Lecture 18 Flashcards

1
Q

What is the name given to the representation of the differences between species and their evolution from common ancestors

A

Phylogenetic tree

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2
Q

It has been shown that most of the genes across kingdom Animalia have been relatively conserved. How has this been achieved

A

BLAST analysis of protein structures to determine regions of significant homology

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3
Q

It was determined that what makes members of the animal phyla different is not differences in the genetic sequence as such but what difference was seen

A

Changes in expression of a common set of genes

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4
Q

For great apes and man the change in the nucleotide sequence is about 1% every 10million years, T or F

A

T

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5
Q

If the human and great ape nucleotide sequence changes by roughly 1% every 10 million years and the common ancestor of humans and chimpanzees evolved 5 million years ago, how different are their genomes. Represent this as a fraction and as a number of nucleotides

A

0.5% difference – 1 in 200 nucleotides

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6
Q

Firstly, molecular data is used to distinguish specices which is then backed up by morphological data, T or F

A

F – vice versa

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7
Q

When assembling the phylogenetic tree a specific gene is used to determine relation, this gene is FOXP2. Why is FOXP2 used as a way of differentiating between species

A

FOXP2 is a highly conserved protein which only shows differences at a few positions in the amino acid sequence

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8
Q

Which positions in the amino acid sequence does the FOXP2 vary

A

80, 303 and 325

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9
Q

Mice and chimps both have a threonine residue at position 303, what therefore can be inferred about the common ancestor of these species

A

Their common ancestor must have also had a 303T

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10
Q

Humans and chimps both have 80D in the FOXP2 gene meaning that the common ancestor between these species also possess an 80D. Which amino acid is denoted by D

A

Aspartate

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11
Q

When sorting animals into phyla, programmes similar to BLAST consider all possible relations between animals. How are they then sorted

A

The tree is assembled based on the simplest model with the fewest changes

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12
Q

What is meant by the term parsimony

A

The idea that you always assume the simplest model

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13
Q

Convergent evolution goes against the parsimony model. How does convergent evolution account for differences in the amino acid sequence

A

Changes in the amino acid sequence of two animals occur independently of each other

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14
Q

When assembling the phylogenetic tree, molecular phylogeny is compared with morphological phylogeny and fossil records to give us a deeper understanding of evolution, T or F

A

T

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15
Q

Although there are only 4 families of vertebrate FGF receptors, how many distinct receptors are there

A

22

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16
Q

The Ciona or sea squirt is a distant vertebrate ancestor that only contains 4 FGF receptors. What does this tell us about the common ancestor of Ciona and modern vertebrates

A

The common ancestor also had only 4 FGF receptors

17
Q

What can explain the other 16 FGF receptors present in vertebrates that aren’t in sea squirts

A

These will likely have arisen due to genome duplication both locally and by ploidy events

18
Q

What is the name given to a duplicated gene present in the genome

A

Paralogue

19
Q

Chromosome duplications or duplication mutations are seen frequently when comparing genomes, T or F

A

T

20
Q

When a gene is first duplicated, what is its role

A

It is redundant

21
Q

Over time duplicated genes evolve allowing a refinement of function or for a new function to development, T or F

A

T

22
Q

What ways can the extra copy of a gene change

A

Can change the pattern of gene expression or the structure/function of the protein

23
Q

Big changes to protein structure are caused by what type of mutations

A

Domain swapping

24
Q

Smaller changes in the protein structure of a duplicated gene are caused by nonsense mutations, T or F

A

F – missense mutations

25
Q

What is considered to be the common driving force for morphological evolution of animals

A

Changes in expression of genes

26
Q

What changes in the transcription machinery present within the DNA explain why expression pattern changes have a major role in morphological evolution

A

Enhancers can change easily

27
Q

What process can account for bringing a new enhancer regions close to the coding sequence of a gene

A

Non-homologous recombination

28
Q

Enhancers must occur upstream of a target gene, T or F

A

F – enhancers can occur anywhere in the gene sequence and their exact position is usually unimportant

29
Q

Changes in protein structure have to be precise so as not to introduce a variety of negative effects. Give some examples of these effects

A

Introduction of a stop codon, change in the reading frame, interference with protein folding or a disruption in RNA splicing

30
Q

Describe the differences seen in the development of appendages in the fruit fly and Crustacea

A

Crustaceans development limbs throughout their abdominal and thoracic segments whereas in Drosophila, no legs develop in the abdominal regions

31
Q

Explain the interactions between distal-less and ultrabithorax in forming legs in Drosophila

A

Distal-less (Dlx) specifies leg precursor cells in the fly embryo and is expressed in the abdominal and thoracic segments. However, ultrabithorax (Ubx) is also expressed in the abdomen where is represses Dlx expression. Thus, legs form only in the thorax of the fly

32
Q

How do Dlx and Ubx act differently in Crustacea to fruit flies

A

In crustaceans Dlx and Ubx are both expressed in the abdomen and thorax. However, Crustacean Ubx has an anti-repression motif that was lost in insects. Thus dlx expression is not repressed in Crustaceans and abdominal legs develop. These help crustaceans to swim

33
Q

It was found that the Ubx protein in flies lacked an anti-repression domain in the ubx protein. What was seen when comparing the two copies of the ubx gene

A

There was a dramatic change in the Ubx C-terminus in flies. Crustaceans have a motif that block repression. On the other hand, Drosophila contain a polyalanine amino acid sequence which is absent in Crustaceans

34
Q

What would be the results of ectopic expression of Crustacean ubx in the abdominal segments of Drosophila embryos

A

Limb formation in the abdomen due to loss of inhibition of dlx expression