classification
species
a group of similar organisms that have certain features in common
how do we classify organisms
• identify different species
• predict characteristics
• find evolutionary links
• recognise biodiversity
• exploit related species (medecines)
what evidence do we use the classify species
reproductive
anatomical
embryological
behavioral
biochemical
anatomical similarities
pentadactyl limb (homologous structure - same underlying structure but different function)
taxonomic groups
Kingdom
phylum
class
order
family
genus
species
binomial system
1st - Genus
2nd - species
the 5 kingdoms
prokaryotae
protoctista
fungi
plantae
animalia
prokaryotae
no nucleus
no membrane bound organelles
circular DNA
70s ribosomes
cell wall made of peptidoglycan
unicellular
protoctista
eukaryotic
unicellular
membrane bound organelles
80s ribosomes
heterotrophic - eat other organisms
can be autotrophic - make their own food
fungi
eukaryotic
heterotrophic
cell walls made of chitin
carbohydrate stored as glycogen
unicellular or multicellular
saprotrophic - feed on dead material
plantae
eukaryotic
multicellular
photoautotrophic - uses sunlight to make food
cell walls of cellulose
carbohydrate stored as starch
animalia
eukaryotic
multicellular
heterotrophic
no cell walls
carbohydrate stored as glycogen
display nervous coordination
using DNA evidence
• changes caused by mutations
• mutations will change base sequence of new species
• closely related species = similar DNA sequence
phylogenetic tree
shows evolutionary relationships between species
all species are related but some have a much closer phylogenetic relationship
how hybridisation works
the higher the temperature needed to break the strands apart the more H bonds
therefore the more closely related the species
cytochrome c
protein used for respiration
not identical in all species
can compare the sequence of amino acid sequence in the cytochrome c protein to define how closely related organisms are
the 3 domains
eukarya
archaea
bacteria
why did he create the three domains
prokaryotes found in extreme conditions - extremophiles
features in common with bacteria and eukaryotes
bacteria
prokaryote
circular DNA
no histones
no membrane bound organelles
five proteins
cell wall of peptidoglycan
archaea
prokaryote
circular DNA
no histones
no membrane bound organelles
8-10 proteins
no cell will with peptidoglycan
eukarya
eukaryote
linear DNA
histones
membrane bound organelles
12 proteins
no cell wall of peptidoglycan
evolution
the theory in which organisms evolve or change over many years as a result of natural selection
organisms best suited to their environment and more likely to survive and reproduce passing on their characteristics to their offspring
how did Darwin develop his theory of evolution
Alfred Wallace sent his ideas to Darwin, they were very similar
they jointly presented their findings
Darwin published a book
but it was controversial at the time
divergent evolution
when species have a recent common ancestor but they develop different adaptations due to the different environmental conditions
process of evolution by natural selection
1. variation within the population
2. mutations can create new adaptations
3. different selection pressures (e.g. food availability)
4. best adapted Will survive reproduced and pass on their alleles so over time they evolve adaptations suited to their environment
paleontology
the study of fossils and the fossil record
comparative anatomy
the study of the similarities and differences between organisms anatomy
comparative biochemistry
similarities in differences between the base sequence in DNA in the amino acid sequence in proteins
evidence provided by the fossil record
• fossils of the simplest organisms like bacteria and algae are found in the oldest rocks
• the sequence in which the organisms are found matches their ecological link
homologous structures
structure that appears superficially different but has the same underlying structure
what causes variation
genetic material
the environment
genetic causes of variation
alleles
mutations
meiosis
sexual reproduction
continuous variation
no distinct categories
no limit on the value
quantitative
e.g. height
discontinuous variation
distinct categories
no in between categories
qualitative
e.g. eye colour
standard deviation
a measure of how spread out the numbers are from the mean
the larger the standard deviation, the more spread out the numbers are and the more variation there is
how to calculate standard deviation on my calculator
1. statistics on menu setup
2. 1- variable
3. put data in
4. OPTN
5. 1- variable calc
6. find sx
adaptations
characteristics that increase in organisms chance of survival and reproduction
anatomical adaptations
body covering e.g. scales, fur
colour e.g camouflage or bright
teeth
mimicry
physiological adaptations
take place inside an organism
hibernation
antibiotic resistance (bacteria)
venom production
behavioral adaptations
survival
courtship
seasonal
innate
learned
analogous structures
structures that have adapted to perform the same function but have different genetic origin
convergent evolution
when unrelated species begin to share similar traits
marsupials (example of convergent evolution)
have a short pregnancy
don't develop the full placenta
born early in development and climb into mother's pouch, continue to develop
natural selection process
1. individuals in a species show a wide range of variation
2. new alleles can arise by mutations
3. selection pressure of species cause struggle for survival
4. an adaptation helps the individual overcome this selection pressure
5. they have a greater chance of survival and were more likely to reproduce
6. the beneficial alleles are passed on to the next generation