a eukaryote that is neither plant, nor animal, nor fungi
Are protists a kingdom?
formerly were but not any more becuase wed have to include fungi animals and plants as protists which are their own kingdoms . it puts all eukaryotes in one kingdom bc protists are so diverse and we cant do that
Are protists polyphyletic or monophyletic?
polyphyletic- members of this group have different ancestors
what is a plastid?
organ that allows photosynthesis (ex: chloroplast)
What are some structural and functional differences of protists?
most unicellular, some multicellular
most nutritionally diverse eukaryotes
Reproduction- some exclusively asexual, some sexual and reproduce by meiosis
What does it mean that protists are the most nutritionally diverse?
they can be photoautotrophs, containing chloroplasts, heterotrophs and absorb organic molecules or ingest larger food particles, or mixotrophs which can survive by photosynthesis or heterotrophic nutrition
Are prokaryotes sexual or asexual?
are protists eukaryotic or prokaryotic?
What are some differences between eukaryotic and prokaryotic cells?
eukaryotic mulitcellular and unicellular while prokaryotes just unicellular
eukaryotes true nucleus while prokaryote naked dna
eukaryote has organelles bounded by membrane, prokaryotes do not
What are mitochondria?
power house of the cell
the location of cellular energy production (produce cellular energy using chemical energy from sugars)
What are chloroplasts?
powerhouse of plant cells
produce sugars using light energy
What is the equation for photosynthesis?
Energy+ CO2 +H2O--->sugars + O2
What is the equation for metabolism?
sugars + O2 ---->CO2 + H2O + Energy
What is endosymbiosis?
a process in which unicellular organisms engulf other cells which ultimately become organelles in the host cells
there is now considerable evidence that much protist diversity has origins in endosymbiosis
What are 2 examples of endosymbiosis?
Mitochondria used to be their own organisms and evolved by endosymbiosis of an aerobic prokaryote (anerobic eukaryote engulfs aerobic prokaryote= mitochondria that cant live independently)
Plastids evolved by endosymbiosis of a photosynthetic cyanobacterium
Which of the following statements would NOT provide support for the endosymbiotic origin of mitochondria and chloroplasts?
D. because this shows that these organelles are different than the prokaryotes not similar, (and doesnt matter if their similar to eachother since they were engulfed by different organisms) bc they were once their own organisms
All eukaryotes have mitochondria or remanents of these organelles but only some have chloroplatsts or plastids. based on this what is the most likely to be the correct sequence of these events, from earliest to most recent in the evolution of life on earth?
1. origin of mitochondria
2. origin of multicellular eukaryotes
3. origin of chloroplasts
4. origin of cyanobacteria
5. origin of fungal- plant symbioses
bacteria were first organisms (so cyanobacteria)
all bacteria have mitochondria so mitochondria
some prokaryotes have chloroplasts so they must have come before eukaryotes
multicellular have both so must be after both
you need multicellular organisms for symbiosis
What did the world used to be like before protists and plants?
anaerobic. the world became increasingly aerobic when protists and plants contributed oxygen to environment
a heterotrophic eukaryote engulfs a cyanobacterium evolves into red and green algae and the green algae engulfs another organism. explain the endosymbiosis.
the heterotrophic eukaryote engulfing a cyanobacterium first is primary endosymbiosis bc its the first one
the green algae engulfing another organism is secondary endosymbiosis bc it is the second engulfing.
What are the 5 supergroups of eukaryotes?
What is excavata?
a clade characterized by its cytoskeleton and modified mitochondria
What are Euglenozoans?
