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Chapter 28 Flashcards

1
Q

Eukaryotic cells differ from prokaryotes​

A

Presence of a complex cytoskeleton.​

Compartmentalization (nucleus and organelles).

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2
Q

Endosymbiosis

A

Many organelles evolved via endosymbiosis between an ancestral eukaryote and a bacterial cell

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3
Q

Endosymbiosis supported by

A

D N A inside mitochondria and chloroplasts.

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4
Q

Chloroplasts and mitochondria replicate by

A

binary fission – not mitosis.

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5
Q

Protists Vary considerably in every other aspect

A

Unicellular, colonial, and multicellular groups.​

Most are microscopic but some are huge.​

Many forms and symmetries.​

All types of nutrition.

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6
Q

Protists are not monophyletic

A

They are paraphyletic

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7
Q

Protists are present in all five eukaryotic supergroups​

A

Excavata​

S A R​

Archaeplastida​

Amoebozoa​

Ophisthokonta

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8
Q

Protists have varied array of cell surfaces

A

Plasma membrane​

Extracellular matrix (E C M) as well in some​

Diatoms and foraminfera – Silica shells.

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9
Q

Cysts

A

Dormant cell with resistant outer covering.​

Used for disease transmission.

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10
Q

Locomotion in protists

A

Flagella​

One or more.​

Cilia​

Shorter and more numerous than flagella.​

Pseudopodia (“false feet”)​

Chief means of locomotion for amoebas.​

Used by other protists as well.

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11
Q

Nutrition in protists

A

Autotrophs​

Some photosynthetic.​

Some chemoautotrophic.​

Heterotrophs​

Phagotrophs – Ingest particulate food matter.​

Mixotrophs are both phototrophic and heterotrophic

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12
Q

Reproduction in protists

A

Sexual reproduction

Asexual reproduction

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13
Q

Asexual reproduction

A

Typical mode of reproduction.​

Some species have an unusual mitosis.​

Mitosis – equal size daughter cells.​

Budding – one daughter cell smaller.​

Schizogony – cell division preceded by several nuclear divisions; produces several individuals.

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14
Q

Sexual reproduction

A

Some regularly reproduce sexually, some under stress.​

Meiosis is a major eukaryote innovation.​

Union of haploid gametes which are produced by meiosis.​

Advantage in allowing frequent genetic recombination.

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15
Q

Protists are bridge to multicellularity

A

From single cells to colonies to true multicellularity

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16
Q

Excavata

A

This group consists of diplomonads, parabasalids, and euglenozoans​

They share similarities in cytoskeletal features and D N A sequences

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17
Q

Diplomonads

A

Unicellular​

Move with multiple flagella

Lack functional mitochondria

2 haploid nuclei

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18
Q

Parabasalids

A

Some live in termite guts​

Have symbiotic relationship with cellulose-degrading bacteria.​

Undulating membrane for locomotion​

Use flagella​

Have semifunctional mitochondria

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19
Q

Euglenozoa

A

Bodies change shape when swimming – alternate between being stretched out and rounded up​

Can change shape because they lack cell walls​

Among the earliest eukaryotes to possess mitochondria​

Include free-living euglenids and parasitic kinetoplastids

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20
Q

Euglenids

A

1/3 of euglenids have chloroplasts and are autotrophic; the others lack chloroplasts, ingest their food, and are heterotrophic​

Reproduction is asexual; occurs via mitosis

Euglena have two anterior (and unequal) flagella​

Attached at reservoir.​

Contractile vacuoles – collect excess water​

Stigma – movement towards light​

Numerous small chloroplasts​

Likely evolved from symbiotic relationship through ingestion of green algae.

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21
Q

Parasitic kinetoplastids

A

2nd major group in Euglenozoa

Unique, single mitochondrion​

D N A maxicircles and minicircles – responsible for rapid glycolysis and unusual R N A editing.

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22
Q

Trypanosomes cause human diseases

A

African sleeping sickness – tsetse fly.​

Leishmaniasis – sand fly.​

Chagas disease – skin contact with urine or blood of infected wild animal.

23
Q

Parasitic kinetoplastids

A

Difficult to control because organisms repeatedly change their protective coat​

Elaborate genetic mechanism for changing antigen on coat.​

Difficult to make a vaccine; other methods used to control flies.​

Sequencing of genomes revealed core of common genes in all 3 – hope for single drug target.

