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F1 generation
first generation - dominant
[produced purple flowers in Mendel's experiment]
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F2 generation (results)
3:1 ratio of dominant: recessive
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Why is F1 dominant, but F2 different?
because F1 is heterozygous dominant so F2 will vary
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phenotype v. genotype
phenotype: expression of a trait
genotype: individual's genetic make up
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what is complete dominance?
a diploid individual will have 2 chromosomes
each chromosome contains a separate gene that codes for that specific trait
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does each gene contribute?
yes, each gene contributes to an allele to genotype-
but only one phenotype is expressed
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kinds of chromosomes in complete dominance?
where are the genes located?
homologous
located at the same locus
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law of segregation
alleles segregate independently of each other when forming gamete
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incomplete dominance
heterozygote exhibits a phenotype that is intermediate between he homozygous counterparts
[same capital letter, different superscript]
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codominant
heterozygote exhibits both phenotypes
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what allele is codominant?
blood type
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Law of Independent Assortment
genes on different chromosomes assort independently of each other
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what kind of genes assort independently? (in other words, what genes are on different chromosomes)
genes that code for different traits:
i.e. pea shape and pea color
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phenotypic ratio of a dihybrid cross
9:3:3:1
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II. Humans - which chromosome establishes sex of the individual?
23rd chromosome
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male v. female
male = X and Y
female = X and X
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what does sex-linked mean?
when a gene is found on the sex chromosome -
will sort dependently on the sex of the individual
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which male chromosome carries the allele for sex-linked traits?
X not Y
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if a dominant allele is carried by X chromosome in the male is it expressed? what about if it's recessive?
always expressed: dominant or recessive
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III. Evolution - what is a gene pool?
total of all alleles in a population
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the course of development (zygote to adult) reflects....
evolutionary history
[human fetus has pouches reflecting a gilled ancestor]
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taxonomic classification
Kingdom, Phylum, Class, Order, Family, Genus, Species
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what determines a species?
all organisms that can reproduce fertile offspring
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natural selection
whoever produces more offspring
[doesn't matter what you do, all that matters is that the species doesn't go extinct]
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survival of the fittest
one species will exploit the environment more efficiently
leads to extinction of the others with the same niche
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r-selection
involves producing large numbers of offspring that mature rapidly
(little or no parental care)
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k-selection
slow maturing of offspring
(strong parental care)
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growth curves for r- and k-selection
r-selection = exponential
k-selection = sigmoidal
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who has high mortality rate? who can survive in changing environments?
r-selection
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what is polymorphism?
some phenotypes vary gradually within a species [ex: height]
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what is symbiosis?
relationship between two species
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mutualism
beneficial for both
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commensalism
beneficial for one, doesn't affect the other
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parasitism
beneficial for one, detrimental for the other
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genetic drift
one allele may be permanently lost due to the death of all members having that allele
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binomial theory: what does it predict?
genotype frequency of a gene in a population in Hardy-Weinberg equilibrium
-
what are the equations?
p2 + 2pq + q2
p + q = 1
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What are chordates characterized by?
bilateral symmetry
(not all of them have a backbone)
-
or chordates proteostomes or deuterostomes?
deuterostomes -
anus develops from or near blastopore
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What other features do chordates have?
- coelom
- notochord
- paryngeal slits
- dorsal, hollow nerve chord
- tail
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what is a notochord?
axial support, not the backbone
-
verbrata
have notochord replaced by cartilage or bone structure
also have a distinct brain enclosed in skull
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