Human Genetics Exam 1

true

unlike nuclear DNA, mitochondrial DNA is not wrapped in proteins

stem cells

unspecialized cells that are able to renew themselves for long periods of time by cell division

false

A cis-regulatory mutation occurs in the coding sequence of the affected gene

a study of males in stressful positions (air traffic controllers); degree of stress and rate of telomere shortening

studies show that women experiencing chronic stress, such as from caring for a severely disabled child, have telomeres that shorten at an accelerated rate; suggest a study that would address the question of whether men have a similar reaction to chronic stress

the risk of danger of separating conjoined twins depends on the extent of shared tissue

surgical separation of conjoined twins is more likely to succeed if fewer body parts are shared or attached; if you had conjoined twins, what would you do and would you attempt surgical separation

false

the Lemba and Cohanim were found to have a shared ancestry owing to genetic information from the X chromosome

pleiotropy

the ability of a single gene to have multiple effects

Mendelian Inheritance

the basic principles associated with the transmission of genetic material, forming the basis of genetics, including the law of segregation and the law of independent assortment

expressivity

the degree to which a trait is expressed

3

the genetic code is read __ nucleotides at a time to direct the building of proteins from amino acids

false

the least common monozygotic twinning event involves separate chorions and separate amnions

smoking

the lung condition emphysema may be caused by lack of an enzyme, or by smoking; which cause is a phenocopy

true

the mutation causing HGPS described in meeting #3 causes a splice-site mutation

penetrance

the percentage of individuals with a particular genotype that actually displays the phenotype associated with the genotype

ESCs

these are laboratory-cultured cells derived from the inner cell mass of a developing embryo

sympathetic

this type of innervation mediates melanocyte stem cell activation in hair follicles

multiple alleles

three or more forms of a gene that code for a single trait

true

two parents with the genotypes |A|i and |B|i can produce children with any of the four possible blood types

prenatal environmental stress, such as lack of nutrients, can alter gene expression in ways that enhance utilization of nutrients, which is adaptive for the fetus but may set the stage for future diabetes or heart disease; evidence is epidemiological and based on animal studies

what types of evidence have led researchers to hypothesize that a poor prenatal environment can raise the risk for certain adult illnesses and how are genes part of this picture

UV rays from the sun

which of the following is an environmental contribution to the hair color phenotype

it can skip generations in terms of phenotype

why can transmission of an autosomal dominant trait with incomplete penetrance look like autosomal recessive inheritance

teratogens are more dangerous to an embryo than they are to a fetus because structures form in the first 8 weeks

why does exposure to teratogens produce more severe health effects in an embryo than in a fetus

false

Unfortunately, early changes in diet do not impact the progression of metabolic disorders such as phenylketonuria

true

Long QT Syndrome can also involve deafness

SNP

single nucleotide polymorphism, change of base of single DNA nucleotide, makes up 90% of all human genetic variation

incomplete dominance

situation in which one allele is not completely dominant over another allele

true

some genetic variants can lead to mild PKU associated with excess phenylalanine in the urine

mitosis

part of eukaryotic cell division during which the cell nucleus divides

gene pool, genome, chromosome, gene, DNA

place the following terms in size order, from largest to smallest

true

a cis-regulatory mutation can affect the expression level of a gene

true

dizygotic twinning results from two sperm fertilizing two separate ova during the same cycle

Most patients affected with cystic fibrosis have an altered CFTR protein. Explain how this disorder arises (p.27). Would you predict this alteration occurs as the result of a coding sequence mutation or a cis-regulatory mutation?

A defective CFTR protein may remain in the cytoplasm where it will not reach the plasma membrane for proper functioning. As a result of this, sodium channels will be disrupted and salt will get trapped in cells, drawing in moisture, causing mucous thickening. This alteration may be the result of a coding sequence mutation because it has to do more-so with where the mutation takes place and how the channel is able to function, not necessarily gene expression; the channels are still functional, but not entirely due to where these end up in the cell. In the end, there's no impact on transcriptional abundance.

