Amazing Shots Of A Cell Splitting In Two! [Photos Via María José Calasanz]

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.

From the observed rate of expansion, astronomers can estimate the age of the universe. For every year, light travels one light-year across space. So the farthest parts of the universe that we can see are as distant in light-years as the universe is old in years. Light from more distant regions has not had time to reach us. This distance marks the limits of the observable universe–our “cosmic horizon.” Image: NASA Hubble Space Telescope

Mitosis, Neurons, and the DNA replication complex.

Kinesin (a motor protein) pulling some kind of vesicle along some kind of cytoskeletal filament.

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

The microscopic diversity of a single droplet of water. 

¿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!

The downside to making your own food…you’re probably going to get eaten by a heterotroph.

Bacteria and fungi in petri dishes

Klari Reis uses plastics, paints and other mediums to create the idea of bacteria and biological matter within petri dishes