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BIO 111 > Chapter 16 > Flashcards

Chapter 16 Flashcards

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Biology 101 flashcards
1
Q

how does inheritance work?

A
  • inheritance: traits passed parents to the offspring
  • Pre-Mendel, blending inheritance was assumed
  • blue-eyed parent X green-eyed parent -> gray-eyed child
  • OR if one was “stronger”, child would have traits of that parent
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2
Q

inheritance

A
  • we now know that blending inheritance is WRONG
  • Mendel- mid 1800s
  • conducted experiments, collected data, and used statistics to help explain the results
  • he figured out what occurred in the black box
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3
Q

Garden Pea, Pisum sativum

A
  • why did Mendel study peas?
  • Reason 1- many readily apparent traits
  • either/ or inheritance
  • either tall OR short, smooth OR wrinkled
  • Reason 2- normally self-fertilizing
  • true breeding lines exhibit the same traits
  • Reason 3- easy to use
  • cross-fertilization or hybridization
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4
Q

Genotype

A
  • genetic (allele) composition of individual
  • TT and tt- homozygous
  • Tt- heterozygous
  • each letter represents one gene on one chromosome
  • each pair of letters represents the two copies of a gene on both homologous chromosomes
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5
Q

Phenotype

A
  • characteristics that are the result of gene expression
  • TT or Tt are tall
  • tt are dwarf
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6
Q

single-factor cross

A
  • experimenter follows the variants of only 1 trait

- monohybrid

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7
Q

P generation

A

-true-breeding parents

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8
Q

F1 generation

A
  • offspring of P cross

- monohybrids- if parents differ in 1 trait

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9
Q

F2 generation

A

-F1 self-fertilizes

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10
Q

Traits are dominant and recessive (mendels 3 ideas)

A
  • dominant- displayed in hybrids

- recessive- masked by dominant

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11
Q

Genes and alleles (mendels 3 ideas)

A
  • particulate mechanism of inheritance
  • “unit factors” (aka genes)
  • every individual has two genes for a character
  • gene has 2 variants forms, or alleles
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12
Q

segregation of alleles (mendels 3 ideas)

A

-two copies of a gene carried by an F1 plant segregate (separate) from each other, so that each sperm or egg carries only one allele
0F2 traits follow approximately 3:1 ratio

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13
Q

Mendels law of segregation

A
  • two copies of a gene segregate from each other during the transmission from parent to offspring
  • during sexual reproduction, homologues replicate and pair
  • the pairs segregate (Meiosis I)
  • one cell has 2 copies of T-> TT
  • one cell has 2 copies of t-> tt
  • sister chromatids separate (Meiosis II)
  • 2 gametes with T and 2 gametes with t
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14
Q

testcross

A
  • dominant phenotype; genotype could be TT or Tt
  • multiple by
  • recessive phenotype; genotype must be tt
  • to determine the genotype of a parent with a dominant phenotype, examine genotypes of offspring when cross with a recessive phenotype
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15
Q

law of independent assortment

A
  • alleles of different genes assort independently of each other during gamete formation
  • each trait sorts itself independently of the others
  • not always he case- if genes are on the same chromosome
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16
Q

chromosome theory of inheritance

A
  1. chromosomes contain the genetic material
  2. chromosomes are replicated and passed from parent to offspring (cells or kids)
    - each chromosome retains its individuality during cell division and gamete formation
  3. each diploid cell contains two sets of chromosomes, which are found in homologous pairs
    - one inherited from mom and one from dad
    - each chromosome of the the set carries a full complement of the same genes
  4. during meiosis, one of each chromosome pair segregates randomly into the gamete nucleus
  5. gametes are haploid cells that combine to form a diploid cell during fertilization
    - each gamete transmits one set of chromosomes to the offspring
17
Q

Pedigree analysis

A
  • trait analyzed over multiple generations
  • medical pedigrees can be helpful for genetic disorders
  • provide a family history
  • help establish probabilities for future inheritance
  • help determine whether condition is
  • dominant or recessive
  • X-linked or autosomal
18
Q

Cystic fibrosis (pedigree analysis)

A
  • autosomal recessive traint
  • approximately 3% of Americans with European descent are heterozygous carries of the recessive CF allele and phenotypically normal
  • genotype Cc
  • individuals who are homozygous recessive exhibit disease systems
  • genotype?
  • 2 unaffected individuals CAN HAVE an affected child!
  • what is the probability?
19
Q

autosomal dominant disease pedigree- HD

A
  • autosomal dominant usually seen in every generation

- every affected individual has on affected parent

20
Q

X-linked inheritance

A
  • genes found on the X but not the Y are X-linked
  • sex-linked genes: on one sex chromosome but not the other
  • in humans X is larger, carries more gene
  • 1,500 vs 70 genes
  • males are hemizygous for X-linked genes
21
Q

X-linked inheritance- Color blindness

A
  • affects more males than females
  • 8% of the male population has some degree of colorblindness
  • 0.5% of the female population has some degree of colorblindness
  • females are “protected”
22
Q

sex-ratio dependent sex determination

A
  • in some fish, sex is controlled dominance heiarchy
  • clownfish are all born male
  • a dominant male will turn female when the current female of the group dies
23
Q

mendelian inheritance- variations

A
  • inheritance pattern of genes that segregate and assort independently
  • simple Mendelian inheritance- one trait is completely dominant over the other
  • phenotypic ratios are predictable via Mendels laws
  • occurs because dominant gene is enough for functionality
24
Q

incomplete dominance

A
  • heterozygote displays intermediate trait

- why is this not “blending”

25
Q

Phenylketonuria (incomplete dominance)

A
  • autosomal recessive metabolic disorder

- cannot break down phenyalanine

26
Q

homozygotes (incomplete dominance)

A

-mental impairment and seizures

27
Q

heterozygotes (incomplete dominance)

A
  • do not exhibit symptoms

- but 2x amount of phenylalanine in blood

28
Q

codominance

A

more than two alleles expressed

29
Q

Human blood type (codominance)

A
  • human blood types; A, B, AB and O
  • determined by antigens on the surface of RBC
  • antigens are glycoproteins; used for cell-cell recognition
  • coded for single gene on chromosome 9
  • each individual has 2 alleles of gene that codes for antigens
  • can be identical or non-identical
  • 3 alleles of this gene exist in the population
  • “I^A” allele-> “A” antigen
  • “I^B” allele -> “B” antigen
  • “O” allele -> no antigen encoded
30
Q

determining blood type

A
  • body attacks cells with foreign antigens with antibodies
  • individuals with blood type A will not recognized by bodies with blood type B or vice versa
  • results in rejection of blood transfusion
  • O is universal blood donor (has no antigens)
31
Q

pleiotropy

A
  • genes can exhibit this

- affects multiple trait

32
Q

role of environment

A
  • expression of genes is determined by the environment

- genetically identical plants- different heights in different temps

33
Q

gene-environment interactions

A
  • gene expression can vary depending on environment
  • example: hydrangeas
  • clones express different colors based on soil conditions
34
Q

Phenotypic plasticity

A

the ability of an individual to alter genetic expression in response to the environment

35
Q

Role of environment; human example

A
  • Phenylkaptonurians can develop normally if given a diet free of phenylalanine
  • if their diet contains phenylalanine, they develop mental impairments, underdeveloped teeth and more

BIO 111 (17 decks)

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