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Biochem Exam 2 > Genetics > Flashcards

Genetics Flashcards

1
Q

What is the word for normal number of genes?

A

Euploid

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2
Q

What is the name for abnormal number of chromosomes?

A

Aneuploid

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3
Q

What is epigenetics

A

Modifications to DNA that turns genes off controlling the production of proteins in particular cells, do not change sequence of DNA

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4
Q

What is a karyotype?

A

a visual representation of an individual’s complete set of chromosomes, including their number, size, and shape

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5
Q

What are the general steps of karyotyping?

A

get sample, mitogen to make them replicate, mitosis blocker to stop, centriguge, put on slide and look at through microscope

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6
Q

What can karyotype be used for?

A

identifying some diseases

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7
Q

What is FISH?

A

synthesize DNA attach a fluorescent tag on different chromosomes and when you separate and put it under a microscope you can see where the tag is

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8
Q

What is FISH of interphase nuclei good for?

A

diagnosing trisomy 21
(21 stains red, 13 is green and you can count the amount of cromosomes)

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9
Q

What is array comparative genome hybridization? (Array cGH)

A

–patient and control DNA are labeled with fluorescent dies and added to microarray
–the patient and control compete to attach to microarray
–scanner measured florescent signals

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10
Q

How can you read a Array cGH test?

A

counting the amount of tagged DNA, if there’s too much its probably a trisomy, too little could be a deletion

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11
Q

In chromosomal nomenclature what is p and q?

A

P is short arm
q is long arm
(arms separated by centromere)

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12
Q

Ends of chromosomes are called _____

A

telomeres

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13
Q

Acrocentric means:

A

one chromosomal arm is much shorter than the other

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14
Q

what is triploidy?

A

double of all chromosomes, 69 chromosomes instead of 46
(common fertilization of one egg by 2 sperm)

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15
Q

when does trisomy usually happen?

A

Usually occurs when one pair of chromosomes fails to separate during meiosis: non-disjunction

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16
Q

What is trisomy 21? What is it marked by

A

Down syndrome
* Decreased intellectual development
* Congenital heart defects
* Classic facial changes
– epicanthal folds with upslanting palpebral
fissures

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17
Q

What is trisomy 18?

A

Second most common trisomic condition.
* Severe developmental and functional abnormalities
* Most affected children are stillborn
* Of those that are born alive, more than 90% die in
first year of life

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18
Q

What is trisomy 13?

A
  • Severe developmental and functional
  • Stillbirths and early neonatal deaths are common
  • Of those who are born alive, more than 90% die
    within the first year of life
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18
Q

Which trisomy’s can you survive with?

A

21 and 18

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19
Q

What is trisomy X?

A

3 X chromosomes (only in females)
Inactivation of 2 of the 3 Xs most likely reason for
the normal phenotype.
* Individuals are taller than average and are taller
than most family members

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20
Q

What is klinefelters syndrome?

A

trisomy SEX
47, XXY

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21
Q

what are the effects of Klinefelter’s syndrome?

A

Individuals taller than average, long legs, normal
puberty
* In young adulthood testosterone levels decline,
luteinizing hormone [LH] and follicle-stimulating
hormone [FSH]) levels become very high.
– Small genitalia
– Gynecomastia
– Reduced fertility

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22
Q

What is turners syndrome?

A

only have one X chromosome

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23
Q

what is a translocation of a chromosome?

A

take one piece of a chromosome and put it on another and take piece of other to that

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24
Q

what are the symptoms of turner syndrome?

A
  • Short stature
  • Normal intelligence
  • Infertility
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25
Q

what is the effect of balanced translocations?

A
  • Common
  • Usually no effect on health or development
  • Reciprocol
    –total amount of DNA unchanged
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26
Q

what are reciprocal translocation?

A

Segments of two nonhomologous chromosomes break and are equally exchanged

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27
Q

What is Angelman syndrome?

A

deletion of long arm of MATERNAL chromosome 15 from

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28
Q

what is likely the effect of duplications and/or deletions?

A

–more likely to cause a change in phenotype and
symptoms if the region is large
–Reduced intellectual capacity in children sometimes
associated with small deletions of specific gene regions

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29
Q

what are the effects of Angelman syndrome?

A

—developmental delays
– Children learn to walk but usually have unsteady or clumsy gait with jerky motions
–The child smiles and laughs frequently regardless of
circumstances

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30
Q

what is special about chromosome UBE3A?

A

in neuronal cells only maternal copy is only expressed, paternal is turned off (this is why there is the motor problems in Angelman’s)

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31
Q

what is Prader Willi syndrome?

A

deletion on long arm of paternal chromosome 15

32
Q

what is a dental side effect of Prader Willi?

A

decreased, thick and sticky saliva that adheres to teeth and harbors bacteria that can cause decay and periodontal disease (also breath through mouth so risk for crowding and increased tooth wear)

32
Q

what is a symptom of Prader Willi?

A
  • Insatiable appetite that usually manifests by age 3 years
    leading to obesity
  • When obesity and its associated health problems are controlled, life expectancy normal
33
Q

What is SNV?

A

Single base pair change from most in population
COMMON

34
Q

What is Single Nucleotide Polymorphism (SNP)?

A

rare, normal genetic variation, SNP is a SNV but not all SNV are SNP

35
Q

What is copy number variant (CNV)?

A

– Change in number of copies of DNA
– Insertions
– Deletions

36
Q

What is an allele?

A

different forms of a given gene (due to SNVs, SNPs, CNVs, etc)

37
Q

huntingtins disease is an example of what kind of inheritance

A

autosomal dominant

38
Q

examples of Autosomal Recessive diseases are

A

– Cystic fibrosis
– Sickle Cell Disease

39
Q

in Autosomal-dominant (AD) diseases?

