Non-Mendelian Genetics Flashcards
What color of offspring would you get when you cross a pure (homozygous) red snapdragon with a pure white snapdragon?
Pink
Incomplete dominance can be seen in:
Horses (Chestnut x Cremello
→Palomino)
Snapdragons
Japanese Four O’ Clocks
Ratio for cross between heterozygous alleles
1:2:1
Codominance occurs in:
Shorthorn Cow (White + Red)
Blue Roosters (White + Black)
Human Blood Typing (AB)
Tabby Cats (Black and Tan Fur)
Can Tan Cat be heterozygous? Why or Why not?
No, because in order for the cat to be tan, it must contain the homozygous allele
If you mate a tabby with a black cat, what is the phenotypic ratio of their offspring?
1 black: 1 tabby
50% black, 50% tabby
If the offspring of two cats are composed of 36 tabbies and 40 black cats, what are the parental phenotypes and genotypes?
Using backcrossing
1:1
1 tabby, 1 black
What does Multiple Alleles Mean?
When a gene is controlled of many alleles
three or more different versions of a gene that exist in a population
A and B blood types are coded for by the alleles: IA and IB respectively. These two alleles are CODOMINANT.
Blood type O is coded for by the allele i and is recessive to both IA and IB (notice the lower case letter).
I designation stands for ___________, another term for antigen
isoagglutinogen
Could a man with AB blood have an AB child with a woman with type O blood?
No, since type O is recessive, the child will have either type A or type B
If a child has type B blood, what are all the possible blood types for his/her parents?
1.) AB x BB
2.) AB x ii
3.) BB x BB
4. BB x ii
5.) Bi x ii
6.) Bi x Ai
7.) AB x Ai
8.) BB x Ai
9.) AB x Bi
10.) BB x Bi
11.) Bi x Bi
12.) AB x AB
A paternity test is being performed. The child has type A blood. The mother is type A. Potential Dad #1 has type B blood. Potential Dad #2 has type O blood. Who is the father?
Either can be the father
Challenge: What two parents could produce the most diverse children as far as blood type is concerned?
Ai x Bii
4 possible blood type:
1. AB
2. Ai
3. Bi
4. ii
a situation in which a single phenotype is affected by more than one set of genes
gene interaction
Antisera against monkey
Rhesus macacca
The allele that occurs most frequently in a population, the one that we arbitrarily designate as normal
wild-type allele
contains modified genetic information and often specifies an altered gene product
mutant allele
loss-of-function mutation. If the loss is complete, the mutation has resulted in what is called a
null allele
mutations that enhance the function of the wild-type product
also provide an example:
gain-of-function mutations
Proto-oncogenes to oncogenes-> regulation of cell cycle is overriddenby excess gene product
mutations that create an allele that produces no detectable change in function
neutral mutations
homozygous recessive individuals are severely affected with a fatal lipid-storage disorder and neonates die during their first one to three years of life
Tay–Sachs disease
an enzyme normally involved in lipid metabolism
hexosaminidase A
whereby normal phenotypic expression occurs anytime a minimal level of gene product is attained
threshold effect
the joint expression of both alleles in a heterozygote is called
also provide an example:
codominance
MN blood group in humans illustrates this phenomenon
found on the surface of red blood cells that acts as a native antigen, providing biochemical and immunological identity to individuals
glycoprotein molecule
The MN system is under the control of a locus found on chromosome #
chromosome 4
When three or more alleles of the same gene—which we designate as __________—are present in a population, the resulting mode of inheritance may be unique
multiple alleles
The genes for A and B antigens are located on chromosome #
Chromosome 9
mode of inheritance in blood types
Codominance
Almost all individuals possess what is called the ________, to which one or two terminal sugars are added
H substance
Failure to produce the H substance results in the _______, in which individuals are type O regardless of the presence of an IA or IB allele
Bombay phenotype
_____ allele directs the addition of fucose to the H substance precursor
FUT1 allele
H substance itself contains three sugar molecules—
galactose (Gal)
N-acetylglucosamine (AcGluNH)
fucose
H Substance precursor
Gal—AcGluNH
The IA allele is responsible for an enzyme that can add the terminal sugar N-acetylgalactosamine (AcGalNH) to the H substance
The IB allele is responsible for a modified enzyme that can not add N-acetylgalactosamine, but instead can add a terminal galactose
type O (ii) cannot add either terminal sugar; these persons have only the H substance protruding from the surface of their red blood cells
the presence of just one copy of the allele results in the death of the individual
dominant lethal allele
due to a dominant autosomal allele H, where the onset of the disease in heterozygotes (Hh) is delayed, usually well into adulthood.
Affected individuals then undergo gradual nervous and motor degeneration until they die.
