population genetics and non-mendelian inheritance Flashcards Preview

2020 MHS Genetics Unit2 > population genetics and non-mendelian inheritance > Flashcards

Flashcards in population genetics and non-mendelian inheritance Deck (60)
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1

allows calculation of allele distribution in a population. Formulate the law and list the requirements

hardy-Weinberg law

  1. requirements
    1. population is large
    2. mating is random
    3. allele frequencies remain constatnt over time
      1. no selection against any genotype
      2. departing individuals from the population have similar allele frequencies than the original population 
      3. there is no significant rate of new mutations in the population

2

In the hardy weinberg equation what does p and q stand for?

p always refers to the most common allele and q refers to the variant allele

3

describe the conditions used in the hardy weingberg calculation for autosomal recessive diseases

4

describe the conditions used in the hardy weinberg calculation for an autosomal dominant disease

5

describe the conditions used in the hardy weinberg calculation for an X-linked recessive disease

6

describe the condtions used in the hardy weinberg calculation for X-linked dominant diseases

7

formulate the probability calculations using population frequencies

8

What are the two requirements for hardy weingberg and what are the 7 violations? (just list them)

  1. violation of random mating
    1. stratification
    2. assortive mating
    3. consaguinity and inbreeding
  2. violation of the constatnt allele frequency criteria
    1. impaired reproductive fitness
    2. genetic drift
    3. migration and gene flow
    4. heterozygote advantage

9

African americans have a greater frequency for sickle cell because of mate selection to stay with in a sub group. 

Does this deviate from hardy weinberg and how?

Yes it does

  1. STRATIFICATION
    1. subgroups in a population tend to mater within the subgroup
    2. African american mate with eachother in the american population
  2. violates the random mating in large population criteria

10

Many people marry and multiply due to religous reasons.

Does this deviate from hardy weinberg and how?

yes it does,

consaguinity and inbreeding

  1. mating between related individuals
  2. mating within genetic isolates
    1. ​cultural
    2. geographical
    3. religous
  3. violates the random mating in large population criteria

11

two people seek eachother out on facebook and end up together because they both have a condition called anchondroplasia.

Does this deviate from hardy weinberg and how?

yes it does,

  1. choice of the mate i based on a particular trait
  2. marry and mate because they have similar physical traits
  3. violation of the random mating in large population criteria

12

a population is large and there is a random mating.

Does this deviate from hardy weinberg and how?

no, this is one of the two requirements for the hardy weinberg equation

13

a klinfelter patient can marry but is unable to continue his lineage.

Does this deviate from hardy weinberg and how?

yes it does,

impaired reproductive fitness

  1. the variant allele causes infertility, reduced fertility or death before reproductive age 
  2. violation of the constatnt allele frequency criteria

14

a small population has a change in allele frequency.

Does this deviate from hardy weinberg and how?

yes it does,

genetic drift- random(non genetic) changes

  1. violation of the constant allele frequency criteria

15

a group of main islanders move to an isolated island and live there for 100 generations. These people are well known for their 

Does this deviate from hardy weinberg and how?

yes it does,

genetic drift- founder effect

  1. a small subpopulation breaks off from a larger one and by chance carries a variant allele in higher frequencies
  2. violation of the constant allele frequency criteria

16

the spanards expolrers moved from spain to mexico  and mated with the locals of the land. 

Does this deviate from hardy weinberg and how?

yes it does,

migration and gene flow

  1. changing of allele frequencis in mixing populations
  2. violation of the constant allele freuency criteria

17

in Africa bein heterozygous for sickle cell will not generate the debilitating symptoms of sickle cell and you are resistant to malaria.

Does this deviate from hardy weinberg and how?

yes it does,

heterozygote advantage

  1. positive evolutionary selection for heterozygote genotype
  2. in the example
    1. homozygous wild-type
      1. susceptible to malaria
    2. homozygous variant allele
      1. sickle cell disease
    3. heterozygous
      1. do not have sickle cell disease and are protected from malaria
  3. violation of the constatnt allele frequency criteria

18

only one parental allele is active

what type of inheritance pattern is this?

genomic imprinting

  1. only one parental allele is active
  2. allele activity depends on the origin of the allele
  3. takes place in the germ line
  4. initiated by and imprinting center and involves the generation of non-coding RNAs and chromatin changes
  5. can be tissue specific

