Genetics Exam 2 Flashcards
New sh!t
1
How many phenotypes show in the F1 generation after a monohybrid cross?
Homo/different
A monohybrid cross is a cross between (Homo/Heterozygotes) for (the same/different) alleles of the same gene
Monohybrid
The offspring of two parents that are homozygous for alternative alleles of the same gene
Homozygous recessive
A testcross is the cross of any individual with a __________ _________ parent
1:1
Backcross of the F1 generation results in a ___ ratio for genotype and a ___ ratio for phenotype
Law of Segregation
Mendel’s law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete
Law of Dominance
Mendel’s law that states that in many traits one allele is dominant over the other allele. The “weaker (recessive)” allele is only expressed when it is paired with another recessive allele
Law of Independent Assortment
Mendel’s law that states each pair of alleles segregates independently of each other pair of alleles during gamete formation
Consanguinous
Two individuals are _____________ if they share at least one ancester in common (no more remote than great grandparent)
Compound Heterozygote
An individual with two mutated alleles that are not the same mutation but present as a recessive phenotype.
Transcription Factor
The SRY gene codes for a _____________ ______ that is located on the Y chromosome and plays a major role in development of “maleness”
Maternal/Paternal
Prader-Willi Syndrome is a disease that develops as a result of a mutation passed down on the ________ allele and a de novo mutation on the _______ allele
Paternal/Maternal
Angelman’s Syndrome is a disease that develops as a result of a mutation passed down on the ________ allele and a de novo mutation on the _______ allele
Hetero
A monohybrid is always a (Homo/Heterozygote)
Incomplete Penetrance
Dominant alleles that are not always expressed display a characteristic known as __________ __________
D
Which of the following is not a factor controlling penetrance of an allele?
a) Genetic modifiers
b) Epigenetic regulation
c) Environmental codeterminants
d) Mutation in gene processing
Haploinsufficiency
Incomplete dominance is known as __________________
Incomplete Dominance
A heterozygous phenotype that is an intermediate of the two homozygous phenotypes displays a characteristic known as __________ _________
Codominant
__________ alleles are both detected in the presence of the other allele
Pleiotropy
A single gene mutation affecting multiple parts of the body it is known as __________
Locus Heterogeneity
Mutations at different loci can produce the same phenotype display a characteristic known as _____ _____________
Allelic Heterogeneity
Different mutations at the same locus that exhibit the same phenotype display a characteristic known as _______ _____________
F (Allelic Heterogeneity
(T/F) The CF mutation is characterized by both locus heterogeneity and pleiotrophy
Expressivity
____________ is the degree to which the allele expresses the phenotype in an individual
Genetic Anticipation
A factor tied to expressivity where a trait seems to be more severe or show an earlier onset in successive generations is known as _______ ____________ (i.e. Huntington’s)
Clinical Heterogeneity
Different mutations at the same locus that exhibit the different phenotypes display a characteristic known as ________ _____________
New Mutation
A ___ ________ arises in the germ cell of the parent or early on during embryogenesis of the affected individual
Gonadal (Germline) Mosaicism
The presence of a new mutation during early embryogenesis in a germline cell of an unaffected individual may lead to _______ __________
Mitochondrial
A maternal pattern of inheritance is likely related to _____________ inheritance
Heteroplasmy
Presence of both normal and mutated mtDNA, resulting in variable expression in mitochondrial inherited disease
Dosage Compensation
The process by which excessive numbers of a sex chromosome are equalized b/w M and F, often by methylating the X chromosome to form a Barr body.
XIST gene
Gene located on the X chromosome that codes for a long noncoding mRNA that stays in the nucleus and coats the X chomosome
T
(T/F) X Inactivation is random
F (X-inactivation is fixed)
(T/F) X inactivation can switch if there is a mutation on the X chromosome
F (Only ~85% of genes inactivated)
(T/F) X inactivation causes a barr body to form, keeping all of the genes on that chromosome from being transcribed
Manifesting Heterozygote
A female carrier of x-linked recessive gene who expresses the phenotype b/c the normal allele is inactivated in some tissues
Genomic Imprinting
A phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent. Usually occurs when the gene from one parent is methylated (methylation occurs in ~200 genes)
Garrod (Sir Archibald Edward)
First man to propose that diseases were caused by inborn errors or missing steps in the body’s chemical pathways.
Monogenic (relating to a single pair of genes)
Most inborn metabolic diseases are _________ and inherited in an autosomal recessive pattern
Polygenic (multifactorial inheritance)
Late onset metabolic disorders are often _________ disorders
B
Which of the following is not an example of a cause of a single gene (monogenic) disorder?
