Lecture 3: Origin of Life and Evolution

Question 1

Origin of life

Answer 1

began 3.5 billion years ago

Question 2

Prokaryotes

Answer 2

Cells with no nucleus (bacteria and archaea)

Question 3

All organism are classified into 3 domains…

Answer 3

• Domain Baceria (Prokaryote)
• Domain Achaea (Prokaryote)
• Domain Eukarya

*all 3 have common ancestor

Question 4

Eukaryote:

Answer 4

Organism consisting of cells in which genetic info is contained within distinct nucleus.

Question 5

Photosynthesis

Answer 5

2.8 billion years ago in early cyanobacterium (a later prokaryote).

Question 6

Membrane

Answer 6

• protective covering or sheath
• acts as a buffer/barrier
• “sock”

Question 7

Endosymbiosis

Answer 7

• symbiosis in which one of the symbiotic organisms lives inside the other
• early eukaryotes gained chloroplasts and mitochondria through endosymbiosis

Question 8

Endosymbiotic Theory

Answer 8

Eukaryotes evolved when different types of free-living PROkaryotes were incorporated inside larger EUkaryotes (engulfed but not digested).

Question 9

Cells with mitochondria evolved into…

Answer 9

protozoans, fungi, and animals.

Question 10

Cells with chloroplasts and mitochondria evolved into…

Answer 10

algae

• algea evolved many times (ie-green, red, brown)
• plants evolved from early green algae

Question 11

Microbes bumped into each other 3 times and changed the course of history…

Answer 11

(1) some prokaryote got stuck in another cell…eventually became mitochondria, marking origin of Eukaryotes
(2) cyanobacteria set up shop inside some Euakryotic cell and eventually became chloroplasts, which in turn made plant life
(3) another lineage of single-celled Eukaryotes swallowed up cells of red algae, marked origin of the group that includes brown algae, like kelp

Question 12

Founder of natural selection theory

Answer 12

Charles Darwin

Question 13

Explain Dunes vs Scrub lizard example of natural selection

Answer 13

Lizards coloration adapted to the white sands.

Dunes are white and scrub is brown. Lizards initially varied in color. Lizards move into dunes, white lizards blend in and brown genotype lizards stand out. White genotype more likely to live to reproduce therefore increase in frequency over time to become dominate .

Question 14

Crypsis

Answer 14

(adaptation)

matching body coloration to surroundings (substrate)

Question 15

Genotype

Answer 15

underlying genetic makeup of an organism, either entirely or for a specific trait, both physically visible and non-visible. (ie - non-expressed alleles)

Question 16

Phenotype

Answer 16

observable traits expressed by an organism

Question 17

Adaptations

Answer 17

inherited traits favored by natural selection

Question 18

Evolution by natural selection REQUIRES that…

Answer 18

(1) individuals in a population vary in some trait
(2) at least some variation is genetically-based (=heritable)
(3) certain genotypes produce more surviving offspring than others
(4) differences in survival among genotypes are due to an agent of selection

Question 19

Evolution

Answer 19

a change in allele frequency over time in a population of organisms

Question 20

population

Answer 20

a group of potentially interbreeding individuals of the same species (usually in same geographic area)
ie - all catfish of same species in given lake, all e-coli bacteria in you stomach, the bighorn sheep in the catalina mountains.

Question 21

allele

Answer 21

a form or version of a gene

Question 22

allele frequency

Answer 22

proportion of that allele in a particular population (varies over time)

Question 23

gene vs allele

Answer 23

-humans get 2 copies of every gene, 1 from each parent (copies don’t have to be identical)
-each variation of a gene is called an allele
ie - gene=eye color; one allele might code for blue eyes and another might code for brown

*alleles create diversity

Question 24

diploid individuals

Answer 24

have 2 copies of gene x

Question 25

Genetic Drift

Answer 25

random changes in allele frequency from generation to the next
-bottleneck example with jar of red and yellow beans

Question 26

Gene Flow

Answer 26

transfer of alleles from one population to another (usually involves movement of individuals)
-ie: snow geese; brown and white in population 1, brown only in population 2 but white migrate from population 1 to population 2.

Question 27

Mutation

Answer 27

alteration of a gene that gives rise to a new allele (usually involves a change in DNA sequence)
ie-point mutation (one nucleotide change)

Question 28

Summarize 4 mechanisms of evolution

Answer 28

• individuals vary in some trait
• variation is heritable
• some genotypes produce more surviving offspring (over time)
• difference in survival due to selection

Question 29

Variation is not always genetically based. It can also be…

Answer 29

environmentally based meaning that genes are the same but their expression changes in different environments. ie-leaves of white oak grown in sun s grown in shade (size)