origin of life

Question 1

miller-urey experiment

Answer 1

mixture of water and simple chemicals + electric pulses (“lightning”) form amino acids easily
ie. organic molecules formed from inorganic compounds

Question 2

RNA hypothesis

Answer 2

RNA can store genetic info AND catalyse primitive chemical reactions
RNA based-life as a precursor to DNA based life

Question 3

likely location where life began

Answer 3

deep sea hydrothermal vents
mineral rich temp gradient
cells harvest energy gradient (proton-motive force due to pH diff across membrane)

Question 4

universal features of cells

Answer 4

the minimal self-reproducing unit (by templated polymerisation of DNA)
proteins as catalysts
enclosed in PM
require free energy

Question 5

LUCA

Answer 5

last universal common ancestor

Question 6

branches of the phylogenetic tree of life

Answer 6

bacteria and archaea split first
eucarya branch from archaea

Question 7

Archaea vs bacteria key difference

Answer 7

archaea often survive in harsh environments

Question 8

how does genome size link to replication time

Answer 8

larger genome, longer to replicate (for single celled organism, multi-celled more complex)
human cell 11-20hrs to replicate

Question 9

most of DNA codes for:

Answer 9

sequences that positively/negatively regulate gene activity (eg. turning on or off in response to different things)

only a small part of DNA codes for proteins / RNA molecules

Question 10

four events occurring in the generation of new genes

Answer 10

intragenic mutation: changes in DNA of existing gene (errors in replication)
gene duplication: identical set produced
segment shuffling: 2+ genes broken+rejoined –> hybrid gene
horizontal transfer: piece of DNA transferred from genome of one cell to another

Question 11

define homolog, ortholog, paralog

Answer 11

homolog: genes related by descent
ortholog: genes in two separate species from the same ancestral gene, by speciation
paralog: related genes resulting from gene duplication within a single genome, can evolve to have different functions in the same organism

Question 12

eukaryote vs prokaryote

Answer 12

eukaryote has a NUCLEUS
about 10x longer, 1000x volume
have cytoskeleton
prokaryotes have tough cell walls

Question 13

define endosymbiosis

Answer 13

proposed origin of mitochondria
engulfing a bacterium into ancient eukaryotic cell precursor

Question 14

evidence for endosymbiosis

Answer 14

most eukaryotes contain mitochondria
mit similar size to bacteria
own DNA / ribosomes
double membrane

Question 15

evolution of mitochondria hypothesis

Answer 15

anaerobic eukaryotic cells
endosymbiotic relation w bacterium –> advantage in O2 rich environments

Question 16

model eukaryote

Answer 16

baker’s yeast, saccharommyces cerevisiae
fungi
nucleus, cell wall, mitochondria

Question 17

model prokaryote

Answer 17

E. coli
gram-negative, rod-shaped
no nucleus, 1-5microns in length, complex cell wall

Question 18

two types of eukaryotes

Answer 18

unicellular: protists, fungi
multicellular: plants, animals

Question 19

model plant

Answer 19

arabidopsis, common wall cress
chloroplasts to fix CO2
AND mitochondria to use in the dark

Question 20

general structural features of mitochondria

Answer 20

outer / inner membrane w inter membrane space
christae
matrix

Question 21

structural features of chloroplasts

Answer 21

outer/inner membrane w intermembrane space
stroma (vs matrix)
thylakoids (memb+space)