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BIO 140 3rd LE > Modifications of Mendelian Genetics (Lec 3-7) > Flashcards

Modifications of Mendelian Genetics (Lec 3-7) Flashcards

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1
Q

Non-Mendelian mode of inheritance where the heterozygote condition is intermediate between the extreme phenotypes

A

Incomplete dominance (ex. flower color in snapdragons or raphanus shape and color)

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2
Q

Heterozygote condition manifests both extremes of dominant and recessive phenotypes.

A

Co-Dominance (ex. Cattle coat color and MN Blood Group System)

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3
Q

Differentiate incomplete dominance from codominance.

A

Incomplete dominance will be a mix of the two extremes of the trait.

Codominance will distinctly show the extremes of the trait

(Analogy: for incomplete dominance, red and white make pink. For codominance, red and white will appear at the same time)

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4
Q

One gene pair, many effects. Different subsets of symptoms may superficially appear as if caused by different disorders

A

Pleiotropy (ex. Phenylketonuria)

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5
Q

Caused by any mutation in the PAH gene (found on 12q23.2) that codes for the phenylalanine hydroxylase enzyme that converts phenylalanine (Phe) to tyrosine (Tyr)

A

Phenylketonuria

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6
Q

Atleast three types of alleles for a particular trait, with two alleles in a single locus at a time.

Dominant hierarchy may be exhibited.

A

Multiple Alleles (ex. Coat color in rabbits: C>cch>ch>c or ABO Blood typing in Humans)

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7
Q

Formula for # of genotypes for multiple alleles?

A

(n/2)(n+1) where n is the # of alleles in a series

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8
Q

For the coat color of rabbits, C>cch>ch>c is the dominance hierarchy. How many genotypes can be made?

A

n = 4
Using (n/2)(n+1) = (2)(5)=10

=10 Genotypes.

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9
Q

What is Bombay Phenotyping?

A

H-antigen is the base antigen in blood.

A- B- and O- genes will affect terminal sugar

O-gene will not add anything and retain that base antigen

B-Gene will use Galactosyl Transferase to turn H into a B antigen by adding Gal

A-Gene will use N-Acetylgalactosaminyl transferase to add GalNAc turning H into an A Antigen.

People are either hh, Ha_ or Hb_

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10
Q

What is the general pattern of X-linked dominant inheritance?

A

Affected fathers will always have affected daughters

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11
Q

What is the general pattern for x-linked recessive inheritance?

A

Affected mothers will always have affected sons

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12
Q

For y-linked traits, what is the expected pattern of inheritance?

A

Father to son only

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13
Q

What is Sex-linked inheritance

A

Traits are located on the sex chromosomes (X or Y).

Ex. RG Color blindness

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14
Q

Why is sex-linked, inheritance more likely to affect males than females.

A

Males have only one X chromosome, so any recessive trait on that chromosome will be expressed.

Females have two X chromosomes, so a recessive trait needs to be present on both X chromosomes to be expressed.

Y chromosome linked traits are only passed from father to son

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15
Q

What is sex-limited inheritance

A

Traits are located on autosomes but expression is limited to one sex.

Ex. Lactation

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16
Q

What differentiates sex-limited from sex-linked.

A

For sex limited, traits can be present in both sexes but only activated in one due to hormonal or other regulatory factors.

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17
Q

What is sex-influenced inheritance?

A

Traits are located on autosomes but their expression is influenced by sex hormones

Ex. Male Pattern Baldness

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18
Q

What differentiates sex-influenced from sex-limited and sex-linked

A

Traits can be present in both and can still be exhibited despite regulatory and genetic factors but with different degrees.

Ex. Pattern baldness as alopecia in women.

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19
Q

Gene interaction where some genes may mask or hide the effects of other genes?

A

Epistatic Genes

Ex. Rat Coat Color

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20
Q

Term for genes that mask other genes

A

Epistatic Genes

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21
Q

Term for genes that are masked

A

Hypostatic Genes

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22
Q

Occurs when the phenotypic expression of an epistatic gene masks the effect of a hypostatic gene when the epistatic gene is in homozygous recessive form.

