Antibiotics, bacteria anatomy and antibiotic reistance

What type of growth pattern is exhibited by a bacterial population during the log phase?

Exponential growth

What is the primary difference between chemotrophs and phototrophs?

Source of energy: chemical sources for chemotrophs and light for phototrophs

How does a bacterium's growth rate change during the stationary phase?

No net change, with the number of living cells equal to the number of dead cells

What is the primary function of a spectrometer in monitoring bacterial growth?

To monitor the growing population of bacteria Signup and view all the answers

What is the term for the regulation of growth environment in bacterial cultures, including the control of pH, nutrients, and temperature?

Chemostatic bacterial growth Signup and view all the answers

What is the term for organisms that require organic forms of carbon and cannot synthesize organic molecules from inorganic molecules?

Heterotrophs Signup and view all the answers

What is the ideal range of pH for optimal bacterial growth?

pH has an ideal range for optimum activity Signup and view all the answers

What is the term for the phase of growth where bacteria start to die due to a lack of nutrients?

Death phase Signup and view all the answers

What is the function of the slime layer in bacteria, and how does it relate to the immune response?

The slime layer provides protection and allows attachment to surfaces, and it also masks markers on the cell wall that trigger an immune response. Signup and view all the answers

Describe the structure and function of peptidoglycan in bacterial cell walls.

Peptidoglycan is a complex, semi-rigid structure composed of a carbohydrate backbone with peptide cross-bridges and tetrapeptide side chains, and it prevents osmotic rupture. Signup and view all the answers

What are the differences in cell wall structure between Gram-negative and Gram-positive bacteria?

Gram-negative bacteria have a thin layer of peptidoglycan and an outer membrane made up of lipopolysaccharide, giving them a rough appearance under the microscope, whereas Gram-positive bacteria have a thick layer of peptidoglycan and a smoother appearance. Signup and view all the answers

What are the functions of the cytoplasmic membrane in bacteria?

The cytoplasmic membrane acts as a permeability barrier, allowing certain molecules to pass through while keeping others out, and is also the site of many proteins involved in transport, communication, and energy conservation. Signup and view all the answers

Describe the structure and function of flagella in bacteria.

Flagella are important for motility and come in different arrangements, including monotrichous, lophotrichous, amphitrichous, and peritrichous, and are composed of multiple rings, including the L ring, P ring, M ring, and C ring. Signup and view all the answers

How does the structure of flagella differ between Gram-negative and Gram-positive bacteria?

Gram-negative bacteria have an L ring, P ring, M ring, and C ring, whereas Gram-positive bacteria lack the L ring but have a larger P ring. Signup and view all the answers

What is the function of the outer membrane in Gram-negative bacteria?

The outer membrane is composed of lipopolysaccharide and provides an additional layer of protection and structure to the cell. Signup and view all the answers

What is the primary source of energy for the movement of flagella in bacteria?

Electrochemical gradient between inside and outside of the cytoplasm Signup and view all the answers

What is the term for the movement of flagella that drives bacteria forward due to a high gradient?

Run Signup and view all the answers

What is the purpose of chemoreceptors in bacteria?

To detect nutrients that are beneficial to them Signup and view all the answers

What is the primary function of fimbriae in bacteria?

To allow adherence Signup and view all the answers

What is the difference between the ribosomes of prokaryotic and eukaryotic cells?

Prokaryotic ribosomes are 70S, while eukaryotic ribosomes are 80S Signup and view all the answers

What is the characteristic of exotoxins produced by Gram-positive bacteria?

Highly soluble in blood, allowing rapid transmission Signup and view all the answers

What is the purpose of inclusion bodies in bacterial cells?

To store reserve materials such as glycogen, carbohydrates, and lipids Signup and view all the answers

What is the process by which bacteria can take up plasmids through the alteration of their cell wall using electricity or chemicals?

Transformation Signup and view all the answers

What is the specific enzyme inhibited by β-Lactam Antibiotics in the peptidoglycan formation process?

