Topic 13: Evolution

Question 1

An organisms complete genetic makeup is contained within its?

Answer 1

Genome

Question 2

Genomes can vary in what?

Answer 2

size, number of genes, and gene density between organisms

eukaryotes- genomes tend to be larger in most cases

Question 3

Gene densities tend to be higher in what?

Answer 3

of genes per length of DNA
-higher in prokaryotes
-shorter DNA but still many genes results in higher densities

Question 4

Multicellular eukaryotes have lots of non-going DNA and many multigenerational families contained within their genomes, what are they?

Answer 4

-introns (DNA between protein coding genes)
*20%
-gene-related regulatory sequences
*5%
-unique single copy DNA
-pseudogenes (former genes that no longer function)
-repetitive DNA (present in multi copies in the genome)
-simple DNA repeats

Question 5

What are multigene families?

Answer 5

collections of 2 or more identical or similar genes

ex. global genes that make up hemoglobin

Question 6

What are transposable elements?

Answer 6

are stretches of DNA that can move from one location to another within the genome
-moves via recombinant events

1. Transposons-move by an intermediate enzyme called transposase (‘cut and paste’)
2. Retrotransposons- move via an RNA intermediate (‘copy and paste’)

Question 7

How to Transposable elements contribute to genome evolution?

Answer 7

1. promote recombination
2. disrupt celular genes or control elements
3. carry entire genes or axons to new locations

Question 8

What happens if a transposon jumps into the middle of a protein-coding gene?

Answer 8

it could prevent the normal transcription of the gene

Question 9

What happens if a transposon jumps into the middle of a regulatory gene?

Answer 9

it increases or decreases the production of one or more proteins

Question 10

What happens to genome evolution if duplication of entire chromosomes sets?

Answer 10

errors in meiosis (such as failure to separate homologous chromosomes can result in polyploidy
-usually lethal, some cases can facilitate gene evolution
-duplicated genes have mutation that occur that allow them to function differently
-pass these duplicated genes to offspring
-many plants evolve this way

Question 11

What is divergent evolution? ***

Answer 11

lecture 32 slide 9

Question 12

Duplicated of gene-sized regions of DNA can contribute to genome evolution how?

Answer 12

errors in meiosis can cause duplication of chromosomal regions
-unequal crossing over during prophase 1 can results in chromosomal deletions in one chromosome and chromosomal duplicated in the other

Question 13

How can human global genes evolve from duplication events?

Answer 13

-a single global gene underwent duplication and divergence
-mutations in the diverged global genes results in two different functioning genes on two different chromosomes

Question 14

How can related genes have different functions after duplication and divergence?

Answer 14

-lecture 32 slide 12

Question 15

How do exons lead to genome evolution?

Answer 15

EXONS ARE DNA sequences THAT CODE FOR PROTEINS

-can be duplicated or deleted in homologous chromosomes due to unequal crossing over in meiosis
-duplicated exons could code for more of the protein, resulting in protein stability within it domains, increase ability to bind to ligands

IF different axons are moved within a gene or between two different genes due to errors in recombination during meiosis, this exon shuffling could lead to new proteins with novel functions

Question 16

The more similar in sequences the genes and genomes of two species are they are closer or further in evolutionary history?

Answer 16

the more closely related they are in their evolutionary history

Question 17

What does it mean to be highly conserved?

Answer 17

genes that have remained similar over time are highly conserved

Question 18

What does comparing genes show us?

Answer 18

allows us to see if certain genes are evolving faster in certain organisms

Question 19

Genes that code for transcription factors evolve faster or slower?

Answer 19

evolve faster than others

Question 20

Comparing genomes within the same species allows us to see what?

Answer 20

genetic differences that lead to diverse phenotypes
-most genetic variation appears in the form of single nucleotide polymorphisms (SNPs), which are single base pair sites found in at least 1% of the population

-also occur from copy-number variants, where individuals have one or multiple copies of a gene or gene region (caused by duplication) father than one copy per homologue

Question 21

What is evolutionary development?

Answer 21

is the study of developmental processes of different multicellular organisms
-goal: to understand how processes evolved and how these changes modify existing organismal features or lead to new ones

Question 22

What is a homeobox?

Answer 22

180-nucleotide sequence that goes for a 60-amino acid homeodomain

Question 23

What are homeotic genes?