A

Recessive epistasis

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23
Q

Give the modified phenotypic ratio for Recessive Epistasis. Let A be dominant to a, B be dominant to b, and bb recessively epistatic to A.

A

9:3:4:: A_B_ : aaB_ : __bb

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24
Q

Occurs when the phenotypic expression of an epistatic gene masks the effect of a hypostatic gene as long as the epistatic gene has a dominant gene.

A

Dominant Epistasis

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25
Q

Give the modified phenotypic ratio for Dominant Epistasis. Let A be dominant to a, B be dominant to b, and A_ be dominantly epistatic to B

A

12:3:1:: A_ _ _ :aaB_:aabb

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26
Q

Occur when two genes produce the same phenotype when both the genes have a phenotype with dominant allele either in heterozygous or homozygous dominant condition.

TL;DR: More dominant genes = More “complete” trait, similar to incomplete dominance but with two different loci

A

Duplicate Genes with cumulative effects

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27
Q

What is the phenotypic ratio for Duplicate genes with cumulative effect? Let A be dominant to a, B be dominant to b

A

9:6:1::A_B_: A_bb+aaB_ :aabb

28
Q

Occurs when two loci code for the same trait where in only the homozygous recessive traits for both loci will show a different trait. Or, As long as there is one dominant gene, dominant trait is expressed

A

Duplicate dominant gene interaction

29
Q

Give the phenotypic ratio for Dominant Gene interaction. Let A be dominant to a, B be dominant to b

A

15:1::A_ _ _+ _ _ _ B : aabb

30
Q

Occurs when a homozygous recessive gene pair is present in either of the two loci that code for the same trait.

A

Duplicate Recessive Gene interaction

31
Q

Give the phenotypic ratio for Duplicate Recessive Gene Interaction

A

9:7::Dominant:Recessive

32
Q

Similar to dominant epistasis, occurs when certain genes have the ability to suppress the expression of a gene at a second locus.

A

Dominant and Recessive Gene interaction.

(Dominant suppression epistasis in other literature)

33
Q

Give the phenotypic ratio of Dominant and Recessive Gene interaction.

A

13:3 Dominant: Recessive

34
Q

Genes with effects drastic enough to cause death of the individual at the embryonic stage

A

Lethal Genes

35
Q

Genes that shorten the normal life expectancy of an individual.

A

Sublethal genes

36
Q

Example for Lethal Genes in the Lecture, and give the phenotypic ratio. (Either of the two, for mouse or for humans)

A

Coat color in mice
* Yellow fur color heterozygous (A^Y A)
* Hybrids yield phenotypic ratio of 2/3 yellow and 1/3 agouti
* Hybrids associated with obesity, diabetes, and tumors
* AYAY genotypes result in preimplantation embryonic lethality
* AY mutation disrupts structure & expression of Merc gene (renamed Raly) that codes for an RNA-binding protein expressed throughout development

Achondroplasia in Humans
* homozygote dominants are usually lethal

37
Q

Condition defined by multiple basal cell carcinomas (basaliomas) and other skin malignancies occuring at a young age. This is an example of?

A

Xeroderma pigmentosum; Sublethal genes.

38
Q

Occurs when a single phenotypic character is affected by two or more genes

A

Polygenic Inheritance

39
Q

Extrachromosomal or Extranuclear Inheritance involving DNA in chloroplasts and mitochondria

A

Organelle Heredity

40
Q

How is organelle heredity transmitted?

A

Transmission occurs form maternal parent through the ooplasm

41
Q

Where is DNA found in chloroplasts?

A

In the Stroma

42
Q

Chloroplast DNA (cpDNA) is commonly how large in size?

A

100-225 kbp

43
Q

T/F Chloroplast contains circular DNA and a complete gene expression system

A

True

44
Q

T/F Mitochondrial DNA is commonly circular, and sometimes normal.

A

True

45
Q

Mitochondrial DNA is usually how large

A

10-81 kb, average 16 kb in animals

46
Q

How large is the Human Mitochondrial DNA?

A

16.6 kb

47
Q

Where is mitochondrial DNA found?

