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Organismal Bio > Unit 2 > Flashcards

Unit 2 Flashcards

lecture 11 - 13 (95 cards)

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1
Q

What are the 3 general life cycles?

A

Haplontic, haplo-diplontic, and diplontic

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2
Q

Traits of a haplontic life cycle?

A

The mature organism is haploid (1 portion) and the zygote is diplontic (double the genetic information)

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3
Q

Traits of a diplontic life cycle?

A

The organism is diploid and the gametes are the only haploid stage (half of the genetic information found in organism)

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4
Q

Traits of haplo-diplontic cycle?

A

The organism spends time in both haploid and diploid stage (it depends on organism type for when each steps happens)

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5
Q

In a typical unicellular eukaryote, what are the traits in the haplontic life cycle?

A

There is a reproductive (sexual) stage and a vegetative (asexual) stage where the zygote is protected, usually in a dormant stage

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6
Q

What is isogamy?

A

The gametes are the same size

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7
Q

When is it best for gametes to be isogamous/most common?

A

When both gametes are mobile

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8
Q

What is anisogamy?

A

When the gametes are two different sizes

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9
Q

What is Oogamy?

A

When the egg is larger and the sperm is smaller?

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10
Q

How are gametes different in Chlamydomonas?

A

isogamy is present so gametes are differentiated by being + or -

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11
Q

How are + or - gametes expressed in Chlamydomonas?

A

The haploid cells have a single, mating-type that expresses alleles that are either:
- gsp (gamete-specific plus)
- gsm (gamete-specific minus)

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12
Q

What happens to vegetative haploid cells of Chlamydomonas in not-great conditions?

A

The vegetative cells (blanks) will differentiate into opposing gametes in order to fuse and create a zygote and leads to 4 more haploid daughter cells = more vegetative cell growth

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13
Q

what controls gamete identity?

A

A specific allele at the mating-type locus:
- gsp allele codes the transcription factor for starting the expression of + proteins that develop the + gamete
-gsm allele codes the transcription factor for starting the expression of - proteins that develop the - gamete

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14
Q

How does the mating type gene encode a transcription factor that drives the expression of key genes?

A
  • low population size triggers the expression of gsp allele
  • the + protein is made by the triggered gsp transcription factor
  • the gsp transcription factor binds to promoter or other genes
  • protein generate the + gamete phenotype
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15
Q

What does gsm and gsp form when fused?

A

They form a heterodimer transcription factor within the zygote?

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16
Q

What is a heterodimer?

A

A heterodimer is a molecule or complex formed by two different subunits. This combo of gsp/gsm causes a new function of zygote formation and meiosis

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17
Q

What is the simplest model?

A

Mating type locus:
- transforms cells into two gamete types (+ to - )
- allows fertilization
- drives the development of a zygote
- allows meiosis to form 4 haploid spores

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18
Q

What is the reason for the haploid life cycle in eukaryotes?

A

The mating-type locus evolved in the haploid cells of the common eukaryotic ancestor

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19
Q

When did eukaryotes arise?

A

1.5 billion years ago (the earliest microfossils of eukaryotes date back to ~900 million years ago, 400 million years b4 the earliest animal fossil appeared)

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20
Q

Hadean?

A

Formation of earth and first oceans

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21
Q

Archean?

A

Origin of life and the beginning of photosynthesis

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22
Q

Proterozoic?

A

First colonial cyanobacteria, first eukaryotes, first photosynthetic eukaryotes, first multicellular eukaryotes, and first fossils of multicellular animals

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23
Q

Phanerzoic?

A

Visible life, fossil evidence for multicellular organisms

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24
Q

What is multicellularity?