(p57) What is the difference between a monozygotic and dizygotic twinning event? What are the three types of monozygotic twins? How do conjoined twins arise?

A dizygotic twin occurs when two sperm cells fertilize two oocytes, while a monozygotic twin occurs when a single fertilization (one egg and one sperm) occurs. The three types of monozygotic twins are twins with separate amnions and chorions (separation occurs earliest), twins that share an amnion and a chorion (separation occurs latest), and twins that share a chorion but have separate amnions. The most common monozygotic twins have a shared placenta but a separate amnion and the least common monozygotic twins share both a placenta and an amnion. Conjoined twins arise when an embryo divides into twins between 13 to 15 days of development but cannot develop as individuals. In the cases of conjoined twins, they share both a placenta and amnion.

Mendelian

Augustinian monk and botanist whose experiments in breeding garden peas led to his eventual recognition as founder of the science of genetics (1822-1884) dominant and recessive traits

Defend a position (pro and con) on the use of human stem cells for scientific research/clinical therapy.

Pros are that human stem cells can produce specialized cells and can be used to treat and study life-threatening diseases. Positives of using ES cells are that they are pluripotent and can self-renew. Cons on the use of human stem cells would be the ethical and controversial dilemmas of how the stem cells are obtained from embryos.

(p60) What is meant by "critical periods of development"? Explain why some physical structures have longer critical periods (e.g., CNS) than others (e.g., ears)?

Critical periods refer to the period of development where a structure is sensitive to genetic abnormalities, toxic substances, or viruses. The timing of a structure's development determines its critical period. Structures such as the central nervous system have a long critical period lasting almost all of development because it is constantly changing and developing. Structures such as the ears have a short critical period in early development because they are basic structures that can develop quicker than the central nervous system. As a basic system, the more important a structure is the longer its critical period and vice versa.

What is the difference between 'embryonic stem cells' and 'induced pluripotent stem cells? How is the genome "reprogrammed" through the process of nuclear transfer?

Embryonic Stem Cells: Some of a region of a very early embryo (inner cell mass→ICM) is put under certain conditions in a laboratory dish where it becomes pluripotent and can self-renew can come from "left-over" embryos that would've been medical waste (medical clinics) or, nuclear transfer→nucleus from somatic cell is transferred to an egg cell that has its own nucleus removed Induced Pluripotent Stem Cells: Uses differentiated (somatic) cells and put them under certain conditions in a lab to dedifferentiate and then, under a different set of conditions, they re-differentiate into the desired cell type Differences: ES cells self-renew; ES cells are being used to treat disease, IPSCs are research only; IPSCs do not require an embryo Nuclear Transfer: A nucleus from a somatic cell is transferred to an egg cell that has its own nucleus removed. Genome reprogramming describes the changes in gene activity when the nucleus is introduced to a new cytoplasm; epigenetic changes only? → sequence doesn't change, just what is expressed. How mammals have been cloned.

(p75) Is eye color a Mendelian trait in human beings? With respect to eye color - what is the wild type condition? What are the roles of Oca2 and Herc2 in this phenotype?

Eye color is not a Mendelian trait, as it involves two genes, OCA2 and HERC2 Wild type: brown eyes OCA2 controls synthesis of melanin that determines the eye color, but HERC2 controls the expression of OCA2. The recessive allele is blue, dominant is brown eyes. A specific SNP stops HERC2's control over OCA2, resulting in blue eyes, but a person must have two copies of this. if HERC2 is not present, but oCA2 is, the result is blue eyes. If HERC2 is present, but no OCA2 is, the result is blue eyes. If both HERC2 and OCA2 are present, the result is brown eyes

True or false: two parents with the genotypes IAIi and IBIi can produce children with any of the four possible genotypes. Explain your answer and depict this cross with Punnett square.

