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BIO 5C > 20 > Flashcards

20 Flashcards

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Biology 101 flashcards
1
Q

Evidence of ancient life

A

stromatolites: 3.2 BYA

layers of sediment left by cyanobacterial mats

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2
Q

Are stromatolites evidence of life or non-organic origin?

A

2008 study of 2.7 Gy stromatolites: Found shapes similar to bacteria, associated with the kind of nanocrystals in modern bacteria-grown stromatolites.

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3
Q

What was in the microfractures? (originally thought to be carbon)

A

hematite deposits

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4
Q

What happened when energy was added to Earth’s early atmosphere?

A

The basic building blocks of life were created

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5
Q

primordial soup model (list characteristics)

A

– Early oceans full of organic material
– Methane-ammonia atmosphere
– Addition of external energy (heat/UV/lightning)
into these gases end up into monomers
– Most widely accepted model

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6
Q

Urey-Miller Experiment

A

Abiotic production of amino acids, resulting in the production of 13 of 22 amino acids used in living systems

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7
Q

How did life come from outer space?

A

comets

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8
Q

Evidence of comets carrying life + what did these comets carry?

A

intense early bombardment of Earth by rocky and icy bodies

carry organic molecules, amino acids
ex. Murchison meteorite

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9
Q

How did life come from the center of the Earth?

A

hydrothermal waters

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10
Q

Primitive bacteria at surface of Earth

A

chemotrophs – Yellowstone hot spring bacteria

similar bacteria found in very deep wells, mid-ocean ridge black smokers

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11
Q

2 main types of organisms

A

prokaryote, eukaryote

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12
Q

characteristics of prokaryote

A

small, no nucleus, limited organelles, simple ring chromosome with few genes

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13
Q

characteristics of eukaryote

A

large, organelles, nucleus, complex chromosomes with many genes

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14
Q

symbiosis

A

evolution of eukaryotes from prokaryotes

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15
Q

gene flow

A

movement of alleles between pop due to migration

tends to make pop more genetically similar over time (uniform allele freq)

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16
Q

genetic swamping

A

the reduction in a population’s ability to adapt due to gene flow from a maladapted population

local genotypes replaced with hybrids

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17
Q

adaptive introgression

A

alleles move between populations via gene flow, helping local pop adapt to environment w/o needing new mutations

introducing something foreign that leads to better fitness

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18
Q

what can gene flow lead to?

A

new populations, new traits, even new species

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19
Q

speciation

A

the process by which one species splits into two species

this is an example of macroevolution

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20
Q

microevolution

A

changes in allele frequency in a population over time

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21
Q

macroevolution

A

broad patterns of evolutionary change above the species level

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22
Q

How do new species originate from existing species?

A

Over time, populations of a single species connected by gene flow can diverge genetically, giving rise to a new species

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23
Q

species

A

basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity

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24
Q

most common way to define species

A

biological species concept

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25
Q

biological species concept

A

according to BSC, a species is a group of pop whose members
- have potential to interbreed in nature
- produce viable, fertile offspring
- do NOT produce viable, fertile offspring with members of other such groups

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26
Q

how does reproductive isolation occur

A

it results when biological barriers impede members of two species from interbreeding and producing viable, fertile offspring

classified by whether factors act before or after fertilization

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27
Q

what do these barriers limit

A

formation of hybrids and gene flow between the forming species

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28
Q

the BSC relies on the disruption of which aspect of pop genetics?

A

gene flow

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29
Q

2 main types of biological barriers

A

prezygotic barriers, postzygotic barriers

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30
Q

prezygotic barrier

A

blocks fertilization from occuring by:
- impeding diff species from attempting to mate
- preventing successful completion of mating
- hindering fertilization if mating is successful

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31
Q

zygote

A

diploid cell produced by the union of haploid gametes during fertilization; i.e. a fertilized egg

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32
Q

types of prezygotic barriers

A

habitat isolation
temporal isolation
behavioral isolation
mechanical isolation
pollinator isolation
gametic isolation

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33
Q

habitat isolation

A

2 species that occupy diff habitat within same area may encounter each other rarely

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34
Q

temporal isolation

A

species that breed at diff times of day cannot mix their gametes

nocturnal animals and diurnal animals

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35
Q

behavioral islation

A

courtship rituals and other unique behaviors to a species are effective barriers to mating

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36
Q

pollinator isolation

A

species of plant that attract diff types of pollinators have barrier to reprod

bee pollinating flower vs hummingbird pollinating flower

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37
Q

mechanical isolation

A

mating attempted, but morphological diff prevent completion

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38
Q

gametic isolation

A

sperm of one species may not be able to fertilize eggs of another sperm

L sperm fr

39
Q

postzygotic barriers

A

prevent hybrid zygotes from developing into viable, fertile adults
- reduced hybrid viability
- reduced hybrid fertility
- hybrid breakdown

40
Q

reduced hybrid viability

A

genes of diff parent species may interact in ways that impair hybrid’s development or survival in environment

41
Q

reduced hybrid fertility

A

meiosis may fail to produce normal gametes, resulting in sterility

mules (donkey + horse) are sterile

42
Q

hybrid breakdown

A

first gen viable, offspring in next gen are not

43
Q

limitations of BSC

A

of species to which BSC is applied is limited, cannot be applied to extinct, asexual organisms bc mating cannot observed

44
Q

morphological species concept

A

distinguishes a species by its structural features, applied to sexual and asexual species and does not require info on the extent of gene flow

disadvantage is that it relies on subjective criteria

45
Q

ecological species concept

A

defines a species by its ecological niche (sum of its interactions with nonliving and living parts of the environment), applies to sexual and asexual species, emphasizes role of disruptive selection

46
Q

2 types of speciation

A

allopatric speciation, sympatric speciation

47
Q

allopatric speciation

A

pop are geographically isolated; physical separation due to geographic isolation prevents interbreeding

most common form of speciation

48
Q

sympatric speciation

A

pop not geographically isolated

49
Q

process of allopatric speciation

A

geographic separation creates 2 populations of same species isolated from each other (no genetic exchange can occur between them)

can occur when pop is divided into geographically isolated subpopulations (vicariance) or when individuals colonize a remote area (dispersal)

50
Q

how is reprod isolation affected by geographic distance?

