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Eukaryotes and prokaryotes Flashcards

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1
Q

what are stromatolites and how are they formed?

A

sedimentary structures made up of alternating layers of limestone
some contain microfossils
they are formed from manipulation of minerals by bacterial communities known as microbial mats

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2
Q

what did the chemical origin of life hypothesis investigate?

A

how simple molecules were created under the harsh conditions of primitive earth

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3
Q

what happened during Miller’s experiment and what did it show?

A

he provided water, heat, hydrogen methane and ammonia to mimic sedimentary rocks to produce a few basic amino acids
it showed that you could synthesise amino acids using energy from lightening in harsh conditions

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4
Q

what was the problem with Miller’s experiment?

A

the conditions might not be the same as primitive earth conditions because he used a high hydrogen concentration which might not have been correct

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5
Q

what is the prebiotic/primordial soup used in the chemical origin of life hypothesis and why was it used?

A

a ‘soup’ containing precursors of ribonucleotides, amino acids and lipids
used so all the experiments could be done under the same conditions

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6
Q

what is the RNA world hypothesis?

A

that RNA was the first macromolecule encoding information produced from phospholipids, amino acids and nucleotides

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7
Q

what is the evidence for the RNA world hypothesis?

A

RNA only needs 4 building blocks compared to proteins which need 20
it requires less energy to form and degrade compared to DNA
uracil is easy to produce so it could have been formed in early biochemical pathways
some ssRNA are used in viruses as genetic material
some RNA molecules have catalytic activities for example ribozymes which cleave and ligate RNA during splicing, used in replication and form peptide bonds

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8
Q

what is the apparition of cellular life hypothesis?

A

that compartmentalisation allowed cellular life to evolve

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9
Q

how does compartmentalisation of cell happen and what is it for?

A

phospholipids form sealed compartments trapping amino acids and RNA to form cells
it provides protection from the environment, forms a selective barrier to move nutrients in and waste out and concentrates molecules for metabolism to increase the rate of reactions

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10
Q

what is the surface origin theory of apparition?

A

primitive cells were formed spontaneously on earth’s surface from a prebiotic soup, natural selection optimised metabolic processes

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11
Q

what is the subsurface theory of apparition?

A

life appeared in more stable conditions on the ocean floor in hydrothermal mounds containing porous clays that trapped hydrogen and hydrogen sulphate to form organic molecules

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12
Q

what is the panspermia hypothesis?

A

life origins from space because evolution is driven by the constant influx of bacteria from space containing viruses that lead to pandemics

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13
Q

what did carl woese suggest about kingdoms in 1990?

A

there are 3 kingdoms: archaea, bacteria and eukarya

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14
Q

what is taxonomy?

A

the discipline that deals with the classification of organisms

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15
Q

why are taxonomy subdivisions used?

A

they allow species to be defined by their genus and species

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16
Q

what are the methods of classifying microbes by phenotypic analyses and what is needed?

A

differential staining, metabolic properties, phage typing, fatty acid profiling and mass spec
it requires pure isolates of the microbes

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17
Q

what are the methods of classifying microbes by genotypic analyses?

A

DNA hybridisation, FISH, rDNA sequencing, MLST and whole genome sequencing

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18
Q

why do bacteria evolve quickly?

A

they are usually haploid (they have 1 chromosome per cell) so during cell division if there is a mutation it will be passed on directly to the next generation
they multiply rapidly
horizontal gene transfer which is the process allows mutations to be passed between species

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19
Q

what is gene transformation?

A

taking up free DNA form the environment and integrating it into its genome

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20
Q

what is conjugation?

A

transfer of plasmids between cells of different species that can be distantly related

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21
Q

what is transduction?

A

transfer of genetic material through phage ghosts, the phage ghost infects a host cell and packages some of the DNA into its capsid then it transfers the DNA to the next host cell

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22
Q

what does phylogeny study?

A

the evolutionary history of organisms
evolutionary relationships are measured by comparing genetic information (DNA)

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23
Q

what are molecular clocks?

A

DNA sequences that encode for conserved proteins (proteins that have undergone few amino acid substitutions)
they have random and neutral mutations so mutate at a steady state

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24
Q

how are molecular clocks used in phylogeny?

