Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Principles of Genetic Inheritance (Dr. Creamer) > Principles of Genetic Inheritance > Flashcards

Principles of Genetic Inheritance Flashcards

1
Q

Lyonization

A 
is called
X-inactivation. The
choice of which X
chromosome to be
inactivated is random
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mosaicism

A 
is a condition in
which cells from a patient have
different genotypes (& karyotypes):
– Downs Syndrome: some 46XX;
some 47XX,+21
– Klinefelter Syndrome: some
46XY; some 47XXY
– Turner Syndrome: some 46XX;
some 45XO
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Interphase:

A

chromosome duplication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cell division:

A

one copy of each chromosome (chromatid)
and ½ of the cytoplasm/organelles are distributed
between the two daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Mitosis of somatic cells results in

A

two identical diploid

daughter cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Stem cells undergo mitosis, but

A

divide asymmetrically,

resulting in one stem cell, and one daughter cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Meiosis

A 
reduces the total
number of chromosomes by
half, producing four gametes
(haploid)
– Occurs in germ-line cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

In meiosis, —————— can
produce new combinations of
genes

A

homologous recombination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Meiosis

consists of

A 
one round of
DNA replication
– two rounds of
nuclear
divisions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Meiosis creates
genetic diversity in
2 ways:

A 
Random segregation
of homologs
– Cross-over exchange
(homologous
recombination)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Euploid

A

Cells with a normal number of chromosomes

– Ex. Haploid gametes and diploid somatic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Polyploidy

A

presence of a complete set of extra chromosomes in a
cells
– Often seen in plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Aneuploidy

A

Cells with a missing or additional individual
chromosomes
– Monosomy, trisomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Translocation

A

Non-homologous
chromosomes exchange
genetic material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Reciprocal Translocation

A

an exchange of material
between nonhomologous
chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Robertsonian Translocation

A

Long arm of two
acrocentric chromosomes
combined, short arm
typically is lost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Turner Syndrome

A 
EXAMPLE OF MOSACISIM
45, XO karyotype
– Female (no Y)
– Short stature
– Ovarian hypofunction/premature
ovarian failure
– Many do not undergo puberty
without hormone therapy
– Most are infertile
– ~30% webbed neck
– Low hairline on neck
– CV defects (coarctation of aorta,
bicuspid aortic valve)
– Normal intelligence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Klinefelter Syndrome

A 
EXAMPLE OF MOSAICISM 
47, XXY
– Some with no/limited symptoms
– Varying degrees of cognitive, social,
behavioral, learning difficulties
– Primary hypogonadism (low T)
– Small and/or undescended testes
– Gynecomastia
– Tall stature
– Infertility
– Can be mosaic
– Variability in X numbers can increase
symptoms (48, XXXY; 49, XXXXY)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Trisomy 13

A 
Patau Syndrome 
EXAMPLE OF MOSAICISM
Autosomal trisomy
Robertsonian translocation 
der(14:21)(q10;q10)+21 or be mosaic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

47, XX +13;

A

Patau Syndrome– Severe developmental abnormalities
– Most perinatal death within 1 week (13% of
live births survive to 10 y.o.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

47, XX +18

A

Edwards Syndrome
– Abnormal development
– Most perinatal death within 1 year (10% of
live births survive to 10 y.0.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Genomic Imprinting

A

CARRIED OUT BY DNA METHYLATION
for some human genes, one of the alleles is
transcriptionally inactive (no mRNA produced)
– Depending on the parent from whom the allele was received
Imprinting is essentially gene
silencing
– Through methylation of 5’ region
of gene
– Chromatin condensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Genomic imprinting and role of epigenetics

A 
Epigenetic imprints remain
throughout the lifespan of
the individual in somatic
cells
• In germ cells, epigenetic
imprints are reset at each
generation
• During meiosis, imprints
are erased and new ones
are set
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Prader Willie Sydrome

A 
example of uniparental disomy 
Deletion of a region of chromosome
15
Phenotype depends on if deletion is on
paternal or maternal chromosome
– Paternal = Prader Willie Sydrome
Paternal PWS genes are active and AS gene in mother is inactive
• Short stature, hypotonia, small
hands/feet, obesity, mild to moderate
intellectual disability
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Angelman Syndrome

