The Development of Understanding of Evolution and Genetics Flashcards
What is evidence of evolution?
1) Fossils: the remains of organisms from many years ago
2) Antibiotic resistance in bacteria: the selection pressure of antibiotics leads to advantageous mutations being selected for in bacteria populations so they are no longer killed when exposed to antibiotics
What are fossils formed from?
1) Parts of the organism that have not decayed because oxygen or moisture were not present
2) Parts of the organism such as teeth, shells and bones are replaced by minerals as they decay, forming a rock structure
3) Preserved traces, such as footprints, remain due to the ground hardening around them and forming a cast
What are fossils used for?
To show how organisms have changed over time, by comparing two organisms
Why can fossils not tell us how life started on Earth?
- most early life forms are soft-bodied so decayed completely, meaning there are few fossils
- any traces left have been destroyed by geological activity
Factors contributing to extinction:
- changes in environment which species cannot adapt fast enough to
- new predators may have evolved or migrated to this area
- a new disease may arise and there are no resistant alleles to it
- they have to compete with a species which has advantageous mutations for the same food source
- a catastrophic event can wipe out the species
- destruction of a habitat
What are resistant bacteria?
when they are not killed by antibiotics which were previously used for cures against them
Process of resistant bacteria:
1) bacteria reproduce at a fast rate
2) mutations during reproduction result in new genes, such as antibiotic resistance. This is the creation of a new strain
3) Exposure to antibiotics creates a selection pressure, as those with antibiotic resistance genes survive and those without die
4) Antibiotic resistant bacteria can reproduce and pass on the advantageous gene to their offspring, the population increases
5) Bacterial diseases spread rapidly because people are not immune to this new bacteria and there is no treatment for it.
How to slow the development of resistance in bacteria:
- antibiotics should not be given for viral or non-serious infections
- specific antibodies should be given for specific bacteria
- patients should complete their course of antibiotics (if they don’t some bacteria may survive and mutate)
- antibiotics should be used less in agriculture - overuse (to prevent their livestock from dying of disease) leads to antibiotic resistant bacteria in the meat we eat
How to slow the transmission of bacteria:
- hygiene in hospitals
- medical staff + visitors wash hands regularly
- medical staff should wear disposable clothing or clothing that is regularly sterilised
Why is it hard to keep up with the development of resistant strains?
As the develoment of antibiotics is expensive and slow
What is classification of living organisms?
Putting organisms into groups depending on their structure and characteristics
The Linnaean system:
- Carl Linnaeus put this forward in 1700s
- living species were divided into kingdoms, phylum, class, order, family, genus, species
The binomial system:
- gives each organism a name which is used worldwide
- the first part is their genus and the second part is their species
Three domain system:
- Archaea: primitive bacteria which live in extreme environments
- Bacteria
- Eukaryota: organisms who have a nucleus enclosed in membranes
Evolutionary trees:
used to show how closely related organisms are. To complete this they use classification of data and fossils for extincy species
