BIO 358 Lecture Notes - Lecture 2: Richard Dawkins, Teleology, Genetic Variation
14 Jun 2018
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Topic 2: We know what life is - A particular case of chemistry
Key Terms:
1. Chromosome: These are the physical objects in which genetic design information is packaged in
contemporary organisms. Chromosomes consist of a single very long DNA molecule, together with a large,
complex array of protein molecules which package, control, express, and replicate that genetic design
information. A typical chromosome in a human or other animal might have one to three thousand genes
encoded along its DNA molecule. A typical mammal might have fifteen to thirty such chromosomes making up
its entire genome. Of course, these animals – including us – are diploid so that they actually have two copies
of eah of these hroosoes oe op fro the orgais’s other ad one from its father).
2. Genetic variation
3. Cryptic genetic variation
4. Mutation: Can be used as either a verb or a noun, depending on context. As a verb, it refers to the process
whereby DNA sequence is accidentally changed – generally rarely – during replication of a DNA molecule. For
example, an A base might be put in where a G base was before. This changes the sequence of the DNA,
thereby altering the genetic design information it encodes. Such changes generate the differences between
different copies of individual pieces of genetic design information or genes. These differences constitute the
genetic variation on which Darwinian selection acts (Chapter 2). As a noun it generally refers to the change in
DNA sequence produced by mutation (the verb). Also see allele.
5. Allele: Refers to different versions of the same piece of genetic design information produced by mutation
(Chapter 2). For example, two different versions of a 3000 DNA base long eye color gene might be identical in
all but one position, say position 1357. At this single position one version might have a C base and the other a
G base in the DNA molecule. One version might produce green eyes and the other blue eyes. Each of these
two forms would be called a different allele of this gene.
6. Natural selection/Darwinian selection: Can be used as either a verb or a noun, depending on context. As a
verb, it refers to the process whereby DNA sequence is accidentally changed – generally rarely – during
replication of a DNA molecule. For example, an A base might be put in where a G base was before. This
changes the sequence of the DNA, thereby altering the genetic design information it encodes. Such changes
generate the differences between different copies of individual pieces of genetic design information or genes.
These differences constitute the genetic variation on which Darwinian selection acts (Chapter 2). As a noun it
generally refers to the change in DNA sequence produced by mutation (the verb). Also see allele.
7. Sexual reproduction: Refers to a particular reproductive or replication strategy whereby genetic design
information building an individual organism (vehicle) is provided in two copies – one from each of two
parents. Typically one copy is provided by the female in an egg cell and the other copy by the male in a sperm
cell. The sperm and egg are each said to be haploid having one copy of each gene or element of genetic design
information. The fertilized egg (that will go on to grow in to the mature offspring) resulting from the fusion of
the sperm and egg at fertilization is said to be diploid as a result of having two copies of each piece of genetic
design information.
8. Asexual reproduction
9. Gamete
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10. Haploid: Refers to genomes of gametes (eggs and sperm). The term refers to the condition of having half
of the diploid number of genes in the adult organism (and the fertilized egg that will grow into this adult). A
haploid gamete has one copy of each piece of genetic design information (each gene) while the diploid
individual has two copies of each piece, one from each of parent.
11. Diploid
12. Independent assortment
13. Crossing over (recombination)
14. Vehicle: We will use this term in a specific technical sense and as it was originally used by Richard Dawkins
in the Selfish Gene (1976). It refers to the physical entity that is an organism (Chapter 2). It can be any
organism, including a virus, an oak or a human being, for example. This term emphasizes the status of the
organism in the long sweep of evolutionary history. The organism is built by genetic design information for the
sole teleological purpose of replicating that design information through what we think of as biological
reproduction. In other words, on an evolutionary time scale an individual organism is merely a transient,
ultimately disposable vehicle for the replication of potentially immortal genetic design information. Use of the
term vehicle – rather than animal or organism – tends to focus our attention on ultimate causation where this
attention needs to be focused for authentic understanding.
15. Design information = genetic design information: Refers to the information encoded in DNA sequence,
that is capable of replication and that directs the production of tools (often proteins acting as catalysts or to
build structures like organs and skin) that build the vehicles that, in turn, support and permit replication of the
design information (Chapter 2). The logic of getting this design information replicated in a Malthusian world
determines how natural selection shapes all animal behaviors, including social behaviors (Chapter 3).
There are several slightly subtle but crucial points here. First, it is the information that is important. It is the
information encoded in DNA and not the physical DNA molecule itself that matters. This is quite analogous to
saying that Shakespeare is not the paper and ink in which it is encoded but the information Shakespeare
intended to convey. Second, genetic design information is encoded in DNA as a result of historical accident.
There is nothing unique or magical about DNA. Any physical medium – on another planet, perhaps – that has
the necessary properties would work just as well as and analogously to DNA.
16. Germline (design information) and Soma (vehicle)
Germline: The ells i a aial’s od that ill ature ito eggs or sper. This ter also applies to
eggs and sperm themselves. The germ line is where the genetic design information responsible for the
building of the class of vehicles we call multicellular animals is recorded, stored and replicated in
preparation for sexual reproduction.
17. Genotype and Phenotype
Genotype: Refers to the specific collection of versions of pieces of genetic design information (alleles
of gees i a speifi idiidual orgais’s genome. For example, an individual might have brown hair
and brown eyes rather than, say, red hair and blue eyes. These differences in our appearance are due
to differences in our genotypes, the specific versions of our genes we inherited from our particular
parents. The anatomical differences themselves (brown eyes, say) are referred to as our phenotype,
the consequence of our genotype. A crucial detail is that genotype can control behavior in startling
extensive and specific detail. Thus, behavior will evolve to serve the interests of replicating the genetic
design information that produces that behavior (Chapter 3).
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Document Summary
Topic 2: we know what life is - a particular case of chemistry. Key terms: chromosome: these are the physical objects in which genetic design information is packaged in contemporary organisms. Chromosomes consist of a single very long dna molecule, together with a large, complex array of protein molecules which package, control, express, and replicate that genetic design information. A typical chromosome in a human or other animal might have one to three thousand genes encoded along its dna molecule. A typical mammal might have fifteen to thirty such chromosomes making up its entire genome. As a noun it generally refers to the change in. Also see allele: allele: refers to different versions of the same piece of genetic design information produced by mutation (chapter 2). For example, two different versions of a 3000 dna base long eye color gene might be identical in all but one position, say position 1357.
