19 - Biological Complexity Flashcards
Levels of biological organization
- Biosphere
- Biome
- Ecosystem
- Community
- Population
- Organism
- Organs
- Tissues
- Cells
- Organelles
- Proteins
- Genes
Two ways of going about biological organization
- Reductionism: explains biological complexity by reducing systems to simpler components
- System biology: explains biological complexity in terms of increasing complexity within hierarchical levels
When is reductionism used vs systems biology? Analogy for each:
Reductionism: primary approach to research and teaching in Medicine and Public Health. Analogy = quantum physics (understand the small)
SB: one health approach. Analogy = gravitational physics
Complexity increases with…
Each increasing level of biological organization
What are emergent properties?
Complexity that is greater than the sum of the parts, representing the new/unpredictable interactions among the players
What is genomics? Two types
Study of genome structures
- metagenomics: study of composite collection of genomes represented within an ecological niche or sample
- transcriptomics: study of composite collection of mRNA transcripts produced by the genome under certain condition
What is proteomics
Study of the complete repertoire of proteins in a cell, tissue, organ, system or organism
What is metabolomics
Study of metabolites produced by a tissue, organ, system or organism
What is the genetic code?
- discovery of DNA molecule associated with genetic inheritance
- code is universal and therefore complexity is encoded in simplicity
What are the information coding molecules? other possibilities?
Nucleic acids
Other possibilities are proteins? Carbohydrates?
Describe the human genome
3.2 billion base pairs of DNA, encoding an estimated 20,500 genes, on 46 chromosomes
Mouse genome? Fruit fly? Largest genome?
Mouse = 2.5 billion bp, 30,000 proteins, 40 chr
Fruit fly = 0.18 billion bp, 13,600 proteins, 8 chr
Largest genome = Amoeba dubia (600 billion bp)
What % of nucleotides are exactly the same in all people
99.9%
1.4 million locations where single-base DNA differences (SNPs) occur in humans
Similarity of human and chimp genome? How much of genome is composed of transposable elements? Derived from viruses? Junk DNA?
96% similarity
Nearly half genome is jumping DNA
8% derived from viruses
50% considered junk DNA
What is the human genome project? Cost?
Sequencing the human genome. Took 15 years to complete
95% of genome published in 2001, complete by 2005
Cost ~$3 billion
How fast can the human genome be sequenced now?
A few days
Slides 15-17
DNA microarrays
How many human cells on a person? Microbes?
10^3 human cells
10^4 microbes
“second genome”
What benefits do the gut microbiome provide the host (5)
- nutrition and colonization sites
- digest food (nutrients normally indigestible for humans)
- produce important compounds (Vit K)
- stimulate immune system
- barrier to defend pathogen infection
What human/animal diseases may be a result of an altered microbiome
- obesity
- diabetes
- cancer, autoimmunity
- enteric infections (antibiotic treatment clears microbiome = C difficile recolonizes)
- autism
Distinct nodes of control between proteins
- Negative (inhibitory)
- Positive (stimulatory)
- Variations
What is biological degeneracy
Ability of elements that are structurally different to perform the same function or yield the same output
Prominent property of many biological systems
What is biological redundancy?
When the same function is performed by identical elements
Biological degeneracy and redundancy are both necessary for…
natural selection (evolution)
(and an outcome of)
Examples of degeneracy at different levels of biological organization
- genetic code (many nucleotide sequences encode a polypeptide)
- genes (functionally equivalent alleles)
- protein functions
- interanimal communication (transmit same message)
- body movements (muscle contractions yield equivalent outcomes)
Why is biological degeneracy and redundancy important in one health context (4)
- Disease is a major driver of them
- buffer against environmental stresses/changes
- biochemical/metabolic plasticity, ensures that no one biochemical pathway can be exploited (e.g. induction of cancer growth requires 7-10 mutation events)
- allows for high degree of fine tuning of individual physiological responses (e.g. immune responses)
Biological complexity and the insurance hypothesis
- healthy ecosystems have high lvl complexity (and red/deg)
- biodiversity can buffer ecosystem from env pressures/fluctuations
- biodiv can have enhancing effect on ecosystem productivity
- greater species richness can support maintenance of ecosystem, some spp persist while others fail
- biodiv insures ecosystem sustainability