Answer 23

master regulatory genes that control placement and spatial organization of body parts in organism by controlling the development fate of groups of cells

Question 24

What was Charles Darwin scientific explanation for 3 observations?

Answer 24

1. the striking way organisms are suited for life in their environment
   -natural selection, adaptations
2. the many shared characteristics
   -(unity) of life
3. the rich diversity of life
   -descent with modification
   -branched, not linear

Question 25

What is Charles Darwins definition of EVOLUTION?

Answer 25

evolution to be descent with modification -species are descendants of an ancestral species that were different from the species we see today evolution is both a pattern and a process pattern: scientific evidence process: natural observed changes

Question 26

What was Aristotles early ideology?

Answer 26

Aristotle (384-322 BCE) saw species as unchanging/ fixed -scale naturae (scale of nature) -basis of Old Testament, life is permanent and perfect

Question 27

What was Carolus Linnaeus early ideology?

Answer 27

Carolus Linnaeus (1707-1778) classified life according to their similarities -Linnaean classification of taxonomy -nested classification compared to Scale Naturae -described based on pattern of their creation (what they looked like)

Question 28

What were Darwins theories influenced by?

Answer 28

1.Fossils -remains of traces of organisms from the past -contained within rock layers called strata 2. Slow and Subtle processes were changing organisms over time

Question 29

What was Georges Cuvier's idea?

Answer 29

(1769-1832) notes older strata had different species than newer strata -speculated that each stratum represented a single catastrophic event leading to the extinction of that species

Question 30

What was James Hutton's idea?

Answer 30

(1726-1797) proposed that Earth's geological features were a result of gradual processes (erosion, valleys being formed by rivers)

Question 31

What was Charles Lyell's idea?

Answer 31

(!797-1875) proposed that the same geological processes in the past were occurring in the present, at the same rate (based off James Hutton's idea)

Question 32

What did Jean-Baptiste de Lamarck propose?

Answer 32

(1744-1829) proposed the first hypothesized mechanism for evolution -suggested: evolutionary change explains that patterns seen in the fossils and how certain organisms are found in certain environments -suggested: (1809 year Darwin was born) there were multiple lines of descent. -suggested: it was explained by use and disuse -body parts that were needed became stronger and larger, body parts that were no longer needed deteriorated ex. giraffes long necks -suggested: inheritance of acquired characteristics could be passed too offspring suggested: organisms had a nature need to become more complex

Question 33

What was Darwins observation of adaptations?

Answer 33

Galapagos Islands -darwin's finches had different beak size and shapes based on environment and food sources

Question 34

What is natural selection?

Answer 34

where individuals that have certain inherited traits tend to survive better and reproduce due to those traits NOTES TO REMEMBER: 1. individuals do not evolve, populations do 2. traits must be heritable and vary within a population for selection to occur 3. favourable traits depend on the context of the environment; evolution is not goal directed

Question 35

What is a common ancestor?

Answer 35

similar organisms that share a common ancestor from which they formed

Question 36

Diverse environment means diverse selective pressures, what do they lead to?

Answer 36

1. leads to diverse adaptation to the environment 2. lead to new divergent species

Question 37

What is Adaptive Radiation?

Answer 37

a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges or opens new environmental niches

Question 38

What do phylogenetic trees show?

Answer 38

1. dedicated are the evolutionary relationships of vertebrates 2. all organisms here have been evolving for the same amount of time

Question 39

What is Artificial Selection?

Answer 39

Darwin notes that humans have modified other species by selective breeding with desire traits -trait must be variable in the species and heritable

Question 40

What factor provides selective pressure?

Answer 40

the environment -takes a LONG time -different population adapt to their environments and eventually become separate species

Question 41

What is Relative Fitness?

Answer 41

Contribution an individual makes to the gene pool of the next generation relative to other individuals in that population -reproductive success of an individual -better term for "survival of the fittest" examples: -no genetic disorder, no disease, surviving environmental condition, not getting eaten, ability to attract a mate

Question 42

Natural Selection cannot make a "perfect" organism, why?

Answer 42

1. selection can only act on existing variations -favours only fittest variants from phenotypes available -may not be the best trait for an environment 2. Evolution is limited by historical constraints -each species has a leafy of "descent with modification" from ancestral forms -evolution doesn't start 'fresh', but modifies previous ones and adapts to existing conditions 3. Adaptations are often compromises