Evolution & Techniques

Question 1

2 possible origins of life (synthesis of prebiotic chemicals)
- Miller-Urey experiment

Answer 1

1) Extraterrestrial origin: Meteorites w/ organic material PAH, amino and irganic acids, ketones + alcohol, purines and C10
2) Terrestrial origin: Organic material was already on earth and spontaneous evolution occurred (amino acids, sugars, purines from CH4, NH3, H2O and N2)
- Simulated spontaneous evolution with gas, water (ocean), and electricity (lightning); Produced aspartic acid, glycine and alanine

Question 2

What developed in cells from the switch from chemical to biological evolution (3)

Answer 2

• Nucleus formed
• Aerobic prokaryote (precursor to mitochondria) engulfed
• Photosynthetic prokaryote plastid engulfed

Question 3

Required attributes for metabolic and genetic replication ability (3)

Answer 3

• Stable membrane
• Cytoskeleton (for adhesion, signalling, endocytosis, exocytosis)
• Reasonably accurate replication

Question 4

Signalling processes in early vs evolved systems

Answer 4

Early:
- Surface receptors to detect water-soluble nutrients and toxins + Intracellular receptors
- Intacrine and exocrine abilities

Evolved:
- Juxtacrine mechanisms
- Autocrine/Paracrine mechanisms

Question 5

Protosomia vs Deutrosomia
Trichoplast adhaerens (Phylum Placozoa)
Epithelial cells of sponges
Cnidaria nerve net

Answer 5

First opening became mouth
First opening became anus
—
Simplest known metazoan
- Had no endocrine or nervous system
- Expresses neuropeptides and ion channels
- Asymmetrical
—
Can transmit signals but had no true nervous system
- Sensed enviro cues and communicate w/ other cells via chemical secretions
—
First functional neural/neurosecretory system

Question 6

The number of hormones in an organism is (directly/indirectly) related to the amount of genetic material present
Increase in genetic complexity is caused by? How many major events in early vertebrates?
Paralogues (Paralagous lineages) vs Orthologues

Answer 6

Directly
Genomic duplications, 2
Paralogue: Came from same ancestor; no speciation; all genes are from same family; Gene divergence
Orthologue: Same ancestor; Similar genes, similar roles, but split into different species; Species divergence

Question 7

Polymerase chain reaction w/ hybridization assays vs chip-based assays + Transcriptome vs Proteome
Microscopy imaging
Protein-chromatin probing
Transgenic models; Floxing vs Flex-switches

Answer 7

Hybridization: Look for 1-2 colours
Chip-based: Multiple visualizations in one sample
Transcriptome: Look at all all transcripts present in cytosol
Proteome: Look at all proteins and interacting partners in a cell
—
Visualizes protein/RNA expression in a sample to allow cellular/regional localization
- Done on fixed tissue or live samples by using antibodies interacting w/ cells expressing target proteins
—
For investigating histone modifications
- Sequence DNA and see how interaction with transcription factors changes under different experimental conditions
—
- Cre/Lox system can turn on and off genes (Cre excises stop seuqnce by recombining loxP sites, allowing transcription of POMC)
- Floxing: 2 loxP sites oriented in same direction and cut gene out
- Flex-switches: 2 loxP sites facing opposite directions and flip target gene around to turn it off (and again to turn on)