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CYTOGEN FINALS > MIDTERM LEC 2: MODIFICATIONS OF MENDELIAN RATIOS > Flashcards

MIDTERM LEC 2: MODIFICATIONS OF MENDELIAN RATIOS Flashcards

1
Q
  • genotype ( allele combination) that causes DEATH, homozygous

Ex: Achondroplastic dwarfism
GENOTYPES: PHENOTYPES:
AA Lethal
Aa Achondroplasia
aa Normal Height

ratio:
1/4 die as embryos (AA)
survivors - 2/3 = achondroplasia (Aa), 1/3 = normal height (aa)

A

LETHAL GENOTYPES

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2
Q
  • 3 or more alleles of the same gene
  • different allele combinations can produce variations in the phenotype
  • simplest case: 3 alternative alleles of 1 gene exist

Ex: ABO blood group system in humans
- involves 3 alleles: Ia, Ib, and Io

A

MULTIPLE ALLELES

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3
Q

individual with 2 different mutant alleles with the same gene is called….

A

COMPOUND HETEROZYGOUS

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4
Q
  • characterized by the presence or absence of antigens (A & B) on the surface of RBCs
A

ABO BLOOD GROUP SYSTEM

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5
Q

ABO BLOOD GROUP SYSTEM is discovered by

A

KARL LANDSTEINER

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6
Q

When individuals are tested using antisera that contain antibodies against the A or B antigen, 4 phenotypes are revealed, either:

A
  • A antigen (A phenotype)
  • B antigen (B phenotype)
  • A and B antigen (AB phenotype)
  • or neither antigen (O phenotype)
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7
Q

reagent that is used to determine what antigens is preset on the RBC of an individual

A

ANTISERA

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8
Q

ABO blood group system in humans involves 3 alleles and these are….

A

Ia, Ib, and Io

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9
Q

the I designation stands for

A

ISOAGGLUTINOGEN

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10
Q

GENOTYPE: Ia Ia

ANTIGEN: A

PHENOTYPE:

A

A

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11
Q

GENOTYPE: Ia Io

ANTIGEN: A

PHENOTYPE:

A

A

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12
Q

GENOTYPE: Ib Ib

ANTIGEN: B

PHENOTYPE:

A

B

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13
Q

GENOTYPE: Ib Io

ANTIGEN: B

PHENOTYPE:

A

B

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14
Q

GENOTYPE: Ia Ib

ANTIGEN: A, B

PHENOTYPE:

A

AB

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15
Q

GENOTYPE: Io Io

ANTIGEN: Neither

PHENOTYPE:

A

O

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16
Q

______ are codominant (joint expression of both alleles in a heterozygote)

A

Ia & Ib

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17
Q

DIFFERENT DOMINANCE RELATIONSHIPS:
- 1 allele is expressed while the other is not
- Dominant allele completely masks the recessive allele
Ex: Mendel’s pea plants

A. COMPLETE DOMINANCE
B. INCOMPLETE DOMINANCE
C. CODOMINANCE

A

COMPLETE DOMINANCE

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18
Q

DIFFERENT DOMINANCE RELATIONSHIPS:
- partial dominance
- neither allele dominants the other
- heterozygous phenotype is an intermediate or blended expression of 2 alleles
- 3 genotypes = 3 phenotypes
ex: flower of snapdragon

A. COMPLETE DOMINANCE
B. INCOMPLETE DOMINANCE
C. CODOMINANCE

A

INCOMPLETE DOMINANCE

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19
Q

DIFFERENT DOMINANCE RELATIONSHIPS:
- different alleles are both expressed in a heterozygote
- neither allele is dominant over the other & both contribute to the observable characteristics of the organism
ex: ABO blood group

A. COMPLETE DOMINANCE
B. INCOMPLETE DOMINANCE
C. CODOMINANCE

A

CODOMINANCE

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20
Q
  • absence/ dysfunction of the beta-hexosaminidase A enzyme
A

TAY - SACHS DISEASE

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21
Q

TAY - SACHS DISEASE
- full enzyme level

A. HOMOZYGOUS DOMINANT
B. HETEROZYGOTES
C. HOMOZYGOUS RECESSIVE

A

HOMOZYGOUS DOMINANT

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22
Q

TAY - SACHS DISEASE
- intermediate level of enzyme

A. HOMOZYGOUS DOMINANT
B. HETEROZYGOTES
C. HOMOZYGOUS RECESSIVE

A

HETEROZYGOTES

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23
Q

TAY - SACHS DISEASE
- no enzyme

A. HOMOZYGOUS DOMINANT
B. HETEROZYGOTES
C. HOMOZYGOUS RECESSIVE

A

HOMOZYGOUS RECESSIVE

24
Q
  • effect of one gene masks or modifies the expression of another gene

ex: hh blood group (Bombay phenotype) = interaction between H gene and the I gene (confers ABO blood group)

A

EPISTASIS

25
Q

building block for the production of the antigens within the ABO blood group

A

H antigen

26
Q
  • has/forms the H antigen
A

HH & Hh

27
Q

hh individuals cannot produce antigens of the A & B, & appear to be O - type

true or false?

