Week 1 - Cell Origins, Diversity and Composition

Question 1

Why do we study cells?

Answer 1

• we are made of them (fundamental unit of life)
• critical to our understanding of health
• understanding how organisms function (metabolism, immunity, and other physiology)

Question 2

ALL cells

Answer 2

-plasma membrane
-genetic info (dna)
-ribosomes
-cytosol/cytoplasm

Question 3

tree of life

Answer 3

bacteria, archaea, eukarya

Question 4

cellular diversity occurs…

Answer 4

within organisms, and among organisms

Question 5

LUCA

Answer 5

last universal common ancestor
- evolved 3.9 billion yrs ago

Question 6

between 3.9 and 1.8 bil yrs ago

Answer 6

1. most cellular biochem evolved
2. lineages leading to modern bacteria and archaea evolved
3. endosymbiosis - evol. of mitochondria & chloroplasts
   4.

Question 7

1.8 billion yrs ago

Answer 7

ancestor to all eukaryotes evolved

Question 8

1.5 billion yrs ago

Answer 8

multicellularity evolved multiple times in eukaryotes

Question 9

theory of endosymbiosis

Answer 9

organism living inside another.

pre-eukaryote engulfed but did not digest prok. cells

proof: modern bacteria similarities to chloroplasts and mitochondria

Question 10

similarities between mitochondria, chloroplasts and modern bacteria

Answer 10

structure, size, biochemical function, DNA&ribosomes, reproduction by binary fission

Question 11

Cell theory

Answer 11

• all living organisms are composed of 1+ cells
• the cell is the basic unit of structure and organization in organisms
• cells arise from pre-existing cells

Question 12

theory vs hypothesis

Answer 12

hypothesis probable but can be disproven while theories are very well established/supported

Question 13

prokaryotes were alone for…

Answer 13

2.1 billion years

Question 14

did mitochondria or chloroplasts evolve first?

Answer 14

mitochondria

Question 15

main evidence of endosymbiosis

Answer 15

chloroplasts and mitochondria have their own genetic material

Question 16

2 major increases in organism size during the evolution of life

Answer 16

1. new cell type : eukaryotes
2. rise of multicellularity

Question 17

Urey-miller experiment

Answer 17

Simulation of earth’s early atm

supposed to show that important biomolecules can be generated in the absence of cells and enzymes

Question 18

amphipathic

Answer 18

has both hydrophobic and phylic parts

Question 19

why have organisms evolved to use DNA over RNA for information storage

Answer 19

• less likely to be damaged
• double stranded (held by H+ bonds)
• RNA reacts w itself in a damaging way (extra O reacts w phosphates in backbone)

Question 20

abiogenesis

Answer 20

origin of life from non-living components (simple organic compounds)

Question 21

evidence of biomolecules arising

Answer 21

urey-miller exp. (&others) –> abiotic synthesis or biomolecules (or precursors) is possible

Question 22

protocells

Answer 22

compartmentalization of biomolecules into enclosed spaces
(microenviro. makes some chem rxns more likely)

Question 23

hypothesized steps of abiogenesis

Answer 23

1. biomolecules arise
2. protocells
3. RNA-based system for storing and transmitting genetic info
4. DNA becomes favoured (stable)

Question 24

traits of RNA

Answer 24

• can store genetic info (viruses)
• can catalyze chemical reactions
• can catalyze its own replication