UNIT 2.2. Non Mendelian Genetics Flashcards
T/F: When genes are close to each other on the same chromosome, they usually segregate and combine with the other chromosome
F (they do not segregate)
T/F: linkage does not support Mendel’s predictions as it violates independent assortment
T
Genes close on a chromosome are packaged into the same gametes and are said to be “___”
Linked
___ refers to the transmission of genes on the same chromosome
Linkage
T/F: linked genes do not assort independently and do not produce Mendelian ratios for crosses tracking two or more genes
T
Developed Punnett square
William Bateson
R. C. Punnett
Identified genes on Drosophila’s 4 pairs of chromosomes
Thomas Morgan
How many genes did Morgan identify in Drosophilia?
50
Linkage maps were first developed by ___
Alfred Sturtevant
A map based on the frequencies of recombination between markers during crossover of homologous chromosome
Linkage map
A map of the genes on a chromosome based on linkage analysis
Linkage map
T/F: A linkage map does not show the relative position of the genes, but the physical distances between them
F (it shows relative position, not distance)
The nonrandom association between DNA sequence which is always inherited together
Linkage disequilibrium (LD)
LD blocks that could be used to track genes in populations
Haplotypes
A combination of alleles at multiple linked loci that are transmitted together
Haplotype
The term haplotype is a portmanteau of “___”
Haploid genotype
A set of single nucleotide polymorphisms (SNPs) on a single chromatid that are statistically associated
Haplotype
May be categorized by how sex affects phenotypic traits
Sex-related genetics
Extensively controls physical, psychological, and behavioral traits which are also influenced by genetic information
Sex-linked traits
Males with translocation of the gene can have chromosomes of __
XX
Females with mutation of the gene can have chromosomes of __
XY
__-linked traits are rare because the chromosome has few genes
Y
___-linked traits are passed from male to male
Y
T/F: no other Y-linked traits besides infertility are yet clearly defined
T
Sex-linked traits are more likely ___-linked
X
___-linked traits are passed just like autosomal traits
X
Two copies are required for expression of a recessive allele and one copy for a dominant allele
X-linked trait
A man inherits an X-linked trait only from his ___ (mother or father)
Mother
The human male is considered ___ for X-linked traits, because he has only one set of X-linked genes
Hemizygous
Identify if X-linked Recessive Trait or X-linked Dominant Trait: always expressed in the male
X-linked Recessive Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: affected male inherits trait from heterozygote or homozygote mother
X-linked Recessive Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: expressed in a female homozygote and very rarely in a female heterozygote
X-linked Recessive Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: affected female inherits trait from affected father and affected or heterozygote mother
X-linked Recessive Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: expressed in females in one copy
X-linked Dominant Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: much more severe effects in males
X-linked Dominant Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: high rates of miscarriage due to early lethality in males
X-linked Dominant Trait
Identify if X-linked Recessive Trait or X-linked Dominant Trait: passed from male to all daughters but to no sons
X-linked Dominant Trait
Hemophilia B is a ___-linked trait
X
Hemophilia B is also known as ___ and factor ___ deficiency
Christmas disease
IX
A female who has an X-linked dominant trait has a 1 in __ probability of passing it to her offspring, male or female
2
T/F: males are more severely affected than females
T
A rare neurodevelopmental disorder where a child cannot speak, use her hands, walk, eat, or breathe easily
Rett syndrome
T/F: Rett syndrome is degenerative, not progressive
F (it is progressive, not degenerative)
Affects the structure or function of the body that is present in only males or only females
Sex-limited trait
The gene for sex-limited trait is ___
Autosomal
Due to genes on autosomes, and the expressions of these traits are limited to only one sex
Sex-limited trait
Lactation is an example of ___
Sex-limited trait
A sudden rise in blood pressure late in pregnancy, which kills 50 000 women worldwide each year
Preeclampsia
Preeclampsia is a disease where the ___ (male or female) genome play a role by contributing to the development of placenta during pregnancy
Male
Autosomal traits that are influenced by sex
Sex-influenced traits
If a male has one recessive allele (in the context of sex-influenced traits), will the trait show?
