How related are we? 13

Question 1

Master Gene

Answer 1

Genes that control the expression or a large number of gene in early development

Question 2

Know how to use of phylogenetic trees to show relatedness between species

Answer 2

yes

Question 3

Amino acid sequencing

Answer 3

• Comparing amino acid sequences can be used to determined relatedness between two organism

Question 4

Nucleotide sequencing ( DNA sequence)

Answer 4

• Comparing Nucleotide differences ( DNA sequence) between organisms can determine the relatedness of them
• Use genes such as Cytochrome C or β hemoglobin, as these genes are in most species.

Question 5

Mitochondrial DNA

Answer 5

• Mitochondrial DNA can be used as a molecular clock

- mitochondrial DNA (mtDNA) is maternally inheritable, meaning inherited from only mother.

Question 6

DNA hybridisation

Answer 6

A technique used to compare the similarities of DNA sequences of different species. The greater the
melting temperature the closer related the species of DNA sequences are similar the use of phylogenetic
trees to show relatedness between species

Question 7

Two main advantages of using mtDNA over nuclear DNA as a molecular clock:

Answer 7

• The mutation rate in mtDNA is much faster than in nuclear DNA making it useful for more closely related species which have had less time to accumulate mutations.
• There is no recombination (mixing of DNA between homologous chromosomes during gamete development) in mtDNA because it’s inherited from the mother, making it possible to trace unbroken lineages.

Question 8

DNA hybridisation Method: read

Answer 8

1. Denaturation – DNA from two different species are heated ( 95°C) to break all of the hydrogen bonds to create single-stranded DNA.

2 Hybridisation – Single-stranded DNA from both species mixed together and cooled, (allow complementary bases pairs of DNA from each species to form hydrogen bonds.)
- The more related the species= the more homology there will be between the two DNA strands,=and the more hydrogen bonds will form.

3 Melting – Samples are heated to determine melting temperature (Tm).
- As the temperature increases, more hydrogen bonds will break until ultimately all DNA in the sample is single-stranded (like in step 1).
- More hydrogen bonds between strands means that more heat will be needed to separate those two strands of DNA.
- Therefore, high Tm correlates with high
sequence homology and closer relatedness

Question 9

BMP4

Answer 9

• Stands for ‘ Bone morphogenetic protein 4( BMP4) and encoded by gene BMP4
• BMP4 is a signaling protein found in all vertebrates that controls cartilage =, bone, and muscle development in embryo

Question 10

Example BMP4 in African Cichlid fish

Answer 10

• (Native to East Africa) Within and between the species there are many phenotypic differences, they had a distant ancestor (Convergent Evolution).
• They lived in different lakes and under similar selection pressures
• -> developed analogous jaw structures.
• BMP4 Master Regulatory Genes codes for the BMP4 Regulatory Protein,
• at high concentration BMP4 protein promotes the development of shorter jaws during embryonic development,
• low BMP4 concentration = more elongated jaws. (same function different structure)
  Similar selection pressure = natural selection( require more muscular , larger and stronger) favoured a common jaw shape.

Question 11

Example BMP4 in Galapagos finches

Answer 11

• Darwin’s Finches differed in size, shape, mass
  and size and shape of beaks.
• All of the finches came from one ancestral population and had changed over time due to unique selection pressures.( divergent evolution)
• Both BMP4 and CaM were responsible in beak differences.
• Mutations in these master regulatory genes = dramatic changes to beak shape.
• Phenotypic changes were selected for by the selection pressure for each Finch’s niche.
• -> BMP4 codes for beak shape
  (1) High BMP4 Concentration = stout, strong, larger beaks ideal for crushing seeds and nuts
  (2) Low BMP4 Concentration = narrow and shallow beaks.
• -> CaM codes for beak length
  (1) High CaM = elongated beaks
  (2) Low CaM = short beaks

Question 12

Sterlie

Answer 12

Free from bacteria or other living microorganisms, totally clean.

Question 13

closely related

Answer 13

most recent common ancestor

Question 14

most recent ancestors on phylogenetic trees

Answer 14

look at nodes

Question 15

Explain how morphological data of various lizard species could be used to construct a phylogenetic tree.