A

molecular clocks from different species are sequenced and aligned to analyse their similarities and draw phylogenetic trees that show how far apart the organisms are and reflect genetic diversity

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25
what is the structure of DNA in the nucleus?
it is complexed with histones to form chromatin euchromatin is less dense and more actively transcribed heterochromatin is denser and less actively transcribed
26
what is the function of the nucleus?
stores genetic information and nucleic acids site of mRNA, tRNA and rRNA synthesis and processing
27
what is the structure of the endoplasmic reticulum?
a network of lipid membranes projecting from the nucleus to form invaginations called cisternae the rough ER has ribosomes on its membrane the smooth ER doesn't have ribosomes
28
what is the function of the endoplasmic reticulum?
protein trafficking rough ER: protein synthesis and secretion smooth ER: lipid and steroid synthesis
29
how does RNA enter the rough ER?
RNA contains specific signals that are sorted and allow it to move across the membrane
30
what is the structure of the golgi?
made up of cisternae has a cis face and a trans face (the trans face faces to the outside of the cell) giving it polarity
31
what is the function of the golgi?
carbohydrate synthesis for cell walls and extracellular matrix modifies proteins and traffics them using vesicles nuclear membrane vesicles fuse with the cis face of the golgi
32
what is the structure and function of lysosomes?
they originate from the golgi and can fuse with vesicles contain digestive enzymes to hydrolyse macromolecules destroy pathogens and old organelles
33
what is the structure and function of peroxisomes?
originate from the endoplasmic reticulum oxidise fatty acids and alcohols for lipid metabolism
34
what is the structure of mitochondria?
rich in membrane giving them a large surface area contains proteins involved in respiration have their own genome that is around 15kbp and contains 37 genes can divide by binary fission
35
what is the function of mitochondria and what is used to generate ATP?
produces ATP reducing power used to generate ATP is formed from movement of electrons and protons being pumped out of the membrane
36
what is the structure of chloroplasts?
made up of membranes called thylakoids that form granum the matrix is called the stroma have their own genome that is around 150kbp DNA is circular and they can do their own translation they can multiply by binary fission
37
what is the function of chloroplasts?
generate organic compounds such as sugars using light in the calvin cycle
38
what is the structure of flagella or cilia?
9+2 arrangement: 9 pairs of tubulin microtubules surrounding a central pair the microtubules are connected by nexin
39
how do flagella move in eukaryotes?
it is driven by ATP hydrolysis and dynein molecules that are joined to the microtubules as ATP is hydrolysed the dynein change shape and move along the microtubules making them slide over each other this produces a whip-like motion
40
what does the hydrogen theory of origin state about the origin of eukaryotes?
mitochondria originated from the engulfment of a hydrogen-producing bacterium by a hydrogen-producing archaea the genes for lipid synthesis were transferred to the host cell producing the nucleus chloroplasts were later acquired by endosymbiosis
41
what is the structure of the nucleoid in prokaryotes?
usually a singular circular chromosome which is less than 10Mbp and plasmids the DNA is complexed with proteins to make it compact
42
what is the structure of the cytoplasm in prokaryotes?
contains proteins, tRNA, mRNA and ribosomes contains inclusion bodies site of protein synthesis
43
what are inclusion bodies in prokaryotes?
storage compartments that are protein-bound to keep them in place contains carboxysomes for carbon dioxide reduction in photosynthetic bacteria contain storage granules and gas vesicles (in aquatic bacteria so they float)
44
what is the structure of the envelope in prokaryotes?
combination of the cell membrane, peptidoglycan cell wall and sometimes the outer membrane contains polymers that bind covalently to peptidoglycan
45
what are appendages in prokaryotes?
structures that allow movement on the surface of bacteria pilus, fimbrae or flagella
46
what are pilus in prokaryotes?
hollow structures that allow plasmids to move through into other bacterial cells for conjunction (exchange of plasmids)
47
what are fimbriae or pili in prokaryotes?
allow bacteria to adhere to host cells and surfaces can retract to move along surfaces
48
how do flagella cause movement in prokaryotes?
they are anchored to the peptidoglycan later of the cytoplasmic membrane they have a hook structure that changes the shape of a protein when ATP is hydrolysed to rotate the flagella for propeller-like movement
49
what is endosymbiosis?
a symbiotic relationship where one organism lives inside another
50
what is LUCA?
the last universal common ancestor that bacteria, eukarya and archaea all evolved from
51
how did respiring and photosynthetic bacteria evolve?
