Chapter 4: Origin of Life on Earth

Question 1

4 Steps (conditions) that happened for the origin of life on earth

Answer 1

1) synthesis of organic molecules
2) creating macromolecules
3) Creation og protobionts
4) origin of RNA and DNA

Question 2

Creation of organic molecules without life

1950 Miller-Urey experiment

Answer 2

Step 1: Synthesis of organic molecules

Question 3

nitrogen, carbon dioxide, methane, ammonia, hydrogen, and water vapors

Answer 3

what did early atmosphere of earth had

Question 4

• experiment that successfully replicated conditions and creation of organic molecules and variety of amino acids

Answer 4

Miller-Urey experiment 1953

Question 5

• after organic molecules it was linking monomers to create polymers
• concentrated amino acids bond together to make polypeptides (which made proteins in protein synthesis)

Answer 5

Step 2: Birth of Macromolecules

Question 6

protobions - have no DNA
- **membrane structures that enclosed molecules
> separates outside from inside
- precursors to prokaryotic cells

Answer 6

Step 3: Creation of protobionts

Question 7

RNA - 1st genetic material
> had molecules called ribozymes
> acted as both genetic info and had the enzymatic job
> believed to be a precursor to DNA and RNA of today
- acts as catalyst and makes complementary copies of their own sequence or other short pieces of RNA

Answer 7

Step 4: Origin of RNA and DNA
(self-replicating molecules)

Question 8

catalyze specific biochem reactions
> plays role in ribosomes: links amino acids to another in protein synthesis
> has role in RNA splicing - important for RNA replication and synthesis of transfer RNA

Answer 8

Rybozymes

Question 9

determines absolute ages of fossils and is based of decay of radioactive isotopes

Answer 9

Radiometric dating

Question 10

rate of decay, time required for 50% of parent isotope to decay
example C14 has half-life of 5730 yrs

and by measuring ration of C14 to C12(parent isotope) in a fossil we can determine fossil age

C14 divided by C12

Answer 10

Half-life

Question 11

an isotope of carbon and the higher number of neutrons the more unstable

so ___ is more unstable than C13 or C12

Answer 11

C14 is

Question 12

mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes that entered larger host cells, creating the first eukaryotic cell

Answer 12

Theory of Endosymbiosis

Question 13

amalgamation of a cell into another and their symbiotic relationship creating the first eukaryotic cell

Answer 13

what led to eukaryotic cells

Question 14

3 pieces of evidence that support theory of Endosymbiosis

Answer 14

Membrane, DNA, and mode of Reproduction

Question 15

mitochondria and chloroplasts have their own membranes enclosing them

Answer 15

Membranes

Question 16

mitochondria and chloroplasts have their own unique DNA and is independent of chromosomal DNA from nucleus

Answer 16

DNA

Question 17

mitochondria and chloroplasts reproduce in similar way to binary fission of prokaryotes (parent makes 2 identical copies)

Answer 17

Mode of Reproduction

Question 18

Continental drift leads to mass extinction which leads to adaptive radiations

Answer 18

• led to rise and fall of dominant groups and significantly shaped history of life on earth

Question 19

continents move towards/away from each other

• three of these happened so far
• major continents came together and made supercontinents but then broke apart later

Answer 19

Continental drift

Question 20

Continental drift then leads to:

Answer 20

• Mass extinctions **
• new boundaries and new land masses (affects organisms’ habitats)
• climate change leads to species adapting to new environments or going extinct

Question 21

large numbers of species (over 50%) are wiped off from the face of the earth and become extinct forever

• already happened 5 times in planet history

Answer 21

Mass Extinctions

Question 22

Mass Extinctions leads to:

Answer 22

Adaptive radiation

Question 23

period of evolutionary change in which group of organisms allow them to fill different ecological roles or niche in their communities

> in basic words: when top of species hierarchy goes extinct, another specie will replace it
- ex: dinosaurs extinct = mammals replaced them

Answer 23

Adaptive radiation

Question 24

There are 3 types of Changes in sequence and regulation of genes

Answer 24

Heterochrony, Paedomorphosis, homeotic genes

Question 25

evolutionary change in rate and or timing of developmental events

• diff grow rate of body parts is relative to each other

this can alter timing of reproductive development as well
> which can lead to Paedomorphosis

Answer 25

heterochrony

Question 26

the condition where reproductive development is accelerated in comparison with non-reproductive organs

= sexually mature stage may retain body features that were juvenile structures in ancestral species

Answer 26

Paedomorphosis

Question 27

regulate the development of anatomical structures
- conserved genes: not altered much over time
—-> hox genes
help determine basic features like wings and legs on birds or petal arrangement on bird

Answer 27

Homeotic genes

Question 28

subclass of homeotic genes have had huge impact in the morphology of animals

-was duplicated then introduced backbone to invertebrates which led to evolution of vertebrates

Answer 28

hox genes