Final - Exam 1+2+3

Question 1

Eugenics laws passed by many states in the early 20th century were:

Answer 1

fundamentally unconstitutional and un-american in both premise and procedure AND based on untested scientific premises, which turned out to be scientifically wrong.

Question 2

Which of the following significantly contributed to the difficulty of understanding whether a particular disease is genetic, and if so how is it inherited

Answer 2

small modern family size, long generation times combined with short memories, variable expressivity and incomplete penetrance, and failures of communication within families

Question 3

Meiosis and mitosis are

Answer 3

both processes start with chromosomes that each consist of 2 chromatids

Question 4

when discussing multiple alleles (2+) of a single gene, which of the following is true

Answer 4

A population may have more than 2 alleles

Question 5

Cross occurs between AaBbCcddEe and aabbCCDdEe. What proportion of the offspring would be expected to be heterozygous at all 5 loci.

Answer 5

1/32

Question 6

Mutations in DNA can alter phenotypes by changing the:

Answer 6

1. amount of a particular protein produced2. sequence of amino acids in a protein

Question 7

Which of the following are possible reasons why identical genotypes at a particular locus don’t always give identical phenotypes?

Answer 7

Could be because of epistatic interactions with other loci, sex-influenced or sex-limitation, or variations in the environment

Question 8

Both parents are carries of cystic fibrosis allele. Assuming complete pentrance, if they have 3 children, what is the chance that at least one will eventually be affected with cystic fibrosis

Answer 8

37/64

Question 9

PKU is caused by a recessive allele that produces an altered protein. Why is this allele recessive instead of dominant?

Answer 9

heterozygotes produce half the normal level of the functional enzyme, but that is enough for a normal metabolism

Question 10

Gregor mendel utilize probability theory when analyzing his results

Answer 10

Because he recognized that a probabilistic process was at work

Question 11

Human germ line cell immediately after meiosis contains

Answer 11

23 chromosomes, 46 chromatids

Question 12

Cell cycle leading to mitosis is

Answer 12

continuously occurring in all of us

Question 13

The profound retardation caused by PKU can be prevented by modifying the environment in what way?

Answer 13

limit the phenylaline in the diet

Question 14

rare inheritance of 1/100,000 in a particular family, most probable mode of inheritance of this trait is? Pedigree B

Answer 14

mitochondrial

Question 15

rare inheritance of 1/100,000 in a particular family, most likely explanation of the phenotype is? Pedigree B

Answer 15

Best explained as an example of incomplete penetrance

Question 16

Many drugs that are safe for most of the population can cause lethal side effects in some individuals. Would we expect these side effects to show a familial pattern?

Answer 16

Yes, because families share genes

Question 17

Hemochromatosis is an example of a very common, deleterious allele that demonstrates:

Answer 17

phenotypes depend on both genes and the environment

Question 18

OMIM is part of the National Center for Biotechnology Information. What sort of information does OMIM contain

Answer 18

Information about individual genetic loci that have alleles that cause human disease

Question 19

Pedigree C shows the inheritance of a common (1/400) trait in a particular family. What is the most probable mode of inheritance of this trait?

Answer 19

Too little info

Question 20

Which of the following is true difference between DNA and RNA?

Answer 20

DNA used deoxyribose, RNA uses ribose

Question 21

Mendel’s principle of Independent Assortment occurs because

Answer 21

chromosomes independently assort during meiosis and chromosomes routinely crossover during prophase 1.

Question 22

Homologous chromsomes normally

Answer 22

have identical loci

Question 23

The epidemiological evidence is that smoking starts 20 years or more before the age at which smokers start showing a significantly higher cancer rate. What is the most probable explanation?

Answer 23

1. A normal cell requires multiple mutations in at least one daughter cell before that cell becomes fully malignant2. the first steps in the development of cancer are typically small and slow growing

Question 24

Individuals with sickle-cell anemia, pain in many different parts of the body, strokes that cause cumulative brain damage, and sometimes, heart attacks. Thus the condition is an example of:

Answer 24

pleiotropy

Question 25

Following can be directly explained by the biology of meiosis and fertilization

Answer 25

Mendel’s law of segregation and some alleles are dominant to others

Question 26

The allele that is responsible for cystic fibrosis codes for an abnormal form of:

Answer 26

Protein that transports chloride ions across cell membranes

Question 27

Which of the following is not directly involved in translation?

