EFB-311 Principles of Evolution Exam 4
Terms
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- JUMPING GENE
- Transposable element
- How does a transposon transpose itself?
- A transposon codes for proteins that catalyze its own transposition.
- What are the 3 Type I transposons?
- LTRs, SINEs and LINEs
- TYPE I TRANSPOSON
- RNA intermediate
- CLASSIC TRANSPOSON
- Type II Transposon
- TYPE II TRANSPOSON
- DNA
- TRANSPOSON
- Gene that migrates (transposes) and copies itself
- LINE
- Type I transposon; encodes reverse transcriptase, lacks LTRs, transcribed by RNA polymerase II
- LTR
- Long terminal repeat; type I transposon; contain LTRs ranging from 100bp-5kb in size, 8% of human genome
- LINE (acronym)
- Long interspersed nuclear elements
- SINE
- Short interspersed nuclear element; type I transposon; less than 500bp DNA segments that do not code for reverse transcriptase and rely on other mobile elements for transposition
- Why are Type I transposons considered "RNA intermediate" and Type IIs are considered "DNA?"
- Type I transposons have an RNA intermediate form-- they copy and paste themselves. Type II transposons have no intermediate and rely on the transposase enzyme to copy and paste their sequences.
- What are 2 hypotheses for the existence of transposons?
-
- 1. They benefit the organism (they introduce antibiotics through plasmids from Type IIs, and generate non-forward-looking variation.
- 2. They replicate selfishly (at gene level, not organism level).
- The selfish replication and genetic parasitism of a transposon can be counteracted by what?
- Natural selection on the afflicted individual
- Is the genome a cohesive unit? Why or why not?
- No. The genome consists of a collection of mostly cooperating, sometimes warring genes.
- LATERAL GENE TRANSFER
- Genes moving between organisms, esp. in bacteria
- What are 3 forms of lateral gene transfer in bacteria?
-
- TRANSDUCTION (phage picks up and moves host DNA)
- TRANSFORMATION (bacteria picks up DNA from the environment)
- CONJUGATION (bacteria sex with plasmids)
- PLASMID
- Circular genetic element that codes for antibiotic resistance, virulence factors and metabolic enzymes
- Genes and gene groups can have different evolutionary interests from the ______.
- genome
- ENDOSYMBIONT
- Organism which lives in the body/cells of another organism
- Can a host acquire genes from its endosymbiont?
- Yes, freq
- Master switches for regulatory cascades are ____ _____.
- highly conserved
- What are 3 ways a developmental plan can be modified?
- Location, timing and amount of development
- Where does evolution work on a gene sequence?
- Promoter region
- If all cells have the same genes, how do cells know where they are?
- Position in space and time relative to others determines function
- Bodies are developed by the interactions of a ______ ___ ____ ____.
- network of regulatory genes
- PATTERNING
- Cell fate is determined by position, time and concentration of signals
- HOX
- Group of genes that specify the anterior-posterior axis and segment identity during development
- How does evolution produce tremendous diversity from highly conserved patterning genes?
- Tweaking, co-opting and copying
- Hox genes occur in ____ of __ to ___.
- clusters, 5 to 10
- Fewer Hox genes are produced ___ in development when the ___ is formed, and more ___ in development when the ____ is formed.
- late, posterior, early, anterior
-
TRUE/FALSE:
Hox genes arose after the division between plants and animals. - FALSE
- HOMEOTIC REGION
- Portion of a gene sequence that interacts with DNA transcriptional regulator; location of Hox genes
- There were __ ancestral Hox genes that duplicated in the ____ ______ to produce __ to __ Hox genes in Bilaterata.
- 5, Cambrian Explosion, 8 to 10
- The __ to __ Bilaterata Hox genes duplicated to form the Hox genes of __, which duplicated again to form the Hox genes of ___ _____ ____.
- 8 to 10, vertebrata, ray finned fishes
- We have 9 Hox genes in common with what group of organisms?
- Arthropods
- APICAL ECTODERMAL RIDGE (AER)
- Ectodermal structure overlying embryonic limb bud, becomes skin of limb; formation initiated by secretion of FGF-10, then the AER secretes FGF-8 and FGF-4 to stimulate limb development
- ZONE OF POLARIZING ACTIVITY (ZPA)
- Segment of mesenchyme signaled by the AER which in-turn signals a limb bud to form an anterior-posterior axis
- Hox genes are co-opted by the ____ __ ____ ___ to set up limb segments.