Transpeptidase Signup and view all the answers

What is the primary mechanism of antibiotic resistance in bacteria, in the context of β-Lactam Antibiotics?

Ability of bacteria to survive treatment by certain antibiotics Signup and view all the answers

What is the purpose of the disk diffusion assay in determining antibiotic susceptibility?

To provide a qualitative assessment of antibiotic effectiveness Signup and view all the answers

What is the purpose of the minimum inhibitory concentration (MIC) test in determining antibiotic susceptibility?

To determine the lowest concentration of antibiotic required to inhibit bacterial growth Signup and view all the answers

What is the specific bond formed through the action of Transpeptidase in peptidoglycan formation?

A cross-bridge between D-Alanine molecules Signup and view all the answers

What is the difference between bactericidal and bacteriostatic antibiotics, and how do they affect bacterial cells?

Bactericidal antibiotics kill bacteria, whereas bacteriostatic antibiotics prevent bacterial cell division. Bactericidal antibiotics target and kill bacterial cells, while bacteriostatic antibiotics prevent bacteria from multiplying, giving the host's immune system a chance to fight the infection. Signup and view all the answers

How do β-Lactam antibiotics, such as penicillin, work to inhibit bacterial growth, and what is the significance of their ring structure?

β-Lactam antibiotics, like penicillin, target the peptidoglycan cell wall of bacteria, weakening it and ultimately leading to the death of the bacterial cell. The ring structure of β-Lactam antibiotics is crucial for their antibacterial activity. Signup and view all the answers

What are the main differences between natural, semi-synthetic, and totally synthetic antibiotics, and how are they classified?

Natural antibiotics are produced naturally by fungi or bacteria, semi-synthetic antibiotics are chemically modified natural antibiotics, and totally synthetic antibiotics are manufactured. Each type is classified based on its origin and method of production. Signup and view all the answers

How do broad-spectrum and narrow-spectrum antibiotics differ in their mechanism of action and application?

Broad-spectrum antibiotics target a wide range of bacteria, whereas narrow-spectrum antibiotics target specific types or groups of bacteria. Broad-spectrum antibiotics are often used empirically, while narrow-spectrum antibiotics are used for specific infections. Signup and view all the answers

What is the significance of the peptidoglycan cell wall in bacterial cell structure, and how do antibiotics target it?

The peptidoglycan cell wall provides structural integrity to bacterial cells. Antibiotics, such as β-Lactam antibiotics, target the peptidoglycan cell wall, weakening it and ultimately leading to bacterial lysis. Signup and view all the answers

What is the role of antibiotics in agriculture, and how do they differ from their medical application?

In agriculture, antibiotics are used to promote livestock growth and prevent disease. The use of antibiotics in agriculture differs from their medical application, as they are often used prophylactically and at subtherapeutic levels. Signup and view all the answers

What is the primary purpose of Luria broth and cooked meat media in bacterial culture?

To allow for the growth of the organism Signup and view all the answers

How do alpha, beta, and gamma haemolytic reactions differ in terms of their effects on red blood cells?

Alpha haemolytic: reduction of red blood cells' haemoglobin to methaemoglobin; Beta haemolytic: complete lysis of red blood cells; Gamma haemolytic: lack of haemolysis Signup and view all the answers

What is the function of selective agents in selective culture media, and how do they work?

Selective agents encourage the growth of desired organisms by making them resistant to the agent, while inhibiting the growth of other organisms Signup and view all the answers

What is the significance of XLD agar in bacterial culture, and how does it work?

XLD agar is a selective and differential media used to isolate suspected salmonella, appearing black due to the presence of sodium thiosulfate, which prevents the growth of gram-positive bacteria Signup and view all the answers

How do MacConkey agar and Mannitol salt agar differ in their applications and mechanisms of action?