Answer 27

DNA

Question 28

What where eugenics mistakes involving human genetics

Answer 28

Human phenotypes are almost totally genetically determined, bad genes that will be passed to children can readily by determined by looking at individuals, and some human races are obviously superior to others

Question 29

the allele that is responsible for cystic fibrosis codes for an abnormal form of:

Answer 29

Protein that transports chloride ions across cell membranes

Question 30

spermatogenesis and oogenesis both involve meiosis, but which of the following is a true difference between the 2 processes

Answer 30

oogenesis takes longer than spermatogenesis

Question 31

Several human loci are known where normal alleles contain trinucleotide repeats. But some families transmit abnormal alleles that cause disease, and the disease often seems to get worse in succeeding generations. What do we believe is happening here?

Answer 31

Additional trinucleotides are added to the alle during gametogenesis, which worsens the phenotypic effect

Question 32

The monohybrid crosses, Mendel deduced that one trait was recessive because that trait

Answer 32

Was not present in F1 by did reappear in F2

Question 33

Phenotypically normal, 20 year old man learns that his paternal grandfather has been diagnosed as having Huntingdon disease. From this, what is the chance that his newborn son will eventually develop the disease?

Answer 33

1/8

Question 34

Inheritance pattern of mitochondrial disorders is distinctive, and variable expressivity and incomplete penetrance commonly occur in these families. What biological facts cause this pattern

Answer 34

Mitochondria have their own chromosome which code for some mitochondrial functions, all (most) of our mitochondria come from our mothers, and there are multiple mitochondria in cells, and they are not uniformly divided during either mitosis or meiosis

Question 35

Which of the following is true in eukaryotes like humans?

Answer 35

Much of the DNA sequence is not transcribed and even less is translate

Question 36

Couple who have a child with cystic fibrosis ask a physician whether they will have another affected if they have a second baby. The doctor tells them that, since the chance of having an affected child is 1 in , and they’ve already had an affected child, the next 3 children will be normal. The advice is

Answer 36

Wrong, because each child is an independent event

Question 37

Phenotypically normal couple have 2 normal sons, a normal daughter, and then a son with duchenne muscular dystrophy. What is the chance that the next child will also have muscular dystrophy?

Answer 37

Depends on child’s sex, 0 for a daughter, and 1/2 for a son

Question 38

Pedigree d shows the inheritance of a rare 1/100,000 trait in a particular family. what is the most probable mode of inheritance of this trait?

Answer 38

X-linked dominant

Question 39

What 3’ and 5’ important?

Answer 39

They refer to different directions along nucleic acid chains, and those differences are important for biological function

Question 40

True-breeding line of black chickens is crossed with a true-breeding line of white chickens. The F1 are all gray. A gray hen is now crossed with a gray rooster. After 12 broods of chicks, their offspring include 27 white chickens, 48 gray chickens, 24 black chickens. This suggests that the inheritance of gray feather color in chickens is an example of:

Answer 40

incomplete dominance

Question 41

Chin dimples are caused by an autosomal dominant allele. A couple has 20 children, 8 with dimples and 12 without. What are the probable phenotypes and genotypes of the parents

Answer 41

one has a dimple and is heterozygous, the other doesn’t and is homozygous

Question 42

A female heterozygote for an X-linked mutant allele will pass it on to:

Answer 42

1/2 of her daughters and 1/2 of her sons

Question 43

A proto-oncogene is a gene that:

Answer 43

1. functions to promote cell division when the proper signals are received2. Can be mutated to form an oncogene

Question 44

Each of a couple have a color-blind father, but both have normal color vision. What is the chance that they will have a color-blind daughter

Answer 44

0

Question 45

Couple have achoo syndrome (sneezing in the bright light), which is caused by an autosomal dominant allele. each has one parent who does not have the syndrome. What is the chance that their first child will not have achoo syndrome

Answer 45

1/4

Question 46

Ultraviolet light:

Answer 46

is a mutagen

Question 47

What is the chance that if the above couple have 3 children, all of the 3 will have achoo syndrome both parents heterozygous

Answer 47

27/64

Question 48

An individual is RrSsTt. What is the chance that he will produce a gamete that is rSs

Answer 48

0

Question 49

A woman with blood type A and a man with blood type B have 8 children: 3 sons with Type AB and 5 daughters with Type A. Most probable geneotypes of the parents

Answer 49

IAIA x IBi

Question 50

Females that are fully affected by Duchenne muscular dystrophy are only known in cases of rare chromosomal errors. Females that are fully affected by red-green colorblindness are uncommon compared to affected males, but not truly rare. Why are these two traits so different in their occurrence in females

Answer 50

Male reproduction is usually prevented by Duchenne muscular dystrophy, but not by color blindness

Question 51

Cells in rapidly growing tissue are more susceptible to mutagens than cells that are slowly growing, whY?