19

the variant allele changes from generation to generation.

what type of inheritance pattern is this?

unstable repeat expansion

  1. the bariant allele changes from generation to generation
    1. tinucleotide sequences multiply
  2. disease exmaples
    1. huntingtons disease
      1. larger the repeat number = earlier onset
    2. fragile x syndrome
      1. excessive CGG repeats in the promoter of the FMR1 gene = intellectual disability
    3. friedreich ataxia
      1. excessive GAA = spinocerebeller ataxia

20

the father cannot pass his mtDNA down.

what type of inheritance pattern is this?

inheritance of mitochondrial DNA

  1. only the maternal mitochondrial DNA is inherited
  2. maternal mitochondria are randomly distribute to the daughter cells
    1. homoplasmy - cells with mutatnt mtDNA
    2. heteroplasmy - cells with both normal and mutant
  3. diseases- phenotype dependent on ratio. have reduced penetrance and variable expression
    1. OXPHOS = leber hereditary optic neuropathy (NADH reductase deficiency

21

Describe the imprinting process for chromosome 15

  1. the paternal IC generates a long polycistronic RNAthat silences the paternal UBE3A expression in neurons (tissue specific)
  2. the maternal IC is silenced and cannot generate the polycistronic RNA, so the materna lUBE3A is not silenced
  3. UBE3A is only expressed from the maternal allele  in neurons

22

A patient presents a deletion in the maternal chromosome 15. what is the disease and what is the loss of function?

Angelman syndrom

  1. deletion in the maternal chromosome 15
  2. loss of UBE3A function
  3. presentation
    1. intellectual disability 
    2. happy demeanor
    3. balance disorder
    4. speech impariment

23

a patient presents with a deletion in the paternal chromosome 15.

prader-willi syndrome

  1. deletion in the paternal chromosome 15
  2. loss of the polycistronic RNA or other genes
  3. presentation
    1. intellectual disability
    2. obesity
    3. short stature
    4. hypodonadism

24

loss of UBE3A function 

what is the disease and cause?

angelman syndrome

  1. deletion in the maternal chromosome 15
  2. loss of maternal UBE3A
    1. the two c'somes
      1. the maternal UBE3A is the only chromosome that can express this gene
      2. The paternal generates a polycistronic RNA that silences the paternal 
    2. the maternal is deleted and paternal is silenced (naturally) = no expression in UBE3A

25

loss of the polycistronic RNA or other genes.

What is the disease and the cause?

prader-willi syndrome.

  1. deletion in the paternal chromosome 15
  2. loss of the polycistronic RNA and other genes
    1. two c'somes
      1. the maternal UBE3A is the only chromosome that can express this gene

      2. The paternal generates a polycistronic RNA that silences the paternal 

    2. the UBE3A is tissue specific, so with out the expression level in some tissue, prader-willi syndrome manifests

26

what arethe three causes of angelman syndrom or prader willi syndrome?

the basis of these two diseases revolves around c'some 15.

angelman=loss maternal

prader-willi syndrome = loss of paternal

  1. causes
    1. uniparental disomy
    2. IC mutations
    3. UBE3A or polycistronic RNA mutations

27

what are the three diseases to know for unstable repeat expansion?

  1. disease
    1. repeat
    2. inheritance

  1. huntingtons
    1. CAG repeats
    2. autosomal dominant
  2. fragile X syndrom
    1. CGG - promoter of FMR1 gene
    2. Xlinked dominant
  3. friedreich ataxia
    1. GAA repeats - intron of the frataxin gene
    2. autosomal recessive

28

autosomal dominant neurodegenerative disorder

Huntington disease

  1. polyglutamine disorder
  2. more CAG repeats = higher younger symptoms appear
  3. 29-35 premutation range

29

what is this pedigree exhibiting?

larger the repeat number is the earlier the onset of the disease is. 

CAG repeats alter the function of the protein

30

x linked dominant

moderate intellect disability

  1. disease
  2. cause 
  3. repeats explaination

 

  1. fragile x syndrome
  2. c chromosome condensation effect
    1. caused by excessive CGG repeats in the promoter of the FMR1 gene and silences the gene
      1. FMR1 is a translational regulator in neurons
  3. repeats
    1. normal
      1.  up to 55
    2. premutation
      1. 55 -200
    3. affected 
    4. >200, can be several thousand