4.5 Species and Taxonomy Flashcards
What is species?
organsism with shared characteristics that interbreed to produce fertile offspring
Why doesnt the definition of species apply to single-celled orgs?
they are asexual = no interbreeding
How is interbreeding tested?
- pops are isolated and interbred
- orgs in fossil records
What is an example of the difficulties defining species?
mule = cross between a horse and a donkey
mules are sterile = infertile
mules have odd no. of chromosomes so cannot form homo pairs = no meiosis
Why is it difficult to distinguish different species using fossil records?
cant see all characteristics
difficult to test interbreeding
How is it difficut to distinguish a species?
variation within a species
What are courtship behaviours?
complex displays that help an individual attract a mate
What are the purposes of courtship behaviours?
helps individuals to recognise members of their own species
helps ensure both individuals are in the correct physiological state for breeding
forms a pair bond
synchronise mating for when the female is fertile
What is classification?
orgs are placed in groups = taxonomy
What are the 2 purposes of classification?
gives an idea of what species are related
predict characteristics of newly discovered orgs
What is a taxon?
the specific group a org is in
What is the 5 kingdom classification based on?
cell type and organisation of cells
nutrition
What are the 5 kingdoms?
Plantae
Fungi
Animalia
Protoctista
Prokaryota
What is the limitation of 5 kingdom classification?
doesnt show how diff prokaryotic bacteria are diff
What is hierachal classification?
large groups sub-divided into smaller groups
How is the hierachal classification discrete?
no overlapp in taxons
What does orgs with shared taxons tell you?
they have more shared and similar characteristics
What is humans full taxons?
kingdom = animalia
phylum = chordates (vertebrates)
class = mammals
order = primates
family = homondids
genus = homo
species = sapien
What are features of the bionomial naming system?
unambiguous = not open to interpretation
universal = understood by all
uses latin = recognised scholary language
What does the bionomial naming system show?
evolutionary relationships
How do you write a biomial name?
Genus species
capital for genus
lower case for species
underline
What do phylogenetic trees show?
provides an idea of evolutionary relationships and shared characteristics
What does the end of the branch in a phylogenetic tree show?
species that currently exist
How can you tell if species are more closely related from a phylogenetic tree?
they share a greater proportion of lines of decent
What is homologous structures?
same fundamental structure but different structure
What is an example of homologous structures?
pentadactile limbs - includes lizard, bird, human, whale
bone structure is 1-2-5 from top of arm
What are homologous structures evidence of?
a recent common ancestor
What type of evolution results in homologous structures?
divergent evolution
What is divergent evolution?
a process in which closely related species or populations develop different traits over time, usually due to geographic separation or different selective pressures
What are analogous structures?
different structures but same fundamental function
What is the issue with analogous structures?
they are not from a common ancestor - causes problems for classification and phylogenetics due to similar structures
What are examples of analogous structures?
whale, turtle, fish, penguin
What type of evoltion leads to analogous structures?
convergent evolution
What is convergent evolution?
biological process that occurs when organisms that are not closely related evolve similar traits or behaviors
What are the 3 domains?
Eubacteria
Archaea
Eukaryota
Which 2 domains include Prokaryotes?
Eubacteria and Archaea
Which 2 domains are most closely related?
Archaea and Eukaryota
What kingdoms is in the Eukaryota domain?
protoctista
fungi
plantae
animalia
What type of bacteria is in the Archaea domain?
extremaphiles
What are extremaphiles?
bacteria which can survive in very harsh conditions
Why is there 2 seperate domains for prokaryotes?
extremaphiles part of archaea domain have a different rRNA base sequence to prokaryotes in Eubacteria domain
What is a phylogenetic group?
a group of organisms classified together based on common ancestors and shared characteristics
What is taxonomy?
classifying orgs based on characteristics and evolutionary relationships
What 6 common characteristics do all organisms share?
- all have DNA or RNA as their genetic material
- genetic code is universal = same codon on mRNA for an aa
- proteins are formed from the same 20 aa
- ATP = universal molecule for energy
- all have phospholipid membranes
- vital physiological processes follow very similar metabolic pathways
What are the 3 ways of investigating evolutionary relationships?
comparision of DNA base seqeunces - genetic fingerprinting and DNA hybridisation
comparision of protein and amino acid sequences
immunology
How does comparing DNA base sequences show evolutionary relationships?
provides a reliable indicator of similarity without the problem or morphological covergence (analogous structures)
What are the 2 methods of comparing DNA base sequences?
genetic fingerprinting
DNA hybridisation
What are VNTRs?
variable number tandem repeats = found in introns, long sequences of DNA bases that repeat over and over
How can you tell if 2 people are related by VNTRs?
more similar VNTRs = more closely related
What is genetic fingerprinting?
the analysis of VNTR DNA fragments used to determine genetic relationships and the genetic variabiliy within a population
What is done to a small DNA ample to amplify the amount of DNA?
PCR = polymerase chain reaction
What is DNA hybridisation?
a process in which 2 complementary DNA/RNA strands bond together to form a double-stranded molecule
What is the process of DNA hybridisation?
- compares DNA base seq od two species
- DNA from both species extracted and cut into fragments
- fragment of 2 species are mixed together
- complementary base seq hybridise (bond) together
How is comparisions of protein and amino acid seq be used to test evolutionary relationships?
- changes in DNA base seq will alter a.a seq in a protein
- comparisons of a.a seq of common proteins used to estimate relatedness between species
What is the issue with using comparison of protein amino acid sequences to find evolutionary relationships?
the number of common proteins is limited as most of the new studied use RNA or DNA sequence
How is immunology used to test for evolutionary relationships?
mix antigens of one species (blood plasma proteins) with specific antibodies of another so that a precipitate will form
the closer the evolutionary advantage = more precipitate will form
What is used to work out evolutionary relationships?
homologous structures and biochemical analysis
Why is taxonomy known as dynamic?
diff opinions about whether morphology or genetics are more central for the basis of classification
How do scientists classify species based on comparing genetic characteristics?
the base sequence of DNA
the base sequence of mRNA
the amino acid sequences of proteins
What does the same genus mean in a phylogenetic classification?
same evolutionary origin and common ancestor
