Chapter 4 Flashcards
Forces of Evolution
Origins of life
How the first living organism came into being
Phylogenies
The study of the evolutionary relationship between groups of organisms.
Phylogenetic tree of life
A family tree of all living organisms, based on genetic relationships
Last Universal Common Ancestor (LUCA)
A single celled organism that gave rise to the world and species we know today through its own cellular division.
Modern Synthesis
Integration of various signs of evolutional evidence to form a unified theory of evolution
What is a chromosome?
A career of collections of genetic information.
What is polymorphism?
Multiple forms of a trait; alternative phenotypes within a given species.
Define population
A group of individuals from the same species who are geographically near enough that they can breed and breed new generations of individuals.
Define genes
the basic unit of information that encodes the proteins needed to grow and function as a living organism.
Allele
A nonidentical DNA sequence found in the same gene location on a homologous chromosome, or gene copy that codes for the same trait but results in a different phenotype.
Gene pool
The entire collection of genetic material in a breeding community that can be passed from one generation to the next.
Homozygous genotype
When the two alleles are the same. ie XX, AA, BB
Heterozygous genotype
When the two alleles do not match. Aa, Bb, XY
What is evolution?
a change in the allele frequencies in a population over time.
What are allele frequencies?
Refer to the ratio or percentage of one allele in comparison to the other alleles for that gene within that study population.
Define genotype
The combination of two alleles that code for or are associated with the same genes.
Define mutation
Change to the genetic code
deleterious mutations
mutations associated with negative effects.
beneficial mutations
a change in the DNA that provides some beneficial advantage to a population at a a particular time.
UV crosslinking
UV rays interact with skin cells causing a mutation causing adjacent thymine bases to bond.
DNA repair mechanism
Mutations are corrected by enzymes that patrol and repair DNA in living cells .
Autosomal recessive
A phenotype produced by a gene on an autosomal chromosome that is expressed only in individuals homozygous fir the recessive allele.
Xeroderma pigmentosum
A disease which causes the repair mechanisms to not function properly resulting in a host of problems after sun exposure such as severe sun burn, dry skin, and heavy freckling.
Define somatic cells
the cells of our organs and other vital body tissues.
Gametes
reproductive cells
Spontaneous mutation
When a new mutation pops up at random in a family lineage.
Inherited mutation
When a spontaneous mutation is passed onto the offspring.
Define point mutation
A single letter change in genetic code resulting in the substitution of one nucleic acid base for a different one.
synonymous mutation
A mutation that does not change the resulting protein.
Nonsynonymous mutation
mutations which do cause a change in the protein. May change the resulting proteins amino acid sequence by altering the DNA sequence that encodes the mRNA or by changing how the mRNA is spliced prior to translation.
Insertions and deletions of indels
The addition or removal of one or more coding sequence letters. Entire codons may be added or removed if they are a multiple of 3.
Frameshift mutations
types of indels that involve the insertion or deletion of any number of nucleotides that is not a multiple of 3. Causes all codon beyond the mutation to be missed.
Transposable elements/transposons
Fragments of DNA that can jump around in the genome.
Retrotransposons
Transcribe from DNA to into RNA and then reverse transcribed to make a duplicate copy which can be copied into a new location in the DNA.
DNA Transposons
Clipped out of the DNA sequence itself and inserted elsewhere in the genome. Does not utilize RNA.
What is a crossover event?
Occurs when DNA is swapped between homologous chromosomes while they are paired up for meiosis I.
Nondisjunction event
Occurs when sister chromosomes or alleles fail to split after pairing and causing the sister cell to be absent of chromosomes. At the gamete level this is fatal to the embryo.
Trisomies
triple chromosome condition- condition in which three copies of the same chromosome end up in the same cell, as the result of a disjunction event. (Down syndrome)
monosomies
inheritance of one an X chromosome from one parent and no sex chromosome from the other.
Chromosomal translocations
Involve transfers of DNA between non homologous chromosomes. May include swapping large portions of two or more chromosomes.
balanced translocations
The genes are swapped but no genetic information is lost.
Unbalanced translocations
An unequal exchange of genetic information resulting in loss of information or duplication of genes.
Derivative chromasomes
New chromosomal structures that are created from two different chromosomes as a result of translocations.
