Life Flashcards
Mechanism
Descartes, 17th
Mechanical explanation of life in which organisms are like a living machine
Neomechanism
19th
Chemical & physical explanation of life
Vitalism & neovitalism
Early 20th
Organism has a body & soul
Living vs nonliving
= Different because living contain some non-physical force that control form & development, also direct activities
Holism
Early 20th
Hierarchy in body composition
Theory that properties of a given system can’t be determined or explained by its component parts alone
INSTEAD, the system as a whole determines how the parts behave
Phylogenesis
History of evolutionary development of a species or taxonomic group of animals
Phyloclade
New formal code of nomenclature under development, deals with clades
Clades
Group of organisms that are more closely related to each other than any other group
-> Imply a shared most recent common ancestor
Cladogram vs Phylogenetic tree
C: Lacks info, represent hypothesis about actual evolutionary history
P: Branch lengths represent evolutionary time
Antogenesis
Development of an individual (from egg to individual)
Living system
Hierarchically organised OPEN self-organising system that have the special characteristics of life aiming to maintain its existence & reproduce itself
General characteristics of living system
Exists in space & time Genetic & structural unity, hierarchical organisation (auto) reproduction Open thermodynamic systen (reduction of entropy): flow of matter, energy, info Metabolism Autoregulation (feedback system) Reactivity to external stimuli Ontogeny Phylogeny
Eobiont (protobiont)
Primitive living system
Abiogenesis
Aristoteles
Life spontaneously evolved from non-living things
Biogenesis
Life comes from living things
Oparin
Miller & Urey
Earliest cells
Anaerobic, heterotrophic prokaryotes
Chemosynthetic prokaryotes
Photosynthetic prokaryotes
Chemosynthetic prokaryotes
Evolved when food ran out
Make organic food using energy from inorganic chemicals
Photosynthetic prokaryotes
Evolved & produced oxygen (induced formation of ozone layer)
Make organic food using energy from sunlight
Ribozyme
RNA enzyme
Catalyse
Hypercycle
Organization of self-replicating molecules connected in a cyclic manner
Noncellular form of life, why?
Nonliving infectious agents
Virus
Unable to grow & reproduce itself outside of a host cell
Infect all cellular life, not all cause disease
Some cause life-long/chronic infections
Virion
Single complete infective viral particle = whole virus (RNA/DNA + protein coat)
Vector
Disease-bearing organisms, i.e. blood-sucking insects
Capsomeres
Identical protein subunits that form capsid
Bacteriophages
Infects a specific bacteria
CAN be used in phage therapy directed against SPECIFIC bacteria
DNA viruses
Enter host via endocytosis
Release by lysis or budding
RNA viruses
4 different mode of replication based on polarity of RNA & number of strands
Reverse transcribing viruses
Retroviruses
Replication by reverse transcription (enzyme transcriptase)
Viral replication (lytic cycle) steps
1) Attachment
2) Penetration
3) Synthesis of NA & proteins (gene expression)
4) Maturation
5) Release
Lytic cycle
Viral replication that result in destruction of hostel cell
Lysogenic cycle
Integration of viral NA into host cell’s genome
Repressor genes on virus -> host cell can’t tell it’s there (pro-virus/phage)
If repressor gene is weakened -> lytic cycle
3 ways for virus to get into cell
1) Bacteriophages (inject their genetic material into cell)
2) Non-enveloped (trick cell receptors to let them in)
3) Enveloped (trick/directly fuse with the membrane)
Viroids
Viroid DNA does not code for any protein
Smaller BECAUSE only made of circular ssRNA -> catalytic RNA
Self-replicative to create more viroids
Virusoids
Infects plants in conjugation with an assistant virus
Codes for nothing but its own structure
Classified as satellites
Satellites
Subviral agents composed of NA that depends on the coinfection of a host cell with a helper virus for their multiplication
