Chapter 10 - Classification and Evolution Flashcards
Taxonomy
➜ study of biological classification
Taxon
➜ each group in hierarchical system is called taxon (taxa = plural)
Taxonomic groups
➜ 7 groups ordered in a hierarchy
The 7 Groups
➜ Kingdom - King
➜ Phylum - Philip
➜ Class - Came
➜ Order - Over
➜ Family - For
➜ Genus - Gay
➜ Species - Sex
How to order the groups per living thing?
KING PHILLIP CAME OVER FOR GAY SEX!!!
e.g Wolf
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: lupus
Binomial System
➜ binomial are the scientific names given to individuals species
➜ consist of the organism’s genus and species name in modern Latin
e.g Humans - Homo sapiens
e.g dogs - Canis familiaris
Swedish scientist Carl Linnaeus
➜ developed and established the naming convention - binomial system
➜ this was to avoid confusion about what group of organisms scientists are talking about
➜ always italicized or underlined
e.g Yeast - Saccharomyces cerevisiae or when abbreviated S. cerevisiae
Domain
➜ highest taxonomic rank in the system
e.g Archaea, the Bacteria, and the Eukarya
Archaea
➜ sometimes referred to as the extremophile prokaryotes as they were first discovered living in extreme environments
➜ no nucleus
➜ initially classed as bacteria until discovering unique properties:
↳ unique lipids found in membrane - consist of branched hydrocarbons bonded to glycerol by ether linkage
↳ no peptidoglycan in cell walls
↳ ribosomal structure similar to
eukaryotic ribosome than bacteria - such as the base sequence and primary structure of ribosome proteins
➜ similar size range as bacteria
➜ Transcription similar to eukaryotes
e.g Halobacterium salinarum - found in environments with high salt conc
Bacteria
➜ organisms with prokaryotic cells which have no nucleus
➜ vary in size
➜ divide via binary fission
e.g Staphylococcus pneumoniae - causes pneumonia
Eukarya
➜ contain nuclei and are membrane bound organelles
➜ massively vary in size
➜ single celled organisms and large multicellular organisms exist
➜ divide by mitosis
➜ can reproduce sexually and asexually
e.g canis lupus - wolves
Kingdoms
➜ living things are divided into 5 kingdoms
↳ Prokaryota
↳ Protoctista
↳ fungi
↳ Plantae
↳ Animalia
➜ was thought to be the top of classification hierarch before domains were introduced
Prokaryota
➜ includes bacteria and blue-green bacteria
➜ unicellular & have cell walls & cytoplasm & small ribosomes
➜ no nucleus or mitochondria
➜ less than 5µm but vary in size
➜ divide by binary fission
➜ blue green bacteria and some bacteria = autotrophic (photosynthetic)
➜ many bacteria = heterotrophic (feeding on living or dead organic materials) like hoomans x
➜ no visible feeding mechanism - absorbed via cell wall
Kingdom Protoctista
➼ eukaryotic cells (so they have nucleus duh)
➼ unicellular or single celled
➼ no cell wall and similar to animal cells - known as protozoa
➼ some have chloroplasts and cellulose cell walls - known as algae
➼ usually live in water
Kingdom Fungi
➜ eukaryotic
➜ chitin cell wall and no cilia
➜ heterotrophs - obtain energy and carbon by digesting dead/decaying matter extracellularly or from being parasites on living organisms
➜ unicellular or multicellular organisms
➜ store food as glycogen
➜ some consist of long threads (hyphae) that grow from main fungus body and form a network of filaments called mycelium
➜ larger fungi have fruiting bodies to release large number of spores
➜ reproduce using spores that disperse
Kingdom Plantae
➜ eukaryotic
➜ multicellular
➜ cellulose cell wall and large vacuoles for structural support
➜ able to differentiate into specialized cells to form tissues and organs
➜ photosynthesise with chloroplasts
➜ sometimes have flagella
➜ autotrophic (produce their own food)
Kingdom Animalia
➜ eukaryotic
➜ able to differentiate into many different specialised cell types that can form tissues and organs
➜ small temporary vacuoles e.g lysosomes
➜ no cell walls
➜ sometimes have cilia
➼ heterotrophic and have wide range of feeding mechanisms
➜ communication - nervous system and chemical signalling
Phylogeny
➼ study of evolutionary history of groups of organisms
➼ tells us who’s related to whom and how closely related they are
➼ all organisms have evolved from shared common ancestors
➼ species is the smallest group that shares a common ancestor
homology
➜ organisms were grouped based on their features
➜ features are homologous if they are shared by organisms that have evolved from a common ancestor
➜ many limitations due to using physical features of species = lead to wrong classification
Sequencing tech
➜ scientists choose specific proteins/sections of genome
➜ look at multiple proteins or regions = for accuracy
➜ protein used needs to be present in a wide range of organisms and show sufficient variation between species