Huntington disease
the genes controlling each character are located on the same chromosome
genetic linkage
several genes influence a particular characteristic
gene interaction
each step of development increases the complexity of the organ or feature of interest and is under the control and influence of many genes
epigenesis
the expression of one gene masks or modifies the effect of a second gene
epistasis
________, where phenotypic categories are discrete and qualitatively different from one another
discontinuous variation
_________, occurs when a dominant allele at one genetic locus masks the expression of the alleles of a second locus
dominant epistasis
An analytical procedure called _______________ allows us to determine whether two independently isolated mutations are in the same gene—that is, whether they are alleles—or whether they represent mutations in separate genes
complementation analysis
All mutations determined to be present in any single gene are said to fall into the same ____________, and they will complement mutations in all other groups
complementation group
expression of a single gene has multiple phenotypic effects, is also quite common. This phenomenon, which often becomes apparent when phenotypes are examined carefully, is referred to as
pleiotropy
__________, a human malady resulting from an autosomal dominant mutation in the gene encoding the connective tissue protein fibrillin
Marfan syndrome
ex: Abraham Lincoln
phenotype associated with Marfan syndrome includes
lens dislocation
increased risk of aortic aneurysm
lengthened long bones in limbs
human autosomal dominant disorder where afflicted individuals cannot adequately metabolize the porphyrin component of hemoglobin when this respiratory pigment is broken down as red blood cells are replaced.
The accumulation of excess porphyrins is immediately evident in the urine, which takes on a deep red color
porphyria variegata
possession of only one copy of a gene in an otherwise diploid cell—is referred to as
hemizygosity
___________, in which phenotypic traits controlled by recessive X-linked genes are passed from homozygous mothers to all sons
crisscross pattern of inheritance
Human X-Linked Traits
Color blindness, deutan type
= Insensitivity to green light
G-6-PD deficiency
= Deficiency of glucose-6-phosphate dehydrogenase
Hemophilia A
= Classic form of clotting deficiency; deficiency of clotting factor VIII
Hemophilia B
= Christmas disease; deficiency of clotting factor IX
Lesch–Nyhan syndrome
= Deficiency of hypoxanthine-guanine phosphoribosyl transferase enzyme (HPRT) leading to motor and mental retardation, self-mutilation, and early death
Duchenne muscular dystrophy
= Progressive, life-shortening disorder characterized by muscle degeneration and weakness; deficiency of the protein dystrophin
heterozygous genotype may exhibit one phenotype in males and the contrasting one in females
Inheritance of these phenotypes is controlled by a single pair of autosomal alleles whose expression is modified by the individual’s sex hormones.
sex-limited inheritance
The percentage of individuals that show at least some degree of expression of a mutant genotype defines the __________of the mutation
penetrance
_________ reflects the range of expression of the mutant genotype
expressivity
if a region of a chromosome is relocated or rearranged
translocation or inversion event
certain areas of the chromosome that are condensed and genetically inert
heterochromatin
mutations that prevent synthesis of nutrient molecules, such as when an enzyme essential to a biosynthetic pathway becomes inactive
auxotroph
those afflicted with the genetic disorder ________cannot metabolize the amino acid phenylalanine
phenylketonuria (PKU)
__________ cannot metabolize galactose
galactosemia
_______ cannot metabolize lactose
lactose intolerance
____________, inherited as an X linked recessive disease, is characterized by abnormal nucleic acid metabolism (inability to salvage nitrogenous purine bases), leading to the accumulation of uric acid in blood and tissues, mental retardation, palsy, and self-mutilation of the lips and fingers
Lesch–Nyhan syndrome
________,an X-linked recessive disorder associated with progressive muscular wasting
Duchenne muscular dystrophy (DMD)
Inherited as an autosomal dominant disorder, _________ affects the frontal lobes of the cerebral cortex, where progressive cell death occurs over a period of more than a decade. Brain deterioration is accompanied by spastic uncontrolled movements, intellectual deterioration, and ultimately death
Huntington disease
heritable disorders that exhibit a progressively earlier age of onset and an increased severity of the disorder in each successive generation
