Midterm 1 Study Guide Flashcards
Contribution of Linnaeus
Linnaeus challenged the Great Chain of Being but placed humans in category with other animals
FATHER OF TAXONOMY
- Systema established the taxonomic practices we still use today:
~ Hierarchical system
~ Binomial nomenclature
~ Typology in biology (essentialism)
Contribution of Buffon
Histoire Naturelle (1749) deviated from biblical accounts of creation
- degeneration theory proposed minor improvements/degenerations (from original life forms)
- argued for old Earth
Contribution of Cuvier
- established extinction as a scientific fact
- proposed idea of catastrophism
- but did NOT believe that one species could change into another
Contribution of Lamarck
Proposed that new species could originate via natural processes
- first fully-articulated theory of evolution driven by complexifying force and adaptive force
Who made the first detailed proposal for evolution and how it worked?
Lamarck
Evolution driven by two forces: complexifying force and adaptive force (transmutation and adaptation)
Inheritance of acquired characteristics: first mechanism proposed to explain fit between organism and environment
Transmutation: the idea that a species, as a whole, could change into another, more complex, species
Contribution of Hutton and Lyell
Hutton: “Father of Geology”
- concerning the System of the Earth, its Duration and Stability (1785)
(land today was sea floor in the past)
(Timeless and cyclical nature of geology)
Lyell:
- Principles of Geology (1830)
(Uniformitarianism)
- Led to the belief that Earth was much older than people had previously thought
What are the two “big ideas” presented by Darwin in Origin?
1.) All living things descend from one or a few original forms of life
2.) Natural selection is the mechanism
How does Darwin’s theory of evolution differ from Lamarck’s theory?
Lamarck’s theory was based on the principle that physical changes in individual organisms during their lifetime could be transmitted to their offspring. Darwin’s theory revolves around the idea that populations evolve, not individuals. Because individuals in a population vary, some are better able to survive and reproduce given a particular set of environmental conditions.
When was Origin of Species published?
1859
What does it mean that “individuals do not evolve?”
Individuals do not evolve since evolution is a “change over time” and these individuals are stuck with the genes they are born with. The changes occur during reproduction, so natural selection acts by shifting the characteristics of the population as a whole and no one individual.
What are the observations that Darwin’s theory is based on?
1.) Populations have the potential to increase exponentially
2.) But they generally maintain a stable size
3.) Resources are limited
4.) Variation in all species
5.) Variation is heritable
Who was Alfred Russel Wallace?
A naturalist and explorer working in Indonesia that independently comes up with the idea of natural selection (On the Tendencies of Varieties to Depart Indefinitely from the Original Type (1858))
Nucleotide
1.) Sugar-phosphate backbone
2.) A base (A, T, C, G)
DNA
Deoxyribonucleic acid
- a molecule made up of nucleotides
- carries genetic information
DNA triplet
encodes for a specific amino acid
mRNA
Ribonucleic acid
- synthesis of proteins
RNA codon
translated into an amino acid to create a polypeptide chain
Amino Acid (polypeptide chain)
building blocks for proteins
Protein
a chain of amino acids (and other stuff) that provides a function in a cell
- folds up into a specific shape
- shape=function
Gene
A DNA sequence that codes for a functional RNA product
Outdated: an uninterrupted segment of DNA specifying an amino acid sequence
Allele
One of two or more versions of a genetic sequence at a particular region on a chromosome
Locus
Location on a chromosome
Chromosome
Chromatin condenses into chromosomes when division is about to divide
-DNA organized into genes
Meiosis
the process of replicating gamete cells
Mitosis
The process of replicating somatic cells
Gamete cell
Sex cell (sperm or egg)
- haploid (23)
Somatic cell
body cell
- diploid (46)
Polygenic
Descriptor for a phenotypic trait influenced by more than one gene
Pleiotropic
Descriptor for a single gene that affects more than one phenotypic trait
Ex. ear wax and body odor
Polymorphic/polymorphism
The existence of multiple forms
- a variant occurring at over 1% frequency in a population or sample
Mendel’s 4 postulates and laws of inheritance?
