Classification and evolution Flashcards
what is classification
placing organisms into groups according to similarities
what is the order of taxonomic hierarchy with an example of the human classification
domain=eukaryote
kingdom=animalia
phylum=chortata
class=mammalia
order=primates
family=hominidae
genus=homo
species=sapiens
what is this system
universal
what is the binomial system
all organisms are given one internationally accepted scientific name
how to write a binomial name
example
first part of the name=genus name and has a capital letter
second part of the name=species name and begins with a lower case letter
always written in italics and or underlined if they are handwritten
eg. Homo sapiens
prokaryotae features
example
-unicellular
-no membrane-bound organelles
-small ribosomes
-a ring of DNA with no associated proteins
-has no feeding system (absorbs nutrients across its system or photosynthesises)
bacteria
protoctista features
example
-unicellular or simple multicellular
-eukaryotic cells
-usually live in water
-does have a nucleus and membrane-bound organelles
-some have cillia for movement
-some have flagella for mobility
-nutrients are absorbed (either by photosynthesis, ingestion of other organisms or some are parasites).
algae, protoza
fungi
example
-unicellular or multicellular
-eukaryotic
-chitin cell wall
-have a nucleus and membrane-bound organelles
-no chloroplasts
-cannot move
-saprotrophic (nutrients/substances absorbed by dead or decaying organisms)
-food can be stored at glycogen
moulds, yeasts, mushrooms
plantae
example
-multicellular
-eukaryotic
-have a nucleus and membrane-bound organelles
have chloroplasts and don’t move
-cell walls made of cellulose
-contain chlorophyll
-nutrients absorbed by photosynthesis (autotrophic)
-food stored as starch
mosses, ferns, flowering plants
animalia
examples
-multicellular
-eukaryotic
-have a nucleus and membrane-bound organelles
-no cell walls
-no chloroplasts
-can move using cilia, flagella or muscles
-nutrients obtained by ingestion (heterotrophic) and food can be stored as glycogen
molluscs, insects, fish, reptiles, birds, mammals
EVIDENCE FOR CLASSIFICATION-
what did early classification systems use?
how was the accuracy of classification improved?
observable features, and groups based solely on physical features do not show how closely related they are.
taxonomists look at embryological evidence, fossil evidence and molecular evidence.
MOLECULAR EVIDENCE FOR CLASSIFICATION-
- the more similar the DNA base sequence, the more closely related they are
- the more similar amino acid sequence of cytochrome C in two different species, the more closely related the species are likely to be
changing the classification of species
with new technologies (eg new DNA analysis techniques and better microscopes) , new discoveries can be made and scientists can share their new discoveries in meetings and scientific journals.
who proposed a new classification system?
And in 1990 what happened?
- Carl Woese
- 3 domains were added
what were the 3 domains?
what happened to the kingdom prokaryotae?
where are the organisms with cells that contain a nucleus?
what does Eukarya include?
- Bacteria, Archaea, Eukarya
- (contains unicellular organisms without a nucleus) are separated into 2 domains = Bacteria and Archea.
- Eukarya
- 4/5 kingdoms = protoctista, fungi, plantae, animalia
what does the 3 domain system reflect?
-how different the Archea and Bacteria are and this system is an example of how scientific knowledge is always changing and improving
the lower hierarchy stays what?
why was the 3 domain system proposed?
evidence showing differences between archea and bacteria:
- the same = kingdom, phylum, class, order, family, genus, species
- because of new evidence, mainly molecular
molecular evidence:
-RNA polymerase is different in bacteria and archea
- Archea, but not Bacteria, have similar histones to Eukarya
cellular evidence:
- the bonds of the lipids in the cell membranes of Bacteria and Archea are different
- the development and composition of flagellae are also different
- most scientists agree that Archea and Bacteria evolved separately and that Archea are more closely related to Eukarya than bacteria
EVIDENCE THAT HAS LEAD TO NEW CLASSIFICATION SYSTEMS-
explain how biological molecules can provide evidence that species have evolved?
-nuclear DNA or nucleic acid or RNA
-in samples from two species, similarity in nucleic acid or nuclear DNA or RNA can imply an evolutionary relationship, difference in sequence implies evolutionary distance.
-proteins or cytochrome C or haemoglobin or polypeptides
-in the same protein from two species, amino acid sequence similarity implies evolutionary relationship, difference in sequence implies evolutionary distance
EVIDENCE THAT HAS LEAD TO NEW CLASSIFICATION SYSTEMS-
how is DNA used to provide evidence?
- DNA is found in all organisms
-some sequences are highly conserved
-can make a comparison of DNA between species
-similar base sequence indicates recent common ancestor
individuals can also be classified using
the phylogenetic system, this is when species are grouped according to their evolutionary relationships and origins
what is phylogeny
-evolutionary relationships between organisms
- the study of closeness of evolutionary relationships
-phylogeny is used in modern classification
-the closer the evolutionary relationship, the closer the taxonomic grouping
- eg. gorillas and chimpanzees are closely grouped
all organisms have evolved from what?
and what is this shown on?
shared common ancestors
a phylogenetic tree
what is the smallest group that shares a common ancestor?
a species
what does each branchpoint in the phylogenetic tree indicate?
the common ancestor a species evolved from
