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BIOL 1407 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

Ecological Species Concept

A

defines a species by its ecological niche; applies to sexual and asexual species and emphasizes the role of disruptive selection

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2
Q

Macroevolution

A

-broad patterns of evolutionary change above the species level
-cumulative effect of many speciation and extinction events

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3
Q

Speciation

A

the process by which one species splits into 2 species

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4
Q

What does speciation contribute to biology?

A

-produced tremendous diversity of life
-helps to explain the unity of life
-forms a conceptual bridge between micro- and macroevolution

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5
Q

Temporal Isolation

A

species that breed at different times of day, in different seasons, or different years –can’t mix their gametes

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6
Q

Microevolution

A

changes in allele frequencies in a population over time

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7
Q

Behavioral Isolation

A

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

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8
Q

Biological Species Concept

A

-have the potential to interbreed in nature
-produce viable, fertile offspring
-don’t produce viable, fertile offspring with members of other such groups

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9
Q

Reproductive Isolation

A

-when biological barriers impede members of 2 species from interbreeding and producing viable, fertile offspring
-limits the formation of hybrids

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10
Q

Habitat Isolation

A

-prezygotic barrier
-two species that occupy different habitats within same area may encounter each other rarely, if at all

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11
Q

What was early life on Earth like?

A

-inhospitable
-little to no oxygen in atmosphere
-meteorite impacts and volcanic eruptions common
-seas full of mineral salts

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12
Q

Gametic Isolation

A

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

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13
Q

Prezygotic Barriers

A

-block fertilization from occurring by impeding different species from attempting to mate
-preventing the successful completion of mating
-hindering fertilization if mating is successful

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14
Q

Mechanical Isolation

A

-prezygotic barrier
-mating attempted, but morphological differences prevent its successful completion

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15
Q

Postzygotic Barriers

A

-prevent hybrid zygotes from developing into viable, fertile adults

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16
Q

Reduced Hybrid Variability

A

-genes of different parent species may interact in ways that impair the hybrid’s development or survival in its environment

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17
Q

Reduced Hybrid Fertility

A

Meiosis may fail to produce normal gametes, resulting in sterility if the parent species have chromosomes of different number or structure (i.e. mules)

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18
Q

Hybrid Breakdown

A

First generation of hybrids are viable and fertile, but offspring in the next generation are feeble or sterile

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19
Q

What are the limitations of the Biological Species Concept?

A

-cannot be applied to fossils or asexual organisms (including all prokaryotes) because mating can’t be observed
-emphasizes absence of gene flow, but gene flow occurs between many morphologically and ecologically distinct species (i.e. grizzly bears + polar bears = grolar bears)

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20
Q

Morphological Species Concept

A

-distinguishes a species by its structural features
-applies to sexual and asexual species, doesn’t require info on the extent of gene flow
-Disadvantage: relies on subjective criteria

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21
Q

Allopatric Speciation

A

-gene flow restricted between populations by geographic isolation
-intrinsic barriers to reproduction due to genetic change driven by processes including divergent selection and genetic drift
-reproductive barriers prevent interbreeding even if contact restored

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22
Q

Sympatric Speciation

A

-reproductive barrier isolates subset of populations without geographic separation
-result from polyploidy, sexual selection, or natural selection resulting from switch in food or habitat

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23
Q

What are the two types of polyploidy?

A

Allopolyploids and Autopolyploids

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24
Q

Autopolyploidy

A

-have more than 2 sets of chromosomes from a single species
-in plants, mitotic errors can result in production of tetraploid cell from diploid cell
-fertile offspring produced through self-fertilization or mating with other tetraploids
-mating between tetraploids and diploids produces triploid offspring with reduced fertility

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25
Q

Allopolyploidy

A

-have 2 sets of chromosomes from different species
-don’t pair during meiosis, resulting in hybrid sterility (sterile hybrids can reproduce asexually)
-formed if chromosome number doubles in subsequent generations
-successfully interbreed with each other but not with either parent species
-diploid number of new species = sum of diploid number of both parents

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26
Q

Habitat Differentiation

A

-sympatric speciation can result from exploitation of new habitats or resources
example: apple maggot flies evolved after switching hosts from hawthorn to apple

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27
Q

Hybrid Zones

A

-a region where members of different species mate and produce hybrid offspring
-some hybrid zones form as narrow bands where habitats of 2 or more closely related species meet
-often occurs as isolated patterns scattered across landscape rather than continuous band

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28
Q

How does environmental change affect hybrid zones?