False. It's possible to produce all four possible phenotypes (physical appearance) but not genotypes (genetic makeup). This is due to the alleles/antigens associated with the concept. For example, if you have blood type A, there are two ways to express it - by being IAIA or IAi. Blood type B is the same while type AB can only be IAIB and type O can only be ii. Furthermore, this then explains what type of donors each blood type can have. An example would be that type A blood can receive A or O blood but not B or AB.

GINA

Genetic Information Nondiscrimination Act

What is 'genetic determinism'? How is this concept relevant to a trait such as cystic fibrosis? How is this concept relevant to a trait such as intelligence?

Genetic determinism is the concept that inherited traits will be expressed despite other influences such as environmental factors. Cystic fibrosis is an autosomal recessive disease that genetic determinism can help as an individual with both recessive alleles will have cystic fibrosis and knowing this genetic predisposition can allow the family to prepare for the future and begin treatment if necessary. Relevant to intelligence, while genes play an influence, one's environment has a large significance. Home environment, parenting, nutrition, and other outside factors can also affect intelligence. A good example of this concept and intelligence comes with adopted families. The child will initially be very similar to their birth parents due to the genes they inherited from them. However, as time passes and they become more comfortable with their new family, their intelligence will begin to match theirs. Determining intelligence strictly on one's genotype can lead to discrimination and other issues, thus genetic determinism relevant to intelligence can only be harmful.

Using a blond-headed person as an example, explain what is meant by the statement (p.9): "hair color is multifactorial." What is an example of an environmental contribution to this trait?

Hair being multifactorial means there is not only one thing that causes hair to be blonde or brown or red but rather our genetics and environmental factors together to cause our hair color to change. An example of an environmental contribution to this trait would be sunlight - people tend to have lighter hair in the summer rather than winter due to more sun exposure over that period of time. Mendelian traits can also be multifactorial (hair color is not Mendelian!)

What is the genetic basis for Hutchinson-Gilford progeria syndrome? Explain the cellular basis for this disease? What leads to the accelerated aging phenotype in these patients?

Hutchinson-Gilford progeria syndrome is caused by one single nucleotide base change in the gene that codes for lamin A. This one small shift affects the next 50 amino acids, truncating them, rendering the ending protein short. This protein is known as progerin and doesn't move through the ER to the nucleus pores as it would if it formed as lamin A. Instead, it remains stuck in the ER and builds up. Due to being stuck in the ER, it causes the nuclear membrane to "bubble inwards" and affects the manner in which the chromatin are formed inside the nuclear lamina. Halting proper chromatin production prevents correct DNA repair which helps with aging mutations to arise from baldness, to a larger head compared to the body, to cardiovascular issues.

(p60) Why does the short sensitivity to the drug thalidomide make sense in terms of its effects on development? What is the phenotype of individuals exposed to thalidomide in the womb?

If a pregnant woman were to take the drug thalidomide early on in the pregnancy, during this time the embryo is in a shorter critical period for the formation of the limbs, so the short sensitivity to the drug can cause the negative impact on the embryo and the development of it's limbs. The phenotype would be the missing limbs or incomplete formation also called phocomelia.

Explain the statement (p. 8): "Comparisons of people at the genome level reveal we are more like each other genetically than are other mammals." What are some reasons that may explain this?

In phenological terms, humans branched off fairly recently in comparison to other mammals who branched off earlier in time, so other mammals have experienced a greater number of mutations, and this explains why they are more diverse in comparison to each other than us humans. This is the concept of time and mutations. Across the generation, there must be some sort of low error rate associated across a single generation; the accumulation of these errors lead to variation. Thus, the longer time of divergent point, the more mutations have likely occurred. That is why, humans are more similar to one another in comparison to other.

Evaluate the pedigree in Figure 4.14a. In which generations are there instances of inbreeding? In which generations are there instances of inter-generational inbreeding?

Inbreeding is depicted by double lines in a pedigree. Inbreeding within the same generation is shown with a horizontal double line, shown in generations III, IV, VI, VII, and X. Intergenerational inbreeding is shown with diagonal double lines connect between generations, as shown between generations VI and VII.

independent assortment

Independent segregation of genes during the formation of gametes

King George suffered from porphyria variegata. How did his symptoms illustrate pleiotropy? Although this genetic condition was present in other relatives, it was not appreciated as being the same disorder. Why?