Type of excavates
can be predatory heterotrophs, photosynthetic autotrophs, mixotrophs and parasites
Two best studied types are Trypanosoma and Euglena
What are trypanosoma?
a kinetoplastid that is associated with sleeping sickness and transmitted by the teetsie fly
the euglenozoans of genus trypanosoma are parasites
they are experts at evading immune system bc they can change their surface proteins
What are Euglena?
a mixotroph commonly found in pond water
in sunlight: autotrophic
in no sunlight: heterotrophic (can engulf by phagocytosis)
What are kinetoplasitds?
group that includes trypanosoma
they have a single mitochondrion with an organized mass of DNA called a kinetoplast
What are chroalveolates?
a clade that evidence suggests originated by a secondary endosymbiosis event
---> the proposed endosymbiont (thing ingested) is a red alga, but not all chromalveolates are photosynthetic
clade includes alveolates and stramenopiles
Why is it possible that the endosymbiont is a red alga even though not all chormalveolates are photosythetic?
bc all could have been derived from a common ancestor that engulfed a red algae but may have lost it due to adaptation
What are 2 types of alveolates?
What is the organism of apicomplexans?
plasmodium- a parasite that causes malaria
it is common for apicomplexans to have a two host cell cycle
What is plasmodium
a parasite that causes malaria
they have a nonphotosynthetic plastd that is likely of the red algal origin
plasmodium requires both mosquitoes and humans to complete its life cycle
Why is it hard to fight plasmodium and treat malaria?
efforts ongoing to develop vaccines for it
appx. 2 million people die of malaria every year
plasmodium can change its surface proteins continually, allowing it to evade the immunes system making it hard for drugs to fight it
What is required for plasmodium to reproduce?
must be in the gut of its mosquito host for part of life cycle andbe in liver and blood of humans for the other part
Explain the lifecycle of plasmodium
mosquito bite injects plasmodium in the bloodstream through saliva
plasmodium infect liver cells and divide to become merozoites
merozoites enter RBCs causing fever, chills
merozoites become gametocytes which are picked up when another mosquito bites human
gametes form and fertilization inside mosquito-->release of more sporozoites
What are ciliates?
group of chromalveolates, named for their use of cilia to move and feed
have large macronuclei and small micronuclei
a single cell that can move, feed, remove waste, and undergo sexual recombination
What do the micronuclei in ciliates do?
they function during conjugation (a sexual process that produces genetic variation)
in conjugation, genetic material is exchanged, but not necessarily gamete production)
What is conjugation?
separate from reproduction, which generally occurs by binary fission in cilliates (no new indivaduals are produced, but genetic material is exchanged in conjugation)
What are paramecium made up of?
microtubules (protein very highly conserved)
contractile vacuole (allows it to expell excess water and avoid bursting)
micro and macro nuclei
food vacuoles to help eliminate waste
How many nuclei can paramecium have throughout its life cycle?
anywhere from 2-5
What is the life cycle of paramecium?
micronucleus undergoes meiosis
two cells swap micronuclei
cells seperate and each divides by mitosis (asexual)
Which is not a characteristic of cilliates?
B. because they exchange genetic material by conjugation not mitosis
after exchange they divide by mitosis
they are complex bc of vacuole types, organelles and complex structures
What is the supergroup Archaeplastida?
group including red algae green algae and land plants
red and green algae are the closest relatives of land plants
over a billion years ago, a heterotrophic protist acquird a cyanobacterial endosymbiont
the photsynthetic descendents of this ancient protist evolved into red and green algae
land plants are descended from the green algae
What are some characteristics of red algae?
some red algae not photosynthetic so they lose their pigment
red algae with non functioning plasmid gets nutrients because they are chemoheterotophs and eat other species of green algae
What are some characteristics of green algae?
named for their grass green chloroplasts
plants decended from the green algae
live in diverse environments- fresh water, marine, terrestrial
more complex, evolved in 3 ways
What are the 3 ways that green algae evolved?
single cells form colonies that function together (ex- volvox) (cyanobacteria can also live in colonies even though their not multicellular)
multi-cellular bodies formed by cell division and differentiation (different cells have distinct roles in multicellular organisms [humans have differentiated cells])
repeated rounds of nuclear division without cytoplasmic division
What is a thallus?
algal body that is plantlike but lacks true roots, stems or leaves
What does the supergroup unikonta include?
protists that are closely related to fungi and animals
this group includes 2 clades: amoebozoans and the opisthokonts
it is unclear whether unikonts seperated from other eukaryotes relatively early or late
What are amoebozoans?