A

Trait or disease appears in every generation with clear transmission from parent to child, equal distribution male or female
Risk to pass the trait to child is 50% with each pregnancy.

40
Q

what is an example of autosomal dominant traits?

A

blood type A and B

41
Q

what is incomplete penetrance?

A

sometimes people will have the disease but it will not express itself

42
Q

What is the difference between A B and O for blood typing?

A

A and B are dominant (can be co-dominent)
O is recessive

42
Q

Why is there type O?

A

deletion happened that shifted the reading frame so there is no antigens

42
Q

what is variable expressivity?

A

Degree of gene expression varies by the person who has the dominant acting allele, gene is expressed but some patients have it more severe than others

42
Q

unaffected carriers of autosomal recessive have what % chance of transmission?

A

50
(2 unaffected carriers have 25% chance)

43
Q

what does it mean to have carrier status?

A
  • Carries one allele for a recessive disorder
  • Can transmit mutated allele to children
  • Some carriers may have very mild manifestations
44
Q

what is ellis-van Creveld syndrome?

A

form of dwarfism, much more frequent in old order Amish population (Samuel king and his wife)

45
Q

how is X linked transmission different in males?

A

Any X-linked allele in a male is expressed as if it were a dominant allele (called hemizygosity)
BECAUSE THEY ONLY HAVE ONE X

46
Q

an effected male with X linked dominant disease transmits the disorder to what % of female children?

A

100%

46
Q

an effected female (X linked dominant) transmits the disorder to what % of female children?

A

50%

46
Q

what is mitochondrial inheritance?

A

All mitochondria come from maternal

At fertilization, sperm head with nucleus and no mitochondria enters mature ovum to form zygote

47
Q

what happens with FMR1 repeates?

A

CGG repeats, if gets to 200 repeats it will turn off cell

47
Q

what is mitochondrial homoplasy?

A

– All mitochondrial DNA have identical sequences
– All cells will have same mitochondrial population after cell division

47
Q

what is mitochondrial heteroplasmy?

A

– Mitochondria DNA a mix of usually 2 main sequences
– Because of random segregation, heteroplasmy will be different after cell division

48
Q

what is germline mosaicism?

A

– Spontaneous DNA base change occurs during germ cell development
– At risk of having affected children despite of not being affected with the
trait

48
Q

what is somatic mosaicism?

A

– May express mild manifestations of the phenotype
– May express the phenotype in a restricted region of the body

49
Q

what are repeat disorders?

A

Most are di-, tri-, or tetranucleotide
sequences.
* Number of repeats variable
* Most mutations cause neuromuscular
disorders

49
Q

what is fragile X syndrome?

A

part of X broken or fragile
moderate-severe intellectual disability in males (mild or unaffected in males)

50
Q

go over red flags of genetic disease

A
51
Q

What is ectodermal dysplasia?

A

effects things that arise from the ectoderm
(teeth abnormalities, brittle, sparse or
absent hair, abnormal fingernails, inability to perspire (hypohidrosis))

51
Q

what symptoms occurs with Hypohidrotic Ectodermal Dysplasia?

A

constellation of hair and tooth anomalies
along with an inability to sweat (peg shaped teeth)

52
Q

Hypohidrotic Ectodermal Dysplasia is ___ linked, so it effects ______.

A

X
male

52
Q

in an infant what is the first symptom of Hypohidrotic Ectodermal Dysplasia?

A

fever of unknown origin and hypothermia in first few hours of life

53
Q

what molecular pathways does the skin derive from that is effected by EDA?

A

WNT and P63

54
Q

Many young boys with Hypohidrotic Ectodermal Dysplasia first present with what?

A

no teeth erupt before 12-18 months of age, or teeth erupting with irregular

54
Q

in what ways is amelogenesis imperfecta inherited?

A

X linked or sporadic

55
Q

what is the difference between hypoplastic and hypomineralied amelogenesis imperfecta?

A

–Hypoplastic AI describes thin but mineralized enamel, may be pitted or generalized
–Hypo mineralized AI is caused by maturation stage failure, giving rise to enamel that is of full thickness but is weak and fails prematurely

55
Q

what is the main gene involved in amelogenesis imperfecta?

A

Amelogenin, X linked (AMELX)

56
Q

how might a female present with amelogenesis imperfecta?

A

Heterozygous AMELX mutations can present in female AI patients as stripes of normal and AI affected enamel due to lyonization

57
Q

diagnosis of Hereditary Hemorrhagic Telangiectasia (HHT) requires what?

A

1- epistaxis (nosebleeds)
2- multiple telangiectasias
3- arteriovenous malformations (AVMs)
4- family history of HHT

58
Q

Hereditary Hemorrhagic Telangiectasia (HHT) is what kind of inheritance and what kind of mutation?

A

autosomal dominant
loss of function
mutations in ENG and ACVRK1

58
Q

Neurofibromatosis occurs with what kind of inheritance, what type of mutation?

A

autosomal dominant
NF1 tumor suppressor gene
(in the absence of this protein, tumors develop and the bone becomes dysplastic)

58
Q

what is the most common oral structure to be effected by neurofibromatosis?

A

tongue (all oral structures can be effected tho, tumors grow out of nerves)

59
Q

what is osteogenesis imperfecta? what does it cause?

A

mostly autosomal dominant

Mutations can form low collagen (quantitative mutations) or structurally defective collagen (qualitative mutation) msking brittle bones

59
Q

what is commonly also effected in those with osteogenesis imperfecta?

A

dentinogenesis imperfecta

59
Q

what is nevoid basal cell carcinoma syndrome?

A

Autosomal dominant
high penetrance
multiple odontogenic keratocysts (75%), basal cell carcinoma (50-97%)

Biochem Exam 2 (6 decks)

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