A

-changing environmental conditions can cause them to relocate
-can also drive production of new hybrid zones
-alleles can be transferred from one parent species to the other through breeding between parents and hybrids (may help parent species cope with changing environments)

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29
Q

What happens if hybrids don’t become reproductively isolated from their parent species?

A

Reinforcement, Fusion, or Stability

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30
Q

Reinforcement

A

-strengthening reproductive barriers
-if hybrids are less fit, strong selection for prezygotic barriers should reduce hybrid population
-should be stronger for sympatric than allopatric populations

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31
Q

Fusion

A

-weakening reproductive barriers
-there can be substantial gene flow between species if hybrids are as fit as parents
-reproductive barriers can weaken and 2 parent species may fuse into a single species

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32
Q

Stability

A

-continued formation of hybrid individuals
-extensive gene flow from outside hybrid zone can overwhelm selection for an increase in reproductive isolation inside hybrid zone

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33
Q

Punctuated Equilibria

A

-periods of apparent stasis punctuated by sudden change found in the fossil record
-other species appear to have changed gradually over time

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34
Q

Average time of speciation

A

6.5 million years

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35
Q

What do all cells have?

A

-enzymes (carry out reactions)
-plasma membrane
-genome of DNA

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36
Q

Protocell

A

-believed to be predecessor of cells
-membranous sac containing interacting organic molecules

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37
Q

What was the dynamic between RNA and DNA originally?

A

-RNA may have preceded DNA
-RNA was THE genetic material and dominant
-switching from RNA to DNA would’ve made genome more stable

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38
Q

Ribozymes

A

-RNAs that act like enzymes
-support the idea of RNA being dominant genetic material at first

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39
Q

Cyanobacteria

A

-evolutionary bacteria; first to release oxygen through photosynthesis
-over time, oxygen released by cyanobacteria changed earth’s atmosphere

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40
Q

What did the addition of oxygen do to Earth?

A

-created the ozone
-favored aerobic life forms
-beginning of ATP-forming metabolic pathway (key innovation in evolution of eukaryotic cells)

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41
Q

First Eukaryotes

A

-Protists
-proven by their biomarkers and fossils dating back more than 2 billion years
-their diversification led to plants, fungi, and animals

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42
Q

Eukaryotes

A

-defined by having membrane-enclosed organelles
-some probably evolved from infoldings of plasma membrane in prokaryotic ancestors
-mitochondria and chloroplasts resemble bacteria; maybe evolved through endosymbiosis

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43
Q

Endosymbiosis

A

-an evolutionary process where one cell enters and survives in another cell
-over generations, host and guest cells begin to depend on each other for essential metabolic processes
-proof: modern protists who have bacterial symbionts inside them

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44
Q

Bacteria

A

-small cells with DNA and ribosomes
-no nucleus or typical eukaryotic organelles
-most abundant and metabolically diverse organisms
-autotrophs and heterotrophs
-most are unicellular, though some species form colonies

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45
Q

Autotroph

A

-bacteria that self-feed

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46
Q

Heterotroph

A

-bacteria that feed on others

47
Q

What are the three most common prokaryotic cell shapes?

A

-cocci (spheres/ellipses)
-bacilli (rods)
-spirillus (spirals)

48
Q

What’s special about bacterial cell walls?

