BIOL 107: EXAM 2
72 Cards in this Set
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Sex Chromosomes
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Chromosomes that determine sex
Humans: Male = XY Female= XX
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Autosome
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All chromosomes that aren't sex chromosomes (humans 22 pairs)
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Polyploidy
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more than 2 sets of chromosomes
common in flowering plants but rare in animals
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Karyotype
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display of an individual's chromosomes
photograph of homologous pairs
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Fertilization
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union of 2 gametes to form zygote
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Mitosis
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cell duplication division that produces identical cells
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Meiosis
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cell reduction division that produces haploid cells
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Haploid
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1 set of chromosomes (humans 1n=23)
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Homologous Chromosomes
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Pair of chromosomes that have the same size, genetic loci, centromere position, and staining pattern.
One homologous is inherited from each parent
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Animal Life Cycle
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Gametes (1n) --> zygote (2n) --> development
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What is different between 1st Meiosis and 2nd Meiosis? (as far as division names go)
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1st Meiosis is reduction division
2nd Meiosis is duplication division
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Phases of Meiosis
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Meiosis I
Interphase (chromosomes replicated)
Prophase I (crossing over to exchange genes)
Metaphase I (chromosomes line up independently)
Anaphase I (homologous chromosomes separate)
Telophase I / cytokinesis
Meiosis II (cells now haploid and have undergone recombination)
Prophase…
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Independent assortment of chromosomes
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random distribution of material and paternal homologous to gametes
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2^n
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# of different combinations, gametes
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N
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haploid # of chromosomes
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Crossing over
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exchange of genetic material between non-sister chromatids of homologous chromosomes
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Random fertilization
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egg cell (8 million) + sperm cell (8 million) = zygote (64 trillion)
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Genetic variation
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raw material for evolution
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Spermatogenesis
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sperm produced in seminiferous tubules in testes
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Oogenesis
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eggs produced in follicles of ovary
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Aneuploidy
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Monosomy 2n-1
Trisomy 2n+1
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Nondisjunction
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failure of chromosomes to separate during meiosis
primary- Meiosis I
secondary- Meiosis II
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Barr Body
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inactivated X chromosomes form inactive heterochromatin
genes on barr body are not expressed
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Chromosomes mutations
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Deletion: Cri- du - chate - mainly due to deletion on the sperm- chromosome 5
Duplication: Pallister Killian Syndrome- short arms on chromosome 12
Inversion: chromosomes 6 & 9 are involved
Translocation: Chronic Myelogenous Leukemia- from chromosome 22 to chromosome 9
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Genetics
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the study of transmission of traits from on generation to the next and how these traits are expressed
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Blending Theory
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mixing traits (paint) would forever change the traits
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Particulate Theory
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discrete inheritable units, "genes" (marbles) explains how traits can skip generations
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Allele
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alternative or variant form of a gene
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Dominant Allele
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can mask expression
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Recessive Allele
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masked by another allele
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Gene Locus
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location of a gene on a chromosome
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Mendel's law of segregation
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the 2 gene factors split during meiosis and random fusion of gametes occurs at fertilization
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Mendel's law of independent assortment
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alleles of a gene for 1 trait segregate independently of alleles of another trait
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Multiple alleles
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more than 2 allelic forms for a gene in a population (ex. ABO blood types)
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Rh factor
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gene that has 2 alleles and is inherited in dominant/ recessive fashion
Rh+ = dominant
Rh- = recessive
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Codominance
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heterozygote expresses phenotypes of both homozygotes (ex. blood type AB = A antigen and B antigen)
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Incomplete dominance
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interaction of 2 alleles, neither allele is completely dominant
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Incomplete penetrance
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dominant alleles that are partially expressed or not expressed
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Pleiotropy
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a single mutant gene affects 2 or more unrelated traits
marfan syndrome is due to a mutant gene that codes for the protein fibrin (elastic fibers in connective tissues)
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Polygenic inheritance
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single trait controlled by more than 1 gene
traits vary along a continuum
quantitative (ex. height, skin color)
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Environmental effects on gene expression
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nature vs. nurture
phenotype = genotypes + environment
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Natural Theology
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Believed earth was only a few thousand years old and a "fixed species"
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Linnaeus
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father of taxonomy
hierarchy of classification (order in diversity)
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Cuvier
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French scientist
Explained succession of life forms as catastrophism
After each catastrophe (or extinction) a region was repopulated by a new species
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Erasmus Darwin
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Life evolved from a common ancestor forming "one living filament"
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LaMarck
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In 1802, proposed one of the first theories stating a mechanism for evolutionary change
Inheritance of acquired characteristics (use or lose)
False, but theory recognized that evolution involved interaction of organisms with their environment
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Two facets of Darwinian View of Life
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a) common decent
b) natural selection
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Alfred Wallace
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Developed theory of natural selection independent of Darwin
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Homologous structures
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inherited from a common ancestor
different in function
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Analogous structures
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similar in function; different in origin
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Vestigial structure
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structures retained in organisms even though they may not be functional
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Types of natural selection
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1. Directional- favors extreme
2. Disruptive- favors 2 extreme phenotypes over the average phenotype
3. Stabilizing- favors intermediate variants
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Sexual Selection
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leads to an increased ability to secure a mate
1. Female choice (intersexual)
2. Male competition (intrasexual)
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Maintenance of diversity
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a) Natural selection
b) Heterozygote advantage
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Speciation
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splitting of one species into two or more
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Temporal isolation
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frogs occupy the same habitat but breed at separate times
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Behavioral isolation
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Blue footed boobies present elaborate courtship displays
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Habitat isolation
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crickets occupy different habitats in same geographic zone
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Mechanical isolation
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male dragonfly claspers only work to hold the female of their own species
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Gamete isolation
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gamete of 2 sea urchin species are not compatible
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Prezygotic isolation
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prevent reproductive attempts or successful fertilization
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Postzygotic isolation
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prevent successful development
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Hybrid inviability
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hybrids form but don't complete development
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Hybrid sterility
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female horse and male donkey = sterile mule
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F2 fitness
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hybrid offspring are sterile
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Allopatric speciation
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2 populations are geographically isolated from one another and 2 different species result
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Sympatric speciation
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new species arise in the midst of parent population without a geographical barrier
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Adaptive radiation
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emergence of numerous species from a single ancestral species that spreads to new environments
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Convergent evolution
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similar trait evolves in 2 unrelated species due to similar environmental pressure
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Principles of macroevolution
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1. Rates of evolution
2. Development genes
3. Evolution is not goal oriented
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Rates of evolution
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1. Gradualistic model
"slow gradual changes" in isolated populations
2. Punctuated equilibrium model
"spurts of relatively rapid change" followed by long periods of stasis
THESE 2 THEORIES ARE NOT MUTUALLY EXCLUSIVE
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Development genes
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Regulatory genes that control genes for animal body shapes, patterns, and organs.
Similar to "switches" to turn genes on and off
1. Pax 6 gene- responsible for eye formation in all animals
2. Hox gene- control # and appearance of repeated structures along main body axis of vertebrates
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BIOL 107: EXAM 1