ancestors of mitochondria evolved to produce respiring bacteria ancestors of chloroplasts evolved to form photosynthetic bacteria
52
how did eukarya evolve?
eukarya developed from LUCA when the nucleus was formed before mitochondria or chloroplasts
53
how did animals and plants evolve?
animals evolved from the engulfment of respiring bacteria plants evolved from the engulfment of photosynthetic bacteria
54
what evidence is there for the endosymbiotic theory?
both mitochondria and chloroplasts have an inner and outer membrane with distinct lipid compositions and functional properties similar to prokaryotes prokaryotes have ribosomes that are similar to bacteria
55
what evidence disproves the endosymbiotic theory?
eukarya and prokaryotes have similar lipid compositions but they didn't evolve from a common ancestor
56
what are the 3 groups of fungi?
moulds, yeasts and basidiomycetes (mushrooms)
57
what is the role of fungi?
decomposition of dead material in the carbon cycle used in biotechnology cause diseases in humans and plants
58
what is the structure of fungi?
most form multicellular filaments called hyphae they are pleomorphic meaning they have different morphologies depending on the stage of their life cycle their cell walls are made of carbohydrates they undergo life cycles with asexual and sexual reproduction to form spores they can transition between unicellular and multicellular
59
what are moulds?
filamentous fungi found on spoiled foods they are very diverse and have many morphologies
60
how do moulds grow?
hyphae form and branch into mycelium, the tip of the hyphae absorbs nutrient their cell membrane grows using the golgi and vesicles
61
what are the 2 types of hyphae that moulds form?
septate hyphae that have walls forming a segmented structure coenocytic hyphae that don't have walls or compartments
62
what is the life cycle of moulds?
it is very complex and differs between different types of moulds they can switch between being diploid or haploid cells they can form spores when conditions are unfavourable
63
what are basidiomycetes and how do they interact with their environment?
mushrooms that have many different phenotypes and morphologies they can associate with tree roots or insects to obtain nutrients from the soil while receiving sugars for photosynthesis
64
what is the life cycles of basidiomycetes?
they spend most of it forming mycelia in the soil but under harsh conditions they can form spores
65
what are yeasts and what are they used for?
unicellular fungi used in brewery and bakery some can cause infections while others can be used as probiotics
66
what is the life cycle of yeasts?
they can form buds through asymmetrical binary fission they can shift from haploid to diploid cells dimorphic fungi can form hyphae under certain conditions
67
how are yeasts used in research?
their life cycles are easily manipulated so used for analysing the cell cycle and protein interactions you can cross species of yeast to form diploid organisms to analyse genetics they can be transformed with linear DNA because they will take it up into their genome
68
what are the 3 main types of algae?
primary endosymbiotic, secondary endosymbiotic and dinoflagellates (predatory)
69
how have primary endosymbiotic algae evolved and what is the evidence of this?
from a primary engulfment event of a single photosynthetic bacterium they have 3 membranes
70
how have secondary endosymbiotic algae evolved and what evidence is there?
secondary engulfment event of a primary endosymbiotic algae they have a more complex membrane
71
what are mixotrophs and which type of algae are mixotrophs?
organisms that can obtain energy through photosynthesis and nutrition secondary endosymbiotic algae
72
what are diatoms?
algae that have a hard cell wall made up of silicon dioxide called a frustule frustules have overlapping halves
73
what are the 2 groups of diatoms?
centric which have radial symmetry pennate diatoms that have bilateral symmetry
74
why are primary endosymbiotic algae used as model organisms for photosynthesis?
they are easy to grow in the lab and have a short fission time
75
what is the structure of primary endosymbiotic algae cells?
they have one large chloroplast with 2 membranes, the chloroplasts contain 2 types of chlorophyll and no phycoerythrin they have 2 flagella they have a contractile vesicle that can stretch or shrink for osmoregulation they have a pyrenoid their cell walls are made up of hydroxyproline-rich glycoproteins
76
what is a pyrenoid?
an organelle that stores bicarbonate to be converted into carbon dioxide
77
how do primary endosymbiotic algae reproduce?
they usually undergo asexual reproduction by binary fission when exposed to nutrient starvation they can form gametes to regenerate haploid cells that allow them to withstand harsh conditions
78
what is volvox?
a unicellular primary algae containing many colonies of different species of algae they can reproduce sexually or asexually
79
what are secondary endosymbiotic algae, how are they used and what happens when they die?
a type of algae with a large variety of shapes they have a large biomass they are used in the pharmaceutical industry when they die they form sediment at the bottom of the ocean
