Lecture 7: Microevolution & Mutation Flashcards
allele frquency
- the # of times an allele occurs in the population
- represented as a proportion of the whole(typically in decimal form)
population
- a group of individuals from a single species
- genes are all the same but alleles probably differ
what are the microevolutionary forces?
- gene flow
- non-random mating
- genetic drift
- mutation
- selection
microevolution
-factors that cause evolution are very slow and which results in evolution taking a long time
gene flow
- the movement of alleles from one population to another
- aka migration
does gene flow increase or decrease genetic variation?
-increase
non-random mating
-if a population does not mate at random but instead mate with a select number of individuals, the mixing of genotypes is not random
assortative mating
- organisms of similar phenotype mate more often than expected by random chance
- tends to inc. the frequency of homozygotes in the population
self-fertilization
-the fusion of sperm and egg that produced by same plant
does non-random mating increase or decrease genetic variation?
-decrease
genetic drift
- any random change to the allele frequency of a opoulation due to a chance event
- greater impact on a small population than a large one
founder effect
- an event caused a small population to go to a new to a new island
- animals are the “founding fathers”
bottleneck effect
- an event occurred on the species’s original island and only a few survivors remain
- shrinking of a population
how are founder and bottleneck effects different?
-same result, different cause to make the result
mutation
-ultimate source of genetic variability
where do new genes come from?
-mutations
crick and brenner’s experiment and results
- the reading frame (sequence of codons) of a gene could be destroyed by mutation and then restored
- if the total number of deletions or additions were multiples of 3
degenerate code
-more than one codon codes for the same amino acid
reading frame
-refers to how the nucleotides in a nucleic acid molecule are grouped into codons, with each codon containing 3 nucleotides
frameshift mutation
- a genetic mutation caused by insertions/deletions of a number of nucleotides in a DNA sequence that is not divisible by 3
- when the reading frame has shifted
chromosome level mutations
-involves changes in entire chromosomes, either in number or structure
nondisjunction
- occurs when chromosomes fail to separate during Metaphase 1
- the result is a gamete with a missing chromosome or with an extra chromosome
aneuploidy
-a gamete or individual has gained or lost a chromsome
monosomy
-a nondisjunction in meiosis, where a cell’s chromosome was pulled from it, and has one instead of two
trisomy
-a nondisjunction in meiosis, where a cell pulled an extra chromosome, and has three instead of two
polyploidy
- where the entire genome is copied
- result of either a meiotic error where none of the homologs separate and they all go to one daughter cell OR due to a hybridization event btwn 2 different species that’re similar
ploidy
-number of copies of chromosomes
what are the outcomes of mutations?
- harmful (most common)
- neutral (most common)
- beneficial
harmful outcomes of mutations
- lethal
- minor to major effects
neutral outcomes of mutations
- silent or chromosomal inversions
- non-coding regions of DNA
- no fitness loss (lead to changes in phenotype that don’t really hinder the organisms ability to survive
types of point mutations
- silent mutation
- missense mutation
- frame shift mutation
- nonsense mutation
types of chromosomal mutations
- deletion
- duplication
silent mutation
- one nucleotide switches
- result: exact same amino acid is translated
missense mutation
- occurs when the substitutions lead to the replacement of one amino acid with another
- changes the protein, often has minimal affects on a protein’s fuctioning
nonsense mutation
- lead to the substitution of a stop codon for a codon that actually codes for an amino acid
- stopping the translation of a protein, almost always leads to the loss of function
deletion
- deleltions of 1 or 2 nucelotides are frameshift mutations
- larger scale deletions are chromosomal level
duplication
- when large copies of a chromosome are copied
- may or may not affect the phenotype of the individual
- being put in the middle could have disastrous affects
turner’s syndrome
- only survivable monosomy
- where an individual has an X chromosome without a pair
- have more health consequences but can live normal lives
