MBIO162 Whole Exam Set 1

Morphological species

smallest natural populations permanently separated from each other by a distinct discontinuity in heritable characteristics (organisms with same physical features) = easiest and most used

Biological species

interbreeding natural population that do not successfully mate/reproduce with other groups - test if two organisms mate or not, so takes time and difficult to demonstrate

Evolutionary species

single lineage of ancestor descendent populations distinct from other such lineages and which has its own evolutionary tendencies and historical fate → shows relatedness, distinct lineage but takes effort

OTU (operational taxonomic unites)

a group of closely related individuals which are arranged together based on the similarity of specific sequences (RNA)

How many estimated species are there on the earth?

13.62M

How many described species are there on the earth?

1.75M

How many undescribed?

11.87M

How many new species are found each year?

13,000 new species

Which group of species has the most undescribed and described species?

Arthropods

Most animals are?

Insects (arthropoda)

Most species of lants are?

Angiosperms (flowering) >75%

Most species of mammal are?

Rodents

1960's Whittaker - 5 Kingdom approach

(Plantae, fungi, animalia, protista, monera)

Emphasises macroscopic over microscopic life, focusing more on morphology than molecule (DNA)

Late 1970's Woese - 3 domain approach

classified based on molecules (DNA/RNA) (archaea, bacteria and eucarya)

Order for the Linnaean classical hierarchical classification

A. Da King Prefers Cheese Over Fried Green Spinach = Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Microbes

all microscopic cellular organisms (bacteria, archaea, unicellular protists and fungi), together with the viruses

Microbes have been on earth for

3.8 billion years

Number of bacteria

5×10³⁰ bacteria

Number of viruses

over 10³¹ viruses

Earth formed

4.5 billion ybp

Oceans of liquid water formed

4 billion ybp

Cellular organisms are thought to have evolved by

3.8 billion ybp

Evidence for evolution of cellular organisms

'bacteria-like' microfossils

Stromatolites

microbial formations

Stromatolites can be found in rocks younger than

3.5 billion ybp

Primordial soup (Darwin's warm little pond')

the hypothetical mixture of organic molecules present in Earth's early oceans, from which life is believed to have originated

Why were the surface conditions on early earth too hostile for early evolution of life

great temperature fluctuations, meteor impacts, intense UV

Life arose from ? with ? from harnessing geochemical gradients created at a special kind of deep-sea ? containing tiny, interconnected ?

gases (H2, CO2, N2 and H2S), energy hydrothermal vent, pores

Vent provide a steady and abundant supply of energy available in the form of reduced compounds;

H2 and H2S

What was the first self-replicating molecules?

RNA due to catalytic properties

What have taken over the role of RNA?

Proteins and DNA (repository of coding information as it is more stable)

Order of cell evolution

Prebiotic chemistry →RNA life →RNA and proteins →DNA →LUCA (cellular organism working with DNA and RNA)

Synthesis of ? could have enclosd the replication and biochemical reactions

phospholipid vesicles

a population of primitive cells

LUCA (last universal common ancestor)

After LUCA, life diverged in two directions

early bacteira and early archaea

Bacteria and Archaea

eed by absorption of nutrients. Huge diversity of nutritional types (heterotrophs, photoautotrophs, chemoautotrophs)

Protists (eukarya)

feed by engulfing particles or other organisms or by photosynthesis

Fungi

osmotrophs

Viruses

replicate in host cell by assembly of pre-formed parts

Phylogenic tree

branching diagram showing the inferred evolutionary relationships among various biological species or other entities

Phylogenetic trees based on:

similarities and differences in their physical or genetic characteristics

Linnaeus's classification

2 kingdoms (vegetabilia and animalia) 1730

Haeckel's classification:

3 kingdoms (protista, plantae, animalia) 1866

Chatton's classification

2 domains (prokaryote, eukaryote) 1937

Copeland's classification

4 kingdoms (monera, protoctista, plantae, animalia) 1938/1947

Whittaker's classification

5 kingdoms (monera, protoctista, fungi,plantae, animalia) 1968

Woese's classification

3 domains (bacteria, archaea, eukarya) 1990

Woese used ? and devised the concept of three domains of life

rRNA sequencing

Why rRNA sequencing is used?