A

Maternal deletion of PWS/AS gene
Paternal PWS genes are active and AS gene in mother is inactive
Paternal AS gene is inactive
Severe intellectual disability, seizures,
ataxic gait

26
Q

Uniparental Disomy

A 
Related to non-disjunction and
genomic imprinting
If two chromosomes are
inherited from the same parent
(Uniparental Disomy), they
will have parent-specific
imprinting
– No gene product
27
Q

Genotype

A

an individual’s genetic makeup

28
Q

Phenotype

A

what is actually observed

29
Q

Cystic Fibrosis

A

Individuals with distinct genotypes can

have a single phenotype

30
Q

pleiotropy

A

individuals with the same genotype can have

multiple phenotypes Ex. PKU

31
Q

Proband (propositus)

A

First diagnosed person in the

pedigree

32
Q

Autosomal Dominant Inheritance

A

Only 1 allele of a gene is needed for expression
• Affected offspring has one affected parent
• Unaffected individuals do not transmit trait
• Males and females can transmit trait to both males and females –
autosomal
• Trait is expected in every generation
• Recurrent risk is 50%
ex. POSTAXIAL POLYDACTYLY

33
Q

Autosomal Recessive Inheritance

A

2 copies of a gene is needed to influence phenotype
ex. TYROSINASE-NEGATIVE
ALBINISM

34
Q

X-linked Recessive

A

Disease allele on X in males is termed “hemizygous”
• Females can be heterozygous or homozygous
• Unaffected males don’t transmit the trait (no carriers)
• Female carriers transmit the disease allele to 50% of
sons and 50% of daughters
• All daughters of affected males
are heterozygous carriers
EXAMPLE:
DUCHENNE MUSCULAR DYSTROPHY

35
Q

X-linked Dominant

A

Very rare; no carriersMales with the disease allele transmit the trait:
– only to females
– 100% transmission
• Females with the disease allele transmit the trait:
– To both males and females
– 50% transmission to offspring
HYPOPHOSPHATEMIA:Low phosphorus in blood due to defective reabsorption of phosphate in kidney
Deficient absorption of calcium in intestines causes softening of bone (Rickets)
Vitamin D metabolism abnormal
Short stature
Incidence: 1/60,000
Treatment: oral phosphate & vitamin D

36
Q

HYPOPHOSPHATEMIA

A

X-linked Dominant Disease
Low phosphorus in blood due to defective reabsorption of phosphate in kidney
Deficient absorption of calcium in intestines causes softening of bone (Rickets)
Vitamin D metabolism abnormal
Short stature
Incidence: 1/60,000
Treatment: oral phosphate & vitamin D

37
Q

Reduced Penetrance

A

The frequency a gene manifests itselfIn some cases, 100% of individuals inheriting a genetic defect
show the clinical presentation (phenotype) of the disease (100%
penetrance)
• In other cases penetrance is less than 100%

38
Q

RETINOBLASTOMA

A 
autosomal dominant inheritance
– Phenotype occurs in 90% of
individuals inheriting gene
defect; so 90% penetrance
EXAMPLE OF REDUCED PENETRANCE
39
Q

Variable Expressivity

A

Term used to describe the range of phenotypes that

vary between individuals with a specific genotype

40
Q

NEUROFIBROMATOSIS

A

EXAMPLE OF VARIABLE EXPRESSIVITYDevelop tumor-like growths called neurofibromas
Patients have café-au-lait spots – pigmented areas the color of coffee with cream (spots differ in number, shape, size
and position)

41
Q

Locus Heterogeneity

A

Single disorder, trait, or pattern of traits caused by mutations in genes at different
chromosomal loci

42
Q

OSTEOGENESIS

IMPERFECTA

A 
EXAMPLE OF LOCUS HETEROGENEITY
Brittle-bone disease
– Mutations in
collagen genes (two loci:
chromosome 7 and 17),
either mutation exhibits
the same phenotype
43
Q

PROBABILITY

A

defined as the proportion of times that a specific
outcome occurs in a series of events
• As proportions, probabilities are between 0 and 1

44
Q

INDEPENDENCE PRINCIPLE

A

MULTIPLICATION RULE: probability of a given outcome in multiple trials is the product of the
probabilities of each trial outcome
THE ADDITION RULE: probability of either one outcome or another is the sum of the two probabilities