MacConkey agar is used to isolate gram-negative bacteria and differentiate between lactose fermenting and non-fermenting bacteria, while Mannitol salt agar is used to differentiate between bacteria that can ferment mannitol and those that cannot Signup and view all the answers

What is the purpose of chromogenic media in bacterial culture, and how do they work?

Chromogenic media are used to distinguish between specific organisms by producing colourful reactions, making it easier to identify and differentiate between bacteria Signup and view all the answers

How do bacteria develop resistance to β-lactam antibiotics?

Bacteria produce β-lactamases, enzymes that hydrolyse the β-lactam ring, preventing the antibiotic from inhibiting peptidoglycan synthesis. Signup and view all the answers

What is the mechanism of action of clavulanic acid in combination with amoxicillin?

Clavulanic acid is a suicide inhibitor that binds to β-lactamase, forming a covalent bond and inhibiting its activity. Signup and view all the answers

How do bacteria alter their metabolism to resist antibiotics?

Bacteria can temporarily change their metabolism to resist antibiotics. Signup and view all the answers

What is the role of efflux pumps in antibiotic resistance?

Efflux pumps export antibiotics out of the bacterial cell, reducing their effectiveness. Signup and view all the answers

How do bacteria alter their target site to resist antibiotics?

Bacteria can alter the target site of antibiotic action, reducing antibiotic binding and efficacy. Signup and view all the answers

What is the significance of extended-spectrum β-lactamases (ESBLs) in antibiotic resistance?

ESBLs are enzymes that hydrolyse a wide range of β-lactam antibiotics, rendering them ineffective. Signup and view all the answers

What is the mechanism of action of Quinolones, and how does it lead to cell death?

Quinolones interfere with changes in DNA supercoiling by binding to DNA gyrase, which is important for controlled unwinding of DNA during replication. This prevents the controlled unwinding of supercoiled DNA, leading to cell death and breaks in the double strand. Signup and view all the answers

How do macrolides inhibit protein synthesis, and what is the consequence of this inhibition?

Macrolides reversibly bind to the P site on the 50S subunit, disrupting protein synthesis and leading to cell death. Signup and view all the answers

What is the mechanism of action of Aminoglycosides, and how does it cause cell death?

Aminoglycosides bind to the aminoacyl site of 16S rRNA in the 30S subunit of the ribosome, causing mis-incorporation of amino acids into elongating peptides, which leads to cell death. Signup and view all the answers

What is the significance of the Quinoline backbone in Quinolones, and how does it relate to their mechanism of action?

The Quinoline backbone is a structural feature of Quinolones that allows them to bind to DNA gyrase and inhibit DNA supercoiling. Signup and view all the answers

How do β-Lactam antibiotics inhibit bacterial cell wall formation, and what is the consequence of this inhibition?

β-Lactam antibiotics irreversibly bind to transpeptidase (PBP), preventing the formation of cross-bridges in the bacterial cell wall and ultimately leading to cell death. Signup and view all the answers

What is the significance of the lactone ring in Macrolides, and how does it relate to their mechanism of action?

The lactone ring is a structural feature of Macrolides that allows them to bind to the P site on the 50S subunit and inhibit protein synthesis. Signup and view all the answers

How do Tetracyclines differ from other antibiotics in terms of their structure and mechanism of action?

Tetracyclines have a unique structure with four rings, and they inhibit protein synthesis by binding to the 30S subunit of the ribosome. Signup and view all the answers

What is the significance of the amino acid bonded by glycosidic bond in Aminoglycosides, and how does it relate to their mechanism of action?

The amino acid bonded by glycosidic bond is a structural feature of Aminoglycosides that allows them to bind to the 16S rRNA in the 30S subunit of the ribosome. Signup and view all the answers

what is triple sugar iron agar an example of? and what does it do

it is a differential media used to differentiate on ability to ferment sugars and produce hydrogen sulphide produces black precipitate Signup and view all the answers

what is lactose chromogenic agar used for?

it is a chromogenic agar used to detect coliform in water and food samples. appears pink on agar, Signup and view all the answers