Evolution II Flashcards
What is comparative anatomy?
- The study of the evolutionary relationship between species
- Compares the similarities and difference in anatomy
What are homologous structures?
- Found across different species, have similar patterns and have different functions
- Consequence of divergent evolution
- Basic patterns due to common ancestry
- Different functions or appearance due to environmental conditions
Homologous structure example: pen dactyl limb
- Found in all groups of tetrapods (4 legged vertebrae)
- All limbs follow the same bone pattern: 5,2,1
- 5 fingers
- 2 bones on forearm
- 1 bone in the upper arm
What is comparative embryology?
Study of embryos which highlights evidence towards the theory of evolution
e.g. fish, amphibians, reptiles, birds and mammals
the embryos: all have gills but these will disappear in all but fish
All had tails attached by a tail bone, with the tail disappearing in all but fish
What is molecular biology?
Involves comparing DNA sequencing and amino acid sequences of different species
What is mRNA and what does it do?
- mRNA is messenger ribonucleic acid and a record of DNA
- carries the message from inside the nucleus to outside the nucleus where it can be translated into amino acid sequences which codes for a specific protein
What are the bases in mRNA?
Adenine, Guanine, Cytosine, Uracil (instead of thymine)
Relationship between DNA, mRNA, amino acid sequence and proteins?
DNA sequence determines mRNA sequence determines amino acid sequence determines proteins
What is DNA hybridisation?
- Comparing DNA sequences of different species, give a percentage of the similarities between the species
- Generate a percentage of differences between organisms
- Thus prove the theory of divergent evolution
What are the steps of DNA hybridisation?
- Prepare a section of DNA and separate strands by heating them
- Allow separated DNA strands of different species anneal
- Now have hybrid strands of DNA
- Reheat hybrid strands, until they separate again
Where a lower separating point: the samples are not as closely related due to its less base pairing
Where a higher separating point; the samples are closely related to extensive base paring
How are proteins suggestive of a common ancestor?
- Amino acid code for proteins
- Proteins are common in many different species but have a different number of amino acids coding for that protein
How is haemoglobin suggestive of a common ancestor?
- Found in many different species
- All serve the function of binding oxygen in blood
- Differ in amino acid sequence between species
How is insulin suggestive of a common ancestor?
- Mammals produce insulin to maintain sugar levels in blood
- That insulin from pigs can be used in humans as a replacement
How is cytochrome- c suggestive of a common ancestor?
- Involved in converting energy into a form, cells can use
- The number of cytochrome-c varies
- With fish having 20- 25 more amino acids than we have, but monkey only have 1 more
What does molecular biology reveal about the DNA of humans and chimpanzees?
That their DNA vary by 1%