M4 - Chapter 10 - Classification and Evolution Flashcards
Classification definition
The process by which living organisms are sorted into groups. They all share similar features.
What is the Taxonomic Group
The groups by which animals can be classified
Taxonomic Group
Kingdom Phylum Class Order Family Genus Species
Brief History of classification
Aristotle made a book about all the animals - 350 BC
Conrad Gesner produced another book about animals -1551
Carl Linnaeus produced another 10th edition of Systema Naturae, which was considered to be the starting of the binomial nomenclature - 1758
Ernest Haeckel proposed the 3rd Kingdom - 1866
A 5- kingdom classification system is proposed by Robert Whittaker- 1969
Carl Woese introduces a 6- Kingdom model - 1977
Why should we classify organisms
to identify species
to predict characteristics
(if several organisms in a group have a specific characteristic, then others included are likely to have it too)
To find evolutionary links (common ancestors)
Advantages of classifiying animals
Scientists all across the world can share their research and communicate using the Binomial Nomenclature names.
Species definition
A group of organisms that are able to produce fertile offspring.
What are the 3 domains
Archae
Bacteria
Eukarya
What is a common name
Names given according to a certain physical characteristic
What is wrong with using a common name
Scientists working internationally might have different names
It doesn’t provide any information about relationships
Binomial Nomenclature
- Genus
- Species
When typing, this name should be in italics or when written, it should be underlined
What are the 5 Kingdoms
Prokaryotae Protoctista (unicellular eukaryotes) Fungi Plantae Animalia
Features of Prokaryotae
- Unicellular
- No membrane-bound organelles
- Small ribosomes
- No visible feeding mechanisms (nutrients absorbed)
Features of Protoctista
- Mainly unicellular
- A nucleus and membrane-bound organelles
- Some have chloroplasts
- Some are sessile (immobile), but some can move by cilia/ flagella
- Nutrients gained by photosynthesis (autotrophic) or ingestion of organisms (heterotrophic feeders)
Features of Fungi
- unicellular or multi-cellular
- Membrane-bound organelles
- Cell wall made of chitin
- No chloroplasts/ chlorophyll
- No mechanism for movement
- Body or mycelium (vegetative part of a fungus)
- Nutrients are absorbed
- Saprophytic feeders (energy from decaying material)
- Some are parasitic
- Most store their energy as glycogen
Features of Plantae
- Multicellular
- Nucleus and other membrane- bound organelles
- cell wall made of cellulose
- All contain chlorophyll
- Most don’t move, but they can using cilia/ flagella
- Autotrophic feeders
- Store food as starch
Features of Animalia
- Multicellular
- No cell walls or chloroplasts
- Nucleus and membrane-bound organelles
- Move with cilia or flagella
- Nutrients gained by ingestion
- Food stored as glycogen
What was the original classification
Based on observable features
Three domain system general info
This is the current classification used today that was proposed by Carl Woese in 1997.
This system groups organisms using differences in the sequences in nucleotides in the cells’ ribosomal RNA and the cells’ membrane lipid structure and their sensitivity to antibiotics.
Three domain system Structure
3 domains then 6 kingdoms
Domains: Bacteria –> Eubacteria
Archae –>Archaebacteria
Eukarya –> The rest of the kingdoms
The Prokaryotes are basically replaced by Eubacteria and Archaebacteria
Eukarya
80s ribosomes
RNA polymerase (responsible for mRNA transcription)
contains 12 proteins
Archae
70s ribosomes
RNA polymerase contains 8-10 proteins
Bacteria (domain)
70s ribosomes
RNA polymerase contains 5 proteins
Archaebacteria
Live in extreme environments such as hot air vents or anaerobic.
Eubacteria
Normal conditions
Difference between Archaebacteria and Eubacteria
They have different chemical makeup. For example, peptidoglycan is in Eubacteria, but not in Archaebacteria.
What is phylogeny
the EVOLUTIONARY relationships between organisms
What is the link between phylogeny and classification
Phylogeny is used to classify organisms, and the closer the evolutionary relationships between organisms, the closer the taxonomic groups.