amoeba that have lobe- or tube- shaped rather than threadlike pseudopodia
they include entamoebas and slime molds
What are entamoebas?
parasites (3rd example of parasite) of vertebrates and some invertebrates
entamoeba histolytica causes amebic dysentery in humans (intestine infection)
What are cellular slime molds?
form multicellular aggregates (collections) in which cells are separated by their membranes
cells feed individually but can aggregate to form a fruiting body
dictyostelium discodeum is an experimental model for studying the evolution of multicellularity
What is the life cycle of a slime mold?
some cells inn fruiting body become spores
solitary feeding stage- engulf bacteria
when food is depleted, hundreds of amoeba congregate and form a slug like aggregate
stalk cells dry up after supporting the fruiting body
In what do protists play key roles in?
they are found in diverse aquatic environments and are key producers (by photosynthesis) providing a large percent of energy
Protists are all alike in that they are
Which taxon of eukaryotic organisms are thought to be directly ancestral to the plant kingdom?
Pair up characteristic with protist:
e. green algae
1. micronuclei involved in conjugation
2. multi and unicellular
4. multi and unicellular
euglenozoans: mixotrophs (autotrophs and heterotrophs)
ciliates: micronuclei involved in conjugation
amoebozoans: have uni and multicellular
green algae: have uni and multicellular
how many cells are most living things on earth composed of?
What are the three domains? which are the most closely related?
Eukarya, Archaea and Bacteria
two most closely related: Archae and Eukarya
What are some key adaptations of prokaryotes?
(bacteria and archaea)
they thrive almost everywhere including places too acidic, salty, cold or hot for other organisms
most are microscopic, but their numbers make up for it
they have astonishing genetic diversity
What are the three main shapes of prokaryotes?
bacilli: rod shaped
we can relate bacteria by the morphological species concept
What are the chromosomes of prokaryotes like
cytoplasm bound one circular chromosome tangled up in a supercoil
What is the structure of a prokaryote?
made up of cell wall, fimbriae, sex pillus, capsule, internal organization, chromosome supercoil, and flagella
all of these structures cause for evolutionary success of the prokaryote
What is the role of the cell wall in prokaryotes?
maintain the cell shape
provide physical protection allowing environment survival
prevent cell from bursting in a hypotonic environment
the shape is defined bythe rigid cell wall structure
What is a bacterial cell wall composed of?
peptidoglycan synthesis is targeted by antibiotics such as pennicillin which blocks bacteria frommaking cell walls and hypotonic environnments will kill them
What is peptidoglycan?
a network of sugar molecules linked by poly peptides (links of amino acids)
What are archael cell walls made of
they have chains of carbohydrates but lack peptidoglycan
What are cells like in hypotonic isotonic and hypertonic solutions?
animal cell: lyses
plant or prokaryotic cell: turgid (normal)
animal cell: normal
What is the fimbriae?
hair like appendages that allow prokaryotes to stick together or to the host
what is the capsule?
halo shaped structure surrounding prokaryotes
made up of polysaccharides or proteins
can protect pathogenic bacteria from being recognized by the immune system by forming a meshwork around the cell wall so that antibodies cannot bind to and recognize it
gram negative: 2 membranes. one outer membrane and one peptidoglycan layer below that... does not trap crystal violet and stains red
What is taxis?
movement towards/ away from a stimulus
What is flagella
flagella on a prokaryote is much different than eukaryotic flagela, they are analogous structures, arose independently
help movement in taxis
Explain the internal and genomic organization of prokaryotes.
they usually lack complex compartmentalization like a nucleus
some have specialized membranes that preform metabolic functions.
they can have respiratory membranes that act like amitochondria to utilize oxygen for respiration or thylakoid membranes used for photosynthesis
What is the dna of prokaryotes like?
genes contained on the chromosome and plasmids
prokaryotic genome has less dna than eukaryotc
most of the genome is in circular chromosome but others in plasmid rings
What is binary fission?
