Evolution

• Evolution = testable mechanism which can explain the formation of life and diversification of species (based on scientific evidence)
• What is the scientific theory? (e.g. what are the 5 steps?) 1. Make observations and collect facts 2. Make a hypothesis that attempts to explain the above 3. Use hypothesis to make a prediction 4. Test this prediction 5. You can then either reject or improve hypothesis and repeat NOTE - If your hypothesis stands up to rigorous testing it becomes a theory
• HIV AND DRUG RESISTANCE Replication errors produce mutations in the virus genome. Virions carrying different mutations can vary in their resistance to AZT (medication) The mutant virions pass their resistant version to their offspring. Meaning AZT resistance is heritable During treatment with AZT, some virions are better able to survive and reproduce than others The virions that persist in the presence of AZT are the ones with mutations that confer resistance So essentially drug resistance is evidence for {{c4::survival of th...
• VEVOX NOTES: 1. What does the no of viral particles and no of T cells in a patient over the years show? 2. Drug resistnce in HIV is an example of what? 1. Evolution by competition 2. Drug resistnce in HIV is an example of evolution by natural selection
• HIV AND HUMAN EVOLUTION Research in the 90s showed that individuals carrying a deletion in the gene CCR5 were resistant to infection by HIV --> This gene encodes for a co receptor tht the virus used to enter cellThis deletion is far more common in humans from northern Europe and it's frequency drops towards both the South and East
• HIV AND IT'S ORIGIN HIV = very similar to Siminian Immodeficiency Virus (SIV) in primates (this was figured out by using a phlogenetic tree) HIV 1 = Comes from chimpanzeesHIV 2 = Comes from Sooty mangabeys
• HISTORY OF EVOLUTIONARY THINKING -Aristotle's Scala Naturae (384BC - 322 BC) What was Aristotle's idea? What did this idea further the views of? How long was this theory believed? Ordered organisms into linear sequence fro least to most complex This idea furthered views of natural theology (e.g. the idea of Special creation) Until the 19th century
• HISTORY OF EVOLUTIONARY THINKING -Aristotle's Scala Naturae (384BC - 322 BC) Aristotle's ideas lead to the idea of Special Creation What were the 5 things this meant? Species do not change Lineages do not split Each species is specially created (they were made in their current form by God to fit certain climates) Each species is independtly createdEarth and life are young
• HISTORY OF EVOLUTIONARY THINKING - Caroleus Linnaeus Systema Naturae (1707-1778) Who was Linnaeus and what did he seek to do?What did he develop?What was he the first to do? (x2)Did he believe in evolution? Swedish botanist who sought to classify life's diversity The binomal format (binomal = two part) for naming species - NOTE - THIS IS STILL USED He classified species to the pattern of their creation rather than their kinsip and he classified humans with Primates No it was not created yet
• HISTORY OF EVOLUTIONARY THINKING - Erasmus Darwin: Zoonomia (1707-1778) How was he related to Darwin?What did he write? How did he believe evolution would take place? Grandfather (had great influence on Charles Darwin) Zoonomia (developed several ideas that Charles used later) That all warm looded animals were born from one living being before humans existed
• HISTORY OF EVOLUTIONARY THINKING = Georges Cuvier (Paleontologist) What did Cuvier realise? (x2)What did this lead to him hypothesising? The older the stratum (e.g. layers of rock) the more different the fossils were to current life forms and that one layer to the next life forms disappeared while others appeared That each boundray between each stratum represented a catastrophic event (e.g. flood) that were localised destroying many species in that area living at that time --> He believed that the area w/o any species would be then repopulated by species with different characteristics from n...
• HISTORY OF EVOLUTIONARY THINKING - James Hutton: Geologist (1726-1797) What did he argue and what did he call this concept? That the geological processes that form the Earch are gradual so the Earth must be older than 6000 years to allow time for change
• HISTORY OF EVOLUTIONARY THINKING - Charles Lyell (Geologist - The Princibles of Geology: 1797-1875) Whose theory did he incorporate into his princible of Uniformitarianism and what did this suggest?Whose thinking did Lyell's ideas influence? Hutton's theories - suggested that processes are constant over time (Lyell suggested that the same geological processes are happening today as in the past at the same rate)Both Hutton and Lyell's ideas influenced Darwin who agreed that the Earth must be older than they thought and supported idea that species diversification may have taken place over the ...
• HISTORY OF EVOLUTIONAL THINKING - Jean-Baptise Lamark (1744-1829) What did Lamark believe? (x2)What did Lamark's 'Second Law' state?What did he view evolution as? (x2)What did he believe about extinction? (x2) What was a strange thing he believed? (HINT - this can also help you remember what he believed in)What is the simple evidence against his ideas of Evolution? That a change in environment causes changes in the needs of organism which changes their behabiour leading to greater/lesser use of a given structure/organ --> this use would cause structure to increase in size over many generation...