A

Cooperation among cells for the benefit of an organism

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25
What are the 5 requirements of multicellularity?
1. extracellular connectivity (stay together) 2. Division of labor (can specialize and form tissue) 3. Resource allocation ( make sure everyone gets what they need) 4. Proliferation inhibition ( make sure cell cycles stay in check, on cell type doesn't take over) 5. Programmed cell death (stops bad cell growth, sculpts body during development)
26
What are the convergent designs of photosynthetic organism?
flat "leaves", tubular "stems", and attached to "roots"
27
What are the convergent designs of absorptive organisms?
Unicellular or filamentous vegetative stages and multicellular reproductive stages
28
What are the convergent designs of ingestive organisms?
Multicellular ingestive organisms have specialized tissues: muscular – to move nervous – to coordinate mouth – to ingest stomach, intestines – to digest
29
Who are the closest unicellular relatives of multicellular eukaryotes?
land plants: green algae animals: choanoflagellates fungi: unicellular opisthokonts (unsure of the exact one)
30
Where did multicellularity arise?
Extant species provide evidence that multicellular green plants arose in water
31
How did Dr. Delwiche figure out which green algae was the closest relative to land plants?
Stoneworts were found to be the closest relative by creating a molecular phylogeny based on nuclear (18s rRNA), atpB, plastid genome (rbcL), and mtDNA (nad5)
32
What are the series of forms found in multicellularity?
unicellular -> colonial -> filamentous -> parenchymatous
33
What is parenchymatous?
Functional parts/structural tissue and can divide in all directions
34
What forms can Choanoflagellates be found in?
free-swimming individuals or in rosette colonies
35
What animals resemble Choanoflagellates protists?
Choanocytes found in sponges
36
Why would a choanoflagellate benefit from being reversibly colonial? (current hypothesis)
Maybe it helps feed? If that is true, then colonies should be induced by chemicals from bacteria (potential food source)
37
How was it tested whether or not colonies were reversible in choanoflagellates?
Experiment: Reduce bacteria in choanoflagellate cultures.
38
What were the results of the experiment?
Choanoflagellates only spontaneously form rosette colonies in the presence of bacteria!
39
How many major clades were there in the fungal group?
5
40
What are fungi ancestors most similar to?
chytrids, due to being aquatic and flagellated
41
How do fungi "get around"?
fungal bodies (mycelia) branch out to create networks of branched hyphae
42
What is the name of the branching form of hyphae?
septate hyphae
43
What is the name of the filamentous form of hyphae?
Coenocytic hyphae
44
What are the benefits of multicellularity?
organisms can become bigger, integrate cells, specialize cells, and have extracellular spaces
45
How do multicellular organisms solve the problem of reproduction?
like unicellular organisms, multicellular organisms can also use asexual budding or utilize sexual reproduction by producing a single-celled spore or gamete ( plus sex/fertilization and then meiosis)
46
How is it decided what cells reproduce?
tight control over mitosis and meiosis (im talking like TSA tight)
47
What does an organism need to have sex?
* Form haploid gametes which fuse (“fertilization”) to produce diploid zygote * Meiosis to form haploid stage again
48
How does Daphnia alternate between sexual and asexul reproduction?
During warm months, reproduction is parthenogenetic (offspring develop from unfertilized egg), mother produces daughter clones
49
What happens to Daphnia if its cold?
When it becomes cold or food is limited, gametes are made. They are later fertilized to make "resting eggs" that wait and are viable for hundreds of years
50
How did different cellular forms play a role?
More structure led to more complexity within organisms
51
How is sexual reproduction the greatest challenge to becoming multicellular?
Have to figure out how and what cells get to participate in reproduction
52
How does the alternation of stages sometimes play a role? (haploid vs diploid)
Allows for the creation of gametes and non-reproductive cells that can later be changed into gametes
53
What is the evolutionary context for multicellularity?
There's a lot of benefits for cells that come from living in a colony
54
What things made it easier to live as an aquatic algae?
bathed in nutrients, internal transport is not needed (water carries what you need), gametes and offspring are moved throughout the water, with no chance of drying out, and buoyancy supports against water)
55
What did early colonization of terrestrial environments look like?
plants appeared as a new monophyletic lineage (new clade on the phylo tree) with new helpful adaptations that make it easier to live on land
56
What did early colonization of terrestrial environments look like?
As pioneer species, new plants make surviving easier for the following species where animals were able to colonize
57
What reason did plants have for becoming terrestrial?
direct sunlight from photosynthesis, more O2 (a present from the cyanobacteria), inorganic nutrients are on land, and at some point, no predation from herbivores
58
Challenges from being terrestrial?
water conservation, transport of nutrients, need to figure out a way to move gametes around, protection of zygotes and other vulnerable stages, and gravity
59
What were the 4 key innovations that enabled plants to invade land?
haplodiplontic lifecycles (with alternation of generations), vascular tissue, use of seed and pollen, flowers and fruits
60
How are the 4 key innovations revealed in plant phylogenetic tree?
The separation of different types of land plants/some plants having some more ancestral traits and/or later traits.
61
How have sporophytes and gametophytes evolved and changed?