Advantages of phylogeny
Phylogeny produces a continuous tree, whereas classification requires discrete taxonomical group.
The hierarchy in classification can make it seem as if 2 groups are equal, however this may not always be correct. and can be quite misleading.
Evidence for evolution
- Palaeontology
- Comparative Anatomy
- Comparative Biochemistry
- Fossil Record
- Embryology
Palaeontology
Fossils are created and as the sediment builds up over time, and different layers of rocks are formed, scientists have noticed that the fossils at the bottom (which are older) are different to the ones at the top (which are younger). This is often called the Fossil Record
How are fossils made
Animals’ and plants’ remains that are preserved in rocks over years.
Evidence from the F.R
- Simpler organisms, such as bacteria are at the bottom, whereas more complex ones are at the top.
- The sequence that the organisms are found in matches their ecological links, like how plants were older than animals.
- By studying similarities (etc.) in the anatomy, you can figure out which ones are closely related.
- Fossils also allow relationships between extinct and extant organisms to be investigated.
What is the problem with the F.R
It isn’t complete. This is because some organisms may decay/ decompose before they fossilise, or they may not have the right conditions to fossilise.
What is a homologous structure
A structure that appears superficially different in different organisms, but it has the same underlying structure.
What does the presence of a homologous structure prove
It provides evidence for divergent evolution. This describes how, from a common ancestor, different species have evolved, each with a different set of adaptive features. This happens when species that are closely related diversify to adapt new habitats due to a immigration or a loss of habitat.
What is comparative biochemistry
Study of similarities in the proteins and other molecules that control life processes and are highly conserved.
Hypothesis of neutral evolution
States that most of the variability in the structure of a molecule doesn’t actually affect the function, because the variability usually occurs outside of the molecules’ functional region. This is why it’s called ‘neutral’.
How can you compare 2 species using the molecular sequences
You compare the molecular sequence of a particular molecule. The number of differences that exist are plotted against the rate of molecule undergoes neutral base pair substitutions. Using this, scientists can estimate when the last point that 2 organisms shared a common ancestor was. Ribosomal RNA has a very slow rate of substitution, so it is commonly used to determine relationships.
What is variation
A difference in characteristics between organisms
What is interspecific variation
Variation between different species
What is intraspecific variation
Variation within a species
Causes of variation
- Genetic variation- inherited from parents
2. Environmental variation- variation because of the environment that the organism lives in.
Genetic variation causes
- Alleles
- Mutations
- Meiosis
- Sexual Reproduction
- Chance
Explain alleles and sexual reproduction for Genetic variation
Individuals may inherit different alleles of a gene from their parents. Also, because the offspring inherits alleles from both parents, they will be different to them.
Explain mutations for Genetic variation
This is a change in DNA, therefore affecting the protein made and then the characteristic. If the mutation occurs in a somatic cell, then only 1 characteristic might change, but if it occurs in the gametes, it could be passed down to the offspring.
Explain Meiosis for Genetic variation
Gametes are produced by this process and each gamete shares half its genetic material from each parent. Before the nucleus is split, the chromosomes are mixed up by independent assortment and crossing over.
Explain chance for Genetic variation
Many different gametes are produced from the parental genome, so it is just a result of chance which ones combine. This is often called Random Fertilisation.
Sexual Reproduction leads to
A much greater variation than assexual reproduction
Environmental variation
Plants are generally more affected than animals because of their lack of mobility.
Studying variation in identical twins
Because their genetic makeup is the same, any variation is all environmental.
What is discontinuous variation
Can only result in certain values.
Can be represented by using a bar chart, or a pie chart
What is continuous variation
Can take any value within a range. It is: Controlled by many genes Controlled by environmental factors Collected in a frequency table and plotted on a histogram with a curve drawn
Characteristic of a normal distribution curve
Mean, mode and median are all equal
Bellshape and symmetrical about the mean
50% are less than the mean and 50% greater
Most values are close to the mean
What is standard deviation
a measure of how spread out the data is. As the SD increases, variation does too.
