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CELLULAR BASIS OF MEDICINE > PRINCIPLES OF HEREDITY / MENDELIAN LAWS > Flashcards

PRINCIPLES OF HEREDITY / MENDELIAN LAWS Flashcards

1
Q

DEFINE GENE

A

unit of heredity

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2
Q

DEFINE ALLELE

A

different forms of the same gene

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3
Q

DEFINE GENOTYPE

A

all genes in an organism
-genetic constitution

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4
Q

DEFINE PHENOTYPE

A

physical characteristics of genes
-influenced by environment
-result of genotype

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5
Q

DEFINE HOMOZYGOTE

A

same alleles

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6
Q

DEFINE HETEROZYGOTE

A

different alleles

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7
Q

DEFINE AUTOSOMAL

A

non sex chromosomes

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8
Q

DEFINE GONOSOMAL

A

sex chromosomes

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9
Q

WHAT IS THE P GENERATION?

A

–parental
-dominant homozygote X recessive homozygote
-AA x bb

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10
Q

WHAT IS THE F1 GENERATION?

A

– first filial generation, formed by the crossing of parental generation (AA x bb)
-descendent (children) are always heterozygotes (Ab)

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11
Q

WHAT IS THE MONOHYBRID F2 GENERATION?

A

-second filial generation, crossing of F1
(Ab x Ab)
-descendants have different genotypes (AA, Ab,
Ab, bb)

GENOTYPE = 1:2:1
PHENOTYPE = 3:1

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12
Q

WHAT IS A B1 BACKCROSS?

A

crossing parent with F1 (parent x F1) (AA x Aa)
-AA, AA, Aa, Aa → 1:1 (genotype) - same phenotype

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13
Q

WHAT IS A TEST CROSS?

A
  • crossing an unknown genotypic individual with a known homozygous recessive (PP or Pp x pp)
  • can be used to determine the genotype of the unknown parent
    -Aa, Aa, aa, aa → 1:1 (genotype)
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14
Q

DEFINE MONOHYBRID

A

observation of 1 allele

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15
Q

DEFINE DIHYBRID

A

observation of 2 alleles

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16
Q

WHAT IS THE MEANING OF PHENOCOPY?

A

non-genetic, non-heritable, outer environment causes one genotype to look like another genotype

EG: woman dyes her hair from brown to black, looks like a different genotype, but her children will inherit brown hair

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17
Q

DEFINE PENETRATION

A

determines the probability that the allele will be expressed in the phenotype

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18
Q

WHAT IS THE IDENTITY OF RECIPRICAL CROSSES?

A

inheritance of autosomal genes is not dependent on sex

19
Q

DEFINE DOMINANT RECESSIVE

A

dominant allele completely masks the expression of recessive allele

20
Q

DEFINE CODOMINANCE

A

phenotype will express both alleles independent to each other (e.g. blood: allele A + allele B = blood type AB)

21
Q

DEFINE INCOMPLETE DOMINANCE

A

–will express both phenotypes of both alleles, phenotype is an intermediate between the
dominant and recessive homozygotes (dominant blue + recessive red = purple flower)

22
Q

NAME THE 3 LEVELS WHICH ALLELES CAN EFFECT

A

a) whole organisms - complete dominance, heterozygote looks like a homozygote
(round seed shape vs. wrinkled seed shape)

b) cell – incomplete dominance, we can distinguish individual cells
(low osmotic pressure vs. high osmotic pressure )

c) molecule - codominance, 50 % dominant and 50 % recessive allele
(functional enzyme vs. defective form of an enzyme)

23
Q

WHO DOES MENDELS LAWS NOT APPLY TO?

A

does not apply to asexual or haploid organisms

24
Q

WHAT IS MENDELS FIRST LAW?

A

Uniformity of F1 generation
-if you cross two homozygotes (AA x aa) → all individuals in F1 are equal (Aa)

25
Q

WHAT IS MENDELS SECOND LAW?

A

Principle of segregation
-two alleles in one gene separate from each other into two gametes, each carrying one allele
-refers to F2

DOMINANT RECESSIVE
-phenotype: 3.1
-genotype: 1.2.1

INTERMEDIATE & CODOMINANCE
-phenotype: 1.2.1
-genotype: 1.2.1

26
Q

WHAT IS MENDELS THIRD LAW?

A

Independent assortment
-alleles of two or more genes assort independently of one another

27
Q

WHAT IS THE DIHYBRID F2 GENERATION?