Rather than having a haplontic lifecycle, they alternate through generations to create a haplodiplontic life cycle
62
How do these 4 groups vary in their dependence on water?
The bryophytes and pteridophytes need water for fertilization to happen while the other two do not
63
What are some differences between gymnosperms and angiosperms?
Angiosperms have double fertilization and keep their seeds in a flower or fruit to aid with dispersal for sexual reproduction
64
When did plant-fungi mutualism start colonizing land?
450 million years ago
65
What is the point of the alteration of generations in early plants?
Now there is 2 multicellular life stages: a diploid sporophyte and a haploid gametophyte ( true for all land plants but not all green algae)
66
What are the 3 improvements bryophytes have for surviving terrestrial environments
waxy cuticles (prevents drying out?), enclosed embryo, and stomata (mosses and hornworts)
67
traits of a bryophyte?
readily found in moist areas ->doesn't dry out easily, and no xylem/phloem (short and small)
68
What happens to zygotes in development?
they become diploid sporophytes
69
What land plants require water for fertilization?
bryophytes,
70
Reproduction cycle of bryophytes?
- gametophytes (taller plant-like structure) contain archegonia (there are male and female contain gametophytes, structures aren't on the same plant) - sperm is transferred into the archegonia by water facilitation - after fertilization, the egg divides into a multicellular diploid (2n) sporophyte embryo - once the sporophyte is mature, it grows on a stalk (sporangium) at the top of the gametophyte (it's nutritiously dependent on it) - the mature sporophyte, under goes meiosis (causes spores to be haploid) and releases ungerminated spores - The spores travel and grow into the gametophytes
71
What is the archegonia in bryophytes
Egg-containing structure found in the gametophyte (haploid)
72
What is the Antheridia in bryophytes
The sperm-containing structure in the gametophyte of the bryophytes (haploid)
73
What part of the bryophyte life cycle is diploid?
post-fertilization through right before the sporangium undergoes meiosis
74
How long do bryophytes sporophytes last?
not long and are protected by gametophytes
75
What were the benefits of having vascular tissues?
xylem provides water and ion transport. Phloem provides (sugar transport) = more efficient transport of nutrients between cells) xylem was also reinforced with lignin = now can grow taller **small free-living gametophytes still don't have vas. tissue**
76
Xylem histograph traits?
the inner most cells, long and wide cells, and has not cytoplasm
77
Phloem histograph traits?
outside of xylem, long, narrow cells with limited cytoplasm
78
How are pteridophytes different from other plants
no seeds (unlike angiosperms and gymnosperms) and vascular (unlike bryophytes)
79
Pteridophytes life cycles?
- starts with a **TINY** gametophyte that contains both female and male structure (archegonium - egg, antheridium - sperm - are flagellated) *haploid* - After fertilization (requires water) embryo forms to create sporophyte at the top of gametophyte *diploid* - the mature sporophyte is a lot larger and has the sporangium on the backs of the leaves *diploid* - the sporangium undergoes meiosis *becomes haploid* and releases the germination spore which creates the new baby gametophyte
80
What is the general life cycle for land plants?
fertilization → diploid sporophyte (mitosis) → meiosis → haploid gametophytes (mitosis) → back to fertilization
81
What land plant is gametophyte-dominant?
bryophytes
82
What land plant is sporophyte-dominant?
Pteridophyte
83
How are pteridophytes limited?
still have vulnerable gametophytes (mad tiny) and still need water for fertilization
84
Which plant are brown algae more like (hint: sporophyte is larger)
More like the pteridophyte
85
how are gametophytes and sporophytes different in gymnosperms?
Sporophytes are **MASSIVE** and hold the gametophytes on them (think cones on a tree)
86
Are gymnosperms angio-, iso-, or oo- gamy?
They are oogamy; megaspore = egg, and microspore = sperm
87
The life cycle of gymnosperm?
- massive sporophyte has diploid gametes. -the female cone has an ovule that contains the megasporangium (egg) and the male cone, has the microsporangium internally. **Both will do meiosis** After meiosis, the gametes become haploid (microspores and megaspore) - the pollen grain enter the micropyle (entrance of megaspore) and fertilizes the egg through the pollen tube *fertilization* - Zygote becomes diploid again and chills in the megastrobilus (seed) - Seed is made up of the embryo, seed coat, and female gametophyte (nutrients for embryo like yolk) - Seed eventually grows into the sporophyte
88
Why are gymnosperm seeds called a 3-gen. package deal?
- old sporophyte: seed coat (2n) - Food supply: female gametophyte tissue (n) - Embryo: new sporophyte (2n)
89
What did the introduction of flowers and fruits bring to evolution?
led to diversification around 130 mya
90
What is the sepal?
The leaf-like structures underneath the petals that protect the flower bud
91
What is the petal?
colored organ that attracts pollinators
92
What is the stamen?
the male organ that produced pollen?
93
What is the carpal (stigma/style/ovary)
female organ that makes eggs, ovules develop inside of ovary
94
the life cycle of the angiosperm?
- Anther contains the microsporocyte and the ovary contains the megasporocyte *diploid* - Both undergo meiosis to create microspores (4) and a surviving megaspore (3 of the 4 degenerate after meiosis) *haploid* - The pollen grain from the meiosis travels down the pollen tube down to the egg and polar nuclei (2) and the typical angiosperm has a megagametophyte (n) that has seven cells - **Double fertilization happens and creates a zygote (2n) and an endosperm nucleus (3n)** - The embryo contains the endosperm and the cotyledons (acts as the nutrient yolk)
95

Organismal Bio (4 decks)

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