King George suffered from red urine, abdominal pain, fever, weakness and then attacks the nervous system (delirium). Porphyria Variegata is considered a pleiotropic condition because individuals with the same condition can have many different subsets of phenotypes. This is due to pleiotropy, causing a single protein to affect different body parts and/or biochemical reactions. This can explain why his relatives were not diagnosed with the same condition because different symptoms/pathways were affected causing different phenotypes to be expressed.

Would you describe "Long QT Syndrome" (p. 27) as an example of a pleiotropic condition? Why or why not.

Long QT Syndrome is an example of a pleiotropic condition because it is caused by a single gene and it affects multiple phenotypes. This syndrome affects potassium channels in the heart and the inner ear, and causes disruptive electrical activity in both heart rhythm and the ear, leading to impaired hearing.

true

Maple Syrup Urine Disease involves the inability to metabolize isoleucine, leucine, and valine

What are the causes and symptoms of "Maple Syrup Urine Disease" and "Lesch- Nyhan Disease" (p.21)? What class of human diseases are these? Why is screening shortly after birth so critical for treatment of this class of diseases?

Maple Syrup urine disease and Lesch-Nyhan disease are metabolic disorders. Screening shortly after birth is important for metabolic diseases because diet changes can help reverse the effects of the condition or reduce symptoms. Maple syrup urine disease or branched-chain ketoaciduria is caused by a mutation in the BCKD complex- this causes the body to be unable to break down leucine, isoleucine, and valine which build up in the bloodstream as a result. Symptoms include urine smelling like maple syrup, lethargy, and vomiting, and a strict diet reducing the intake of these amino acids can control the effects of this disease. Lesch-Nyhan Disease is an inherited disorder in which the body cannot recycle 2 of the 4 nucleotide bases due to a defective HGPRT enzyme. These nucleotides crystallize as uric acid in the urine. An early diagnostic symptom includes orange particles present in the diaper, and later symptoms may include uncontrollable self-destructive behavior, intellectual disability, seizures, and trouble with movement.

How does mitochondrial DNA differ from nuclear DNA in terms of 1) inheritance pattern, 2) mutation rate, and 3) gene structure. Explain your answers.

Mitochondrial gene inheritance patterns differ in that they are only maternally inherited; they are passed down only from an individual's mother because sperm almost never contribute to mitochondria when they fertilize. Mitochondrial DNA does not cross over, leading to faster mutations in the nucleus than DNA. As it has less ways to repair, mitochondria are sites that produce oxygen radicals that damage DNA. Mt DNA is not wrapped in histones also. Genes are also not interrupted by DNA sequences that do not encode protein due to this change in structure. A given cell only has one nucleus and one complement, but you can have multiple Mt DNA in a cell. Mt DNA mutates faster. No introns in Mt DNA.

Explain how and why multiple alleles affect the severity of a disease, using phenylketonuria as an example.

Multiple Alleles is the concept that an autosomal gene can have more than two allele forms in a population because it can mutate in many ways. With regards to the phenylketonuria(PKU) disorder too little or the lack of an enzyme causes the amino acid phenylalanine to build up in brain cells. Some of the many different possible mutant alleles include; 2 different mutant alleles pair up, the individual is then considered a compound heterozygote. It is important to note that hundreds of mutant alleles pair to cause 4 basic phenotypes: classic PKU with profound mental slowness, moderate PKU, mild PKU, an asymptomatic PKU, with excretion of excess phenylalanine in urine.

(p59) Explain the statement: "The birth of a healthy baby is against the odds."

Of every 100 secondary oocytes/eggs (formed by primary oocytes by first meiotic division) that meet sperm, only 84 are fertilized, 69 of these implant into the uterus, in which 42 survive one week or longer while 37 survive 6 weeks or longer, and only 31 are born in the end. About 31% of all zygotes result in a live birth. Out of the ones that don't survive, roughly 50% have chromosomal abnormalities that are too severe to allow development to continue. Given that there are a multitude of mutations or even environmental factors that can affect whether you'll have a healthy baby, these stats aren't too surprising.