80
how do secondary endosymbiotic algae move?
they produce mucus so they can slide along surfaces using actin and myosin
81
how do secondary endosymbiotic algae divide?
each daughter cell inherits half of the frustule and is smaller than the parent cell when it reaches the critical size the cell undergoes meiosis to form gametes which fuse to form a zygote the zygote has a frustule and is the same size as the parent cell
82
what are coccolithophores?
a type of algae that have a variety of morphologies and frustules made up of calcium carbonate
83
what are alveolates and what are the 3 different types?
a type of aquatic protist ciliates (predatory), apicomplexans (parasites) and dinoflagellates (predatory algae)
84
what do all alveolates have?
alveoli located under the cytoplasmic membrane surrounded by a lipid membrane, their role is unknown
85
how do alveolates move?
using flagella or cilia they can adhere to surfaces using stalks
86
what is the role of alveolates in the environment?
involved in the food web apicomplexans have affect human health dinoflagellates are involved in the carbon cycle
87
what are ciliates and how do they carry out their function?
specialised predatory alveolates they capture prey by engulfing them in a phagocytic vesicle and digest them using enzymes released from their digestive vacuole
88
what is the structure of ciliate cells?
contain lots of digestive and contractile vacuoles to regulate exchange and digestion of prey have an oral groove to prey on organisms have filaments called trichocysts that sting prey
89
how do ciliates reproduce?
by binary fission (asexual) by conjugation which is the exchange of plasmids (sexual)
90
how are ciliates DNA arranged?
within 3 nuclei that can be combinations of micro and macronuclei they are usually diploid and macronuclei are usually polyploidy to ensure bacteria can have multiple copies of their genome for transcription
91
what are apicomplexans?
spore-forming parasitic alveolates they cause diseases in humans such as malaria
92
what is the structure of apicomplexans cells?
they don't contain flagella, cilia or pseudopods at one end of the cell there is an apical complex that helps them enter into host cells they contain an organelle called an apicoplast that degenerates chloroplasts by metabolising fatty acids apicoplasts have their own genome
93
how do apicomplexans cause infection through their life cycle?
the infectious form is called a sporozoite that multiplies to form a schizont that bursts open the host cell to release merozoites that enter circulation and differentiate into gametes
94
what are dinoflagellates?
a type of predatory algae with many different morphologies they are usually aquatic and are mixotrophs because they can capture energy through light and predation they feed on bacteria. algae and diatoms they cause algal bloom they can cause symbiotic and parasitic infections
95
what is the structure of dinoflagellate cells?
they have an extrusome (a membrane-bound organelle) that releases digestive enzymes and toxins the have 2 flagella, one is free and the other is wrapped around the cell they have a large chloroplast their cell walls are made up of complex cellulose plates called thecae
96
how do dinoflagellates reproduce?
they can enter a stage where they produce a diploid form called a hyponozygote and can form cysts which help them survive harsh conditions
97
what are mixotricha paradoxa?
a type of protist found living in the gut of termites they live in symbiosis with other bacteria
98
what is the role of mixotricha paradoxa in termites?
they help the termites break down ingested material one type of endosymbiotic bacteria helps the insect degrade cellulose replacing it with mitochondria 3 other ectosymbiotic bacteria help with motility by steering the flagella
99
what are giardia lamblia?
a human parasite that causes diarrhoea
100
what are trypanosoma brucei and how are they transmitted?
a type of protist that can cause a disease that disrupts sleep cycles it is transmitted using flies as vectors
101
what are slime moulds and amoebas?
common predatory organisms found in damp and aquatic environments
102
where are slime moulds found and how do they grow?
found on the surface of wood form pseudopods and move by changing shape can differentiate into a multicellular reproductive state when food supply is low
103
where are amoebas found and how do they grow?
can be free-living or shelled found in contaminated water can undergo polymerisation and depolymerisation at the tip of the pseudopod to grow or retract
104
what is dictyostelium discoideum and how does it grow?
a slime mould spends most of its life as a haploid cell under stress the cells can fuse together to form a slug the slugs can differentiate into fruiting bodies that form spores
105
what is physarum polucephalum and how does it grow?
a slime mould that grows and divides by binary fission under stress the cells can fuse to form a plasmodium containing many nuclei the plasmodium can differentiate into a fruiting body that forms spores

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