BIOL 206: Mendelian 1 Trait
carpel
contains ovary and eggs
expressed
dominant
if you are informed that tune deafness is a heritable trait, and that a tune deaf couple is expecting a child, can you conclude that the child will be tune deaf?
no
stigma
where the pollen enters to fertilize the flower
fundamental unit of heredity; it encodes a specific product (e.g. pigment determining eye color)
gene
mendel worked over ____-____ years, on ____ different characteristics, _____-_____ plants each, and over _____-_____ fertilizations to generate LARGE numbers of seeds (lots of work and exquisite detail)
8-10, 7, 10-15, 25-75
Ss x Ss = SS Ss sS ss generation? phenotypic ratio? genotypic ratio?
F1, 3:1, 1:2:1
mendel started his parental experiments always by "_____ _____", such as smooth x smooth = all smooth and wrinkled x wrinkled = all wrinkled
breeding true
the position of a gene on a chromosome; in a normal situation, all alleles of a gene would have the same
locus
refers to an observable trait caused by the genotype
phenotype
Mendel proposed that members of a gene pair must SEGREGATE from each other during gamete formation; as a result, each gamete receives only ONE of the two genes that control a particular trait
Mendel's law of segregation
set out to understand inheritance
gregor medel in 1860
alleles not expressed in the heterozygous condition because it is masked by the dominant; two copies must be present in an individual to be expressed
recessive
present but not expressed
recessive
generations: parental: ______ x _______ = f1 all ______ f1: ______ x ______ = f2: mostly ______ and some ______ f2: ______ x ______ = f3: ______! and ______ x _____ = all ______
smooth, wrinkled, smooth smooth, smooth, smooth, wrinkled smooth, smooth, mix, wrinkled, wrinkled, wrinkled
mendel started with trial breedings of _____ varieties; with _____, he found _____ distinct alternating traits
34, 7, 2
wet ear wax (W) is dominant over dry ear wax (w). A 3:1 phenotypic ratio of F1 progeny indicates that the parents are of what genotype? A 1:1 phenotypic ratio of F1 progeny indicates that the parents are of what genotype?
Ww and Ww Ww and ww
what is the chance that a man with type AB blood and a woman with type A blood whose mother is type O can produce a child that is: a. Type A: b. Type AB: c. Type O: d. Type B:
a. ½ b. ¼ c. none d. ¼
suppose that organisms have the following genotypes. What types of gametes will these organisms produce, and in what proportions? a. Aa: b. AA: c. aa:
a. ½ A and ½ a b. all A c. all a
given the following matings, what are the predicted genotypic ratios of the offspring? a. Aa X aa: b. Aa X Aa: c. AA x Aa:
a. ½ Aa and ½ aa b. ¼ AA, ¼ Aa, and ½ aa c. : ½ AA and ½ Aa
what will backcrossing SS and Ss with ss result in?
all Ss, and Ss with ss (50:50)
Sickle cell anemia (SCA) is a human genetic disorder caused by a recessive allele. A couple plan to marry and want to know the probability that they will have an affected child. With your knowledge of Mendelian inheritance, what can you tell them if (1) each has one affected parent and a parent with no family history of SCA (2) the man is affected by the disorder by the woman has no history of SCA?
(1) 1/4 probability for SCA (2) no chance
consider the following cross in pea plants, in which smooth pea shape is dominant to wrinkled, and yellow pea color is dominant to green. A plant with smooth yellow peas is crossed to a plant with wrinkled green peas. The offspring produced peas that were all smooth and yellow. What are the genotypes of the parents? What are the genotypes of the offspring?
a. Parents were SSYY and ssyy b. Offspring were SsYy
alternate forms of a gene that may cause various phenotypic effects (e.g. gene for eye color can be blue, brown, etc.)
allele
how do we distinguish a phenotype expressed by the genotype SS and Ss?
backcross to homozygote recessive
alleles that are expressed in the heterozygous condition; therefore, only one copy needs to be present to express the phenotype
dominant
conclusions: 1. traits are _____ as they pass through generations 2. traits are inherited as _____, non-mixing units (genes) 3. traits can be _____, only to reappear unchanged 4. phenotype is not _____ to genotype 5. there are 2 _____ units for each characteristic (_____) 6. the 2 ______ must segregate from each other during pollen + egg formation and rejoin in ______ combination during _____
unchanged, separate, hidden, equal, independent, alleles, alleles, random, fertilization
typical cross: plant _____, cross _____ both flowers, wait _____ days, and observe pea _____
seeds, fertilize, 100, pods
7 distinct traits of pea plants: 1. ______ of pea 2. color of _____ 3. _____ coat color 4. form of _____ 5. color of _____ 6. _____ position 7. length of _____
shape, interior, seed, pod, pod, flower, stem
occurs when there is full expression of both alleles in the heterozygous condition (e.g. AB blood type)
codominance inheritance
occurs when a dominant allele completely masks the expression of a recessive allele
complete dominance
refers to the genetic constitution of the individual; it always includes at least 2 letters, each representing one allele of a gene pair in a diploid organism (a gamete would contain only one allele of each gene because of its haploid state)
genotype
stamen
holds the filaments and anther which produce the pollen
mendel used garden peas... 1. ______ traits 2. ______ life cycle (100 days) 3. many ______ 4. experimentally ______ 5. cover and protect from unwanted ______ (from insects)
identifiable, short, offspring, fertilized, fertilization
occurs when the phenotype of the heterozygote is intermediate between the two homozygotes (e.g. in Mirabilis, a red flower crossed with a white flower gives a pink flower)
incomplete dominance
a man with blood type A and a woman with blood type B have three children: a daughter with type AB and two sons, one with type B and one with type O blood. What are the genotypes of the parents?
AO and BO
mendel found that traits that disappeared in the _____ generation reappeared in the _____
F1, F2
