10 - Classification and evolution Flashcards
classification systems - taxonomic
Kingdom
phylum
class
order
family
genus
species
why do scientist classify organisms
- to identify species
- to predict characteristics
- to find evolutionary links
how are organisms classified?
- begins by separating organism into the three domains archaea, bacteria and eukarya
- s move down the groups there are fewer organisms in each, they become more similar and share more characteristics
species
- contains only one type of organisms
- a group or organisms that are able to reproduce to produce fertile offspring
how to name organism
binomial nomenclature
Genus species
the five kingdoms
- prokaryotae (bacteria)
- Protoctista (unicellular eukaryotes)
- Fungi (yeast, mould and mushrooms)
- Plantae (the plants)
- Animalie (the animals)
Prokaryotae
- prokaryotes
- unicellular
- no nucleus or other membrane bound organelles
- small ribosomes - naked DNA
- no visible feeding mechanism - nutrients absorbed through the cell wall or produced by PHS
- Staphylococcus aureus
Protoctista
- mainly unicellular
- eukaryotes
- a nucleus and membrane bound organelles
- some chloroplasts
- some are sessile, other move by cillia, flagella or by amoeboid mechanisms
- nutrients acquired by PHS of by ingestion of other organisms
- Amoeba and paramecium
Fungi
- eukaryotes
- uni or multicellular
- a nucleus and membrane bound organelles and a cell wall made of chitin
- no chloroplast or chlorophyll
- no mechanism for locomotion
- most have a body or mycelium made of threads of hyphae
- nutrients acquired by absorption - mainly form decaying material (saprophytic)
- store food as glycogen
- mushrooms, mould and yeast
plantae
- eukaryotes
- multicellular
- a nucleus and membrane bound organelles like chloroplasts and a cell wall made of cellulose
- contains chlorophyll
- most don’t move but gametes can by cillia or flagella
- nutrients from PHS
-store food as starch
Animalia
- eukaryotes
- multicellular
- nucleus and membrane bound organelles
- no cell wall
- no chloroplast
- move with cillia, flagella or contractile proteins
- nutrients form ingestion
- store food as glycogen
what is the Three Domain System
- organisms are classified into 3 domains and 6 kingdoms based on differences in nucleotides in rRNA, membrane lipid structures and sensitivity to antibiotics
- Eukarya, Archaea and bacteria
Domain -> kingdom
Bacteria - > eubacteria
Archaea -> archaebacteria
Eukarya -> protoctista, plantae, fungi and animalia
Eukarya
- 80s ribosomes
- RNA polymerase contains 12 proteins
archaea
- 70s ribosomes
- RNA polymerase have between 8 to 10 proteins and are similar to eukaryotic ribosome
Bacteria
- 70s ribosomes
- RNA polymerase contains 5 proteins
archaebacteria
- can live in extreme environments
- like hot thermal vent, anaerobic conditions and highly acidic conditions
Eubacteria
‘true bacteria’
phylogeny
- evolutionary relationships
- shows how related organisms are
evidence for evolution
- palaeontology - study of fossils
- comparative anatomy - study of similarities and differences between anatomy
- comparative biochemistry- similarities and differences between the chemical makeup of organism
Fossils
formed when animal and plant remains are preserved in rocks
- over time sediment on the earths surfaces forms layers (strata) of rock
- different layers correspond to different geological era, so can show how organisms change over time
evidence provided by the fossil record
- fossils of the simplest organisms like bacteria are found in the oldest rocks. More complex ones are found in recent rocks, SO simple life forms gradually evolved over a long time into something more complex
- sequence in how organisms are found matches their ecological links to each other
- similarities in anatomy of fossils show how closely related organisms have evolved from the same ancestor
comparative anatomy
the study of similarities and differences in the anatomy of different living species
Homologous structures
- a structure that appears superficially different in different organism, it has the same underlying structure
- they have evolved from a common ancestor and the structure has evolved from the same structures
- it is evidence for divergent evolution
-> how from a common ancestor, different species have evolved with a different set of features (adapting to different environment)
comparative biochemistry
- the study of similarities and differences between the proteins and other molecules that control life processes
- they are highly conserved
-main ones are cytochrome c and rRNA - can discover how closely two species are related by comparing the order of DNA bases in a gene for a protein
- the number of differences are plotted against the rate the molecules undergoes neutral substitutions
-more similar the more related
variation
