, while Gram-negative cells stain red.

Peptidoglycan Layer

The peptidoglycan layer is a crystal lattice structure formed from linear chains of two alternating amino sugars, N-acetylglucosamine (GlcNAc or NAGA) and N-acetylmuramic acid (MurNAc or NAMA).
The alternating sugars are connected by a β-(1, 4)-glycosidic bond.
Each MurNAc is attached to a short amino acid chain, containing L-alanine, D-glutamic acid, meso-diaminopimelic acid, and D-alanine in the case of Escherichia coli (a Gram-negative bacterium).
Peptidoglycan is one of the most important sources of D-amino acids in nature.
The peptidoglycan layer protects the cell from lysis caused by the turgor pressure of the cell, and it retains its shape throughout its life.

Enzymes Involved in Peptidoglycan Synthesis

DD-transpeptidase is involved in cross-linking between amino acids in different linear amino sugar chains.
murF, mraY, and murG are enzymes involved in peptidoglycan precursor biosynthesis.
uppS is involved in cell wall biosynthesis, providing the precursor for the carrier lipid, undecaprenyl phosphate (C55-P).

Flippase

Flippase is a transmembrane lipid transporter protein located in the membrane, which belongs to the ABC transporter or P4-type ATPase families.
It is responsible for aiding the movement of phospholipid molecules between the two leaflets that compose a cell's membrane (transverse diffusion, also known as a "flip-flop" transition).

Teichoic Acids

Teichoic acids are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohydrates linked via phosphodiester bonds.
They are found within the cell wall of most Gram-positive bacteria, such as species in the genera Staphylococcus, Streptococcus, Bacillus, Clostridium, Corynebacterium, and Listeria.
They can be covalently linked to N-acetylmuramic acid or a terminal D-alanine in the tetrapeptide crosslinkage between N-acetylmuramic acid units of the peptidoglycan layer.

Lipopolysaccharide (LPS)

LPS is a component of the outer membrane of Gram-negative bacteria, serving as a permeability barrier, endotoxin, and serotyping agent.
Mg++ bridges stabilize LPS and are essential for its permeability characteristics.

S-Layer

S-layers are a part of the cell envelope found in almost all archaea, as well as in many types of bacteria.
They consist of a monomolecular layer composed of only one (or, in a few cases, two) identical proteins or glycoproteins.
S-layer proteins are poorly conserved or not conserved at all, and can differ markedly even between related species.

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Description

Quiz about ATP synthesis, proton motive force, and cellular structures such as fimbriae and pili in procaryotic cells.