Bacteria And Fungi In Petri Dishes

WIP

With all the biochemistry jokes being thrown around, here’s one from my end of the biology spectrum!

The building blocks of all life; nucleotides, DNA, and chromosomes

A look at levels!

Nucleus…in a GIF!

Penicillin

Penicillin is a widely used antibiotic prescribed to treat staphylococci and streptococci bacterial infections. 

beta-lactam family 

Gram-positive bacteria = thick cell walls containing high levels of peptidoglycan

gram-negative bacteria = thinner cell walls with low levels of peptidoglycan and surrounded by a lipopolysaccharide (LPS) layer that prevents antibiotic entry 

penicillin is most effective against gram-positive bacteria where DD-transpeptidase activity is highest.

Examples of penicillins include:

amoxicillin

ampicillin

bacampicillin

oxacillin

penicillin

Mechanism(s)

Penicillin inhibits the bacterial enzyme transpeptidase, responsible for catalysing the final peptidoglycan crosslinking stage of bacterial cell wall synthesis.

Cells wall is weakened and cells swell as water enters and then burst (lysis)

Becomes permanently covalently bonded to the enzymes’s active site (irreversible)

Alternative theory: penicillin mimics D-Ala D-Ala

Or may act as an umbrella inhibitor

Resistance

production of beta-lactamase - destroys the beta-lactam ring of penicillin and makes it ineffective (eg Staphylococcus aureus - most are now resistant)

In response, synthetic penicillin that is resistant to beta-lactamase is in use including egdicloxacillin, oxacillin, nafcillin, and methicillin. 

Some is resistant to methicillin - methicillin-resistant Staphylococcus aureus (MRSA).  

Demonstrating blanket resistance to all beta-lactam antibiotics -extremely serious health risk.

¿Recuerdas cuando sólo sabías que esto era una célula, y pensabas que eso era todo lo que tenía? 

Era casi tierna cuando tenía sólo unos organelos con funciones que se resumían en unas pocas líneas, y la mitocondria era lo más complejo y abundante que podía existir porque la materia que te pasaban de ella ocupaba dos páginas del cuaderno…

Y qué importaba cómo se relaciona? Para eso tenía unas lindas proteínas en la membrana que comunicaban y hacían magia…

…

Todo ese simple concepto queda atrás cuando tienes biología celular…

Simple concepto escolar de célula, ¡te extraño!

Noche de estudio de Biología Celular, ¡voy por ti!

Image of the Week - September 10, 2018

CIL:39062 - http://cellimagelibrary.org/images/39062

Description: This light micrograph shows the outside edge of two seminiferous tubules of a mouse testis. This section is a 1um thick transverse section, stained with toluidine blue to highlight the cells, with the nucleus staining a darker blue. The dark blue line separating the two seminiferous tubules consists mostly of myoid (muscle) tissue. The majority of cells seen in this image (arranged in layers) are germ cells, which, by repeated cell division, eventually produce spermatozoa. Chromosomes are visible in most of the nuclei of the cells. The cell with a deeply-stained nucleus and even darker nucleolus is a Sertoli cell (‘nurse cell’) that has fine cytoplasmic extensions branching between the other cells to nurture the developing germ cells.

Author: Spike Walker

Licensing: Attribution-NonCommercial-NoDerivs 2.0 UK: England & Wales (CC BY-NC-ND 2.0 UK)