a) Enzyme defect
b) Methylation
c) Receptor/transport protein defect
d) Structural protein defect
Founder Effect
Random effect that can occur when a small population settles in an area separated from the rest of the population and interbreeds, producing unique allelic variations, sometimes diseases
Aminoacidopathies
_________________ are caused by the body’s inability to breakdown or metabolize the certain aa’s or their waste and result in the build up of their by-products days to months following birth
Restrictions/medication
Amino acid disorders can be counteracted by diet ____________ or, in some cases, __________
Urea
Often an amino acid disorder is the result of a defect in the ____ cycle
Phenocopy
a phenotype that resembles the phenotype produced by a specific gene but is caused instead by a different, typically non genetic, factor
Lysosomal Storage Disorder/Sphingolipids
A hereditary disorder associated with abnormal lysosomes, where the sufferer is missing one of the lysosomal digestive enzymes. May lead to an accumulation of _____________ affecting multiorgan systems
Enzyme Replacement Therapy
A medical treatment replacing an enzyme in patients in whom that particular enzyme is deficient or absent
Substrate Reduction Therapy
For lysosome storage disorders: Reducing the amount of substrate so an enzyme can function more efficiently is known as
F
(T/F) Genetic screening can only be done to newborns and infants
T
(T/F) The Newborn Biological Screening process is mandated by each state individually
Screening/Testing
A test done on every member of the population regardless of family history or conditions is a genetic _________, whereas a test done on an individual for a specific disease is known as genetic _______
Preimplantation Genetic Diagnosis
The technique used to identify genetic defects in embryos created through in vitro fertilization (IVF) before transferring them into the uterus is known as ______________ _______ _________
Gene Therapy
The insertion of working copies of a gene into the cells of a person with a genetic disorder in an attempt to correct the disorder
Complementary Groups
Genes that have the ability to complement each other and restore the normal activity of the gene are known as _____________ ______
Epistasis
A type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited., One gene masks the expression of a different gene for a different trait
Epistatic/hypostatic
During epistasis the _________ gene is the gene whose phenotype is expressed and the __________ gene’s phenotype is repressed
Different
Epistasis refers to gene interactions between alleles in (the same/different) genetic locus/loci
Hormone
In sex influenced patterns of inheritance expression of genes is dependent upon _______ expression
Genetic Suppression
When a double mutant has a less severe phenotype than either single mutant
Suppressor
A __________ is a mutant allele of a gene that reverses the effect of a mutation of another gene resulting in a wild type or near wild type expression
Revertant
A _________ occurs when a mutation reverses in a specific gene resulting in wild type expression
Synthetic Lethality
When two single mutations are viable, but a double mutation is lethal it is known as _________ __________ (Common in haploinsufficiency mutants or mutants in compensating genes)
Do not/complement
Mutations displaying synthetic lethality (do/do not) map to the same loci and fail to __________
Polygenic
Combined effect of two or more genes on a single characteristic
Multifactorial
Due to interactions between genes and the environment
Discrete Traits
Traits whose alleles are qualitatively different from each other (it is either present or absent)
Continuous Traits
Traits which have measurable gradations between the two end points, such as height, blood pressure, skin tone, etc.
Additive alleles
alleles that contribute to a quantitative (discrete) phenotype. More of these causes more phenotypic variation.
Selection
If all individuals were phenotypically identical there would be no opportunity for _________
Evolution
If all individuals were genotypically identical there would be no opportunity for _________
Diploidy
________ provides heterozygote protection
Balanced
________ polymorphism provides heterozygote advantage
Inverse
There is a (direct/inverse) relationship between the heritability of a trait and the impact of the environment on that trait
Liability threshold
Often in continuous traits a _________ ________ must be crossed before a disease is expressed.
F
(T/F) Recurrence risks are often the same throughout the generations of a family
Twin/Adoption
____ and _______ studies help us untangle the relationship between genetics and environmental influence on gene expression (able to determine CONCORDANCE)
Cytogenetics
The study of chromosomes and the diseases caused by abnormal chromosome structure/number is ____________
Giemsa
G-banding of chromosomes uses what stain?
AT
Chromosome staining works best on (AT/GC) rich regions
q
Long arm of chromosome
p (petite)
Short arm of chromosome
FISH (Fluorescent in situ hybridization)
A technique used to determine how many copies of a specific segment of DNA are present in a cell
Metacentric
A cromosome with the centromere in the middle
Acrocentric
A chromosome whose centromere is placed very close to, but not at, one end.
13 14 15 21 22
Which chromosomes are acrocentric?
Triploidy
Presence of additional set of chromosomes (3n)
Trisomy
3 copies of a chromosome
Derivative
A structurally rearranged chromosome
Aneuploidy
A change in the number of chromosomes
A
Which of the following is an incorrect way of writing a karyotype? A) 46, XXY B) 47, XX +21 C) 46, XX D) 48, XXY +13
Germline
Older parents have a higher incidence of (somatic/germline) mutations leading to children with single gene disorders
Meiosis I
In females oogenesis is arrested in _______ _ until puberty
Metaphase II
After puberty egg cells complete meiosis I and are arrested in _________ _ until fertilization
Nondisjunction
An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other.
3/1
First division nondisjunction in meiosis leads to two cells with _ copies of a chromosome and two cells with _ copies of a chromosome
2/3/1
Second division nondisjunction in meiosis leads to two cells with _ copies of a chromosome and two cells with _ and _ copies of a chromosome, respectively
Chorionic Villus Sampling
Prenatal diagnosis that can be done at 10-12 weeks and involves a biopsy of tissue containing the same genetic information as the fetus
Amniocentesis
Prenatal diagnosis that can be done at 16-18 weeks and involves a sample of fluid surrounding the baby during gestation
Monosomy
Chromosomal abnormality consisting of the absence of one chromosome from the normal diploid number (2n-1)
Uniparental Disomy
___________ ______ arises when an individual inherits two copies of a chromosome from one parent and no copies from the other parent
Isochromosome
Chromosome in which one arm is missing and other is duplicated in mirror-image fashion
Copy Number Variation
A particular gene or chromosomal region that is present in many copies is a ____ ______ _________
Paracentric Inversion
Inversion of a chromosome that does not include the centromere, involves two breaks along one arm only
Pericentric Inversion
Inversion of a chromosome that does include the centromere
Translocation
When a piece of one chromosome breaks off and attaches to another chromosome
Unbalanced
Genetic information is lost during a(n) (balanced/unbalanced) translocation
Balanced
A (balanced/unbalanced) translocation can lead to partial monosomy/trisomy in the offspring
Robertsonian
A ____________ translocation can only occur between acrocentric chromosomes
