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MED 109- BIOLOGY II > 5. ENVIRONMENTAL IMPACT ON PHENOTYPES > Flashcards

5. ENVIRONMENTAL IMPACT ON PHENOTYPES Flashcards

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1
Q
  1. What are 3 external and internal conditions that can
    affect some phenotypes?
A
  1. temperature
  2. chemicals
  3. nutritional habits
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2
Q
  1. What are Multifactorial characters?
A
  • these are both genetic and environmental factors
  • they influence the phenotype
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3
Q
  1. Do all phenotypes for a character only depend on the genotype?
A
  • no
  • some phenotypes for a character depend on the
    environment as well as the genotypes
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4
Q
  1. Provide a definition for the Norm of a Reaction.
A
  • this is the phenotypic range of a genotype
    that is influenced by the environment
  • this range is broadest for polygenic characters
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5
Q
  1. What example highlights the Norm of a Reaction?
A
  • Hydrangea Flowers of the same genotype
  • these flower colours range from blue-violet to pink
  • this is dependent on soil activity
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6
Q
  1. What 4 aspects make up an organism’s phenotype?
A
  1. Physical Appearance
  2. Internal Anatomy
  3. Physiology
  4. Behaviour
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7
Q
  1. What does an organism’s phenotype reflect?
A
  • it reflects the overall genotype
  • it reflects the unique environmental history
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8
Q
  1. What are the 3 reasons as to why humans are poor subjects for genetic research?
A
  1. the generation time is too long
  2. the parents produce relatively few offspring
  3. breeding experiments are unacceptable
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9
Q
  1. What is the foundation for human genetics?
A
  • basic Mendelian genetics
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10
Q
  1. What is a Karyotype?
A
  • this is an ordered display
  • it shows the pairs of chromosomes from a cell
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11
Q
  1. What are Human Somatic Cells?
A
  • these are any cells other than gametes
  • somatic cells have 23 pairs of chromosomes
  • these chromosomes are diploid (2n)
  • the chromosomes in each pair are called homologous
    chromosomes
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12
Q
  1. What are 4 characteristics of Homologous Chromosomes?
A
  1. they are the same length
  2. they have the same shape
  3. they carry genes that control the same inherited
    characters
  4. they do not necessarily carry the same alleles
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13
Q
  1. What does the Human Karyotype consist of?
A
  1. Somatic cells
    - each consisting of 44 autosomes
    - 22 pairs of autosomes
  2. 2 Sex Chromosomes
    - 1 pair of sex chromosomes
    - females have a homologous pair of X chromosomes
    (XX)
    - males have a one X and one Y chromosome (XY)

∴ 46 chromosomes in total

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14
Q
  1. Provide a definition for autosomes?
A
  • chromosomes that do not determine the sex
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15
Q
  1. What is a Pedigree?
A
  • this is a family tree
  • it describes the interrelationships of parents and
    children
  • it does this across generations
  • it is helpful with identifying the probability of inheriting
    a genetic disorder
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16
Q
  1. What do Pedigrees track?
A
  • they track inheritance patterns of particular traits
  • they can be used to make predictions about future
    generations
17
Q
  1. How can we use probability rules in genetics?
A
  • we can use probability rules to predict the probability
    of specific phenotypes
18
Q
  1. What are Human Genetic Disorders?
A
  • these are the many human diseases that are inherited
  • they can be studied using Pedigree Analyses
19
Q
  1. What is an example of a Human Genetic Disorder that was a result of incest in the Spanish Royal Family?
A
  • Habsburg Lip
20
Q
  1. What are 3 types of Inherited Human Disorders?
A
  1. Autosomal Dominant Disorders
  2. Autosomal Recessive Disorders
  3. Sex-Chromosome Linked Disorders
21
Q
  1. How are many genetic disorders inherited?
A
  • they are inherited in a recessive manner
22
Q
  1. How do recessively inherited disorders show up in individuals?
A
  • these disorders show up only in individuals that are
    homozygous for the allele
23
Q
  1. What are Carriers?
A
  • these are heterozygous individuals
  • they carry the recessive allele for a specific disorder
  • they are phenotypically normal
  • they are healthy and unaffected
24
Q
  1. What is an example of a Carrier?
A
  • a person who is heterozygous for Albinism
  • Albinism is a recessive disorder
  • it is characterised by a lack of pigmentation in skin and
    hair
25
Q
  1. What are Autosomal Recessive Disorders caused by?
A
  • they are caused by a mutation in an allele
  • this allele is located in one of the 22 pairs of
    autosomes
26
Q
  1. In an Autosomal Recessive Disorder, how are the alleles represented?
A

THE MUTANT ALLELE:
- is recessive
- it is the diseases allele
- it is abnormal
- it is written as: “a”

THE NORMAL ALLELE:
- is dominant
- it is written as: “A”

27
Q
  1. What kinds of genotypes can you have with regards to an Autosomal Recessive Disorder?
A

HEALTHY INDIVIDUALS:
- AA
- Aa

INDIVIDUALS WITH THE DISEASE:
- aa

28
Q
  1. What is the most common type of genetic disorder?
A
  • an Autosomal Recessive Disorder
  • it may not appear in the phenotype of the parents
  • the parents may still be heterozygous healthy carriers
    of the diseases allele
29
Q
  1. What are 4 types of Autosomal Recessive Disorders?
A
  1. Cystic Fibrosis
    • this is a mutation in the chloride ion channel protein
  2. Sickle Cell Anaemia
    • this is when glutamic acid is substituted with Valim
    • this happens on the Beta Haemoglobin
  3. Thalassaemia
    - this is a mutation on both the Alpha and Beta
    Haemoglobin
  4. Albinism
    - this is a mutation of the Thyrosine enzyme
    - this enzyme is responsible for Melanin Production
30
Q
  1. What is the probability of 2 heterozygous carriers (Aa) of the mutated allele having offspring with the disease phenotypically showing?
A
  • 25%
  • the offspring will be homozygous recessive (aa)
31
Q
  1. Why are Autosomal Recessive Disorders more common than Autosomal Dominant Disorders?
A
  • the mutated alleles of healthy heterozygous carriers
    are present in the genotype
  • but they are hidden when it comes to the phenotype
  • their phenotype will be normal
  • the mutation will not phenotypically show
32
Q
  1. What can be said about the mutation in Autosomal Dominant Disorders?
A
  • the mutation is obvious
  • the phenotype is affected
33
Q
  1. What happens if the recessive allele that causes a disease is rare?
A
  • the chance of two carriers meeting and mating is low
34
Q
  1. What are Consanguineous Matings?
A
  • this is the mating between close relatives
    EG: first cousins
35
Q
  1. What do Consanguineous Matings result in?
A
  • they increase the chance of mating between 2 carriers
    of the same rare allele
  • most cultures and societies have laws against
    marriages between close relatives

MED 109- BIOLOGY II (90 decks)

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