(p59) When is sex determined in humans? What does "SRY" stand for? On which chromosome is it found?

Sex is determined when the sperm and the oocyte meet or at conception. If the individual has two X chromosomes then it's a female, and one with an X and a Y is a male. The "`SRY" sex-determining region of the Y determines maleness; it is found in the Y gene; it is not expressed under a microscope until week 6 and by ultrasound it starts to make a difference by 12 to 15 weeks. The SRY genes is a transcription factor gene, it binds to parts of the genome which then tell downstream genes whether they are "turned on" or not.

Why are single-gene phenotypes so rare? What is the difference between autosomal dominant and autosomal recessive?

Single gene phenotypes are rare because even traits we thought were monogenic have multiple different genes that affect that trait. It is rare for environmental factors to not have an effect on phenotypes. Autosomal dominant and austomsal recessive can affect both sexes equally. However, autosomal recessive requires both parents to carry the gene and the trait can skip generations. Whereas autosomal dominant only one parent needs carry the gene for possible inheritance and disease symptoms tend happen after later in lafe allowing the gene to be passed down.

Does the "Bombay" blood phenotype illustrate pleiotropy, epistasis, expressivity and/or penetrance? Explain your answer.

The "Bombay" blood phenotype illustrates epistasis. In those with the phenotype, the H gene controls the expression of the I gene, which typically controls blood type. The H gene controls the placement of the molecules on red blood cells that the A and B antigens attach to. In homozygous hh individuals, the antigen is not made at all, leading to them testing as having O type blood. Even though the individual will phenotypically produce O blood, they can have any of the ABO blood genotypes.

H

The Bombay blood phenotype is associated with which of the following genes

How does GINA protect us if we choose direct-to-consumer (e.g., "23andme") genetic testing?

The Genetic Information Nondiscrimination Act (GINA) provides that employers cannot require genetic testing and cannot discriminate against, nor purposefully hire, employees based upon their genetic information. Health insurers also cannot discriminate on the basis of genetic information under GINA. People in the past did not use direct-to-consumer testing as frequently for fear of misuse of their information, or would take genetic tests under false names to avoid that information going on their medical records. More people nowadays will choose to participate in DTC genetic testing due to the privacy given by GINA.

31

roughly what percentage of fertilization attempts are anticipated to result in a live birth in humans

What is an evolutionary explanation for the abundance of blue eyes in humans with European genetic ancestry?

The evolutionary explanation for the abundance of blue eyes in humans with European genetic ancestry is that blue eyes were more desirable and therefore were produced more throughout the population.

Presence of the Huntington disease variant predicts the illness with near certainty. Why is this predictive power not the same for other human diseases?

The predictive power of Huntington disease variant is much higher than other human diseases because it is shown through every age by a single gene. For other diseases, one gene is not predicted for certainty and other factors come into play. Pattern of inheritance is autosomal dominant meaning someone only needs to have one allele to possess this disease - these arise through middle age (around age 40) beyond sexual reproduction age (why they are able to survive and pass to lineage) All have Huntington gene but only some have over 36 residues showing Huntington disease Huntington disease is an inherited condition in which nerve cells in the brain break down over time; treatment has improved (can impact on progression but cannot remove)

How do Y chromosome analyses support the idea of an ancestral relationship between the Lemba (a population of South Africans) and a group of Jewish priests (Cohanim)? How does sequence variation enable us to calculate the origin of this group?

The relationship is supported due to the fact that the Y-chromosome is the genetic component of maleness and is solely passed down from fathers to sons. In the case of the Cohanim, they had distinct DNA sequences on their Y-chromosomes, some of which were found in the Lemba tribe. This allows for the conclusion that these two groups are ancestrally related. The sequence variation of the Y-chromosome allows for the time of origin of the Y-chromosome patterns to be determined. Using the average rate of mutation for DNA, the number of mutations in the DNA, and generation time, it was found that the 5 distinct Y-chromosome patterns originated roughly 3,200 years ago. This would have been during the lifetime of Moses, and supports the religious documentation stating the Moses' brother, Aaron, was the first priest.

