Classification Flashcards
What is a species?
A group of living organisms with similar characteristics which can interbreed to produce fertile offspring
What is taxonomy?
The science of classification of living things
Why must classification be flexible?
So new organisms can be added
So fossils can be added
What does the process of classification involve?
Giving living things an agreed name and imposing a scheme upon the diversity of living things
Explain the binomial system of naming?
Genus name then species name
Give all the groups in the hierarchical scheme of classification
Kingdom, Phylum, Class, Order, Family, Genus, Species
What are analogous structures?
Resemble each other in function but different in fundamental structure
What are homologous structures?
Structures which are built to a common plan but adapted for different purposes
What is an artificial classification?
Classification based on analogous structure
What is a natural classification?
Classification based on similarities and differences due to close relationships between organisms that share a common ancestor (based on evolutionary links)
How can the relatedness of species be estimated?
Looking at the amounts of variation in the DNA
What is DNA sequencing
The process of determining the order of the nucleotides in a DNA molecule
What are the principles of DNA sequencing?
Extract DNA from tissues
Cut up DNA molecule at specific points with enzymes Tag bases with fluorescent dye
Separate with electrophoresis
Determine and compare base sequence
Explain how DNA is extracted from tissue samples
Mechanically broken up
Filtered
Cell membrane broken down with detergents
Protease breaks down protein framework
DNA precipitated out with ethanol and then put in pH buffer solution
Explain how DNA is chopped up
Addition of restriction enzymes like restriction endonucleases cuts DNA at a particular sequence of bases
Where do you find restriction endonucleases and why?
In bacteria to stop infection from viruses by cutting up viral DNA
What is electrophoresis?
A method of separating charged ions in a fluid
What gel is used in electrophoresis and how do they work?
Agar gel or PAG. Small pores which act as a molecular sieve. Small particles move fast large particles move slow
Why does DNA migrate towards the positive pole?
Phosphate groups on the DNA fragments are negative
Why is classification needed?
Trace evolutionary links
Predict characteristics
Identify and name species
Why is a binomial system of naming needed?
So that everyone has the same name for species worldwide
What is molecular phylogeny?
The analysis of molecular differences in the DNA sequence of organisms to establish their evolutionary relationships
What methods can be used to determine evolutionary links?
DNA sequencing
Gel electrophoresis
Bioinformatics
DNA hybridisation
Summarise the stages of gel electrophoresis
Obtain DNA sample - amplify by PCR Cut with restriction enzymes Put into wells in the gel electrophoresis tank Apply current so it separates out Add dye to stain the bands Compare banding patterns
How can you compare the banding patterns of two organisms?
Number of bands
Width of bands
Position of bands
Summarise the stages of DNA hybridisation
DNA sample heated to separate into single strands of DNA
Mixed with single stranded bits of DNA from another species
Hydrogen bonds form between comp. base pairs
Heated to find temp at which all bonds break
Higher temp = more bonds = closely related
What is bioinformatics?
the storage, manipulation and analysis of biological information via computer science
What are the 5 kingdoms?
Prokaryotae Proctotista Animalia Fungi Plantae
Why did the 5 kingdom model have to be changed?
Because extremophiles were discovered and they were found to be slightly different to normal prokaryotes
What are extremophiles?
Species of bacteria which can survive in extremely hostile environments
What evidence was there to change from 5 kingdom to 3 domain?
Extremophiles were found to have bigger ribosomal RNA than normal prokaryotes
Name the three domains and explain each one?
Archae - extremophiles
Eubacteria - true bacteria
Eukaryota - all the eukaryotes
What are the ways in which the scientific community can validate data?
Scientific journals
Peer review
Conferences
Why do we use the same system universally?
So its accessible to all
Everyone can add to it
What is a hierarchical scheme of classification?
Where each successive group has more species within it