asexual method where the chromosome is coppied, restricion cytokinesis and a result of 2 daughter cells
What adaptations make prokaryotes so diverse?
if a prokaryote is in a very harsh environment (no nutrients) they can sort of hibernate for a while by activating signal proteins: instead of 2 identical daughter cells in reproduction, one will be a daughter cell and the other a spore with much more protection
prokaryotes reproduce very quickly by binary fission and can divide every 1-3 hours
many prokaryotes can form metabollically inactive endospores which can help in harsh conditions
What are the 3 main sources of genetic diversity in prokaryotes?
rapid reproduction (every time they reproduce there is a chance of mutation)
genetic recombination due to horizontal gene transfer
What is horizontal gene transfer?
bacteria can share DNA or take it up from environment; movement of genes from one organism to another between species
Why is evolution in prokaryotes rapid?
low mutation rate but they reproduce sofast that the small mutation rate adds up because there are so many of them and they actually end up having multiple mutations
what are the 3 ways that horizontal gene transfer can happen?
What is transformation
uptake of foreign DNA from surroundings
What is transduction?
movement of DNA from one strain to another by bacteriophage viruses that infect bacteria
can result in the formation of pathogenic bacteria
picking up DNA from bacterial viruses
What is the process of transduction?
phage injects its genetic material into host cell
accidental packaging of host cell DNA into phage head
phage with bacterial DNA infects a new host and the bacterial DNA is introduced into the recipient cells genome
What is an example of transduction?
ecoli (harmless) trasducted into a harmful e coli bc of this
k12 got the ability from the phage hosts aquire DNA from bacteriophages
What is conjugation
the process where DNA is transferred between 2 bacterial cells
sex pili allow cells to connect and pull together for DNA transfer
DNA travels through the sex pillus (mating bridge formed) from one to another and recombines in the genome --> you need a plasmid called an f factor for this
What is the F factor
a piece of dna required for the production of sex pilli
can exist as a separate plasmid or as DNA within the bacterial chromosome
plasmid has an F sequence
What are R plasmids?
plasmids that carry genes for antibiotic resistance
bacteria can pass antibiotic resistance from one to another
What are the ways prokaryotes can obtain energy
only prokaryotes can survive by all of these
What are the possible prokaryote metabolisms?
What are obligate aerobes?
require o2 for cellular respiration
What are obligate anaerobes?
will die in the presence of o2. use fermentation or anaerobic respiration
What are facultative anaerobes?
can survive with o2 and do respiration or without and will do anaerobic respiration
What is metabolic cooperation between prokaryotic cells of the same species
each cell is capable of photosynthesis and nitrogen fixation but the presence of o2 inhibits nfixation so cant do both at once
some cells will go through nfixation and pass ammonia between cells
other cells will do photosynthesis and pass sugars between cells
What is nitrogen fixation
can take n2 gas from air and convert it to ammonia
cells that do this are called heterocytes
Where does metabolic cooperation between diff prokaryotic species occur?
dental plaques- many diff species live together
What is unique about archaea?
some live in extreme environments: called extremophiles
What is an extremophile?
2 types: extreme halophiles and extreme thermophiles
extreme halophiles: live in highly saline environments (ex: halobacterium)
extreme thermophiles: live in very hot environments
Do archaea have peptidoglycan in cell walls?
no, still have cell walls but only bacteria have peptidoglycan
they do have a circular chromosome
What are cyanobacteria?
photoautotrophs that generate O2
plant chloroplasts likely evolved from cyanobacteria by endosymbiossi
ecological role: they create a lot of the earths oxygen
What are chlamydias?
these bacteria are parasites that live within animal cells
chlamydia trachomatis causes blindness and nongonococcal urethritis by sexual transmission
Examples of gram pos bacteria?
bacillus anthracis (anthrax)
slostridium botulinum (botulism)
Where does a lot of the oceans nitrogen and oxygen come from?
archaea and certain bacteria working together
What role to prokaryotes play in chemical cycling?