A

reprod isolation between pops generally increase w geographic distance

isolated subdivided regions usually have more species than those w fewer barriers

51
Q

process of sympatric speciation

A

speciation occurs in pop that live in same geographic area, occurs if gene flow reduced by polyploidy, sexual selection, habitat differentiation

52
Q

polyploidy

A

presence of extra sets of chromosomes, process can form new species within single gen w/o geographic separation

can happen with hybridization (allopolyploidy) and without it (autopolyploidy)

53
Q

sexual selection

A

certain traits can increase your chances to mate, can result from the exploitation of new habitats or resources

54
Q

how to study rate of speciation?

A

by observing broad patterns in fossil record

speciation can occur rapid or slow

55
Q

punctuated equilibria model

A

describes a sudden rapid evolution brought on by the pressures (stress) exerted on species

species appear to have changed gradually over time

56
Q

hybrids

A

hybrids result of mating between species with incomplete reprod barriers

57
Q

hybrid zone

A

region in which members of different species mate and produce hybrid offspring

typically located wherever habitats of interbreeding species meet; occurs as isolated patterns scattered across landscape rather than a continuous band

58
Q

possible outcomes in a hybrid zone

A

reinforcement, fusion, stability, hybrid speciation

59
Q

reinforcement

A

substantial gene flow between species if hybrids are as fit as their parents, reprod barriers can weaken and the 2 parent species may fuse into single species

60
Q

stability

A

Extensive gene flow from outside the hybrid zone
can overwhelm selection for increased reproductive isolation inside the hybrid zone

61
Q

hybrid speciation

A

Hybrid in a hybrid zone may become reproductive
isolated from both parental types

62
Q

how does environment affect hybrid zones?

A

changing environmental conditions can result in the relocation of existing hybrid zones, can also drive the production of new hybrid zones

63
Q

fusion

A

gene flow between 2 species that can form hybrid offspring weakens barriers to reproduction between species

process causes gene pools to become increasingly alike and can cause 2 species to fuse into single species

64
Q

uses for phylogenetics

A

Monitor pathogen evolution, track cancer tumor
progression and metastasis, understand protein structure and function, understand evolutionary
adaptations across the tree of life

65
Q

what do nodes represent on phylogenetic tree?

A

common ancestors

66
Q

what do tips represent on phylogenetic tree?

A

taxa

67
Q

what does the root represent on phylogenetic tree?

A

the common ancestor to everything included to tree

68
Q

different shapes of phylogenies

A

triangular tree, circular tree, unrooted tree, rectangular tree

69
Q

sister taxa

A

when 2 taxa share a most common ancestor

70
Q

clade

A

all the tips arising from a node

71
Q

monophyletic

A

group that includes all of a clade

72
Q

paraphyletic

A

group which includes most, but not all of clade which shares a common ancestor

73
Q

convergent evolution

A

same morphology appears independently in the tree of life

the reason why morphological features are limited for phylogenetic analyses

74
Q

what genes used for phylogenetic analyses when using molecular features?

A

housekeeping genes, ex. ribosomal RNA seq

75
Q

polytomy + two types

A

when a node have more than 2 branches

soft polytomy, hard polytomy

76
Q

soft polytomy

A

phylogenies that include polytomys to reflect uncertainty in evolutionary model

77
Q

hard polytomy

A

when there is true multifurcation in tree of life – rare but is possible in allopatric scenario

78
Q

branch lengths

A

number of amino acid substitutions per site

79
Q

homologs

A

genes with similar seq

80
Q

orthologs

A

gene pairs separated by speciation

81
Q

paralogs

A

gene pairs separated by gene duplication

82
Q

duplicate genes can:

A

subfunctionalize or neofunctionalize

83
Q

subfunctionalize

A

two paralogs each take on some of the functions of the ancestral gene

84
Q

neofunctionalize

A

one paralog retains ancestral function, while other can mutate and evolve new functions

85
Q

why are gene family phylogenies discordant with species phylogenies?

A

genetic material can jump across the tree of life, common in prokaryotes and contributes to evolution of antibiotic resistant bacteria

86
Q

why do insects use effectors?

A

to manipulate plant development (galls) and defense

87
Q

What are effectors?

A

small molecules that selectively bind to proteins to regulate biological activity

secreted by pathogens/pests into host cells

88
Q

what are galls

A

abnormal growths on leaves, due to insect feeding, can provide a home for the insect to lay eggs

89
Q

ankyrin repeat proteins

A

33 amino acid motifs mediates protein-protein interaction

predominantly found in eukaryotes with fundamental functions (signal transduction, cell cycle regulation, etc.)

defects in ARPs results in a # of human of diseases

90
Q

insects consume what percentage of major crops?

A

20-40%

91
Q

what does root infestation do?

A

disrupts water and nutrient uptake, resulting in yield reduction and even vine death

92
Q

vicariance

A

population is divided into geographically isolated subpopulations

A|A –> B|C

93
Q

dispersal

A

when individuals colonize a remote area

A| –> A|A –> A|B

BIO 5C (4 decks)

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