1.) Principle of Paired Factors
2.) Principle of Dominance
3.) Law of Segregation
4.) Law of Independent Assortment
Principles of Paired Factors
Hereditary characteristics are controlled by particulate unit factors that exist in pairs in individual organisms
Principle of Dominance
When an individual has two different unit factors for a characteristic, only one is expressed. That unit factor is dominant over the other, which is recessive
Law of Segregation/Purity of Gametes
The paired units of inheritance (chromosomes) segregate and each sex cell receives one copy or the other with equal likelihood
Law of Independent Assortment
Chromosomes get split up into gametes independently; the segregation of any given pair of chromosomes does not affect segregation in other pairs of chromosomes, so that a gamete with “maternal” chromosome 1 will not necessarily contain “maternal” chromosome 2
What are the 4 forces of evolution?
1.) Mutation
2.) Natural selection
3.) Gene Flow
4.) Genetic Drift
Mutation
Source of all variation in populations
- A random change in the genetic code, resulting from errors in DNA replication
Natural Selection
The phenomenon that increases the frequency of alleles that lead to increased survival and reproduction (fitness)
-Proposed by Alfred Russell Wallace and Darwin
Gene Flow
Process by which populations of a species exchange alleles (individuals)
- introduces new variation into a population
- but decreases the difference between populations
Genetic Drift
A random change in allele frequency that can occur as a result of sampling error
What is the Founder’s Effect?
New population formed by a small number of “founding” individuals
- founder population unlikely to accurately represent all the genetic variation in original population
Because founding population was small, DRIFT QUICKLY increases the frequency of rare variants
What is a Bottleneck?
An event that drastically reduces the size of a population such as natural disasters, habitat loss, or overhunting
- the consequence of the bottleneck effect is the loss of variation in a population caused by the reduction of allele frequencies
In other words: Take an original population of many individuals with lots of genetic variation and then shrinks in size and few individuals can only carry two variants of alleles, causing a huge reduction of genetic diversity even when population increases again
How does Founder’s effect generate genetically distinct populations?
The small population will have reduced genetic variation from the original population due to genetic drift
How does Bottleneck generate genetically distinct populations?
A limited number of individuals survive, resulting in genetic drift to reduce a population’s genetic variation…
How are the concepts– fitness, natural selection, adaptation, and evolution– related?
Through natural selection, individuals more adapted to their environment tend to survive and reproduce better, causing the population to evolve to include those traits (that increased fitness)
Without differences in fitness, natural selection cannot act and adaptation cannot occur and evolution cannot take place
What are the necessary conditions for natural selection?
1.) The individuals or units of selection must vary (genetic variation)
2.) Some individuals must be more fit than others (differential fitness)
3.) There must be a correlation between the fitness of parents and offspring (heritability)
What is the heterozygote advantage? What does it explain?
Fitness of the heterozygote is greater than either homozygote… this explains how a seemingly deleterious allele can be maintained in a population
EX. Sickle Cell Anemia allele more resistant to developing Malaria since red blood cells of heterozygotes are less hospitable for the parasite that causes Malaria
What is lactase?
An enzyme that breaks down lactose into glucose and galactose (simple sugars)
What is lactose?
A disaccharide sugar in milk
Is lactase persistence an adaptation? Why or why not?
Yes, the lactose tolerance mutation arose randomly and had a distinct advantage in certain populations that had milk as part of their diet…
** if environment there would make drinking milk an advantage, the gene will continue to be expressed… it isn’t normal for mammals to be able to consume and digest milk in adulthood…
**Describe one way that human biology (evolution) affects culture?
Differences in skin color resulted in segregation in which not everyone was given equal opportunity in the community
Describe one way that human culture affects biological evolution?
Cultures with a history of dairy farming and milk drinking have a much higher frequency of lactose tolerance
Only certain people in some cultures are socially acceptable to marry and reproduce with
Phenotype
Any observable or measurable feature of an organism
Genotype
The genetic makeup of an individual (variants at a specific locus)
