QUIZ Flashcards
(29 cards)
radioisotope
-an atom with an unstable nucleus that is capable of undergoing radioactive decay
Half-life
- the time required for half the quantity of a radioactive substance to undergo decay
- it is a constant
Modern Evolutionary Synthesis
-the modern theory of evolution that takes into account all branches of biology
Gene Pool
-the complete set of all alleles contained within a species or population
Pseudogene
- a vestigial gene that no longer codes for a functioning protein
- no longer serve useful purpose
Plate Tectonics
-the scientific theory that describes the large-scale movements and features of Earth’s crust
Directional Selection
- selection that favours an increase or decrease in the value of a trait from the current population average
- favours one extreme
Stabilizing Selection
- selection against individuals exhibiting traits that deviate from the current population average
- favours average individual
Disruptive Selection
- selection that favours two or more variations of a trait that differ from the current population average
- favours two extremes
Sexual Selection
- differential reproductive success caused by variation in the ability to obtain mates
- the individuals choose desirable traits in a mate (not necessarily the traits needed to survive like natural selection)
Genetic Drift
- changes in allele frequency as a result of random chance
- more pronounced in small populations
Genetic Bottleneck
-a dramatic, often temporary reduction in population size, usually resulting in significant genetic drift
Founder Effect
-genetic drift that results when a small number of individuals separate from their original population and establish a new population
Hardy-Weinberg Principle
-in large populations in which only random chance is at work, allele frequencies are expected to remain constant from generation to generation
Age of the Earth
-4.5 billion years old
How is evolution defined today?
-change in the gene pool of a species over time
Mutations
- change in the DNA
- DNA may be switched or lost or new bases are inserted
Duplication of DNA
-extra copies can be beneficial (extra copy change not the original)
Mutation Rates
- relatively uncommon events
- rates are hard to estimate
- species with large genomes are likely to have mutation rates averaging more than one per individual
- humans average 20 or more mutations per individual
Homologous Genes
-more closely related two species are, the more similar we would expect their homologous genes to be
Olfactory Receptor Genes
- mammals have approx. 1000 functioning olfactory receptor genes that code for the receptors that detect airborne chemicals
- dolphins have same 1000 but only 200 function
GULO Gene
- humans have dysfunctional copy
- gene necessary for production of vitamin C
- normal diet now provides enough amounts of the vitamin
Plate Tectonics & Continental Drift
- explains discovery of same species in Africa, India and Antarctica
- Pangea
Examples of Directional Selection
- giraffe necks
- peppered moths
- humming birds (move to new area where there are large flowers, long beaks are favoured)
