Albert Teen
powered by
Albert logo

YOU ARE LEARNING:

pointer
Evidence for Evolution: Bacterial Resistance
lessonMenuButton

Evidence for Evolution: Bacterial Resistance

lesson introduction

Evidence for Evolution: Bacterial Resistance

The emergence of antibiotic resistance seen in bacteria show support for the theory of evolution by Darwin.

Which of these best describes evolution?

hint button

Why is it often difficult to find evidence for evolution by direct observation?

hint button
1

A Rats' Tale

To control rats, a poison called warfarin was used many years ago.

block image
2

Nearly all rats were killed by this poison, however a few were unaffected by it.

These rats survived to breed and pass on this advantage.

block image
3

Slowly over time the poison had less and less effect.

Today warfarin is no longer used, as it has no effect on today's rat population.

block image
4

What term might be used to describe this idea that some individuals survive in an environment better than others?

A) Survival of the strongest B) Survival of the fittest C) Evolution D) Speciation

hint button
block image

Evidence is vital to prove a theory is true. Evolution works over many generations and over long time periods, so observing change in a species is normally very difficult. However, some organisms reproduce very rapidly, producing thousands of generations in just a few days or week!

Which if these do you think reproduce the fastest?

hint button

So bacteria reproduce incredibly rapidly. In fact, they can double in number, (a whole new generation) in just 20 minutes!

1

The bacteria above have only two chromosomes (collection of genes).

Most of them have the same genes, but one contains a chromosome with a mutant gene.

block image
2

This mutant gene (changed gene) makes it resistant to penicillin.

Penicillin is used as an antibiotic (a medicine) to kill bacteria.

block image
3

If penicillin is added to the bacteria above, what will happen ?

A) They will all die. B) Nothing. C) One of them might live.

hint button
block image

If the bacteria that do survive the penicillin are allowed to reproduce for a few generations, what will eventually happen if these new generations of bacteria come into contact with penicillin?

hint button

If more bacteria are resistant to penicillin, then what has happened to the number of bacteria that contain the mutant (resistant) gene throughout the generations?

hint button

The resistance of bacteria to antibiotics can be used to track how frequently resistant genes occur in a population of bacteria. They show that the genes can quickly spread to most individuals within a few hundred generations. Do these observations seem to support or contradict Charles Darwin's theory of evolution?

hint button

The resistance of bacteria to antibiotics provides evidence for Charles Darwin's theory of evolution. It shows that Darwin's ideas work in practice - not just in theory.

If all the bacteria that cause an illness can evolve to resist the medications we use, what will happen to our ability to control the illness?

hint button