45
Q

The Hardy-Weinberg Principle

A

Specifies the relationship between Gene
Frequencies and Genotype Frequencies
Useful in estimating Gene Frequencies from
Disease Prevalence Data and in estimating the
incidence of heterozygous carriers of recessive
disease genes

46
Q

Cystic Fibrosis

A

In recessive disease, only the affected homzygotes, with
genotype aa, are distinguishable
e frequency of aa should be q^2

47
Q

Autosomal Dominant Inheritance

A

characterized by vertical
transmission of the disease phenotype, a lack of skipped
generations, and roughly equal numbers of affected males
and females. Father-to-son transmission may be observed

48
Q

Autosomal Recessive Inheritance

A

characterized by
clustering of the disease phenotype among siblings, but the
disease is not usually seen among parents or other ancestors.
Equal numbers of affected males and females are usually
seen, and consanguinity may be present

49
Q

Consanguineous mating

A

more likely to produce offspring
affected by rare Autosomal Recessive Disorders
Studies show that mortality rates
among the offspring of first-cousin
mating’s are up to 9% higher than
those of the general population
Each person carries one to five recessive mutations lethal to offspring if matched with
another copy of the mutation (homozygosity)

50
Q

Mitochondrial DNA

A

Several copies of 16,569 bp, double-stranded, circular
mtDNA molecule per mitochondria
– Encodes rRNA, tRNA, and 13 polypeptides involved
in oxidative phosphorylation
– Transcription takes place in the mitochondrion,
independently of the nucleus
– Contain no introns
– Inherited exclusively through the maternal line
– Mutation rate is approx. 10x higher than nDNA
• Relative lack of DNA repair mechanisms
• Damage from free oxygen radicals released
during oxidative phosphorylation

51
Q

Mitochondrial Heteroplasmy

A

Primordial germ line cell has divides into germ line cells and carries mutant mitchondria -> Depending on the amount of mutant mitochondira, the child will express the disease if meet threshold: about 60% diseased mitchonchondria in a cell causes symptoms. Mitchondria are divided unequally, so some germ line cells will be normal, and others can have large amount of mutant mitochondria.

52
Q

Leber’s hereditary optic neuropathy (LHON)

A

EXAMPLE OF MITCHOCHONDRIAL DISEASE
Degeneration of retinal ganglion cells
– Acute or subacute loss of central vision
• Typically early teens or 20’s

53
Q

Mitochondrial encephalomyopathy, lactic acidosis, and

stroke-like episodes (MELAS)

A

Affects many body systems, particularly brain and nervous
system, and muscles
– Stroke and dementia
– Lactic acidosis

54
Q

Polygenic inheritance

A

Traits in which variations are thought to be
caused by the combined effects of multiple
genes

55
Q

Multifactorial Inheritance

A

When environmental factors cause variation
in the trait, the term multifactorial is used

Because these traits are caused by the
additive effects of many genetic and
environmental factors, they tend to follow a
normal, or bell
-shaped distribution in
populations
56
Q

liability

distribution

A

For diseases that do not follow the bell
-curve
distribution

57
Q

threshold of liability

A

For multifactorial diseases that are either
present or absent, it is thought that a ——–must be crossed before
the disease is expressed
• Below the threshold, the person appears normal • Above the threshold, the person is affected by
the disease

58
Q

Transmitting muscular hypertrophy

A

Muscular hypertrophy between stomach and
duodenum – leading to vomiting and obstruction
• Five times more common in males than females
• Males need less risk genes to show disease;
females need more risk genes
• The least affected sex has a higher risk threshold
and transmits the condition more often to the
most frequently affected sex
• Children of women with pyloric stenosis are more
likely to be born with condition (especially males)
• Children of affected males with pyloric stenosis
are less likely to be born with condition

59
Q

Recurrence Risk

A

The recurrence risk is higher if more than one family member is affected
• If the expression of the disease in the proband is more severe, the
recurrence risk is higher
• The recurrence risk is higher if the proband is of the less commonly affected
sex
• The recurrence risk for the disease usually decreases rapidly in more
remotely related relatives

60
Q

Multifactorial Disease

A

is caused by the
simultaneous influence of multiple genetic and
environmental factors

In some cases, a trait may be influenced by the
combination of both a single gene with large
effects and a multifactorial background in
which additional genes and environmental
factors have small individual effects

Principles of Genetic Inheritance (Dr. Creamer) (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions