Flashcards in Test 2 Deck (111)
The theory that mitochondria and chloroplasts originated as free-living bacteria and evolved into energy-producing organelles in eukaryotic organisms millions of years ago. This theory is considered an example of evolutionary evidence.
occurs when a modifier gene suppresses an expressed phenotype of another gene
the random replication of mitochondria, chloroplasts, and other organelles during cell divisions that results in daughter cells with random samples of these organelles
a form of nondisjunction that results in an extra chromosome being added to a cell during meiosis, leading to genetic disorders such as Down Syndrome
a chromosomal abnormality that occurs when non-homologous chromosomes exchange information, which alters the structure of the chromosome
an x-linked recessive genetic disorder, expressed primarily in males, that occurs when a gene that produced blood-clotting proteins is deleted
the complete set of genetic information in a population
What are Mendelian genetics?
Three Laws: Segregation, Independent assortment, and dominance
The Law of Segregation states that genes separate into distinct alleles during meiosis.
The Law of Independent states that genes separate and recombine independently of one other.
The Law of Dominance states that offspring will express the dominant allele.
What occurs during the process of recombination?
Crossing over occurs during Prophase I of meiosis. As duplicated chromosomes separate into chromatids, the chromatids intertwine and exchange alleles in random patterns. The resultant chromosome therefore carries the same genes but has a combination of both parent's alleles.
Why are recessive X-linked traits expressed primarily in males, but not females?
If a female inherits a recessive X-linked allele, it has a greater chance of being masked by a dominant X-linked allele. Males only inherit one X allele so the trait will be expressed whether it is recessive or dominant.
Why are height and weight considered examples or traits that display continuous variation?
Height and weight are traits that exist along a continuum (unlike eye color that does not have a set number of varieties).
How is extranuclear DNA passed on from parent to offspring?
Some organelles, including chloroplast and mitochondria, contain DNA that does not replicate during gamete formations because it is not located within the nucleus. DNA in these organelles is duplicated from the maternal cell when two gametes fertilize, and the offspring inherits extranuclear DNA exclusively from the mother.
How do prokaryotic organisms increase genetic variation during reproduction?
Bacteria and archaea increase variation by exchanging genetic information through transduction, transformation, and conjugation.
Transduction occurs when a cell is infected by a virus that absorbs genetic material and transfers it to another host cell.
Transformation occurs when prokaryotic cells absorb genetic material from a source outside the cell.
Conjunction occurs when two prokaryotic cells exchange plasmids (gene-carrying structures in the cell).
How do chromosomal abnormalities increase genetic diversity and drive evolution around a population of organisms?
Some chromosomal abnormalities introduce new genes and changes to phenotypes that are expressed among a population. In sexually reproducing eukaryotes, these phenotypes can give organisms an ecological advantage and are more likely to be selected for and passed on in a population.
Why is cystic fibrosis considered an autosomal recessive disorder?
It is an inherited recessive disorder that results from a mutation of an autosomal gene (not linked to a sex chromosome).
Which mechanisms allow alleles to be distributed and move within and between populations of species?
Gene flow, Migration, Genetic drift, and nonrandom mating
What are the five conditions of the H-W equilibrium?
Large population, isolated, no genetic mutations, random mating, and no natural selection
How do evolutionary mechanisms lead to change in populations of sexually reproducing organisms?
They alter the variation of genetic information and allele frequency within the population, which alter the reproductive patterns of the population. Certain traits survive while others don't. Over time, this results in change.
Which conditions must be met for natural selection to occur?
variation in traits that can be inherited by offspring, overproduction of offspring, and differential reproduction
How do random events drive genetic drift in a population?
They can wipeout large portions of populations or isolate small populations from the larger population which leads to loss of diversity and causes genetic drift.
What is the role of stasis in the theory of punctuated equilibrium?
Theory: species remain in long periods of equilibrium with no major evolutionary changes (stasis) the majority of the time.
This stasis is punctuated by short, rapid bursts of evolution that drive species change and speciation.
What is the difference between convergent and divergent evolution?
Convergent: two unrelated species evolve similar traits (analogous structures) due to similar environments
Divergent: two species descended from a common ancestor evolve non-similar traits in response to different environments/niches
How does reproductive isolation play a central role in speciation?
Populations of species that become isolated will see reduction in gene flow between the two groups. Overtime, as they both experience evolutionary changes, they become incapable of inbreeding which may lead to speciation.
What are the different types of pre-zygotic isolation?
Habitat, temporal, behavioral, mechanical, and gamete isolation.
Why do hybrid organisms experience infertility?
They do not have a full set of compatible chromosomes.
In that absence of physical barriers, which factors can lead to parapatric speciation?
Populations share the same habitats, but they become isolated due to behavior or timing of breeding.
Why do homologous structures in living organisms indicate evidence of evolutionary relationships?
They indicate that the species shared a common ancestor at some point in its evolutionary history.
What distinguishes evolutionary trends from random trait fluctuation?
Trends: changes to a trait or structure that occur in one linage or across the lineage of multiple organisms. Occurs over and over with increasing quantities, sizes, or complexities.
Random fluctuation: does not show a distinct pattern across linages, and doesn't it display increasing complexity overtime
a kingdom found in the original five-kingdom system and consisted of prokaryotic, unicellular organisms. Now is subdivided into Bacteria and Archaea