- zone of polarizing activity
- SONIC HEDGEHOG (Shh)
- Morphogen required by the ZPA for anterior-posterior patterning; can be transplanted to produce mirror image digit duplications
- SPECIES
- Smallest evolutionarily independent unit
- What are the 3 concepts of "species?"
- Morphospecies, biospecies and phylogenetic species
- PHYLOGENETIC SPECIES
-
Species based on monophyly
Widely applicable to living, extinct, sexual and asexual species, and can ID cryptic species
Does not work well with fossils, requires well-supported phylogeny and time, not sure how much divergence is needed to count - What are the 3 steps of species formation? When does each occur?
-
- 1. Populations become genetically isolated
- 2. Traits and allele frequencies diverge from ancestral population
- 3. Secondary contact reinforces divergence via reproductive isolation
- ALLOPATRY
- Geographically isolated population
- DISPERSAL AND COLONIZATION
- Allopatry where one population wanders and becomes isolated, ex. mainland species coming across a volcano-born island
- VICARIANCE
- Allopatry where an existing population is divided, ex. mainland populations separated onto islands by rising seas
- FOUNDER EFFECT
- Loss of genetic variation when a small number of individuals from a large population found a new population; effect of genetic drift (variation due to chance) increases greatly
- PARAPATRY
- Speciation occurring in a continuously distributed population; gene gradient tends to reflect environmental gradient
- SYMPATRY
- Speciation occurring within the ancestral population range via strong assortive mating (ex. sexual selection)
- What happens when hybrids between new and ancestral pops are less fit than parents?
- Selection for reduction of interbreeding
- What happens when hybrids between new and ancestral pops are equally fit compared to their parents?
- Homogenization of two parent pops
- What happens when hybrids between new and ancestral populations are more fit than their parents?
- Third species forms OR an ecotone
- Who determined the different groups of old world monkeys, apes and humans? How, and in what year?
- Thomas Huxley, anatomy, 1863
- Who determined the groups of apes, chimps, humans monkeys? How? In what year?
- Sarich and Wilson, cross-reactivity of serum albumin, 1967
- Most genetic evidence suggests humans are more closely related to ___ than ___.
- chimps, gorillas
- How long ago did chimps and humans diverge from gorillas?
- 6.4 mya
- How long ago did humans diverge from chimps?
- 5 mya
-
TRUE/FALSE:
Some genes suggest humans are more closely related to gorillas than chimps. - TRUE
- How different is human mtDNA from chimp mtDNA? amino acids? non-coding DNA? in/dels?
-
- 10% difference in mtDNA
- 1.34% difference in amino acids
- 1.24-1.64% (35M SNPs) difference in non-coding DNA
- 5M difference in in/dels
- Who determined the Earth was 74,000 years old?
- deBufon
- Who determined the Earth was less than 40M years old? In what year?
- Lord Kelvin, 1897
- How was the current accepted age of the Earth determined? What is it?
- Radiometric dating, 4.5 billion years
- How old is the oldest terrestrial rock?
- 3.8 billion years
- How old are the oldest bacteria-like microfossils? Where were they found?
- 3.26 billion years, South Africa
- Why did Earth have no life in the first 0.5 billion years of its existence?
- Constantly bombarded by meteors
- How old are the controversial "worms" discovered by Bill Schopf?
- 3.45 billion years
- What are 3 characteristics of a universal ancestral gene?
-
- 1. Present in all extant organisms
- 2. Has a function
- 3. Strong stabilizing selection
- Who used analysis of a small subunit of ribosomal RNA to determine the division of organisms into the modern clades?
- Carl Woese
- LUCA
- Last universal common ancestor (2 bya); enzymes made from protein, capacity to make protein, 30 universal genes as ribosomal proteins, 15 aminoacyl-tRNAs (attach amino acids to tRNAs)
- What are 2 hypotheses about the identity of LUCA?
-
- 1. LUCA is a community with lateral gene transfer.
- 2. LUCA was a virus.
- MIMIVIRUS
- Large virus that looks like a bacterium