Student T’s test
It is used to compare the means of data values of 2 populations
Student T -value equation
difference of the means/ root sum of the SD/No. of samples
Degrees of freedom
(n1 +n2) -2
Steps for a Student T’s test
- create a null hypothesis
- calculate t-value
- calculate degrees of freedom
- If your t-value is below the corresponding student t’s test value on the table, then you can accept your null hypothesis.
THIS MEANS !!!
We cannot be more than 95% confident that the results are not down to chance.
Null Hypothesis
Prediction that there is no significant difference between the specified populations, and so any observed difference is due to a change in variation in the sample.
What is an independent test
2 different samples
What is a paired sample
Running the t test on the same population (before and after a treatment?)
Assumptions to keep in mind while doing the t test
- normal distribution
- similar variance
- same number of data points
- roughly 20-30
What is Spearman’s Rank Correlation coefficient
r = 1 -(6 *sum of rank^2)/ (n^3 -n )
what is a positive correlation
as one set of data increases, the other also increases.
what is a negative correlation
as one set of data increases, the other decreases.
how to find the rank
literally order highest to lowest. highest- 1 , lowest -10 (or number of items)
rs results
+1 - perfect positive correlation
-1 - perfect negative correlation
0- no correlation
how can you workout statistical strength
value need to be looked up in the correlation coefficient critical value tables. For the data to be considered significantly different from the chance, the probability must be less than 5%, creating a certainty of 95%.
what is adaptation
characteristics that improve an organism’s chance of survival and reproduction in its environment.
what are the 3 types of adaptation
- anatomical (physics features- internal and external)
- behavioural
- physiological (processes that occur inside the organism
anatomical adaptations examples
- body coverings
- camouflage
- teeth
- mimicry (animals may mimic others to scare off predators)
behavioural adaptations examples
- survival behaviours
- courtship (to attract males?)
- seasonal behaviour (migration and hibernation- this is where the heart rate, breathing rate etc. all decreases to reduce energy loss)
there are 2 types of behavioural adaptations:
- innate (or instincts)
- learned
physiological adaptation examples
- poison production
- antibiotic production
- water holding
what is analogous structures
adaptation to perform the same function but have a different genetic origin.
what is convergent evolution
when unrelated species begin to share similar traits. These similarities evolve because the organisms adapt to their own environments.
examples of evolution
- marsupial and plancental mole
both burrow through soft soil to find worms
streamlined in body shape
modified forelimbs for digging
velvety fur
differ in colours though (MM: white - orange , PM: grey)
what is selection pressures
the factors that affect the organism’s chance of survival or reproductive success.
Staphylococcus ares
Has become rapidly resistant to many antibiotics.
When the bacteria were exposed to it, some survived and passed on this allele to be resistant to antibiotics to their offspring.
Sheep blowflies
In 1950s, in Australia, blowflies managed to develop a high level of resistance to diazinon. The scientists tested for the allele and they couldn’t find it in a 70-year old blowfly. Then they tested for another pesticide and found the allele for its resistance. So they concluded that pre-adaptations contributed to the development of diazinon- resistance.
Flavobacterium
It has been found to digest nylon 6, therefore quite beneficial.
Nylon 6 provides them with a new source of nutrients.
Scientists believe that the gene mutation to produce this was a result of gene duplication and a frame shift mutation (insertion or deletion of DNA bases)
Potential uses of adult cell cloning
- Preserve endangered animals
- Antiviral proteins
- Produce stem cells
- Create more animals with desirable characteristics
Reasons that support the theory of evolution
Similarities and differences in: Genes RNA Molecules Nucleotide Base sequence Haemoglobin RNA Polymerase Sequence of Amino Acids Sharing a common ancestor Bacteria becoming resistant to antibiotics. Selective breeding.
Why can a lack of genetic variation often allow diseases to be spread
Because if one animal gets this disease, it is quite likely that other animals will get it too.