• HISTORY OF EVOLUTIONARY THINKING - Charles Darwin (1809-1882) What were the 3 main ideas Darwin based his ideas on? Who was he the protege of? What conclusion did he come to after the Galapagos visit? What three types of tortoises did Darwin see and how were they adapted to their environment? After returning home what boo...
• THE ORIGIN OF SPECIES BY MEANS OF NATURAL SELECTION What were Darwin's three broad observations? The unity of life The diversity of life The match between organisms and their environment He beleived natural selection was the mechanism for all this
• What is microevolution? Species are not immutable, but change through time
• What is the evidence for microevolution? Slective breeding/artificial selection From living anatomy (e.g. vestigal structures such as the tailbone in humans, kiwwi's wings and a snake's hindlimbs)
• What are the features of descent with modification? (x5) Species change over time (microevolution)Lineages split and diverge (specification) New life-forms derive from older forms (macroevolution) All life forms are related (common ancestry)Eath and life are old
• What is common ancestry? Species are derived from a common shared ancestor
• What is the evidence for common ancestry? Molecular homology in the form of: The central dogma and the genetic code is the same for all animalsEvidence in the Homeobox - AKA Hox - genes which are transcription factors which play an important role in dev of animal segments and are present in different animals --> means we can track their evolution which shows that no of Hox genes expanded during animal evolution
• What is specification? Lineages split and diverge over time
• What is the evidence for speication? From nautral populations --> Populations can diverge to the point that their individuals can no longer interbred
• What is macroevolution? Over long periods of time, novel forms of life can derive for earlier forms
• What is the evidence for macroevolution? (x2) FossilsBiogeography - Earth's contitents formerly united in 1 contitent (called Pangaea) but have since seperated
• What 4 requirements are needed for an inevitable change to occur from one generation to the next? The individuals within a population differ from one anotherThe differences are, at least in part, passed from parents to offspringSome individuals are more successful at surviving and reproducing than othersThe successful individuals are not merely lucky; instead, they succeed because of the variant traits they have inherited and will pass to their offspring
• MAIN POINTS TO REMEMBER ABOUT NATURAL SELECTION: Natural selection acts on individuals, but its consequences occur in poulations (EXAMPLE - birds have different beak sizes --> drought occurs and irds with bigger beaks survive --> individuals didn't change beak size but AVERAGE BEAK SIZE INCREASED)Natural selection acts on phenotypes but evolution consists of changes in allele frequenciesNatural selection is not forward looking (e.g. organisms cannot anticipate environmental conditions and cannot adapt to furute conditions) Natural selection doesn't lea...
• What is the genome and what does it do? The genome is the DNA sequence of an organism that encodes the information and underpins and directs most of the biological processes of that organism.
• PROKARYOTES: Linear relationship between genome size and number of genes EUKARYOTES: No linear relationship between genome size and number of genes
• What is the Gene capacity? The totat possible genes we can have
• Is the gene capacity usually the number of genes we have? No - most of it is 'junk DNA' that doesn't have a function
• How do you calculate gene capacity? Genome size (bp) / Average length of a gene (bp)
• Calculate the gene length of E Coli with the genome size of 4.6x10^6 bp and the average length of a gene being 1,000 bp. 4.6x10^6 bp / 1,000 bp = 4,600 gene capacity NOTE - IN REALITY E.COLI ONLY HAS 4,400
• Calculate the gene length of a Human with the genome size of 3x10^9 bp and the average length of a gene being 3,000 bp. 3x10^9 bp / 3,000 bp = 1 mill 'gene capacity' NOTE - IN REALITY WE ONLY HAVE ~21,000 GENES (REST IS 'JUNK DNA')
• Who introduced the concept of 'Junk DNA' and when? (x2) Susumo Ohno In 1972
• What is Junk DNA? DNA that doesn't have a 'function' and is noncoding --> gives 'little or no selective advantage for the organism
• What are the two main units for genome size called and what are they both measured in? C - Value - measured typically in picograms Base pairs (bp) - measured in kilo (1,000), mega (1,000,000) and giga (1,000,000,000)
• What does the C-Value mean? The 'constant' (or 'characteristic;) value of haploid DNA content per nucleus
• What is 1 pg (C-Value) equivalent to in Base Pairs? 1 Giga Base Pair (written as 1 Gbp)
• What did they believe in the 1960s about the relationship between organism complexity and genome size? What proved this wrong and who came up with this? That they had a linear relationship (e.g. more complex = more DNA) The C-Value Paradox (found that genome size varies between species and complex species DON'T have more DNA) --> C.A Thomas Jr in 1971