Chapter 9, 10 and 11 Flashcards
Alleles
alternate form of a gene
Mutations
- new alleles will increase genetic diversity
- only passed if the mutations occur in germline cells
Gene Flow
- new alleles into the population through breeding
- this increases the genetic diversity or will make them more the same ( homogenise the popluation)
Genetic drift
a random event that dramatically alters a populations gene pool
- bottleneck effect
- founder effect
Natural Selection
- increases the allele frequency of an advantageous trait
- due to the environmental pressures lect for the advantageou trait that will be passed down from generation
- is the selection of phenotypes that are most suited to overcome the environmental selection pessures.
- they have a higher genetic fitness
Speciation
- when a physical or ecological barrier causes populations to be separated, they will undergo genetic divisions due to different environmnt pressures, now they are no longer able to interbreed, they are a new species
A
Allopatric Speciation
Geographic barriers, physcialy like a mountain
Allopatric Speciation example
Galapagos finches
- they were separeted due to the island
- exposed to different environmental pressures, like the food
- they evolved differently o make the frequency of the advantageous allele to increase, increasing their strength as a population
Sy
Sympatric speciation
Same geographical area, different ecological niche
- m,aybe different pH different conditions
Sympatric speciation example
Howea Palms
- H. forestiana likes sandy with low nutients
- H. balmoreana likes rich nutrients, volcanic rock
they also had different flowing times so they could not pollinate eachother, they now are different species.
Point Mutations
Silent, missense, nonsense, frameshift
l
Silent mutations
- can go unnoticed becuase it could occur in an intron which is spliced out during post transcription modification
- also becuase of the degenerate nature of the genetic code, the same amino acid is swapped into the protein becuase different codons can code for the same amino acid.
j
Missense Mutation
Substittion of a different amino acid, altering the primary structure, this alter functionality and folding
k
Nonsense Mutations
Substition of an amino acid that is a stop codon, when will end the polypeptide chain
Frameshift mutations
Addiiotion or deletion of one or two nucleotides, which changes the reading frmace, all the amino acids will be affected
Block Mutations
deletion, duplication, inversion, translocation
Deletion
Deletion
a section of chromosome is deletied
Dupklication
a section of a chromosome is dupklicated
Inversion
a section of a choromosomes flips upside down
Translocation
two sections of a chromosome swap loactions
Aneuploidy
Addition of loss of an idividual chromosome
polyploidy
There is an entire set of chromosomes added or missing
Environmental selection pressures
predation
competition
climate change
Low genetic variation vs high genetic variation
low = high risk of extinction, more suseptibale to selection pressures
high = low risk of exctintion
Bottleneck effect
large portion of a population if wiped out by a random even like a natural disater, decrease population size and genetic diversity
Founder effect
small sample of unrepresented individuals from a larger population move to a new region to start a new population, decrease genetic diversity
Risks of low
Risks of low genetic diversity (small populations)
interbreeding - low alleles
lower adaptive potential - vulnerable to new selection pressures that could wide out a whol population
more suseptible to genetic drift
larger harm of death
Gene flow
Gene flow
the movement of alleles between individueal from two different populations through either migration or interbreeding
Immigration
increases genetic diversity
Isolating mechanisms
pre and post reproductive
Pre reproductive
geographcal, ecological temporal, behavioural, structural
Post reproductive
gamete mortality, zygote mortality, hybrid sterility
Sele
Selective breeding
- aka artifical selection
- we can select or remove particular traits from a population y directly controlling the breeding of animals and plants, the selection pressure is direct human intervention
Selective breeding on genetic diversity
can lead to smaller gene pools and overexpression of deleterious alleles which can reduce adaptability and fitness. if poor breedin is implmented a human induced bottleneck can occur.
ANTIBIOTIC RESISTANCE
THE EXPOSURE TO ANTIBIOTICS SERVES AS AN ENVIRONMENTAL SLELECTION PRUESS, IF BACTERIA can resist a particular antibiotic then they can present in an exposed population then they will continue to live and replicate. new mutations help bacteria to evelop mechanisms which allows them to increase their ability to combat the action of antibiotics
- impermeability of an antibiotic due to a modified cell walkl
- the active efflux of an antibiotic out of a bacteria
Antibiotic resi
Antibiotic resistance contributing factors
- finishing antibiotics early, not all pathogen has been dead
- using them when thy arent required
- wide spread of antibiotics where it will increase the probability f antibiotic resistence.
Viral antigenic drift
smll gradual changes in the genes encoding for viral surface antigen. memory cells once recognising pathogens wont be able to recognise it anymore
Viral
Viral antigenic shift
sudden and significant changes in the genes encoding, when two or more viruses combine together to form a new subtype through viral recombination.
Cambrian explosion
Cambrian explosion
535my of rapid diversification of multicellular life, hardeened body parts such as shells or bones.
Fossilisation
Requirements
organisms are rapidly covered in sediment, not exposed to oxygen.
they are protected from scavengers and decomposers
constant cool temperatures
low light and oxygen
what happens you may ask? :]
they die, then they get covered in sediment layers over time, a compact is formed where pressure cements the fossil turning it into a permineralised, mould or cast, fossil.
Tr
Trace fossils
indirect evidence for an organisms xsistence, foot prints, nests
Relative Dating
not super accuarte, based on the potion of fossils in comparrison to other ones
1. geographical timescales - we can determine the age of the rock around the fossil (STRATUM), older = further down, younger = higher
2. Index fossils - have to be physically distinctive, large populations, existed in many geographical areas, lived within a known short amount of time.