Answer 15

• By comparing the similarities and differences between homologous structures,
• scientists can deduce relationships between organisms and construct a phylogenetic tree

Question 16

Give an example of a characteristic that would be advantageous for a trunk-dwelling lizard.

Answer 16

• Brown camouflage would allow lizards to blend into tree trunks.
• Large legs would enable lizards to grasp onto tree trunks better.
• Large size would give lizards better protection from predators.
• Claws would allow lizards to defend themselves from predators and cling on trunk easier

Question 17

How can morphological evidence be used to explain divergent evolution between two strains of the virus?

Answer 17

• Two strains that have diverged will have homologous structures in common.
• We expect these homologous structures to change in each strain after divergence, allowing us to use these structures for identification. ( protein coat)

Question 18

molecular clock

Answer 18

a model that
suggests the mutation rate can
be used to determine relatedness
between two organisms

Question 19

mutation rate

Answer 19

number
of mutations that occur in a gene
or genome over time

Question 20

Examples of uncertainity on phylogenetic trees ( Read)

Answer 20

• Since dating techniques not 100% precise uncertainties can occur
• Lack of node: means that exact divergence time is unknown
• The break between species means possible ancestor but no evidence if translational fossil that supports the hypothesis
• node splitting into more than two lineages mean uncertainty called polytomy where it is unclear which species diverged from the others first.

Question 21

Explain how amino acid sequences may be used to determine relatedness between species.

Answer 21

• Amino acid sequences from the same protein are compared between two species.
• Changes from one amino acid to another in the sequence accumulate over time and so more amino acid changes indicate more distant relatedness.

Question 22

DNA hybridisation technique answer style

Answer 22

• DNA is heated to 95°C to break the hydrogen bonds between strands.
• Single strands from both species are mixed together and cooled, allowing the two strands to form hydrogen bonds with each other, creating a double-stranded hybrid DNA.
• Hybrid DNA is then reheated and the temperature at which half of the DNA becomes single-stranded is noted.
• This temperature is known as the melting temperature

Question 23

Describe one way that genes are regulated so that the same genes can produce different appendages when expressed in different locations in the Artemia embryo.

Answer 23

• Genes could be expressed for different lengths of time in the embryo.
• For example, switching on the gene earlier or switching it off later could result in a longer swimming appendage in organism.
• Or each location in organism may contain different regulatory sequences that respond differently to the same master gene.

Question 24

Different beak shapes in finches allow them to specialise on different foods. For example, finches with long thin beaks are better adapted to probing flowers and fruit.

Describe a selective advantage of having a wide, deep beak.

Answer 24

• A wide deep beak would allow a finch to crack open seeds and nuts.
• Prey specialisation means finches won’t face as much competition from species that do not have the appropriate beak shape to access that food
• and will therefore increase their reproductive success

Question 25

Scientists bred a line of chickens that expressed reduced levels of the BMP4 protein during the beak formation stage of embryonic development.

Identify what kind of beak shape you would expect this line of chickens to have.

Answer 25

Small beak with low width and depth.

Question 26

Explain whether or not jaw shape could be used to determine relatedness between cichlid fish species.

Answer 26

• No,jaw shape could not be used to determine relatedness between cichlid fish species, as jaw shape is not inherited from a common ancestor.
• Rather, the jaw shape in each lake is determined by the selective pressures present in each lake.

Question 27

What can mutations in master gene do

Answer 27

• they can cause drastic phenotypical changes in a short period of time

Question 28

Melting Temperature

Answer 28

The melting temperature, is the temperature which half of the DNA strands in a sample becomes single stranded

Question 29

Describe one type of evidence that biologists could use to estimate an approximate time of divergence between these species.

Answer 29

• The number of mutations that accumulate in nuclear DNA between species may indicate time since divergence.
• The number of amino acid differences that accumulate between species may indicate time since divergence.
• Scientists could use DNA hybridisation to estimate how related the species are - the less similar their DNA the longer ago they diverged.
• Fossil or stratigraphic evidence such as the sequence of fossils may indicate divergence time.
• mitochondrial DNA sequences could be compared between species. If the mutation rate is known, the number of mutations that accumulate within mtDNA may indicate time since divergence.

Question 30

What is adaptive radiation

Answer 30

Adaptive radiation is a process in which a number of different species rapidly diverge from a common ancestor in a relatively short period of time.