genetic anticipation
_________ the most common type of adult muscular dystrophy, clearly illustrates genetic anticipation.
Myotonic dystrophy (DM1)
muscle hyperexcitability
myotonia
human traits are shaped overwhelmingly by our social and cultural environments
the blank-slate hypothesis
a rare pregnancy complication that occurs when a pregnant person’s immune system attacks the fetus’s red blood cells
Erythroblastosis fetalis
injection used to prevent Rh incompatibility from developing during pregnancy. The shot contains antibodies (collected from plasma donors) that stop your immune system from reacting to your baby’s Rh positive blood cells
RhoGAM shot
Also known as antibody D
RhoGAM
In chickens, when am embryo contains two copies of the receive gene known as ________, the embryo dies inside the eggshell
Creeper
Are the first 22 homologous pairs of human chromosomes that do not influence the sex of an individual
Autosomes
Are the 23rd pair of chromosomes that determine the sex of an individual
Sex chromosomes
- Serious anemia or breakdown of RBC among newly born fetuses
Erythroblastosis fetalis
examples of condition for lethal genes
- Achondroplasia, cystic fibrosis, sickle-cell anemia (recessive lethal)
- Huntington’s disease (dominant lethal)
is the type of zygosity in which only 1 of the allele is present for a gene
Hemizygous
is the type of zygosity in which both alleles are the same for a gene
homozygosity
a condensed, inactive X chromosome that is found in the nuclei of female somatic cells
Barr body
Sex linked trait, X-linked trait, or Y-linked trait:
- The gene (pair) that determines a character (e.g. hemophilia) is located on the sex chromosomes
Sex linked trait
Sex linked trait, X-linked trait, or Y-linked trait:
- A sex-linked trait is where the gene or allele for the trait is found on the X chromosome
X-linked trait
Sex linked trait, X-linked trait, or Y-linked trait:
- A sex-linked trait where the gene or allele for the trait is found on the Y- chromosome
Y-linked trait
- An X-linked recessive trait where a affected individual could not distinguish red from green color
Color blindness
- An X-linked recessive trait where an affected individual suffers from delayed blood clotting during injuries because of the absence of certain blood clotting factors
Hemophilia
- A Y-linked trait where affected males have hair growing from their external ears
Hypertrichosis pinnae auris
X-LINKED RECESSIVE DISORDERS
“Oblivious Female Will Give Her Boys X-linked Disorders”
Ocular albinism
Fabry disease
Wiskott-Aldrich syndrome
G6PD deficiency
Hunter syndrome
Bruton agammaglobulinemia
Hemophilia A/B
Lesch-Nyhan syndrome
Duchenne muscular dystrophy
a chart used to test for color-blindness
Ishihara color-blindness chart
Rare, X-linked dominant trait
Found in a single multigenerational
Mexican family
Human Werewolf Syndrome
Congenital generalized hypertrichosis (CGH)
Insensitivity to green light
Color blindness, deutan type
Insensitivity to red light
Color blindness, protan type
Deficiency of galactosidase A; heart and kidney defects, early death
Fabry’s disease
Deficiency of glucose-6-phosphate dehydrogenase; severe anemic reaction following intake of primaquines in drugs and certain foods, including fava beans
G-6-PD deficiency
Classic form of clotting deficiency of clotting factor VIII
Hemophilia A
Christmas disease; deficiency of clotting factor IX
Hemophilia B
Mucopolysaccharide storage disease resulting from iduronate sulfatase enzyme deficiency; short stature, claw-like fingers, coarse facial feature, slow mental deterioration, and deafness
Hunter syndrome
Deficiency of steroid sulfatase enzyme; scaly dry skin, particularly on extremities
Icthyosis
Deficiency of hypoxanthine-guanine phosphoribosyltransferase enzyme (HPRT) leading to motor and mental retardation, self-mutilation, and early death
Lesch-Nyhan syndrome
Progressive, life-shortening disorder characterized by muscle degeneration and weakness; sometimes associated with mental retardation; deficiency of the protein dystrophin
Duchenne muscular dystrophy
*are determined by autosomal genes and are inherited according to Mendel’s principles, but they are expressed differently in males and females
Sex influenced characteristics
*extreme form of sex-influenced inheritance, a sex limited characteristic is encoded by autosomal genes that are expressed in only one sex—the trait has zero penetrance in the other sex
Sex- Limited Characteristics
mutation causes the diminution or the loss of the specific wild-type function
loss-of-function mutation
what is the threshold in Tay-Sachs disease
less than 50%
homozygous recessive individuals will not survive
recessive lethal allele
Example of a heterogenous trait where many genes “interact” to produce a common
phenotype
Hereditary deafness
Identify the type of epistasis:
9:3:3:1
Collaboration (Multiple genes)
Identify the type of epistasis:
9:3:4
Single Recessive Epistasis
Identify the type of epistasis:
12:3:1
Single Dominant Epistasis
Identify the type of epistasis:
9:7
Duplicate Recessive Epistasis
Identify the type of epistasis:
9:6:1
Duplicate ‘ Recessive
Identify the type of epistasis:
15:1
Duplicate Dominant Epistasis
developing bipolar disorder is given as 69 percent due to genetics and 32 percent due to environmental factor
eating disorder is approximately 40 percent due to genetics and 60 percent due to environmental conditions
