Chapter 14: Mendellian Genetics Flashcards

1039766375	Blending Hypothesis	traits were of parents were blended, once blended could not be "unblended"	0
1039766376	preformationism	the idea that organisms develop from miniature versions of themselves	1
1039766377	why are pea plants an excellent model system?	1. several varieties available 2. easy to self and cross fertilize 3. relatively fast generation time 4. produce many offspring	2
1039766378	Mendel's Discoveries	1. alleles are alternative versions of a gene 2. a diploid organism has 2 alleles for each gene, one from each parent 3. there are two types of alleles: dominant allele can mask presence of recessive allele 4. law of segregation: a diploid organism has 2 alleles for each gene, & these 2 alleles separate during gamete formation in anaphase I of meiosis	3
1039766379	What is a test cross and why is it used?	breeding an individual with unknown genotype with recessive homozygote -used to determine the genotype of an organism with a dominant phenotype	4
1039766380	Law of Independent Assortment	2 different genes assort independently during gamete formation in metaphase I of meiosis -there are exceptions to this rule	5
1039766381	what is a monohybrid?	heterozygous for the one particular character being followed in the cross	6
1039766382	what is a monohybrid cross?	cross used to observe one trait	7
1039766383	What is a dihybrid cross?	a cross used to observe two traits	8
1039766384	what is a character?	heritable feature that varies among individuals ie. flower color	9
1039766385	what is a trait?	each variant for a character ie. purple, white	10
1039766386	what kind of characters did Mendel choose?	characters that occurred in 2 distinct forms (no intermediate)	11
1039766387	what is true breeding?	organisms that produce offspring of the same variety over many generations of self-pollination	12
1039766388	what is hybridization?	crossing of 2 true breeding varieties	13
1039766389	what is the F1 generation?	first filial generation, hybrid offspring of the P generation	14
1039766390	what is the F2 generation?	offspring of the F1 hybrids self pollinating with other F1 hybrids	15
1039766391	Results of Mendel's key experiment	both purple and white flowered plants appeared in F2 generation; ratio = 3:1	16
1039766392	Conclusion from Mendel's key experiment	-heritable factor for recessive trait was masked by the presence of the factor for the purple flower, which is the dominant trait -refuted blending model -traits are not always inherited together	17
1039766393	If blending model of inheritance were correct..	the F1 hybrids from a cross between purple and white flowers would have been pale purple flowers	18
1039766394	Degrees of Dominance	complete dominance, incomplete dominance, codominance	19
1039766395	what is complete dominance?	phenotype of heterozygote and dominant homozygote are indistinguishable -only 1 allele dominant for each trait -only two phenotypes possible	20
1039766396	what is incomplete dominance? what is an example?	neither allele is completely dominant over the other, and the F1 hybrids have phenotype somewhere between the 2 parental varieties ex.) red and white snapdragon can produce pink offspring	21
1039766397	Is incomplete dominance an example of blending?	No, because they can also produce red or white offspring	22
1039766398	what is co dominance? give example	alleles each affect the phenotype in separate, distinguishable ways -exhibited in a gene with more than two alleles -more than one allele may be dominant ex.) AB0 blood types	23
1039766399	ABO blood types	type A: I^A I^A or I^A I^i type B: I^B I^B or I^B I^i type AB: I^A I^B type O: ii	24
1039766400	Addition Rule for Probability	"either/or" -mutually exclusive events	25
1039766401	Multiplication Rule for Probability	"and" -used for independent events	26
1039766402	melanocytes	cells that make pigment	27
1039766403	eye color with no pigment	blue	28
1039766404	eye color with some pigment	hazel	29
1039766405	eye color with a lot of pigment	brown	30
1039766406	How many genes are involved in eye color?	at least 8	31
1039766407	what kind of genes are responsible for eye color?	OCA2 gene, EYCL3 gene, EYCL1 gene	32
1039766408	OCA2 gene is responsible for..	brown to blue spectrum -depends on how much OCA2 protein is made	33
1039766409	EYCL3 (BEY2) gene	B=brown b=blue	34
1039766410	EYCL1 (GEY) gene	G = green g = blue	35
1039766411	why do people have 2 different eye colors?	1.events in fetal development -some melanocytes are missing or non-functional 2. mosaicism -mutation early in development 3. injury	36
1039766412	what is Epistasis? give an example	-when the phenotypic expression of a gene at one locus alters a gene at a second locus -involves 2 or more genes affecting one trait ex.) labrador coat color	37
1039766413	B gene (labrador coat color)	for making hair pigment -B black -b brown	38
1039766414	E gene (labrador coat color)	-for depositing hair pigment -E (color) -e (no color) -at least one copy of E is needed for dark colors	39
1039766415	polygenic inheritance	the additive effect of two or more genes on a single phenotypic character -usually affects quantitative effects	40
1039766416	quantitative character; ex)	a heritable feature that varies continuously over a range rather than in an either-or-fashion ex.) skin color	41
1039766417	Effects of the environment ex.)	-environment can affect phenotype ex.) hydrangea flower color ranges from blue-violet to pink with the shade intensity of color depending on the acidity and aluminum content of the soil	42
1039766418	pleitropy ex.)	-the ability of a single gene to have multiple effects ex.) PKU disease is caused by defective gene for phenylalanine hydroxylase	43
1039766419	PKU disease	-converts phenylalanine to tyrosine -can cause mental retardation -eye color -skin color	44
1039766420	Recessively Inherited Disorders; results in..	-2 copies of recessive alleles are required -results in non functional protein or no protein	45
1039766421	heterozygotes of recessively inherited disorders	-have normal phenotypes -make enough functional protein -serve as carriers for disorder	46
1039766422	example of a recessively inherited disorder	albinism	47
1039766423	albinism caused by..	-defect in melanin production -tyrosinase is responsible for melanin production	48
1039766424	dominantly inherited disorders	-only one copy of dominant allele required -heterozygotes have disease phenotype -dominant allele is rare in population -disease not as common	49
1039766425	Anchondroplasia	-dominantly inherited disorder -dwarfism due to bone disorder -99.99% of population is homozygous recessive	50