24
Q

S A R

A

Supergroup consisting of 3 branches: ​

Stramenopiles​

Alveolates​

Rhizaria

25
Stramenopiles
Brown algae, diatoms, and oomycetes​ Very fine hairs on their flagella​ A few species have lost their hairs during evolution.
26
Brown algae
Conspicuous seaweeds of northern regions​ Haplodiplontic life cycle involves alternation of generations​ Sporophyte – multicellular and diploid.​ Gametophyte – multicellular and haploid.​ Not plants
27
Haplodiplontic life cycle involves alternation of generations
Sporophyte – multicellular and diploid.​ Gametophyte – multicellular and haploid.
28
Diatoms
Phylum Chrysophyta​ Photosynthetic, unicellular organisms​ Unique double shells made of silica​ Some move using raphes​ Two long grooves lined with vibrating fibrils.
29
Oomycetes
“Water molds”​ Either parasites or saprobes​ Were once considered fungi​ Motile zoospores with two unequal flagella​ Produced asexually.​ Undergo sexual reproduction​ Found in water or on land​ Phytophthora infestans​ Irish potato famine (1845 to1849).​ 400,000 people died.
30
Alveolates
Flattened vesicles called alveoli​ Dinoflagellates​ Apicomplexans​ Ciliates​ Common lineage despite diverse modes of locomotion
31
Dinoflagellates
Photosynthetic, unicellular with flagella​ Live in aquatic environments​ Some are luminescent​ Do not appear to be directly related to any other phylum​ D N A not complexed with histones Most have chlorophylls a and c and cartenoids; biochemistry resembles that of diatoms and brown algae​ Primarily asexual; sexual reproduction under starvation conditions​ “Red tide” are population explosions of dinoflagellates​ Fish, birds, and marine mammals may die from toxins produced by dinoflagellates
32
Apicomplexans
Spore-forming animal parasites​ Apical complex is a unique arrangement of organelles at one end of the cell​ Enables the cell to invade its host.​ Plasmodium causes malaria​ Complex life cycle – sexual, asexual, different hosts.​ Eradication focused on eliminating mosquito vector, drug development, vaccines.​ D D T-resistant mosquitoes.
33
Gregarines
Use their apical complex to attach themselves in the intestines of arthropods, annelids, and mollusks
34
Toxoplasma gondii
Using apical complex, invades epithelial cells of human gut​ Causes infections in humans with immunosuppression​ Can cross placental barrier to harm fetus
35
Ciliates
Feature large numbers of cilia arranged in longitudinal rows or spirals around the cell​ Beat in a coordinated fashion.​ Pellicle – tough but flexible outer covering​ 2 types of nuclei​ Micronucleus – used only as germ line for sexual reproduction; D N A not transcribed.​ Macronucleus – essential for function.​ Have two types of vacuoles​ Food vacuoles – digestion of food.​ Contractile vacuoles – regulation of water balance.
36
Pellicle
tough but flexible outer covering
37
Conjugation
Only different mating types can conjugate.
38
S A R – Rhizaria
Rhizaria use pseudopods for locomotion​ Three distinct monophyletic groups: Radiolaria, Foraminifera, and Cercozoa
39
Radiolarians
Phylum Actinopoda​ Glassy exoskeletons made of silica​ Needlelike pseudopods
40
Foraminifera
Heterotrophic marine protists​ Pore-studded shells called tests, through which thin podia emerge​ Use podia for swimming and feeding​ Complex life cycles with haploid and diploid generations​ Limestones are rich in forams​ White Cliffs of Dover.
41
Cercozoa
Morphologically diverse group of primarily soil protists​ Locomotion with flagella or pseudopods.​ Some have silica-based shells made of scales or plates.
42
Archaeplastida
This group consists of Rhodophyta, Chlorophyta, Charophytes, and land plants​ These photosynthetic organisms acquired their chloroplast through primary endosymbiosis
43
Rhodophyta
Red algae range from microscopic to very large​ Lack flagella and centrioles​ Have accessory photosynthetic pigments which are often red​ Have both haploid and diploid phases
44
Green Algae
Green algae consist of 2 lineages​ -Chlorophyta.​ --Unusual diversity and lines of specialization.​ -Charophytes.​ --Gave rise to the land plants.
45
Unicellular chlorophytes
Early green algae probably resembled Chlamydomonas reinhardtii​ Diverged from land plants over 1 B Y A​ Several lines of evolutionary specialization derived from chlorophytes​ Genome of Chlamydomonas reinhardtii has been sequenced; organism is workhorse for comparative genetic studies; widely used host for recombinant protein expression
46
Cell specialization in colonial chlorophytes
Multicellularity arose many times in the eukaryotes​ Colonial chlorophytes are examples of cellular specialization​ Volvox - hollow sphere made up of a single layer of 500 to 60,000 individual cells each with 2 flagella.
47
Haplodiplontic life cycles in multicellular chlorophytes
Haplodiplontic life cycles found in some chlorophytes and the streptophytes​ Ulva​ Multicellular chlorophyte.​ Identical gametophyte and sporophyte generations.​ Consist of flattened sheets two cells thick.
48
Charophytes
Also green algae; distinguished from chlorophytes by phylogenetic relationship to land plants​ Molecular evidence from rR N A and D N A sequences. Charophytes have haplontic life cycles​ 2 candidate charophyte clades thought to be most closely related to land plants​ Charales.​ Coleochaetales.​ Both charophyte clades form green mats around the edges of freshwater ponds and marshes​ One species must have successfully inched its way onto land through adaptations to drying
49
Amoebozoa
Amoebas move by means of pseudopods​ Pseudopods are flowing projections of cytoplasm.​ Extend and pull the amoeba forward.​ Engulf food particles.​ An amoeba puts a pseudopod forward and then flows into it.​ Microfilaments of actin and myosin are associated with these movements.
50
Amoeba
Most amoeba are free living​ Found in the soil as well as freshwater.​ Some are parasitic.​ Acanthamoeba enters the body through a wound and crosses the blood-brain barrier into the brain; causes inflammation and death.
51
Plasmodial slime molds
Stream along as a plasmodium​ Nonwalled, multinucleate mass of cytoplasm.​ Form called feeding phase.​ Ingests bacteria and other organic material​ When food or moisture is scarce, organism forms sporangia, where spores are produced
52
Cellular slime molds
Important group for the study of cell differentiation because of their relatively simple developmental systems​ Individual organisms behave as separate amoebas​ Move through soil ingesting bacteria​ When food is scarce, organisms aggregate to form a slug​ Slug can make spore cells
53
Opisthokonts
Choanoflagellates​ Unicellular organisms.​ Fungi and animal common ancestor.​ Most like the common ancestor of sponges.​ Have a single emergent flagellum surrounded by a funnel-shaped, contractile collar; structure is exactly matched in sponges, which are animals.
54
Colonial choanoflagellates​
Resemble their close animal relatives, the sponges

Biology (18 decks)

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