A

In the mitochondrial matrix within the inner membrane

48
Q

Describe the organization of Mitochondrial DNA

A

Double stranded, circular, and small, free of proteins.

5-10 copies/organelle in vertebrates, 20-40 in plants

49
Q

Genetic code in mtDNA is similar to nuclear genetic code. How is it different?

A

trp is the stop codon in mtDNA, not UGA

AUA is methionine, in mtDNA, isoleucine in nuclear genetic code

50
Q

Theory proposed by Lynn Margulis to explain presence of DNA in organelles. What does it discuss?

A

Endosymbiont Theory

Primitive eukaryotes engulfed other prokaryotes as endosymbionts

51
Q

What are the traits in Chloroplast Mutations in Chlamydomonas reinhardi

A

unicellular

haploid

single large chloroplast

75-80 copies of circular double-stranded DNA molecule,

195 kb in size

two mating types: mt+ and mt-

Streptomycin resistance or sensitivity come from mt+ parent

52
Q

What are the traits in Mitochondrial Mutations of poky in Neurospora

A
  • slow-growing mutants; loss of several cytochromes
  • cytoplasmic/maternal inheritance
    – maternal poky x paternal wt→ all poky
    – maternal wt x paternal poky→ all wt
  • hyphae fusions between poky and wt produce heterokaryons (two nuclei) with mitochondria from both parental cells
    – begins with normal phenotype
    – become progressively more abnormal (poky)
    – poky is a suppressive mutation
53
Q

Saccharomyces petite Mutations are defined by?

A

petite mutations giving rise to small colonies due to blocked aerobic respiration.

54
Q

What are the two types of petites in Saccharomyces petite mutations?

A

Segregational petites: encoded by nuclear genes showing Mendelian inheritance

Cytoplasmic transmission pattern petites

55
Q

Cytoplasmic transmission pattern petites have two types, what are they?

A

Neutral: give all wt offspring when crossed to wt

suppressive petites: Will mask any other trait making them all petite

56
Q

Variable mixture of genetically distinct mitochondria/mtDNAs is called?

A

Heteroplasmy

57
Q

What are the 3
properties of mtDNA-encoded traits

A

– Maternal inheritance pattern
– Deficiency in bioenergetic function of organelle
– Specific mutation in one or more mtDNA genes

58
Q

Human mtDNA consists of how many base pairs?

A

16,569 bps or 16.6 kbp

59
Q

The human mtDNA is composed of how many rRNAs, tRNAs, and polypeptides?

A

2rRNAs
22tRNAs
13 polypeptides

60
Q

Human mtDNA Disorder characterized by Ataxia, deafness, dementia, epileptic seizures, and presence of fibers from proliferation of aberrant mitochondria

A

Myoclonic epilepsy and ragged red fiber disease (MERRF)

Caused by A-to-G mutation in mtDNA tRNALys gene

61
Q

Human mtDNA disorder characterized by Sudden bilateral blindness (average age 27 yrs)

Most mutations in NADH dehydrogenase gene

Maternal transmission to all offspring

A

Leber’s hereditary optic neuropathy (LHON)

62
Q

What are the two methods of Mitochondrial Replacement Therapy?

A

Maternal Spindle Transfer Technique

Pronuclear Transfer Technique

63
Q

Transmission characterized by cytoplasmically transmitted phenotypes in eukaryotes due to an invading microorganism or particle (e.g. virus)

A

Infectious Heredity

64
Q

T/F in infectious heredity, the invader coexists in a symbiotic relationship with the host.

A

True

65
Q

T/F The invader is never passed through the maternal ooplasm to progeny cells or organism.

A

False, Usually passed through maternal ooplasm

66
Q

For Kappa in Paramecium, Certain strains of P. aurelia are called killers because _________/

A

They release Paramecin, a substance toxic to sensitive strains.

67
Q

Offspring’s phenotype under control of nuclear gene product present in the egg.

(Ex. Right handed or left handed snail shell coiling in Limnaea peregra)

A

Maternal effect/Maternal Influence

BIO 140 3rd LE (3 decks)

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