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The Nature of Scientific Knowledge - Coggle Diagram
The Nature of Scientific Knowledge
Scientific Theories
They provide explanations and allow for predictions.
When a theory explains and predicts many observations, it becomes the consensus.
Falsification:
A key part of science is that theories must be testable.
If a new observation doesn't fit a theory, the theory is either changed (enhanced) or considered falsified (proven wrong).
Claims based on religious faith are often not falsifiable (they can't be tested by observation or experiment). This doesn't make them invalid, just not testable in a scientific way.
Example: James Hutton (1726-1797)
Theory
Hutton developed the theory that geological features are not fixed but are constantly transforming over very long periods.
Evidence
He observed rock formations showing layers of sediment that had been laid down, changed orientation (e.g., from horizontal to vertical), eroded, and then covered by new layers.
Genome Basics:
Genome: All the genetic information of an organism. It's the entire base sequence of all its DNA molecules (chromosomes).
Gene: A functional unit of a genome. It is a length of DNA with a sequence of hundreds or thousands of bases.
Unity in a Species:
Members of a species typically have the same genes in the same sequence along their chromosomes.
This "unity" allows chromosomes to be exchanged during meiosis, which promotes genetic diversity without losing or duplicating genes.
Diversity in a Species
Diversity comes mainly from variation in individual genes.
Alleles: These are alternative forms of a gene. Alleles might differ by only one or a few bases.
Single-Nucleotide Polymorphisms (SNPs)
Definition: A position in a gene where more than one base may be present.
SNP vs. Mutation: It's called an SNP if the variation is present in at least 1% of the population. If it's rarer than 1%, it's considered a mutation.
SNPs are the main factor making individual humans different from each other (unless they are identical twins).
Inheritance: You inherit one allele from each parent.
Inheritance: You inherit one allele from each parent.
Homozygous: The alleles from both parents have the same base at that SNP.
Heterozygous: The alleles from each parent have a different base at that SNP.
Scale in Humans: Over 100 million SNPs have been found in human genomes , but since the genome has over 3 billion base pairs, most bases are the same in all humans.
Scale in Humans
Over 100 million SNPs have been found in human genomes , but since the genome has over 3 billion base pairs, most bases are the same in all humans.
Whole Genome Sequencing:
Definition: The process of determining the entire base sequence of an organism's DNA.
History & Technology:
First done in the 1990s with bacteria, which have smaller genomes.
Landmarks include the first prokaryote (1995), eukaryote (1996), multicellular organism (1998), and the complete human sequence (2003).
Technology has rapidly increased speed and reduced cost.
Example: Sequencing a human genome dropped from $100 million (2001) to under $1,000 (2020).
Current Projects
Earth BioGenome Project: Aims to sequence the genomes of all known species.
Human Sequencing: Over 1 million individual human genomes have been sequenced.
Genomic Databases (A3.1.10):
Database: An organized, electronic collection of data.
Data Mining: The process of turning raw database data into useful information.
Purpose: Storing genome size data helps in research on genome evolution and estimating the cost of future sequencing projects.
Examples: Plant DNA C-values Database , Animal Genome Size Database , and others for fungi and microbes.