➜ cytochrome c is often used as it is an integral protein to respiration
➜ 2 groups or organisms with very similar sequences = separated into diff species more recently than 2 groups with less similarity
DNA Analysis and Comparison
➜ DNA extracted from nuclei - via blood/skin/fossils
➜ extracted DNA processed, analysed and base sequence obtained
➜ compared to other organisms to:
➼ identify species
➼ predict characteristics
➼ find evolutionary links
Immunology: using antibodies in classification
➜ protein albumin is found in many species and is commonly used for these experiments
Method:
- Pure albumin samples extracted from blood of multiple species
- Each pure albumin sample injected into a diff rabbit
- Each rabbit produces antibodies for that specific type of albumen
- different antibodies are extracted from the different rabbits and are then mixed with the different albumin samples
- precipitate (antibody-antigen complexes) resulting from each mixed sample is weighed
Results and Interpretation of experiment:
➜ ↑ the weight of precipitate = ↑ the degree of complementarity between the antibody and albumin
Two key sources of evidence for the theory of evolution by natural selection include:
➜ Fossil evidence
➜ Molecular evidence - our understanding of genetics to see what characteristics were passed on to offspring
Molecular evidence
➜ 3 types of data used to investigate evolutionary relationships: DNA, mRNA, Amino acids
➜ DNA/mRNA are sequenced and used to provide evidence of how the genetic code of species has changed as they have evolved as it shows us the order of the bases
➜ more similar the sequence the more closely related the species are
➜ used to compare with extinct species
➜ proteins can be used to imply evolutionary relationship in 2 species as they can have similar sequences of amino acids CYTOCHROME C as its used by every organism that requires
Fossil evidence
➜ are preserved remains of organisms or other features left by organisms, such as footprints, burrows and faeces
➜ we can tell that environments have changed significantly
➜ can be dated so we can see how organisms changed over time
➜ show similarities between extinct species
Embryological evidence
➼ similarities in the early stages of an organism’s development
Anatomical evidence
➼ similarities in structure and function of different body parts
Behavioural evidence
➼ similarities in behaviour and social organisation of organisms
Variation
➼ refers to the differences that exist between two or more things
➜ genetic variation = variation in genotypes
➜ phenotypic variation
Intraspecific
➼ variation within a species
➜ phenotypic variation of same species can be due to qualitative or quantitative differences
Interspecific
➼ variation between different species
➜ can be useful in identifying and classifying different species
Continuous variation
➼ quantitative differences in the phenotypes of individuals within a population
eg. height
➼ characteristics that show continuous variation are not controlled by a single gene but polygenes (influenced by environmental factors)
Discontinuous variation
➼ Qualitative differences in the phenotypes of individuals within a population
➼ no in-between values - fall into discrete and distinguishable categories
eg. sex
➼ represented by bar chart/ pie chart
➼ controlled by one gene
Examples of continuous variation
eye colour, height, weight, temperature, length, width, blood pressure
Examples of discontinuous variation
➼ animals: blood group, gender
➼ plants: colour, seed shape
➼ microorganisms: antibiotic resistance, pigment production
Genetic causes of variation
➼ diff genes have diff effects on phenotypes
↠ diff alleles at a single gene locus have a large effect on phenotype
↠ gene for human blood groups has 3 diff alleles
➼ mutations: changes to the DNA sequence + therefore to genes can lead to changes in the proteins that are coded for
↠ mutation in gametes- passed on to organism’s offspring
➼ Meosis: gametes are produced- independent assortment and crossing over occurs -> variation
Environmental causes of variation
➼ eg. scars on body, piercings, accents (none of which can be inherited)
➼ can change over an organism’s life
- Length of sunlight hours (which may be seasonal)
- Supply of nutrients (food)
- Availability of water
- Temperature range
- Oxygen levels
Environmental and genetic causes
➼ tall parents - gene to grow to a tell height is inherited BUT can be affected by poor diet or diseases
➼ skin colour-> depends on melanin contained
➼ more melanin, the darker the skin colour (sunlight can affect)
Characteristics of a normal distribution
➼ mean, mode and median are the same
➼ bell shape
➼ 50% is greater than than the mean, 50% is less than the mean
➼ most values lie close to the mean
selection pressures