3. Transitional fossils - intermediataries between an ancestral species and a desendant specides and are usefgul when they are morphologically very distinct
Absolute dating
- Radioactive Dating - radioisotopes are unstable elements that will break down into a more stable product, the reate of breakdown is constant and can be modelled by the half life of that isotope. half everytime
- radiocarbon dating - the catio between isotpies in the atmosphere and in the organism are the same, when an organism dies, its c14 will begin to decay, the carbon in the dead organism will not be replace by exsisting carbon in the atmosphere, the levels of c12 willl remain the same, c14 will decay at a known rate.
Structural Morphology
- Homologous structures
- analogous structures
- vestigial structures
Ho
Homologous structures
similar structure, different function
- they are shown to be derrived from a common ancestor
- evidence for DIVERGENT EVOLUTION
anas
analogous structure
different structure, similar function
- not derived from a common acestor
- evidence for CONVERGENT EVOLUTION
Vestigial structures
- features that have lost all or more of their usefullnes as a result of evolution by natural selection
examples
- coccyx (tailbone) - used for balance but we have evolved our innear ears to help instead
- Pelvic bones in snakes and whales - despite not having legs, whale mammals, snakes reptiles, both came from a common ancestor
Molecular Homology
- how related we are by comparing conserved genes between all specices because they are important to most functionality like haemoglobin which is like a base to compare for all things to see how long ago their divergence point was.
Amino acid sequence similarity
a higher degree of similarity suggests the species being compared are more cosley related.
Molecular clock
based on the theory that mutation occur at a steady rate, can be used to determine how far away the divergence point was/ how closey related.
DNA hybridisation
- get the same gene from two different species
- heat them up to become single standed
- cool them down they switch partners a hybrid is formed
- if they are closely related most of the base pairs will form hydrogen bonds, but we dont want to count them! no no
- heat up the hybrid and check the melting temperature which is required to separate the hybrid formed
- higher melting temp = closely related = more h-bonds
- lower melting temp = distantly related = less h-bonds
Phylogenetic tree
root = where it starts from
node = where it splits off in different directions
branch = the different directions it splits off too
clave = where you could cut and it all stays
Order of what humans are
Kingdom - Animals
Phylum - Chordates
Subphylum - Vertebrates
Class - Mammals
Order - Primates
Family - Hominidae
Genus - Homo
Species - Homo Sapiens
mammals
primates
hominoids
hominins
Mammals
variety of teeth, hair fur, three middle ear bones, single lower jaw bones
mammory gland (milk to offspring)
Primate
Primates
Flexible spines, hip rotation, prehensile ands and/or feet, binocular colour 3D vision, opposable tumb/ big toe, sensitive touch receptors
Hominoids
Y5 shaped molar teeth, broad rib cage, large cranium, long arms, no tail
Hominins
Bipedalism - centralised foramen magnum, s-shaped spine, broader rib cage, bowl-shaped pelvis, increased carring angle of the femur
communication and formation of complex social groups
Changes
Changes in brain size
Large brain compared to body size, brain volume increase 3 fold from australopithecus from the improved human diet, the brain cerebrum folded to increase SA resulting in more neurons
centralised foramen magnum, smaller sagittal crest, smaller brow ridge, flattening of the face, less protruding chin, more domed skull, smaller teeth.
Changes in limb structure
arm:leg ratio changed overtime in response to an increased reliance on bipedal locomotion, the pelvis changed due to wlaking upright aswell.
Arms
GOT SHORTER
- less need for contact points on the forelimbs as we were not living in trees and walking upright freeing up arms for other tasks
Legs
GOT LONGER
- longer stride length = made walking upright more energy efficient, shorter big toe with the other toes being in line, feet with two arches and a wide heel.
Pelvis shape
shorter and more bowl shaped
- this gave more support when walkkning upright, legs attached to the pelvis at an angle allowing more easily to walk upright and sonserve energy
- more circular birth canal from the norrowing od the pelvis which reflects the narrowing of our body shape
Fossil record, why is it hard to interpret? : ]
- its incomplete and different interpretations can be make from the few peices of eviedence we have. Imperfect fragmentts, mall collection
- they all dont die in good conditios that are good for fossilisation, rock layer are not accessible yet.
interbreeding with neanderthals?
1-4% of the human genome is identicle to neanderthals, they may have interbred with them somewhere in the middle east after they left africa
Carbon 14 - Nitrogen 14
1000-50000 years old
- organic materials
- half life = 5730 years
Uranium 235 - Lead 207
1mil - 4.5bil years old
- healf life = 700 millions years
- shells and corals
Uranium 238 -lead 206
Uranium 238 - lead 206
1mil - 4.5bil years old
- half life = 4.5 milion years
- shells and corals
Potassium 40 - argon 40
100000+years
- 1.3 billion year = half life
- used on igneous (volcanic) rocks
Out of Africa
Out of Africa theory, there were 2 waves, the first being H.Erectus leaving Africa and spreading across the continents. Then for the second wave, 2 theories distinguish out of Africa 1 from out of Africa 2. The second wave was when african H. Erectus became H.Sapiens and then H.Sapiens left Africa, the two theories are the different direction they went in
1. evidence of stone tools from yemen and uae 80kya and india 74kya
2. fossil evidence found in france in a cave.
- lots of evidence for this theory
- large sclale analysis of mtDNA that suggest our lineages can all be traced back to a common ancestor that lived in africa, 150000 and 300000 years ago.
Multiregional
H.Erectus evolved in Africa then left africa and went around to all the continents. Then through gene flow, all evolved together into H.Sapiens
- this theory lacks evidence
- the evidence is that ancient fossil records demonstrate morphological clades, which are physical trait that are unique to a particular geographical region across a wide timespan.