Yes
If a female has one recessive allele (in the context of sex-influenced traits), will the trait show?
No (must be two)
A genotype that causes death
Lethal genotype
An example of lethal genotype which has a distinct phenotype of a long trunk, short limbs, and a large head bearing a flat face
Achondroplastic dwarfism
Achondroplastic dwarfism is an autosomal dominant trait, but is most often the result of a ___
Spontaneous (new) mutation
Each child of two people with achondroplasia has a 1 in ___ chance of inheriting both mutant alleles
4
Each child faces a ___ probability of having achondroplasia and a ___ probability of being of normal height
2/3
1/3
Type of relationship between alleles, with a heterozygote phenotype intermediate between the two homozygote phenotypes
Incomplete Dominance
T/F: in Tay-Sachs disease, the heterozygote is as healthy as the homozygous dominant
T
Different alleles that are both expressed in a heterozygote are __
Codominant
The ABO blood group system is based on the expression of ___
Codominant alleles
Where one gene masks or otherwise affects the phenotype of another
Epistasis
T/F: Epistasis is the interaction between different genes, not between the alleles of the same gene
T
A gene that affects expression of another
Modifier gene
Albinism is an example of ___
Epistatic interaction
A blood type which illustrates epistasis, which results from an interaction between H and I gene that confers ABO blood type
Bombay phenotype
In Bombay phenotype, the ___ gene controls the placement of a molecule to which antigens A and B attach on red blood cell surfaces
H
A person of genotype ___ can’t make the molecule, so that A and B antigens cannot attach to red blood cell surfaces
hh
Bombay phenotype is present in ___% of the population
0.004%
Bombay phenotype is discovered in ___ and is named by ___
1952
Dr. Bhande et al.
T/F: the Bombay phenotype can receive and donate to every blood group
F (can only receive from Bombay blood group)
A single-gene disease with many symptoms, or a gene that controls several functions or has more than one effect
Pleiotropy
An autosomal dominant condition which results to a defect in fibrillin
Marfan syndrome
Causes lens dislocation, long limbs, spindly fingers, and a cave-in chest. Most serious symptom is a weakening in the aorta and bursting of it.
Marfan syndrome
Mutations in different genes that produce the same phenotype
Genetic heterogeneity
Can occur when genes encode enzymes or other proteins that are part of the same biochemical pathway, or when proteins affect the same body part
Genetic heterogeneity
An environmentally caused trait that appears to be inherited
Phenocopy
Trait that can either produce symptoms that resemble those of a known single-gene disease or mimic inheritance patterns by affecting certain relatives
Phenocopy
Marfan syndrome is an example of ___
Pleiotropy
Osteogenesis imperfecta is an example of ___
Genetic heterogeneity
Bombay phenotype is an example of ___
Epistasis
Familial hypercholesterolemia is an example of ___
Incomplete dominance
Can be observed in carriers on both the molecular and whole-body levels
Incomplete dominance
Thalidomide vs. Phocomelia is an example of ___
Phenocopies
Genes that regulate organ development
Homeotic genes
Genes that code for transcription factors
Homeobox genes
Genes that determine the identities of each body segment
Hox genes
Meant as a sleeping aid but prescribed to pregnant women to treat anxiety and nausea
Thalidomide
This drug caused serious birth abnormalities for hundreds of children
Thalidomide
Refers to the percentage of individuals who have a particular genotype who have the associated phenotype
Penetrance
Refers to the variability in severity of a phenotype, or the extent to which the gene is expressed
Expressivity
An allele combination that produces a phenotype in everyone who inherits it
Completely penetrant
T/F: complete penetrance is rare
T
T/F: Huntington disease is completely penetrant
F (almost)
Gene causing Huntington’s disease
Huntingtin gene
Level of CAG for complete penetrance in Huntington disease
40 or more CAG repeats
Refers to the inheritance of a trait governed by more than one genes
Polygenic inheritance
Type 2 diabetes mellitus is an example of ___ disorder
Polygenic