Prions
No genetic material, only made from proteins
Alpha -> Beta (same AA’s but different shape, A->B if they come in contact)
These proteins are resistant to proteases (perform proteolysis) -> form amyloid plaques
Bacteria
No introns, organized into operons May contain plasmids Asexual reproduction (evolution is limited)
G+
Thick cell wall with many layers of peptidoglycan
Staphyl/strepto/enterococcus
G-
Thin cell all with few layers of peptidoglycan + 2nd lipid membrane
E. coli, klebsiella pneumoniae
Cultivation of bacteria
Petri dish with mix of protein digests, inorganic salts + 1.5% agar
Plasmids
Small, round extrachromosomal DNA that MAY contain genes for antibiotic resistance
Conjugation
1 bacteria transfers genetic material to another through direct contact
Amyloid
Clumps of misfolded proteins
Builds up & start to interfere with neurons ability
MODERN cell theory
All known things are made up of cells
Structural & functional unit of all living things
All cells come from pre-existing cells (by division)
All cells are basically the same in chemical composition
All cells contain hereditary information
All energy flow of life occurs within cells
Cell theory exceptions
Viruses are considered by some to be alive, BUT are NOT made up of cells
First cell did not originate from pre-existing cellls
Prokaryotic cell
3.5b years ago Unicellular 1-10um Nucleiod Ribsomes 70S Binary fission
Nucleoid
Equivalent to nucleus
Consist of circular bacterical chromosome -> circular dsDNA without histones
Subtypes of prokaryotes
Eubacteria
Archebacteria
Cyanobacteria
Eukaryotic cell
1.5b years ago Uni/multicellular >10um Has a nucleus with chromosome LINEAR dsDNA + histones Mitotic/meiotic Membrane & cytoskeletal systems, organelles
Subdivisions of eukaryotic cells
Plants
Animals
Fungi
Protists
Nuclear pores
Channels through envelope composed of nucleoporins
3000-4000
Allow free passage
Nulcear lamina
Networks of intermediate filaments on internal surface on envelope
Mechanical support + anchoring sites for chromosomes
Nuclear matrix
Protein-containing fibrilar network
Nucleoplasm
Viscous liquid
Similar to cytoplasm
Genetic informaiton in nucleus
Maintains integrity of genes & control cell activites by regulating gene expression
Complex of DNA with histones: Chromatin (interphase) & chromosome (CD)
Nucleolus
Densely-stained suborganelle without membrane
Synthesis of rRNA & tRNA
Cell secretion - types of vesicles
Exocytotic vesicles (continuous)
Secretory (regulated)
Lysosomal
Lysosomal vesicles
Vesicle with proteins for lysosome
Fuses with alte endosome
Contents are then transferred to the lysosome
Secretory vesicles
Vesicle with protein for extracellular release are stored
After signal: move towards the membrane, fuse & release contents
Regulated secretion
Exocytotic vesicles
Vesicle with proteins for extracellular release moves towards the plasma membrane, fuse 6 release the contents
Constitutive secretion
Vacuoles function
Maintain turgor pressure Enable change of cell shape Maintain acidic internal pH Remove unwanted substances Isolate harmful wastes Push contents of cytoplasm against cell membrane (cp closer to light) Role in autophagy
Autophagy
Destruction of invading bacteria
Peroxisomes function
Decomposition of biohazardous chemicals
Breakdown of fatty acids
Production of bile acids
Mitochondria function
Generates ATP
Chloroplast function
Conduct photosynthesis
Generates ATP
Endosymbiosis
Theory that explains evolution of eukaryotic cells from prokaryotic cells
Explains the origins of organelles (M?C)
Endosymbiosis - mitochondria
Anaerobic cell ingested aerobic bacterium
Endosymbiosis - chloroplast
Cell captured photosynthetic cyanobacterium
Transformation
A bacterium takes up a piece of DNA floating in its environment
Transduction
DNA accidentally moved from 1 bacterium to another by a virus
Fertility factor
Conjugation
Chunk of DNA that codes for proteins that make up pilus