Answer 51

There is insufficient time to repair DNA damage before replication in fast growing cells

Question 52

Pedigree A shows the inheritance of a rare (1/100,000) trait in a particular family. What is the most probable mode of inheritance of this trait?

Answer 52

autosomal recessive

Question 53

Which of the following situations is likely to result in a baby with hemolytic disease of the newborn? Assume that, unfortunately, RhoGam has never been appropriately administered?

Answer 53

Mother Rh negative, father Rh positive, 2nd or later pregnancy

Question 54

Individuals with familial hypercholesterolemia have a dominant allele that causes severe atherosclerosis and leads to early (during middle age) heart attacks and strokes. About 1 per million births produce children who are affected with the condition, but so severely that the child starts having heart attacks and strokes by the age of 5. What does this tell us about the condition and these families?

Answer 54

The child is actually homozygous for the allele, both parents are heterozygotes

Question 55

Whats true about human races

Answer 55

What race you consider a particular individual depends on your upbringing, more than their biology

Question 56

Monozygotic twins (neither mosaic) are generally

Answer 56

genotypically identical

Question 57

children that have been adopted are tested for trait T and compared to their biological mothers and their adoptive mothers. They turn out to be much more similar to their adoptive mothers. Their siblings (biological of the adoptive parents) in the adoptive families are almost always identical to their parents when tested for trait T. What should we conclude about trait T?

Answer 57

Trait probably has heritability near 0 or .1

Question 58

Which of the following is true of a threshold trait that is known to be a complex trait?

Answer 58

Relatives of an affected individual will be more likely to be affected than nonrelated individuals, nephews of an affected aunt will be equally at risk as grandchildren of an affected grandmother, individuals who get the same alleles as the affected individuals will be affected in all cases, and all individuals who share the same family environment will be equally at risk

Question 59

phenotypically normal individuals are sometimes found who have only 45 chromosomes, no normal #21 chromosomes, but have a robertsonian translocation chromosome that has two 21q arms joined at the centromere. If they marry a chromosomally normal individual, what is the chance that a child will down syndrome?

Answer 59

1/2 of all conceptions, but the other half will have 21 monosomy, so only Down syndrome babies will be born alive.

Question 60

Which of the following is true about chromosome aberrations?

Answer 60

A large deletions is equivalent to a partial monosomy

Question 61

A hormonal signal always need a receptor. Which of the following disorders demonstrates the consequences of a missing or non-functional receptor?

Answer 61

androgen insensitivity

Question 62

An individual is found to have some tetraploid liver cells, but diploid kidney cells and white blood cells. Possible explanation?

Answer 62

A failure to complete mitosis in a liver cell in the embryo

Question 63

Which of the following is true about height determination in humans and pea plants

Answer 63

eight is dependent on both genotype and environment in both peas and humans, mendel’s experimental conditions made height a discontinuous variable in peas, but it has always been a continuous variable in humans, and mendel picked peas that had only 2 alleles at a single locus that affected height, humans have multiple loci

Question 64

Many more syndromes include mental retardation as one of their common aspects than include foot malformations. Why is this so?

Answer 64

The brain has a longer critical period than the feet

Question 65

Which of the following is a demonstration of differing norms of reaction

Answer 65

Homozygotes for hemochromatosis often become ill from iron overload in our society, but were more likely to survive and reproduce than wild type homozygotes in some past societies

Question 66

how common are babies born with ambiguous genitalia, and what should be done about deciding which sex the child should be raised

Answer 66

It’s a relatively common event (1/3000) and sex assignment can wait until parents and physicians have enough information to avoid mistakes

Question 67

In cats, black or orange is determined by alleles at a locus on the X chromosome. Heterozygotes are described as “tortoise-shell” or “calico”. What kinds of kittens could be expected from the cross of an orange female with a black male?

Answer 67

tortoise-shell females, orange males

Question 68

In the past, some cat fanciers thought they could breed a line of pure-breeding calicos if only they could find a calico male. After the large prices, some calico males were found, but almost all were infertile. We now can explain this infertility, because they male calicos were probably:

Answer 68

Klinefelter syndrome

Question 69

An embryo with which of the following chromosomal abnormalities will NEVER survive

Answer 69

45, -x, y

Question 70

What is the critical event in determining that the gonadal sex will be male

Answer 70

The SRY gene turns on and produces functional TDF

Question 71

What determines the sexual identity of an individual?

Answer 71

Changes in the fetal brain resulting from the presence or absence of testosterone

Question 72

How much alcohol is it safe for a pregnant women to drink?

Answer 72

None

Question 73

Which of the following is true about Down Syndrome individuals?

