Chapter 11 - How Are Species Related?

Question 1

Molecular homology

4 common molecules found across various organisms?

Answer 1

DNA
RNA
ATP
Glucose

Question 2

Molecular homology

Mitochondrial DNA (mtDNA)

1. Can be recovered from?
2. Passed from?
3. Unaltered by?
4. Non-coding region called ? Does what?

Answer 2

1. Ancient skeletal remains - teeth, bones (unlike nuclear/chromosomal DNA).
2. Mother to children.
3. Recombination events that occur with chromosomal DNA during meiosis.
4. D-loop = area of much higher rate of mutational change than the rest of the molecule = person’s phenotype = unique sequence linked to populations and individuals.

Question 3

Comparing DNA between two different species to determine relatedness

1. Comparing DNA sequences
2. Comparing whole genomes
3. Comparing chromosomes - includes examining?
4. DNA-DNA hybridisation - process?

Answer 3

3. Chromosome banding and use chromosome painting.
4. Technique that can be used to compare the sequence between species:
   • DNA extracted from two different species - compared, purified & cut.
   • unique area found.
   • both DNA are heated to make single stranded, then combined together.
   • DNA is cooled to allow renaturation of double stranded DNA.
   • matching areas will bind together.
   • once it has hybridised, it is heated until half of them become single stranded again = Tm = melting temperature.
   • determine degree of hybridisation:
   - complete = organisms identical
   - partial = organisms related
   - no = organisms unrelated

• 1°C Tm difference = 1% difference in DNA sequences

Question 4

Molecular clock

1. Technique for?
2. Limitations?

Answer 4

1. Putting a time scale on speciation events.
2. Each protein ‘ticks’ at a different rate, so cannot compare proteins, rates of change of the same protein can differ in different groups.

Question 5

Showing relatedness

1. Difference between phylogenic trees and cladograms?

• phylogenic trees
• cladograms
• groups called clades = presence of characteristics or features they share.

Answer 5

1. Specific features are added to cladograms, not phylogenic trees.

Question 6

Master genes - homeotic genes

1. Define master genes.
2. What is meant by saying that master genes are highly conserved
3. Express what?
4. BMP4 master gene?

Answer 6

1. Genes that control the expression of many other genes and regulate growth development.
2. A gene that has remained essentially unchanged throughout evolution; changes in the gene may be lethal)
3. Transcription factors that switch genes on or off in a specific order/sequence, especially during development.
4. Bone morphogenetic proteins regulate bone and cartilage growth in embryos, control craniofacial development.

Question 7

Master genes - homeotic genes: cichlids of the African Lakes

1. BMP4 linked to?
2. BMP4 shifts in ? = what? Which allows for?
3. Higher levels of BMP4 = ?
4. Lower levels of BMP4 = ?

• great number of different species that developed quickly in three different lakes in Africa.
• different jaw structures; linked to the variety of diet.

Answer 7

1. The development of the jaw.
2. Shifts in the time of expression of the BMP4 gene, level of expression or where it is expressed = diversity of jaw types. This allows for an increase in survival in an ever-changing environment.
3. Short, robust, small teeth.
4. Long, larger teeth.

Question 8

Master genes - homeotic genes: Darwin’s finches

2 master genes that determine beak structure in Darwin’s finches?
• high levels in early development = ?
• low levels in early development = ?

Answer 8

1. BMP4 = controls beak width.
   • deep, broad beak
   • narrow, shallow beak
2. CaM1 = controls beak length
   • pointed and long
   • less pointed and short