A

-they contain peptidoglycan, a network of sugar polymers crosslinked by polypeptides

49
Q

Gram Stain

A

helps scientists classify many bacterial species into Gram-positive and Gram-negative groups based on cell wall composition

50
Q

Gram-Negative Bacteria

A

-less peptidoglycan and an outer membrane that can be toxic
-have thin cell walls
-stain pink/red
-more likely to be antibiotic resistant because they target peptidoglycan

51
Q

Gram-Positive Bacteria

A

-thick cell walls
-stain purple/blue

52
Q

What shape are prokaryotic chromosomes?

A

Circular

53
Q

Plasmid

A

-small ring of nonchromosomal DNA replicated independently of the chromosome

54
Q

Describe typical prokaryotic DNA

A

-a ring of DNA not surrounded by a membrane, located in nucleoid region

55
Q

Binary Fission

A

-a type of asexual reproduction in bacteria
-divides 1 bacterial cell into 2 identical descendant cells
-can divide every 1-3 hours

56
Q

Endospores

A

-a tough, nonreproductive spore that’s metabolically inactive
-can remain viable in harsh conditions for centuries

57
Q

Are mutations in binary fission common?

A

No, but when they happen they can accumulate rapidly in a population due to rapid reproduction

58
Q

Conjugation

A

-gene exchange in bacteria
-occurs when one cell passes a plasmid to another

59
Q

Phototrophs

A

-obtain energy from light

60
Q

Chemotroph

A

-obtain energy from chemicals

61
Q

Autotrophs

A

-require carbon dioxide as a carbon source

62
Q

Heterotrophs

A

-require an organic nutrient to make organic compounds

63
Q

Lactobacillus

A

-lactate fermenter
-spoils milk
-used to make yogurt, cheese, sauerkraut, sour foods
-common decomposer
-L. acidophilus is part of flora on our skin, in gut, and vagina–lowers pH and keeps pathogenic bacteria in check

64
Q

Clostridium tetani

A

-Gram-positive bacterium
-can form endospores
-endospores germinate in wounds and cause tetanus (toxins produced lock muscles in an ongoing contraction)

65
Q

Bacillus anthracis

A

-produces endospores
-inhale endospores and you get anthrax (toxins produced interferes with your breathing)

66
Q

Clostridium botulinum

A

-Gram-positive
-forms endospores
-anaerobic
-grows in improperly canned food
-produces toxin caused botulism (same toxin, botox, temporarily paralyzes face muscles)

67
Q

Mycobacterium tuberculosis

A

-causes tuberculosis
–1/3 of world population has it
–bacterium is spread via cough droplets
–kills 1.6 mil people each year

68
Q

Streptococcus

A

-causes strep throat
-also spread via cough droplets
-if bacterium gets into open wound can become flesh eating bacteria
–results in a fast-spreading infection that kills surface tissue and can result in death

69
Q

Thermus aquaticus

A

-discovered in a volcanic spring in Yellowstone National Park

70
Q

Spirochetes

A

-small group
-6 genera
-most live in cattle guts
-others are decomposers and nitrogen fixers
-major impact on our lives (syphilis and lyme disease)

71
Q

Parasitic chlamydias

A

-tiny cocci
-live and replicate in eukaryotic host cells
-most common sexually transmitted bacterial disease in US

72
Q

Cyanobacteria

A

-photosynthetic
-produce oxygen during photosynthesis
-carry out nitrogen fixation using atmospheric nitrogen to produce ammonia that plants and algae can use
-Spirulina, Anabaena, Oscillatoria, and Nostoc

73
Q

Proteobacteria

A

-largest bacterial lineage
-includes nitrogen fixers
-includes soil bacteria that show cooperative behavior
-closest relatives of mitochondria
-cells that are a part of our normal flora
-some are pathogens

74
Q

Rhizobium

A

-soil bacterium
-forms associations with the roots of plants
-fixes atmospheric nitrogen for its own use and the use of other plants

75
Q

Myxobacteria

A

-soil bacterium
-exhibit cooperative behavior (work together to move around and feed on other bacteria)
-when food is scarce, thousands of cells get together to form a fruiting body (spores are produced and dispersed by wind)

76
Q

Thiomargarita namibiensis

A

-largest known bacterium
-marine
-stores nitrogen and sulfur on a huge vacuole
-makes it easy to see with the naked eye