differences in the characteristics between organisms
interspecific variation
variation between members of different species
intraspecific variation
variation between members of the same species
factors of variation
- genetic variation - differences in genetic material
- environmental variation
causes of genetic variation
- Alleles
- Mutations
- Meiosis
- sexual reproduction
- chance
Alleles - causes of genetic variation
- genes have different alleles (alternative forms)
- different alleles form different effects
- depending on the parental combination, different characteristic of the offspring happen
- individuals in a species population may inherit different alleles of a gene
Mutations - causes of genetic variation
- changes in DNA sequences changes the proteins coded for
- this can change the physical and metabolic characteristic
- if a mutation is in a somatic cell it only affects the individual
- if it is in the gamete it is passed to offspring
Meiosis - causes of genetic variation
genetic material inherited from the parents is mixed up by independent assortment and crossing over
- leading to the gametes showing variation
sexual reproduction - causes of genetic variation
- offspring inherit genes from two parents, each individual produced differs from the parents
Chance - causes of genetic variation
- many different produced from the parents genome
- it is a result of chance as to which two gametes combine
discontinuous variation
- characteristic can only result in a certain value
- no in between values
- variation determined purely by genetic factors is discontinuous
- use a bar chart or pie chart
continuous variation
- can take any value within a range
- height and mass
- characteristic are controlled by many genes and influenced by the environment
- frequency table and histogram
normal distribution curve
- when continuous variation data is plotted it is bell shaped
- mean=median=mode
- bell shaped, symmetrical about the mean
- 50% of the values are less than and more than the mean
- most values lie close to the mean
standard deviation
measures how spread out the data is
students t-test
compare the means of data values of two populations
spearman’s rank correlation coefficient
used to consider relationships between two sets of data
- no correlation = 0
- positive = +1
- negative =-1
adaptations
are characteristic that increase a organisms chance of survival and reproduction in its environment
- anatomical - physical
- behavioural - how they act
- physiological - processes in the organisms
anatomical adaptations
- body coverings
- camouflage
- teeth
- mimicry
Behavioural adaptations
- survival behaviours
- courtship
- seasonal behaviours- migration, hibernation
can fall in to two categories
- innate - inherited through genes
- learned - adaptations learnt from observing other animals
physiological adaptations
- poison production
- antibiotics
- water holding
analogous structures
structures that have adapted to perform the same function but have different genetic origin
what does analogous structures provide evidence for
convergent evolutions
-> when unrelated species begin to share similar traits
-organisms have adapted to similar environments or selection pressures
selection pressure
factors that affect the organisms chances of survival or reproductive success
natural selection overview
- organism that are best adapted to the environment are more likely to survives and reproduce then those who are poorly adapted
- these adaptations become more common as the characteristics are passed on to the next generation
natural selection steps
- organisms in a species show variation in their characteristics caused by differences in their genes
- organisms whose characteristic is best adapted to a selection pressure like competition have an increased chance of surviving and successfully reproduced. well less adapted ones die or fails to reproduce
- successful organisms pass the allele encoding the advantageous characteristic onto their offspring. organisms that possess the non-advantageous allele are less likely to successfully pass it on
- this process is repeated over generation. Over time the proportion of individuals with the advantageous adaptation increases. So the frequency of the allele increases in the populations gene pool
- over a long time this process can lead to the evolution of a new species
modern examples of evolution
- antibiotic resistant bacteria
- peppered moths
- sheep blowflies
flavobacterium
antibiotic resistant bacteria - modern examples of evolution
- bacteria reproduce very fast and can evolve in a sort time. when they replicate, DNA can be altered and some mutations can provide resistances the biotics
- when exposed to the antibiotics, they survives and reproduces, passing on the advantageous allele - eventually becoming the main characteristic.