Why is the "whole person" phenotype of Tay-Sach's disease regarded as asymptomatic, but the "enzyme level" phenotype is regarded as incompletely dominant? (p. 92)

The whole person phenotype of Tay-Sach's disease is considered asymptomatic because the individual appears to be "healthy" and does not show signs of this disease in their phenotype. However, at the enzyme level, only half of the enzyme Hex-A is shown. Without this enzyme. a lipid (GM2) accumulates abnormally especially in nerve cells of the brain. This disease is autosomal recessive and there are three different ways to express this disease, either as carriers or showing Tay-Sachs through your phenotype.

Evaluate the pedigree in Figure 4.14c. Do the affected great-grandchildren (IV-1 and IV-3) harbor the same or different copies of the allele of their carrier great-grandparent (I-1)? Explain why consanguinity raises the risk of inheritance for rare genetic disorders?

Their grandfather was a carrier with one allele for the trait. IV-1 and IV-3 harbor two of the alleles for the trait, one of which is the same as the grandfather. This therefore results in the great-grandchildren expressing the trait. Consanguinity or shared blood runs the risk of inheriting autosomal recessive diseases because there is a greater chance of offspring between two carriers if it runs in the family.

true

a double line on a human pedigree chart represents an instance of consanguinity

thalidomide

a mild tranquilizer that, taken early in pregnancy, can produce a variety of malformations of the limbs, eyes, ears, and heart

Herc2

a neighboring gene to Oca2, and it controls the expression of this gene

homologous pairs

a pair of chromosomes of the same type, one from each parent

genetic heterogeneity

a phenotype that can be caused by variants of any of several genes

induced pluripotent stem cells

a pluripotent stem cell that was generated by manipulation of a differentiated somatic cell

stem cells could be used to treat severe burns (or other skin disorders) or baldness

a single stem cell in skin gives to skin cells, hair follicle cells, and sebaceous (oil) gland cells; suggest a treatment that might use these cells

epistasis

a type of gene interaction in which one gene alters the phenotypic effects of another gene that is independently inherited

recessive

an allele that is masked when a dominant allele is present

phenocopy

an environmentally caused trait that occurs in a familial pattern, mimicking inheritance

true

another name for Maple Syrup Urine Disease is branched chain ketoaciduria

haplotype

area of linked genetic variations in the human genome

meiosis

cell division that produces reproductive cells in sexually reproducing organisms

answers vary depending on student experience; "he has the gene for sense of humor", or "she has the gene for a great sense of style"

cite an example of a phrase that illustrates genetic determinism

accelerated aging disorders and studies on adopted individuals indicate an inherited component to longevity

cite two pieces of evidence that genes control aging

false

comparisons of people at the genome level reveal we are less like each other genetically than are other mammals

dominant

describes a trait that covers over, or dominates, another form of that trait

embryonic stem (ES) cells are derived in a dish from pluripotent stem cells taken from the inner cell mass of a very early stage embryo; Induced pluripotent stem (iPS) cells are pluripotent stem cells created from non-pluripotent somatic cells by manipulating the expression of a few key genes; adult stem cells are found throughout the body from embryonic development onward; they can reproduce and differentiate to repair and replace specialized cells; pros and cons include ES cells are naturally pluripotent and self-renewing but the use of human ES cells is more controversial than that of iPS cells or adult stem cells and countries vary in their policies regarding such research; the full potential of iPS and adult stem cells is not yet known; adult stem cells are multipotent rather than pluripotent; potential risks involve rejection of implanted somatic cells and induction of cancer

distinguish among ES cells, iPS cells, and adult stem cells, and state the pros and cons of working with each to develop a therapy

