Transmission Genetics Flashcards

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1
Q

What are Mendel’s 4 postulates?

A
  1. Unit factors are in pairs
  2. Dominance/Recessiveness
  3. Random Segregation
  4. Independent assortment
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2
Q

What is a phenotype?

A

physical appearance of a characteristic

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3
Q

What is a gene?

A

unit of inheritance (unit factor)

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4
Q

What is an allele?

A

alternative forms of a single gene, located on homologous chromosomes

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5
Q

What is a genotype?

A

genetic makeup of an individual

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6
Q

What does a monohybrid cross examine?

A

one character, one pair of contrasting traits

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7
Q

What does a dihybrid cross examine?

A

two characters, two pairs of contrasting traits

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8
Q

What does a trihybrid cross examine?

A

three characters, three pairs of contrasting traits

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9
Q

What is a proband on a pedigree?

A

individual whose phenotype first brought attention and led to the construction of the pedigree

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10
Q

What are the characteristics of autosomal recessive traits?

A

typically skip generations and appear equally in both sexes

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11
Q

What are the characteristics of autosomal dominant traits?

A

typically appear in each generation and appear equally in both sexes

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12
Q

What is a locus?

A

location of gene on chromosome

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13
Q

What is incomplete dominance?

A

parents with contrasting traits produce offspring with intermediate phenotype (Red Parent + White Parent = Pink Offspring)

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14
Q

What is codomindance?

A

in heterozygote influence of both alleles is evident (show both phenotypes)

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15
Q

What are lethal alleles?

A

Alleles that can kill

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16
Q

What are recessive lethal alleles?

A
  • can be tolerated in heterozygotes but lethal in homozygotes
  • death depends on need of gene product
  • circulates but never eliminated from population
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17
Q

What are dominant lethal alleles?

A
  • time of death depends on need of gene product
  • easily eliminated from populations if lethal before sexual maturity
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18
Q

What is epistasis?

A

(Stoppage) expression of one gene or gene pair masks or modifies the expression of other genes

19
Q

What are the different types of epistasis?

A
  • homozygous recessive gene at one locus overrides alleles at other loci
  • single dominant allele at the first locus influences the expression of alleles at a second locus
  • two gene pairs complement each other
20
Q

What is pleiotropy?

A

(many affecting) one gene can affect multiple traits- the gene product is involved in multiple biochemical pathways and processes

21
Q

What is sex linkage?

A

gene is located on the sex chromosome

22
Q

What are the different types of sex linkage?

A

X-linked genes and Y-linked genes

23
Q

What is hemizygous?

A

neither dominant nor recessive

24
Q

Characteristics of X-linked genes?

A
  • recessive alleles always expressed in males
  • many X linked disorders
  • lethal X linked disorder affect males, females are carriers
25
Q

What are characteristics of Y-linked genes?

A
  • traits in Y chromosome only found in males
  • father’s Y chromosome traits passed to all sons
  • dominance irrelevant in Y-linkage because Y is hemizygous
26
Q

What is sex limited inheritance?

A

expression of specific phenotypes is limited to one sex only, influenced be sex hormones

27
Q

What is sex influenced inheritance?

A

gene expression in heterozygotes influenced by sex hormones

28
Q

What is genetic suppression?

A

suppressor genes do not let the expression of mutant phenotype

29
Q

What is position effects?

A

phenotypic expression of genes depends on the physical location of the gene on chromosome

30
Q

What is penetrance?

A

the individuals that show at least some degree of expression of a mutant phenotype

31
Q

What is expressivity?

A

reflects the range of expression of a mutant phenotype

32
Q

What is genetic anticipation?

A

onset and severity of genetic disorders tend to progress with each successive generation

33
Q

What is genetic regulation?

A

changes in DNA sequence and genetic code

34
Q

What is epigenetic regulation?

A

changes in gen regulation

35
Q

What are paternally imprinted genes?

A

paternal allele epigenetically modified and inactivated

36
Q

What are maternally imprinted genes?

A

maternal allele epigenetically modified and inactivated

37
Q

What is heteroplasmy?

A

one cell contains many chloroplasts and mitochondrial genomes

38
Q

What type of inheritance are chloroplasts and mitochondria?

A

maternally inherited

39
Q

What are the characteristics of mitochondrial disorders?

A
  • maternally inherited
  • disorder must reflect deficiency in bioenergetic function in the organelle
  • affects most energy demanding organs- brain/muscles
  • specific genetic mutation in one or more mitochondrial genes
40
Q

What is an example of a human mitochondrial disorder?

A

MERRF- Myoclonic Epilepsy and Ragged-Red Fiber disease

41
Q

What are the characteristics of cloning by nuclear transfer?

A
  • clone’s nuclear genome from desired animal
  • clone’s mitochondrial genome from egg donors
  • mitochondrial genomes different from the sire
42
Q

What is the maternal effect?

A

offspring’s phenotype for a particular trait is controlled by gene products present in the egg before fertilization

43
Q

What are the products of nuclear genes of female gamete and what is their role?

A

proteins, mRNAs, and microRNAs: after fertilization these play essential role in regulating early embryonic development