Pre Midterm I Flashcards
Understand definitions of phylogenies, evolution, etc.
What are subfossils vs coprolites?
Subfossils are not old enough to be considered true fossils
Coprolites are fossilized feces
Copros comes from kopros meaning feces
Which kingdom of life evolved first?
Bacteria, then likely archaebacteria
Note: Bacteria are generally haploids
Define supposition
Dating fossils based on surrounding rock layers
Order the eons of geologic time
- Hadeon Eon
- Archeon Eon
- Proterozoic eon (oxygen revolution) (ends with Cambrian)
- Phanerozic eon (current)
- paleozoic
- mesozoic
- cenozoic (current)
Order the key events of the phanerzoic eon
- Earliest chordate fossils
- Oldest trackways
- Land plant fossils
- Oldest land vertebrates
- Dinosaurs
- Common mammalian ancestor
- Birds
About how long ago did eukaryotes come into existence?
~ 1.8 bya
What were the first animals, and why do we consider them animals?
- Sponges
- Cholesterol like-biomarker
What are the key features of the Cambrian explosion?
- Bilateral symmetry, segmentation
- Increased body size, complexity
- Hard body parts
- First Chordates
Likely caused by increased oxygen, predation, evolutionary innovation
When did the first land plants evolve?
Late ordovician or Silurian ~ 450 mya
Characterize the end of the Devonian period
Ferns, horse tails and emergence of first seed plants
Approx how old are humans?
Homo sapiens are around 200k years old
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Define and give an example of a synapomorphy, symplesiomorphy.
Synapomorphy: Shared derived trait from most recent common ancestor of taxa
example: Body hair of mammals
Symplesiomorphy: Ancestral trait
example: Body hair for primates, bipedalism of hominins
Define and give an example of autopomorphy
A derived trait UNIQUE to a single taxa
eg Bird feathers
“self form”
Define in your own words, the differences between* homoplasy* and homology, provide an example for each.
Homoloplasy: “Same form” is an analogous trait, arise from convergent evolution
example: Bird and bat wings
Homology: “Same relation” is a trait arisen from a common ancestor
eg Forearm structure in whales, cats, bats, humans.
The hope is the most parsimonius clado will expose homoplasies
What is the difference between synapomorphy and homology.
A synapomorphy is a shared trait from most recent common ancestor, this may include present or lack of presence of anatomical feature
A homology is an anatomical feature present that arises from most recent common ancestor
- Every homology is a synapomorphy, but not every synapomorphy is a homology
What is the difference between a cladogram and a phylogram?
Cladogram does not depict passage of time, a phylogram depicts passage of time, or # of evolutionary changes
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True or False:
According to Biol221:
A majority of mutations are harmless.
False
Also:Recall all mutations are equally likely, and most are not inherited
Analogy: When writing an essay, how often are typos beneficial?
Which nucleotides are purines?
DNA
Adenine and guanine
Which nucleotides are pyramidines?
i
Thymine and cytosine, and uracil
Which nucleotides pair together?
in DNA
Pyramidine and a purine,
eg AT and GC
What is the purpose of wrapping DNA in histones?
Protection
Limiting access to transcription (regulation)
True or False:
Transcription requires two template strands
False, only one is used
Define isoforms
Similar proteins, that occur because of alternative splicing of mRNA
What is the difference between a missense mutation and a nonsense mutation?
Missense: Encoding of wrong amino acid
Nonsense: Premature encoding of stop codon
What are the types of point mutations?
Will they necessarily have an effect on protein structure or function?
Transition: Purine replaced with purine, or pyramidine with pyramidine
ie AG/ with AG or CT with CT
Transversions: Purine replaced with pyramidine, or vice versa
2) possibly, synonmous = silent (no effect)
Synonymous means “same meaning”
What kind of mutation may cause a frame shift
Hint: Recall we went over 5 types of mutations
Definetly indels and duplications
What is a translocation mutation?
Non homolgous chromosomes fuse
What are transposable elements?
Genes, products of ancient viral infection.
Explain the difference between mono, para, and poly phyla
Mono: contains all descendants of common ancestor
Paraphyla: Contains some descendants
Polyphyla: Taxa do not share common ancestor
When did hard body parts first appear in animals?
Cambrian explosion
Characterize the Archaeon period
~ 3.8 t0 2.5 bya
Life is limited to the ocean
What is the difference between phylogenetics and taxonomy?
Taxonomy is the classifcation of organisms, phylogenetics ensures classification reflects evolutionary relationships
What are pseudogenes?
Ancient genes that lack a promoter, they are evolutionary artifacts
True or False:
Phenotypes cannot change in one’s lifetime.
False.
A phenotype could definitely change in a life time
Note: Phenotypes are not inherited, selection acts on phenotype not geno
What is the difference between polyphenism and genotypic plasticity?
Polyphenism is a special case of genetic plasticity, which involes more than one discrete phenotype, which may arise from single genotype,
plasticity refers to a spectrum
As a reminder most traits are not Mendelian
What is an allele?
Variation in a genetic sequence found in the same loci between different homologous chromosomes. DIploidic organisms will have just 2 alleles, though many can exist in a population.
Where is the codon located?
On the mRNA not DNA
When is carbon dating a good idea?
For specimens < 50k years old
The earliest primate fossils show up around which time period?
In the cenozoic era
Who developed the first “real” trees, ie with time scales?
Ernst Haekel
What are the most common types of mutations? and least common?
Most: Point mutation
Least: change of # of chromosomes
What is Mendel’s Law of Segregation
each gamete recieves just one allele
What is Mendel’s Law of Segregation
Each gamete gets one allele
Give an example of a polyphenism
Dung beetle horns are either large or small depending on nutrition during development, aphid wings are either small or large depending on day length and nutrition during development
When did multicellularity arise?
From 1.6 to 2.1 bya (potentially)
Note: Similar time frame to Eukaryotes
Does diversity always reflect evolution?
Evolution is change in allelic frequency in population, so if diversity is not a result of this, then no.
What is the role of the outgroup?
A species suspected to have split off prior to diversification event, helps root the tree
True or False:
Mutations are adaptively directed
False, mutations are not driven by the environment, the benefit/harm of mutations are driven by the environment
Why don’t most traits follow Mendelian Inheritance?
ie Why don’t phenotypes match Mendelelian predictions?
- More than 2 population alleles exist
- Influence of other genes
- Influence of environment
What causes traits to be continuous?
Polygenetic inheritance,
ie many genes contribute to same trait
True or False:
Environmental conditions will NEVER have a greater impact on phenotype, than the Genotype
False:
They often do have greater impact than genotype