Genetic Drift
Random changes in allele frequencies from one generation to the next.
Asexual reproduction
Reproduction via mitosis, whereby offspring a clones of their parents
Sexual reproduction
Offspring inherits one allele from each parent.
Population bottleneck
occurs when the number of individuals in a population drops dramatically due to some random event.
Cretaceous Paleogene Extinction (K-Pg)
Extinction of the dinosaurs. Occurred 66 million years ago. A giant asteroid crashed into what is now known as the gulf of Mexico.
Antibiotics
Medicines that are prescribed to treat bacterial infections.
Founder effects
occur when members of a population leave the main group and form a new population that no longer breeds in the original group.
Guevedoces
Refers to the young individuals born as female that then developed penises in puberty in the Dominican Republic in the 1970’s. PENIS AT TWELVE.
inbeeding
refers to the selection of mates exclusively from within a small, closed population
Old Order Amish
A culturally isolated population in Lancaster that has aprox 50,000 members all originating from 80 individuals. High rates of genetic disorders.
Ellis-van Crevald syndrome
An autosomal recessive disorder characterized by short stature, polydactyly, abnormal tooth development, and heart defects.
What is gene flow?
The movement of alleles from one population to another.
Admixture
Geneflow among humans. There is only one species of human remaining. We are all the same.
Hybridization
Gene flow between otherwise isolated non human populations.
Scutellata Honey Bees
Gene flow of killer bees in the America’s was a definitive example of hybridization.
Natural Selection
occurs when certain phenotypes confer an advantage or disadvantage in survival and/or reproduction success.
Directional selection
environmental pressures favor one phenotype over the other that cause the frequencies of the associated adventagous alleles to gradually increase.
Balancing selection
Occurs when selection works against the extremes of a trait and favors the intermediate phenotype.
Disruptive selection
(diversifying selection) occurs when the extremes of a trait are favored over the intermediate phenotypes. Darwin’s canaries had either large or small beaks no medium beaks were present because they would have been useless/
Sexual selection
an aspect of natural selection in which the selective pressure specifically effects reproductive success rather than survival.
Neurofibromatosis Type 1
A disorder that displays how a mutation in a single cell can affect multiple systems in the body. Causes the growth of benign tumors and neurofibromas.
Autosomal dominant
everyone born with the condition has a 50/50 chance of passing it on.
Cutaneous neurofibromas
spherical bumps on or just under the skin tissue
Plexiform neurofibromas
Growths involving whole branches of nerves; often giving the appearance that the surface of the skin is melting
Cafe-au-lait-spots CALS
The first sign of NF1 in small children. Flat brown birthmark like spots on the skin.
Sickle cell anemia
An autosomal recessive genetic disorder that can effect most common in Africa. Affects the hemoglobin molecule in red blood cells. Sickled cells cause clotting within the blood stream resulting in bouts of pain and issues with oxygen levels.
Malaria
An infection of the blood by a plasmodium parasite which enters the human body via mosquito bite.
Dictyostelium discoidium
“slime molds”amoeba or single celled organisms that researchers used to study for how they ingest food and liquid for energy.
Hardy-Weinberg Equilibrium
A mathematical equation that allows estimation of the number and distribution of dominant and recessive alleles in a population.
Nonrandom mating
when mate choice in a population follows a nonrandom pattern
Positive assortative mating
patterns result from a tendency for individuals to mate with others who share similar phenotypes.
Artificial selection
Breeding to promote certain characteristics that are favored for instance in livestock.
viable offspring
offspring that are healthy enough to survive to adulthood.
Fertile offspring
offspring that are able to reproduce successfully
Subspecies
Have their own phenotype and are geographically isolated from the main species.
Microevolution
Refers to frequency changes in alleles of a breeding population- within a single species.
Macroevolution
Describes how similarities and differences between species as well as phylogenetic relationships with other taxa lead to relationships that develop new species.
Speciateion
When one species divides into two or more separate species.
Allospatric speciation
Is the effect of long term isolation of subgroups of the population.
Sympatric speciation
Occurs when the population splits into two or more subspecies without isolation or physical separation.
Adaptive radiation
refers to the situation which subgroups of a single celled species rapidly diversity and adapt to fill a variety of ecological niches.
Ecological niche
A set of constraints and resources that is available in an environmental setting.
