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Description
Flashcards by Lewis Johnson, updated more than 1 year ago
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Created by Lewis Johnson
about 7 years ago
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| Question | Answer |
| Evolution | Definition: A gradual process in which something changes into a different and usually more complex or better form. • Evolution is the progressive change in inherited characteristics. It occurs over many generations to produce different species from a common ancestor. • Thus, evidence for evolution must be based on any similarities that exist between these different species & between extinct and surviving species. |
| Comparative studies in Biochemistry DNA | • DNA is the chemical compound which makes up the genes (our genetic code) and information from all cell functions. • Contains 4 Nitrogen bases: → Adenine → Thymine → Cytosine → Guanine. • The more similar the sequences of DNA/Mitochondrial DNA, the more closely related species are. Therefore the more recently they shared a common ancestor/less time since species separated. • Scientists have determined that all living things use the same DNA code which shows that all living things are related to each other and have evolved from a common ancestor. • Although all species have DNA, the actual sequence of bases will vary. • When speciation occurs, the new species would have similar DNA. As the species change, there would be more and more difference between their DNA. • Species that are closely related, will have more similarities in their DNA. • More distantly related species will show greater differences. |
| Comparative studies in Biochemistry DNA Example | • The genome (DNA make up) of chimpanzees shows that they share 98% of human DNA. • Orang-utans and humans are 92% common DNA. They are classed as being more distantly related to humans. • This theory of how humans have evolved from primates is by using the supporting evidence of a ENDOGENOUS VIRUS (ERV) • The ERV is a viral sequence which will invade a cell and copy it’s RNA into DNA. • This DNA will then be inserted into one of the hosts cells chromosomes. • It only inserts into a reproductive cell such as a sperm or ova so it can become a part of the organisms genome. • Scientists have found out that 8% of the human genome is made of of ERV’s. • Primates possess some of the same ERV in the same location as humans. • Species with the same ERV will be closely related. • Human chromosomes vs chimpanzee chromosomes and ER relation. They have the same ERV on chromosome short arm 10, 1 and 6. And chromosome long arm 9. |
| Comparative studies in Biochemistry Mitochondrial DNA (mtDNA) | • mtDNA is only inherited by the mother. (We have the same mtDNA as our mother). • Differences and similarities in mtDNA of species can thus show evolution and relationships. • Scientists can track ancestral lines through looking at mtDNA. |
| Comparative studies in Biochemistry Protein Sequences | • Proteins are the building blocks of cells and are the enzymes which catalyse particular chemical reactions. • Linking together particular amino acids in a precise sequence is determine by the DNA which creates these proteins. • Similar organisms must have similar chemical reactions and this is shown in close protein profiles. • By comparing the type and sequence of these amino acids in similar proteins from different species, the degree of similarity can be established. |
| Ubiquitous Proteins | • Ubiquitous proteins are proteins that appear to be in all species. • Such proteins perform very basic but essential tasks that all organisms require for life no matter where they are found. |
| Cytochrome c | • Cytochrome c is a ubiquitous protein essential in the production of cellular energy. • It contains 104 amino acids • 37 of these have been found in the same position in every cytochrome c molecule that has ever been sequenced regardless of the species. • This suggests that these proteins have descended from a ancestral cytochrome c molecule found in a primitive microbe that existed more than 2000 million years ago. |
| Comparative studies in Biochemistry Bioinformatics | • Bioinformatics uses computers, software and mathematical models to process and integrate biological information from large data sets. • Bioinformatics is used to study and analyse genome sequences to help determine genetics of disease, to understand gene expression/protein synthesis and mutations. • It also used to trace evolutionary changes in DNA and determine relationships between different species. |
| Comparative studies in Biochemistry Comparative Genomics | • Comparative genomics is a field of biological research in which researchers use a variety of tools, including computer-based analysis, to compare the complete genome sequences of different species. • By carefully comparing characteristics that define various organisms - including the genomes of organisms ranging from humans to chimpanzees to yeast - researchers can pinpoint regions of similarity and difference. • This information can help scientists better understand the structure and function of human genes, and develop new strategies to combat human disease. |
| Comparative studies in Anatomy Comparative Embryology | • Comparative embryology is the comparing of the very early stages of the development of organisms • The embryonic gill pouches and arches appear in all the species. • The presence of such structures is significant if the vertebrates are viewed as an evolutionary series that began with fish hundreds of millions of years ago. • Over that time evolution resulted in their divergence into amphibians, reptiles, birds and mammals. • In humans, one of the embryonic gill slits develops into the Eustachian tube, and tissue surrounding other gill slits develops into the thyroid gland and tonsils. • Features also common to all vertebrate embryos at this stage, are a two-chambered heart and similar brain development. |
| Comparative studies in Anatomy Homologous Organs | • Homologous organs are organs that are similar in structure but are used in different ways. • Show a similarity in anatomy. • Forelimb of vertebrates → the same bones appear in various forms throughout the vertebrates: → The feet of amphibians and reptiles → The wings of bats and birds → The leg of a horse → The flipper of a whale or seal → The human hand. • In every case the bones are arranged in a similar way, even though some have developed different functions. • Organisms possessing organs that are similar in structure are likely to have a common ancestor. |
| Comparative studies in Anatomy Vestigal Organs | • Vestigial organs are organs that may once have been important but have lost or changed their function. • Coccyx → The fused vertebrae for a tail Appendix → Narrow, muscular tube attached to the large intestine served as a special area to digest cellulose . • Also produces some white blood cells. Male nipples → serve no purpose as males do not possess mammary glands to produce milk for their young. Erector Pili → Bundles of smooth muscle fibres allow animals to puff up their fur for insulation or to intimidate others. • Humans retain this ability (goose bumps are the indicator) but have obviously lost most of the fur. Body Hair → Is practically useless. • Too fine for insulation. • Brows help keep sweat from the eyes, and male facial hair may play a role in sexual selection. |
| Comparative studies in Anatomy Geographical Distribution | • Further evidence for evolution is found in the natural geographic distribution of related species. Example South American mainland V’s Galapagos Islands • Finches of the Galapagos Islands have evolved by taking advantage of the range of food sources on offer. • Their beaks gradually changed over time to better enable the different populations to survive. • Eventually they evolved into 13 separate species South American mainland V’s Galapagos Islands Finches of the Galapagos Islands have evolved by taking advantage of the range of food sources on offer Their beaks gradually changed over time to better enable the different populations to survive. Eventually they evolved into 13 separate species |
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