77
Q

Escherichia coli

A

-lives in the mammalian gut (part of our normal flora)
-most E. coli benefit their host by producing vitamin K
-strain E. Coli 0157:H7 causes food poisoning

78
Q

Heliobactor pylori

A

Causes ulcers

79
Q

Vibrio cholerae

A

Causes cholera

80
Q

Archaea

A

-discovered relatively recently
-many adapted to life in very hot/very salty environments
-some live in low oxygen environments making methane
-share certain traits with bacteria and others with eukaryotes
-none cause human disease

81
Q

Extremophiles

A

Archaea that live in extreme environments

82
Q

Extreme halophiles

A

Archaea living in highly saline environments

83
Q

Extreme thermophiles

A

Archaea thriving in very hot environments

84
Q

Methanogens

A

Archaea living in swaps and marshes and producing methane as a waste product
-methanogens are strict anaerobes and poisoned by oxygen

85
Q

Methanococcus jannaschii

A

-First organism of kingdom Archaea to be completely sequenced in 1995
-its genome structure finally provided solid support for hypothesis that Archaea is a separate domain than Bacteria and Eukarya, but more closely related to Eukarya
-Archaeans co-exist with bacteria in many habitats and can exchange genes with them

86
Q

What is a protist?

A

-A eukaryotic organism that is not a fungus, plant, or animal
-includes single-celled and multicellular autotrophs and heterotrophs
-don’t have much in common with each other besides simple cellular organization (distinguishes them from other groups)

87
Q

What are the types of unicellular protist lineages?

A

Flagellated protozoans, shelled cells called foraminiferans and radiolarians, alveolates, ciliates, dinoflagellates, and apicomplexans

88
Q

What do all flagellated protozoans have?

A

-single cells
-no cell wall
-protein covering called a pellicle helping cells maintain shape
-possess multiple flagella

89
Q

What do diplomonads and parabasalids have in common?

A

-Flagellated protozoans
-no mitochondria
-both groups include human pathogens
-free-living ones thrive in deep seas and lakes, while others live in bodies of animals (including humans)

90
Q

Giardia lamblia

A

-diplomonad (type of FP)
-has 2 essentially identical nuclei
-water borne human disease
-attaches to the intestinal lining and sucks out nutrients
-infected people and animals excrete cysts (Hardy resting stage)
- drinking cyst-infected water spreads the infection
-symptoms include cramps, nausea, and severe diarrhea

91
Q

Trichomonas vaginalis

A

-parabasalid (type of FP)
-infects human urogenital tract (causes trichomoniasis)
-can’t survive very long outside body
-passed through sexual intercourse
-6 mil in US infected

92
Q

Trypanosomes

A

-type of flagellated protozoan
-long tapered cells
-one large mitochondrion
-flagellum encased in a membrane running length of organism (causes wave-like motion in membrane that moves cell)
-all are parasites and insects are the vectors for human disease

93
Q

Types of trypanosomes

A

-Tseste flies carry the one that causes African sleeping sickness (sub-Saharan Africa, can be fatal)
-Blood sucking bugs in Central and South America transmit the one that causes Chagas disease (16 to 18 mil people, damages the heart)
-Desert sandflies are the vector for leishmaniasis (can harm liver and produce disfiguring scars)

94
Q

Euglenoids

A

-type of FP
-typically live in freshwater
-flagellated
-have a contractile vacuole that squirts out excess water
-have both plant and animal characteristics (chloroplasts and hunters)

95
Q

Mineral-Shelled Protozoans

A

-two related lineages of heterotrophic marine cells
-have porous secreted shells
-foraminiferans and radiolarians

96
Q

Foraminiferans

A

-single cells
-marine
-sieve like shell
-calcium carbonate shells
-chalk and limestone made of their remains
-benthic
-prey on bacteria and smaller protists on the ocean floor
-others are planktonic (plankton drift or swim in water column)
–planktonic forams often have photosynthetic protists living inside