A

TRUE

28
Q
  • all-or-none expression of a genotype
  • frequency of expression of disease phenotype in individuals with a gene lesion
A

PENETRANCE

29
Q

TYPE OF PENETRANCE
- gene(s) for a trait are expressed in ALL POPULATION who have the gene (100 %)

A. COMPLETE PENETRANCE
B. INCOMPLETE PENETRANCE

A

COMPLETE PENETRANCE

30
Q

TYPE OF PENETRANCE
- genetic trait is expressed only PART OF THE POPULATION (genotype is present but phenotype is not observable)

A. COMPLETE PENETRANCE
B. INCOMPLETE PENETRANCE

A

INCOMPLETE PENETRANCE

31
Q
  • severity/extent
  • range of phenotypes in individuals with the same gene lesion

ex: polydactyly

A

EXPRESSIVITY

32
Q
  • if a protein affects different body parts or participate in more than one biochemical reactions or has different effects in different amounts
  • a single gene influences/controls multiple seemingly unrelated traits or phenotypic characteristics
  • a single gene has multiple effects on the phenotype of an organism
  • difficult to trace through families because people with different subsets of symptoms may appear to have different disorders

ex: PORPHYRIA VARIEGATA (missing protoporphyrinogen oxidase enzyme)

A

PLEIOTROPY

33
Q

PORPHYRIA VARIEGATA

  • missing protoporphyrinogen oxidase enzyme)
  • porphyrin accumulates in the
A

URINE, DIGESTIVE SYSTEMS, MUSCLES AND NERVOUS TISSUE

34
Q

porphyrin accumulates in the Urine system results in

A

dark red urine

35
Q

porphyrin accumulates in the digestive system results in

A

constipation and abdominal pain

36
Q

porphyrin accumulates in the muscles results in

A

weak limbs and rapid pulse

37
Q

porphyrin accumulates in the nervous tissue results in

A

delirium, convulsions, mad behavior

38
Q
  • mutation in different genes that produce the same phenotype
  • gene A and gene B has the same phenotype but since gene A mutates then it will produce different phenotype

ex: blindness
- mutation in more than 100 genes causes degeneration of the retina

A

GENETIC HETEROGENEITY

39
Q
  • an acquired condition that resembles a genetic condition or disease
  • caused by environmental exposures, infections,nutritional deficiencies , medications and other non-genetic factors

ex: Limb birth defect caused by the drug THALIDOMIDE is a _________ of the inherited illness PHOCOMELIA (short limbs/ limb defects)

A

PHENOCOPY

40
Q

WHAT PHENOMENON?
- a phenotypic class DOES NOT SURVIVE to reproduce

A

LETHAL ALLELES

41
Q

WHAT PHENOMENON?
- many VARIANTS or degrees of a phenotype are possible

A

MULTIPLE ALLELES

42
Q

WHAT PHENOMENON?
- a heterozygote’s phenotype is INTERMEDIATE between those of the two homozygotes

A

INCOMPLETE DOMINANCE

43
Q

WHAT PHENOMENON?
- a heterozygote’s phenotype is DISTINCT from and not intermediate between those of the two homozygotes

A

CODOMINANCE

44
Q

WHAT PHENOMENON?
- one gene MASKS or otherwise affects another’s phenotype

A

EPISTASIS

45
Q

WHAT PHENOMENON?
- some individuals with a particular genotype DO NOT HAVE THE ASSOCIATED phenotype

A

PENETRANCE

46
Q

WHAT PHENOMENON?
- A genotype is associated with a phenotype of VARYING INTENSITY

A

EXPRESSIVITY

47
Q

WHAT PHENOMENON?
- the phenotype includes many symptoms, with different subsets in different individuals

A

PLEIOTROPY

48
Q

WHAT PHENOMENON?
- An ENVIRONMENTALLY CAUSED CONDITION has symptoms and a recurrence pattern similar to those of a known inherited trait

A

PHENOCOPY

49
Q

WHAT PHENOMENON?
- genotypes of different genes cause the same phenotype

A

GENETIC HETEROGENEITY

50
Q
  • maternally inherited
  • sperm head does not include mitochondria
  • mitochondrion is found in the midsection
A

MITOCHONDRIAL GENES

51
Q

what will happen when the mitochondria from sperm enter an oocyte?

A

They are usually selectively destroyed early in the development

52
Q

features of mtDNA

A
  1. circular, 15,569 bp, 37 genes (24 encode RNA molecules & 13 encode proteins that function in cellular proteins)
  2. mutates than nuclear DNA because it has fewer types of DNA repair
  3. inherited from the mother only
  4. No DNA - associated proteins (histones)
  5. mt genes are not interrupted by DNA sequences that do not encode protein
  6. many copies per mitochondrion and per cell
  7. mitochondria with different alleles for the same gene can reside in the same cell
53
Q
  • MITOCHONDRIAL MYOPATHIES (muscle tissues)
  • Affected tissue are those normally with many mitochondria (skeletal muscle
  • may also result from mutations in nuclear genes that are essential for mitochondrial function
  • HALLMARK: red-ragged fibers
A

MITOCHONDRIAL DISEASES

54
Q
  • Mutated mitochondria and normal mitochondria in the same cell
A

HETEROPLASMY

55
Q

Forensics: to link suspects to crimes
- can identify war dead & support or challenge historical records

A

mtDNA REVEALS THE PAST

CYTOGEN FINALS (11 decks)

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