Answer 73

Older fathers (>40) don’t raise the risk nearly as much as older mothers

Question 74

Height has a heritability of at least .8. What conclusions can we draw from this fact?

Answer 74

Children will tend to be the same height relative to their generation as their parents were relative to their own generation

Question 75

A body is normally found in the nucleus of which kind of cell

Answer 75

somatic cells of females

Question 76

A continuously distributed trait is studied in a series of families. It is found that the children of parents with the same extreme phenotypes (whether high or low on the trait) shwow moderate regression to the mean. What conclusion can we draw from this?

Answer 76

The trait probably is complex, and the regression occurs because the children of extreme parental pairs are unlikely to have the same extreme environment as their parents

Question 77

The food and drug administration requires that studies to determine whether new drugs work, must be done “double blind”. Similarly, research in human genetics that includes psychological evaluations is normally done “double blind” Why is a double blind procedure required for believable results

Answer 77

Humans ofter make results match expectations, even if they’re not consciously doing so

Question 78

A baby is born with phenylketonuria, which is known as a recessive. His mother is a known carrier, but his father has no family history of phenylketonuria. But karotyping reveals that his father has a chromosome 12 with an inversion on the long arm, where the PKU locus is located, and the baby inherited this chromosome from his father. What explanation would be reasonable?

Answer 78

One of the break-points of the inversion is probably in the PKU locus

Question 79

Karyotyping reveals that a down syndrome girl has a Robertsonian translocation between chromosomes 13 and 21, and her father is a translocation carrier. What is the chance that the phenotypically normal children are counted when figuring the odds.

Answer 79

about 1 in 2, or 50%

Question 80

Sex chromosome trisomies are less damaging than autosomal trisomies. Why is this so?

Answer 80

Most genes on Y chromosome affect sperm production, only a small number are otherwise important and extra X chromosomes are mostly inactivated

Question 81

what are the practical consequences of determining whether an abnormal condition is familial or heritable?

Answer 81

Whether it’s familial or heritable suggests what aspects we need to investigate futher to understand the condition

Question 82

Geneticists used to assume that human sex determination was similar to Drosophila, where the ration of x chromosomes to autosomes determines the sex. Which conditions showed that this was wrong?

Answer 82

Klinefelters syndrome and Turner Syndrome

Question 83

Which of the following can damage an embryo or fetus?

Answer 83

smoking, X-rays of the mother’s abdomen, some prescription drugs, vitamin deficiencies, vitamin supplement excesses

Question 84

Karyotype for an embryo is 69, XYY. This individual is:

Answer 84

triploid

Question 85

What is the most probable explanation for the above chromosomal constitution?

Answer 85

Dispermy

Question 86

What is the most probable explanation for an embryo with 69, XYY

Answer 86

gonadally male, phenotypically ambiguous when the internal organs are examined

Question 87

The pseudoautosomal regions of the X and Y are the explanation for:

Answer 87

How such different chromosomes manage to pair during meiosis and XXXXX having a very abnormal phenotype in spite of X inactivation

Question 88

How many barr bodies would a XXXXY individual have?

Answer 88

4

Question 89

Secondary sexual characteristics of females are due to:

Answer 89

estrogen and progesterone exposure during puberty and adulthood

Question 90

Multiple books and articles have been written that explains that programs such as Head Start can never erase racial differences in school achievement because IQ has a high heritability. Does the scientific evidence suggest these authors are right or wrong?

Answer 90

Wrong, heritability measured in one environment don’t apply to other environments

Question 91

What trait has the highest heritability? WhyMZ - A97, B77, C58, D46; DZ - A77, B75, C28, D31.

Answer 91

C, The difference between the MZ and Dz concordances,

Question 92

Which trait has the lowest heritability? WhyMZ - A97, B77, C58, D46; DZ - A77, B75, C28, D31.

Answer 92

B, the lack of difference between the MZ and DZ concordances

Question 93

The “triplet code” refers to the fact that:

Answer 93

3 nucleotides code for an amino acid

Question 94

Base pairs of DNA are held together by hydrogen bonds, while the sugar phosphate backbone is covalently bonded. The consequences of this are:

Answer 94

1. it requires specific enzymes to rejoin a broken sugar phosphate backbone2. random molecular motion at body temperature can separate portions of complementary DNA strands and they will spontaneously re-assemble

Question 95

What is the difference between a human chromatid and a DNA molecule?

Answer 95

Chromatids contain multiple protein molecules along with DNA

Question 96

A gene that had the 5’ promoter region deleted would:

Answer 96

not be transcribed

Question 97

A man and a woman both have impaired metabolism of the amino acid alanine, and in both cases it is due to a genetic defect. They marry have a large family, all of whom have normal alanine metabolism. What is the most likely explanation?

Answer 97

The couple are each mutant heterozygotes, but a different loci

Question 98

The tertiary or quaternary structure of a protein ultimately depends on:

Answer 98

the sequence of amino acids determined by the DNA sequence

Question 99

How does the genotype at the beta-globin locus affect phenotypes?

Answer 99

1. sickle-cell allele homozygotes have severe medical problems2. the norm of reaction for sickle-cell 3. heterozygotes is “wild type” population in the US

Question 100

Mutation is a random process, and therefore we can never predict which nucleotide in the genome will be changed next. None the less, which of the following are true?

Answer 100

1. Large genes have high mutations rates than small genes2. There are mutation hotspots in the genome

Question 101

Which of the following is an explantation of how a mutation at a single locus can have pleiotropic effects?

Answer 101

1. One enzyme can participate in multiple metabolic pathways2. Either a deficiency of a product produced by an enzyme or a buildup of a precursor can cause problems

Question 102

The Watson-Crick model of DN was immediately recognized as important because the structure directly suggested how:

Answer 102

genetic information could be accurately copied repeatedly

Question 103

A codon of the template DNA sequence is GCA. Which of the following would be the corresponding tRNA anticodon?

Answer 103

GCA

Question 104

Cancers are typically a mixture of cells with different abnormal karyotypes. Why should a single cancer have multiple abnormal karyotypes?

Answer 104

These cells are typically mutated in both copies of a tumor suppressing gene, which allows more mutations, including chromosome mutations, to occur in daughter cells

Question 105

Which of the following is true about hemoglobin?

Answer 105

Sickle-cell hemoglobin is only different from normal hemoglobin by the change of a single amino acid in beta globin

Question 106

The following partial DNA sequence is a portion of the template strand of a gene. This portion includes the portion coding for N-terminal end of the protein. How many amino acids will be coded by the portion of the mRNA made from this sequence? CCC CAT TAC TTC GGG

Answer 106

3

Question 107

Comparing Japan to the US, we find higher rates of colon cancer in Japan and lower rates of breast cancer. But when we look at cancer rates in 3rd or 4th generation Japanese-Americans, we find rates comparable to other Americans. Why are Americans of Japanese descent apparently different from their ancestors?

Answer 107

The American environment (probably diet) somehow varies from the Japanese

Question 108

Metastasis refers to a process by which:

Answer 108

tumor cells spread from the initial site and start growing in other locations

Question 109

After sequencing a gene, it is discovered an individual has a mutant DNA sequence, but produces a normal amount of a perfectly normal protein. Which of the following is the most likely site of the mutation?

Answer 109

middle of an intron

Question 110

A mutation will always affect:

Answer 110

nucleotide sequence

Question 111

A family with no history of the disease has a daughter, Helen, with retinoblastoma, an autosomal dominant condition with variable expression which produces eye tumors in children. Both of Helen’s eyes were affected, and 3 of her 5 children develop tumors in both eyes. Where did the original mutation probably occur?

Answer 111

in one of her parent’s gonads

Question 112

A different family with no history of the disease also has a daughter, Diana, with retinoblastoma. One of Diana’s eyes were affected at age 2, but none of here 5 children develop eye tumors or any other early tumors. Where did the original mutation probably occur?

Answer 112

in Diana’s eye

Question 113

Mutations that abolish function in tumor suppressor genes are commonly recessive alleles when considered at the cellular level. But the family inheritance pattern for susceptibility to particular cancers looks like dominant with incomplete penetrance. Why is this so?

Answer 113

Only having one functional allele of a gene in all cells makes each cell vulnerable to a somatic mutation in that allele

Question 114

Achrondroplasia is an autosomal dominant form of dwarfism that seems to be completely penetrant. If we find 39 achondroplastic births to unaffected parents in a total of 499,000 births, what is the mutation rate per gene per generation?

Answer 114

4 x 10^-5

Question 115

Which of the following mutations would be most likely to produce a significantly different phenotype?

Answer 115

adding two bases to the middle of an exon

Question 116

Comparing the sickle-cell allele to wild-type, is it a good allele or a bad allele?

Answer 116

This is too simple of a classification, since heterozygotes are the best genotype in some environments

Question 117

A portion of a DNA strand has the following sequence: ATT CCG AA. What is the complementary strand?

Answer 117

TAA GGC TT

Question 118

In the above 8 base pairs, how many hydrogen bonds should we expect?

Answer 118

19