97
Q

Radiolarians

A

-secrete a glassy silica shell
-major component of the marine plankton in tropical waters
-some have photosynthetic protists living inside

98
Q

Alveolates

A

-single cells
-possess membrane-bound sacs called alveoli under their plasma membrane

99
Q

Dinoflagellates

A

-name means “whirling flagellate”
-single cell
-two flagella: one at tip and one running in a groove around its middle
-combined action causes cell to rotate as it moves forward
-heterotrophic and photoautotrophic
-have cellulose plates
-vast majority are marine plankton
-photosynthetic ones live inside reef-building corals
-some are bioluminescent
-some cause algal blooms called red tides

100
Q

Ciliates

A

-heterotrophic
-cilia cover all or part of cell surface (function in movement and feeding)
-aquatic
-predators and parasites
-some adapted to living in animal gut
-trichonympha (termite gut), paramecium, stentor, and vorticella

101
Q

Apicomplexans

A

-intracellular parasites
-spend part of life cycle living in hosts
-complex of microtubules at top end that let them pierce and enter host cell
-sometimes called sporozoans
-infect worms, insects, and humans
-life cycle often involves more than one host species

102
Q

Plasmodium

A

-apicomplexan
-causes malaria
-leading cause of human death (more than 1.3 mil each year)
-mosquitoes carry the protist from one human host to another

103
Q

Describe the plasmodium life cycle.

A

Infected mosquito bites human, sporozoites enter the blood and are carried to the liver. Once there, they reproduce asexually. When they mature into merozoites they leave the liver and infect red blood cells. In some of the cells they reproduce asexually, and in others they differentiate into gametocytes. A female mosquito bites and sucks blood from an infected human. Gametocytes in blood enter her gut where they mature into gametes. Gametes fuse to form zygotes, then meiosis produces cells that develop into sporozoites, who then migrate to mosquito’s salivary glands. Bites human and cycle starts again.

104
Q

Stramenophiles

A

-apicomplexan
-include diverse lineages that are united on the basis of their genetic similarity, not visible traits

105
Q

Water molds

A

-filamentous decomposers and parasites
-grow as a mesh of absorptive filaments
-some are important plant pathogens

106
Q

Diatoms

A

-apicomplexan
-silica-shelled cells
-shell has 2 parts (upper and lower that fit together like shoebox)
-photosynthetic
-contain the pigment fucoxanthin

107
Q

Diatomaceous Earth

A

-pool filters, toothpaste, fleapowder

108
Q

Brown Algae

A

-multicellular
-photosynthetic (contain fucoxanthin)
-found in temperate seas
-include microscopic species and the giant kelps
-source of algins (thickeners and emulsifiers)

109
Q

Red Algae

A

-belong to the same clade as the land plants
-multicellular
-marine
-cell walls of cellulose
-photosynthetic (use pigments phycobilins)
-can photosynthesize even in deep waters
-store excess sugars as starch
-commercially important
-source of agar (used in gelatins and desserts)
-carrageenan (used in cooking to make things gel)
-nori for sushi

110
Q

Green Algae

A

-includes unicellular, colonial, and multicellular
-cell walls of cellulose
-photosynthetic (chlorophylls a and b)
-stores excess sugars as starch
-freshwater
-marine
-soil
-air
-some form partnerships with fungi (lichens)
-life cycle has alternation of generations

111
Q

What common characteristics do red algae, green algae, and land plants share?

A

-cell walls of cellulose
-excess sugars stored as starch
-chloroplasts that evolved from a cyanobacterial ancestor
-descended from a common ancestor
-closest relatives is a group of green algae: charophyte algae

112
Q

Amoebozoans

A

-heterotrophic no cell wall or pellicle
-can constantly change shape
-amoebas
-slime molds

113
Q

Slime Molds

A

Single Cells (cellular slime molds)
-freshwater habitats
-predators
-guts of animals incl humans (most do no harm, few are pathogenic)
-aggregate into one giant mass = plasmodial slime mold
-form fruiting bodies that release resting spores

BIOL 1407 (3 decks)

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