A

P = AABB x aabb or AAbb x aaBB
F1 = in both cases: AaBb (all uniform)→ 4 times
F2 = AaBb x AaBb → Punnett square

GENOTYPES = genotypes: 9 different genotypes (1:2:1:2:4:2:1:2:1 → (1:2:1)^2 )

PHENOTYPES = 4 different phenotype (ratio 9:3:3:1 → (3:1)^2 )

28
Q

WHAT IS AN ANALYTICAL BACKCROSS?

A

AaBb x aabb
-B1: 1:1:1:1

29
Q

WHAT IS A POLYHYBRID CROSS?

A

more than 2 genes observed
-number of gametes = 2^n
-number of zygotes = 4^n
-genotype = (1:2:1)^n
-phenotype = (3:1)^n

30
Q

NAME SOME DIFFERENCES FROM MENDELS LAW

A

lethality, decreased vitality
sex linked heredity
decreased penetrance
different expressivity
gene linkage
gene interactions
mitochondrial heredity
polygenic heredity
gene imprinting
dynamic mutations
structural balance chromosomal aberrations

31
Q

WHAT DOES LETHALITY / DECREASED VITALITY MEAN?

A

not all genotypes have the same variability

COMPLETE RECESSIVE LETHALITY
-recessive and dominant homozygotes are lethal
-1AA : 2Aa:1aa (dead) or 1AA (dead) : 2Aa : aa

COMPLETE DOMINANT LETHALITY
-dominant homozygote and heterozygote are lethal
-caused by a mutation which is not passed onto next generation
-1AA (dead) : 2Aa (dead) : 1aa

DECREASED VITALITY RECESSIVE
-affect dominant or recessive homozygotes
-1AA : 2Aa : 1aa (sick) or 1AA (sick) : 2Aa : 1aa

DECREASED VITALITY DOMINANT
-affects dominant or recessive homozygote + heterozygote
-1AA : 2Aa (sick) :1aa (sick) or 1AA (sick): 2Aa (sick):1aa

32
Q

WHAT IS MORGANS FIRST LAW?

A

genes are in a linear order on chromosomes

33
Q

WHAT IS MORGANS SECOND LAW?

A

genes of a chromosome form a linkage group
-number of linkage groups is equal to the number of pairs of homologous chromosomes

34
Q

WHAT IS MORGANS THIRD LAW?

A

Genes of homologous paired chromosomes can undergo crossing-over and gene exchange
-frequency of crossing over is directly proportional to the distance between genes (in centimorgans cM)
-distance of 1cM means 1% frequency of recombination during crossing over

35
Q

HOW MANY GENES DETERMINE THE ABO BLOOD GROUP OF HUMANS?

A

1

36
Q

WHERE CAN YOU FIND ANTIGENS AND ANTIBODIES?

A

antigens = surface of erythrocytes
antibodies = in plasma

-antigen produced from precursor polysaccharide and enzyme H adds another polysaccharide = H antigen (blood group O)
-from H antigen A and B antigens can be formed

37
Q

WHAT IS THE FREQUENCY OF BLOOD GROUPS?

A

0 > A > B > AB

38
Q

WHICH BLOOD GROUP IS THE UNIVERSAL DONOR?

A

O

39
Q

WHICH BLOOD GROUP IS THE UNIVERSAL ACCEPTOR?

A

AB

40
Q

WHY CANT ANTIGENS MIX WITH WITH THEIR ANTIBODY?
eg; A antigen and anti-A antibody

A

antigens are similar to bacterial saccharides to
which antibodies react, therefore they cannot mix

41
Q

WHAT IS THE RHESUS FACTOR?

A

a certain type of protein found on the outside of blood cells
-genetically inherited from mother
-mainly influences antigen D
-dominant: Rh+ (83%)
-recessive: Rh- (17%)
Rh- can donate to Rh+ → Rh+ can accept Rh- and Rh+
Rh+ can not donate to Rh- → Rh- can only accept Rh-

problem during 2nd pregnancy:
-Rh- mother and Rh+ child
-body of mother from the 1st pregnancy has antibodies against Rh, which it now used against the child in the womb.
-antibodies in a pregnant woman’s blood destroy her baby’s blood cells

42
Q

HOW MANY GAMETES DOES A TRIHYBRID CROSS FORM?

A

8

43
Q

THE PRODUCT AND SUM RULE OF MENDELIAN GENETICS

A

CELLULAR BASIS OF MEDICINE (32 decks)

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