➜ Environmental factors that affect the chance of survival of an organism
➜ can have different effects on the allele frequencies
Adaptations
➼ anatomical
➼ behavioural
➼ physiological
Analogous structure
➼ adapted to perform the same function but have diff genetic origin
Anatomical Adaptations
➜ Structural or physical features
➼ body covering eg. hairs, scales, spines, feathers, shells
➼ camouflage - outer colour allows it to blend into its environment
➼ teeth
➼ mimicry
Physiological adaptations
➜ Biological processes within the organism
➼ Poison production
➼ Antibiotic production
➼ Water holding
Behavioural adaptations
➜ The way an organism behaves
➼ survival behaviours - eg. an opossum plays dead + a rabbit freezes when they think they have been seen
➼ courtship- many animals exhibit elaborate courtship behaviours to attract a mate
➼ seasonal behaviours - migration, hibernation
2 MAIN CATEGORIES:
➼ innate - ability to do this is inherited through genes
➼ learned behaviour - these adaptation are learnt from experience/ from observing other animals
Evolution
➜ The change in adaptive features of a population over time as a result of natural selection
Convergent evolution
➼ when unrelated species begin to share similar traits (don’t share a common ancestor and are in diff parts of world)
➼ occurs when the two habitats, in which the two species have evolved and to which they have become adapted, are very similar
➜ you would have to travel back many millions of years to find the common ancestor of these species - that would not even posses any of adaptations of recent organism
eg. whales and fish -> both in the ocean
e.g marsupial moles in Australia and European mole are both blind and both burrow
Natural selection
➜ will select for favourable alleles that produce adaptations
➜ will select against unfavourable alleles
➜ will cause favourable allele frequencies to increase and unfavourable allele frequencies to decrease, making the species better adapted to its environment
processes resulting in natural selection
➜ Random mutation can produce new alleles of a gene
➜ Environmental factors - those with advantageous allele to survive environment produce offspring and those without die off
➜ genetic variation - population with a large gene pool or high genetic diversity has a strong ability to adapt to change
Drug resistance in microorganisms
➜ variation due to mutation in bacteria
➜ chance mutation might cause some bacteria to become resistant to an antibiotic
➜ when population treated with antibiotic the resistant bacteria don’t die and so they reproduce with less competition as competition is dead
➜ bacteria only have one copy of each gene, a mutant gene will have an immediate effect on any bacterium possessing it
➜ over time, the whole population of bacteria becomes antibiotic-resistant
How bacteria inherit antibiotic resistance
- Vertical & Horizontal transmission
vertical transmission
➜ reproduce asexually by binary fission very rapidly
➜ so if one bacterium contains mutant gene all of its descendants (which is a shit tonne) will have antibiotic resistance
➜ this form of transmission enables antibiotic resistance to spread within a bacterial population
horizontal transmission
➜ plasmids contain antibiotic resistant genes
➜ plasmids are frequently transferred between bacteria
➜ occurs during conjugation (when a thin tube forms between two bacteria to allow the exchange of DNA)
➜ even between diff species of bacteria
how to reduce cases of antibiotic resistance
- prescribe antibiotics when absolutely necessary
- make sure patients complete full course so no remaining bacteria left over
- Rotate which antibiotics are used so that one type is not continuously used in the treatment of a specific disease
- use antibiotics as a last resort
Consequences of antibiotic resistance
➜ formation of bacteria called superbugs which are very hard to destroy
➜ e.g Staphylococcus aureus - developed resistance to a powerful antibiotic called methicillin as well as other antibiotics and known as MRSA
Types of pesticides
Insecticides (kill insect pests)
Herbicides (kill plant pests)
Fungicides (kill fungal pests)
Molluscicides (kill slug and snail pests)
Rodenticides (kill rodent pests)
Pesticide resistance in insects
➜ insecticides that are sprayed on crops act as selective agents
➜ selective agent is any environmental factor that influences the survival of a particular species and so drives natural selection in that species
Consequences of pesticide resistance
➜ problem for the security of future food supplies
➜ combination of pesticides can delay the emergence and spread of resistance in pest insect populations
➜ farmers encouraged to use other forms of insect pest control - biological control/GM crops
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