a. an autosomal recessive trait is inherited from carriers and affects both sexes; and autosomal dominant trait can be inherited from one parent that is affected; autosomal recessive inheritance can skip generations while autosomal dominant inheritance cannot b. Mendel's first law concerns inheritance of one trait and the second law follows inheritance of two genes on different chromosomes c. a homozygote has identical alleles for a particular genes and a heterozygote has different alleles (TT versus Tt) d. the parents of a monohybrid cross are heterozygotes for a single gene and parents of a dihybrid cross are heterozygous for a pair of genes e. a Punnett square tracks the distribution of alleles of genes on different chromosomes from parents to offspring and a pedigree depicts family members and their inherited traits

distinguish between a. autosomal recessive and autosomal dominant inheritance b. Mendel's first and second laws c. a homozygote and a heterozygote d. a monohybrid and a dihybrid cross e. a Punnett square and a pedigree

primary germ layers

endoderm, mesoderm, ectoderm

the sequence of DNA nucleotides (A, G, C, T) in a gene comprises a genetic code that is read three nucleotides at a time to direct the building of proteins from amino acids

explain how DNA encodes information

humans may have the same genes but differ genetically in the alleles (gene variants) that they have

explain how all humans have the same genes, but vary genetically

a. lethal alleles eliminate a progeny class that Mendel's laws predict should exist b. multiple alleles create the possibility of more than two phenotypic classes c. incomplete dominance introduces a third phenotype for a gene with two alleles d. codominance introduces a third phenotype for a gene with two alleles e. epistasis eliminates a progeny class when a gene masks another's expression f. incomplete penetrance produces a phenotype that does no reveal the genotype g. variable expressivity can make the same genotype appear to different degrees h. pleiotropy can make the same genotype appear as more than one phenotype because subsets of effects are expressed i. a phenocopy mimics inheritance, but is an environmental effect j. conditions with the same symptoms but caused by different genes will not recur with the frequency that they would if there was only one causative gene

explain how each of the following phenomena can disrupt Mendelian phenotypic ratios a. lethal alleles b. multiple alleles c. incomplete dominance d. codominance e. epistasis f. incomplete penetrance g. variable expressivity h. pleiotropy i. phenocopy j. genetic heterogeneity

a genome-wide association study examines the whole genome for variations such as SNPs that can be associated with (are found much more often among individuals with) certain conditions or traits of interest; gene expression profiling measures patterns and levels of mRNA to reveal cellular activity; DNA sequencing analyzes the order of DNA nucleotides (A, G, C, T) in a molecule of DNA or across the entire genome

explain how genome-wide association study, gene expression profiling, and DNA sequencing of a gene or genome differ

determinism

genetic ___ is the notion that an inherited trait is inevitable

true

genetic determinism is probably a concept more relevant to Huntington's Disease than sense of humor

the genome of a bacterial species that lives in the human gut

give an example of a genome that is in a human body, but is not human

specialized cells express different subsets of all the genes that are present in all cell types, except for RBCs

how can all of a person's cells contain exactly the same genetic material, yet specialize as bone cells, nerve cells, muscle cells, and connective tissue cells

incomplete penetrance in the child

how could two people with albinism have a child who has normal skin pigment

the porphyrias are variably expressive because symptoms vary in occurrence and severity among individuals; they are pleiotropic because they have more than one symptom; they are genetically heterogeneic because they have mutations in different genes in the porphyrin-heme pathway

how do the porphyrias exhibit variable expressivity, pleiotropy, and genetic heterogeneity

mitosis divides somatic cells into two daughter cells with the same number of chromosomes as the diploid parent cell; meiosis forms gametes, in which the four daughter cells have half the number of chromosomes of the parent cell; genetic recombination occurs in meiosis

how does meiosis differ from mitosis

mitochondria

in which organelle would a defect cause fatigue

false

like nuclear DNA, mitochondrial DNA has introns

no introns, no crossing over, and not associated with histones

list three ways that mtDNA differs from DNA in a cell's nucleus

lethal alleles

mutated genes that are capable of causing death