Found in all bacteria, archaea and eukaryotes, different regions have different levels of variability, ranging from highly conserved (used to target the gene) to highly variable (used to distinguish between groups)

Ancestors of mitochondria

alphaproteobacteria

Ancestors of chloroplasts

cyanobacteria

Possible our ancestors

asgard archaea (lokiacrhaeota and thorarchaeota)

Different types of eukaryotes (6)

Stramenopiles, Alveolates, Rhizarians, Opisthokonts, , Archaeplastids, Haptista

Stramenopiles

well known algae with large diversity, some are phagotrophic and include some important parasites (e.g. oomycetes)

Microalgae

diatoms

Macroalgae

kelps

Diatoms

highly diverse (over 10000 current species), important in marine productivity (esp/ in temperate and polar regions) to fuel ecosystems, unicellular

Frustle

hard silica (SiO2) 'shell like' enclosing structure on diatoms

Oomycetes

non photosynthetic, parasitic (phytophthora infestans)

Haprista

(protists) haptophytes and centrohelids

Haptophytes

major marine group, mainly photosynthetic, bloom-forming, phytoplankton, glagellated unicells in one stage of the life cycle

Cocoliths

external scales covering haptophytes made of calcium carbonate

Centrihelids

mainly freshwater, distinctive radiation pseudopodia

Archaeplastids

contain primary plastid from endosymbiosis with a cyanobacterium (green algae, red algae and glaucophytes)

Alveolates

ciliates, dinoflagellates and aplicomplexans

Ciliates

possess cilia in at least one stage of the life cycle, over 8000 species, usually 15-80μm, ingest smaller flagellates and bacteria)

Dinoflagellates

heterotrophic, cannot increase in volume so unable to ingest large prey items (photosynthetic and phagotrophic)

Pallium

pseudopodial feeding veil which dinoflagellates surround large prey and secrete digestive enzymes extracellularly

Apicomplexans

unicellular eukaryote that are obligate parasites of other eukaryotes

Rhizarians

wide diversity of amoeboid protists (formaminiferans and acanthareans)

Opisthokons

defined by a single posterior flagella at some life stage, including protist group, animals and fungi

Choanoflagellates

single flagellum draws water current through a collar of 30-40 tentacle like filaments - bacteria are trapped and taken ino food vacuoles

Fungi

one kind of opisthokonts, more closely related to animals than bacteria

Chytridiomycota

type of fungi (opisthokonts), unicellular body with a cell wall that matures into a sporangium and produce zoospores

Zoospores

reproductive cell with flagella that develops in sporangium and parasitize animals and algae

The amphibian parasite Batrachochytrium dendrobatidis is what type of organism?

Fungi

Chytrids infecting arctic diatoms

diatoms present at the bottom of sea ice to avoid direct sunlight, and global warming leads to thinner sea ice and that increases stress for diatoms bc exposed to more sunlight and stressed diatoms are infected more

Mycoloop

pathway in aquatic food webs that moves nutrients from large algae to zooplankton through chytrids. Chytrids can use substrates not available to zooplankton and zoospores contain lipid globule which are readily grazed on by zooplankton

How many named major divisions (phyla) of bacteria using genome phylogeny?

92 phyla

Same species of bacteria

has more than 70% DNA-DNA hybridization, their 16SrRNA gene sequences are more than 97% similar and they share a high degree of similarity, which characteristics that distinguish them from other species (phenotypic, genotypic and phylogenetic properties matching)

Oligotrophs

planktonic heterotrophic bacteria, metabolically active, small size and slow growth rates, adapted to low nutrients

Copiotrophs

planktonic heterotrophic bacteria, high growth rates and large cell size, reduce size when nutrients are limited

Roseobacter clade (alphaproteobacteria)

one of the most abundant components of coastal and ocean bacterioplankton, carry out anoxygenic photosynthesis (doesn't produce O2), copiotrophs

Pelagibacter ubique (alphaproteobacteria)

25% of ocean surface bacterioplankton communities, smallest free-living cell known, heterotroph, oligotrophic

4 types of cyanobacteria

synechococus, prochlorococcus,

Synechococus: found mainly in top ?m in nearly all surface water

20m

Prochlorococcus: found mainly in <?m, possess specific pigments to harvest ?light

<200m, blue

Synechococus and prochlorococcus together account ?% or global CO2 and O2 production:

15-40%

Trichodesmium: most prominent ? in ?% of surface water

prominent nitrogen fixer, 50

Sulfur-oxidising bacteria (SOB):

use reduced S compound as energy source, some anaerobic SOB use nitrate as electron acceptor

Vibrionaceae family (Gammaproteobacteria)

vibrio, photobacteroium, aliivibrio

Osedax worms

on whale skeletons contain large numbers of intracellular symbiotic

Oceanoaspirillales

degrade collagen, cholesterol and lipids from bones

Genetic diversity

the variety of genetic information contained in all living organisms

Gene pool

collection of all the genes and the various alternate or allelic forms of those genes within a population

Genetic variation is subject to natural selection

so the raw material for evolution to act on

How does genetic variation arise?

Mutations, genetic recombination and reassortment of genes

Rate of mutation

10^-9 per nucleotide

How frequent is a mutation?

High frequency of lethal mutation, high frequency of neutral and nearly neutral mutations, low frequency of advantageous mutations

The loss of diversity is associated with

a reduction in reproduction and survival