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Biology
The study of life
How can you differentiate living and non-living things?
By using the principles of biology
10 Principles of Biology
Cells are the simplest unit of life
All organisms require energy from their environment
All organisms interact with their environment
Although life is a dynamic process, all organisms maintain relatively stable internal conditions
All organism change during their lifespan
All living organisms have genetic material composed of DNA
All living organisms evolve from one generation to the next
All organisms at some point share a common ancestor
Structure determines function
Emergent properties arise from the interaction of smaller components or from the interaction with the environment
What are the levels of organization?
Atoms, molecules and macromolecules, cells, tissues, organs, organism, population, community, ecosystem, and biosphere
What is vertical descent?
The progression of changes in a lineage. New species evolve from pre existing species by accumulation of heritable changes in their genetic code defined as Mutations. Natural selection takes advantage of beneficial mutations.
What is horizontal gene transfer?
Horizontal gene transfer is genetic exchange between different species, not directly from a shared ancestor. It is rare and more common in bacteria and mostly occurred at the beginning of life on Earth.
What are the three domains of life?
Bacteria, Eukarya, Archaea
What is science?
It's the observation, identification, experimental investigation and theoretical explanation of natural phenomena.
What is discovery-based science?
A scientific methodology which aims to find new patterns, correlations, and form hypotheses through the analysis of large-scale experimental data.
What is hypothesis-driven research?
One of the main methods for using data to test and, ultimately, prove (or disprove) assertions. To do that, researchers collect a sufficient amount of data on the subject and then approach it with a specific hypothesis in mind.
Which types of data are used by scientists?
Qualitative data Quantitative data
What is a hypothesis?
A proposed explanation for a natural phenomenon.
What is a theory?
A broad explanation of some aspect of the natural world that is substantiated by a large body of evidence.
Hypothesis vs. Theory
Theory allows you to make correct predictions, hypothesis allows you to make predictions that can be right or wrong.
What is the age of our planet?
4.5 billion years old
What is the age of the universe?
13.7 billion years old
When did life start?
3.5-3.8 billion years ago.
What evidence do we have for when life started?
Fossil Prokaryote and Modern cyanobacteria.
What are the 4 stages that gave rise to life?
Stage 1 - Production of nucleotides and amino acids Stage 2 - Polymerization Stage 3 - Polymers became enclosed in membranes Stage 4 - Polymers enclosed in membranes acquired cellular properties
What are the hypotheses that explain where and how organic molecules originated?
Extraterrestrial source Reducing atmosphere Deep sea vents
What is the Miller-Urey experiment?
A simulation of conditions on the early Earth testing the idea that life, or more specifically organic molecules, could have formed by nothing more than simple chemical reactions.
What is the panspermia hypothesis?
he theory that life on the earth originated from microorganisms or chemical precursors of life present in outer space and able to initiate life on reaching a suitable environment.
What is the sea-vent hypothesis?
By creating protocells in hot, alkaline seawater, a UCL-led research team has added to evidence that the origin of life could have been in deep-sea hydrothermal vents rather than shallow pools.
What are protobionts?
Self-organized, spherical collection of polymers and macromolecules within a membrane, proposed as a stepping-stone toward the origin of life.
What are the characteristics of protobionts?
Boundary (e.g., membrane) separated external environment from internal contents
Polymers that contained information
Polymers that had enzymatic functions
Protobionts capable of self-replication
What is the RNA world?
An early Earth period when both information and catalytic activities were done only by RNA
RNA vs. DNA vs. Proteins
DNA contains the information necessary for encoding proteins, although it does not produce proteins directly. RNA carries the information from the DNA and transforms that information into proteins that perform most cellular functions.
What is chemical selection?
In this process, a chemical within a mixture has an advantage that results in an increase in its number in comparison to other chemicals in the mixture. First, polymers of RNA acquired auto-replication properties using one RNA molecule as template Then, polymers of RNA acquired catalytic properties to synthesize ribonucleotides (building blocks) of RNA. This results in an RNA world.
What are fossils?
preserved remains of past life on Earth. Examples: Bones, shells, leaves, amber
Who studies fossils?
Paleontologists
What is radiometric dating?
This method uses the decay rate of radioactive material to date objects.
Why is the fossil record incomplete?
Because few individuals have fossilized, and even fewer have been discovered.
What is continental drift?
the gradual movement of the continents across the earth's surface through geological time.
Are we in the midst of a 6th mass extinction?
Yes
What is systematics?
The study of biological diversity and the evolutionary relationships among organisms, both extinct and modern.
What is taxonomy?
The science of describing, naming, and classifying living (extant) and extinct organisms and viruses
What is the most significant contribution of Carolus Linnaeus?
The publication of a system of taxonomy based on resemblances and similarities
How can we name a species?
The first letter of the genus is capitalized, and the entire species name is italicized Both parts together name the species (not only the specific epithet). This binomial name is used by convention when talking about the same species
What are the taxonomic levels?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
What is a phylogenetic tree?
A simple diagram that depicts the origin and evolution of a group of species.
How are phylogenetic trees inferred?
Morphology and molecular data
What is evolution?
Heritable change in one or more characteristics of a population from one generation to the next
What is microevolution?
Changes in a single gene in a population over time
What is macroevolution?
Evolutionary changes that result in the formation of new species.
What was the early thinking about evolution before Darwin?
Classifications were made by many different people including Aristotle
What is catastrophism?
The belief that the Earth's past geological changes were caused by sudden, violent changes in the Earth's surface.
What is uniformitarianism?
The belief that the Earth's past geological changes can be fully explained by current processes.
What was Thomas Malthus' insight about population growth?
Human population might grow in size, at best, linearly (i.e., one to one). However, human's reproductive potential is exponential (i.e., can double each cycle of reproduction)
What is variation?
Differences in the characteristics of individuals in a population
What is natural selection?
the process through which populations of living organisms adapt and change.
What is artificial selection?
modifying other species by selecting and breeding individuals with desired traits
What are the 5 most important inferences of Darwin's book: On the Origin of Species?
Inference 1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment, tend to leave more offspring than other individuals Inference 2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations Inference 3: Natural selection increases the adaptation of organisms to their environment over time Inference 4: If an environment changes, natural selection may result in the adaptation of these populations to these new conditions and may give rise to new species Inference 5: Complex structures such as eyes, wings and intelligence can emerge from the accumulation of small changes through natural selection
How is it possible that. complex traits, like eyes, evolve in natural systems?
Traits are passed down, we don't all have the same vision or eye shape, but overtime it can change
What is homology?
similarity resulting from common ancestry
What is the smallest unit of evolution?
A population
What is a gene pool?
all the alleles in a population
What are alleles?
Different forms of a gene
Monomorphic
Predominately single allele
Polymorphic
two or more alleles
What is the nomenclature of alleles?
A capital letter, a subscript, allele is a combination of both.
Homozygous
The presence of two identical alleles at a particular gene locus. A homozygous genotype may include two normal alleles or two alleles that have the same variant.
Heterozygous
Having two different alleles of a particular gene or genes.
What are single nucleotide polymorphisms (SNPs)?
Smallest type of genetic change in a gene
What is the Hardy-Weinberg equilibrium equation?
A mathematical function that describes the relationship between allele frequencies and genotype frequencies. p^2 + 2pq + q^2 = 1 p = dominant, q = recessive
What are the conditions to maintain the predications under the. Hardy-Weinberg equilibrium equation?
The population is not evolving. The population has random mating. The population does not go through natural selection.
What are random mutations?
Changes in the genetic code that are responsible for the variety of life
What is gene duplication?
multiple copies of the same gene
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