chemoheterotrophic prokaryotes function as decomposers, breaking down corpses dead vegetation and waste products
nitrogen fixing prokaryotes add usable nitrogen to environment
archaea in oceans perform key steps in nitrogen cycle
prokaryotes can also immobilize or decrease the availability of nutrients
What is symbiosis?
an ecological relationship in which 2 species live in close contact: a larger host and a smaller symbiont
3 types: mutualism, commensalism, and parasitism
What is mutualism? ex?
both organisms bennefit
esynthesis of vitamins by intestinal bacteria
What is commensalism? ex?
one organism benefits, other unaffected
ex: barnicles on whale
What is parasitism?ex?
an organism called a parasite harms but does not kill host and benefits
ticks and dogs
parasites that cause disease are pathogens
How do pathogenic prokaryotes cause disease?
by releasing exotoxins or endotoxins
horizontal gene transfer can turn harmless bacteria into pathogens
What are exotoxins?
cause disease even if the prokaryotes that produce them are not present. released from the cell
ex cholera toxin
What is an endotoxin?
released only when bacteria die and their cell wall breaks down releasing it
ex salmonella typhi
What is bioremediation?
the use of organisms to remove pollutants from environment
prokaryotes principal agents
What was not a challenge for the survival of the first land plants?
predation- barley any animals
What is the most related to land plants?
charophytes (green algae) they have the most in common
What are the requirements for complex multicellularity?
adhesion between cells (physically linked together)
cellular and tissue differentiation (diff cells have diff functions in diff areas)- complications: only some contribute to reproduction and loss of certain ones can be lethal
3 dimentional organization!
some cells not on surface dont have access to O2 and environmental signals
What is bulk transport?
transporting nutrients to cells throughout the body
waste can be taken out this way too
had to happen for multicellularity to happen
How do large invertebrates survive without a circulatory system?
all cells that need o2 get it bc the body plan either all cells face surface bc of holes or all cells that need O2 on surface while anaerobic cells inside
What is the difference between adhesion in animal and plant cells?
animal cells: transmembrane proteins called cadherins and integrins as well as others
plants: polysaccharides called pectins
What are apical meristems?
tissues where there is lots of rapid growth (many divisions)
help plants explore new nutritional environments ex: grow higher more access to sunlight
cells from the apical meristems differentiate into various tissues
What are the 4 main derived traits of land plants
alternation of generations
sporopollinin (walled spores)
multicellular gametangia (archegonium and antheridium)
What does the sporophyte produce?
produces spores in organs called sporangia
sporocytes undergo meiosis to generate haploid spores, which disperse upon maturation
spore walls contain sporopollenin, which helps protect the spores from harsh conditions (allowed land plants to move farther from water)
Where does the sporophyte develop from?
What are multicellular cametangia
gametes are produced by mitosis in haploid gametophytes within organs called gametangia
female gametangia: archegonia produce eggs and non motile, site of fertilization
male gametangia: antheridia, site of sperm production and release
Where does the sporophyte embryo develop?
Explain alternation of generations
haploid generation that produces haploid gametes by MITOSIS
fusion of the gametes gives rise to diploid sporophyte which produces haploid spores by meiosis
diploid embryo is retained within tissue of the female gametophyte (archegonium)
nutrients transferred to embryo through placental transfer cells
Why are land plants called embryophytes?
bc of the dependency of the embryo on the parent
What are some other adventageous derived traits of land plants
cuticle: waxy surface that prevents excessive water loss
secondary compounds: bitter tasting, strong odor or toxic effects that help defend against herbavores and parasites
symbiotic associations between fungi and the first land plants: fungi helped first plants absorb nutrients bc they didnt have true roots
In what plants would we expect a vascular system?
ex: tall tree bc nutrients need to reach top leaves on that tree. vascular system is how
What term associates with non vascular plants?
vascular plants can either be seed or seedless plants
Which type of plant is the most evolutionary successful?
angiosperms bc they have largest #of species they were able to diversify and gain adaptations
what is a seed?
an embryo that has nutrients and parts that physically protect it