Chapter 8: Patterns of Inheritance Flashcards

1
Q

define character

A
  • a heritable feature
  • flower color
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2
Q

define trait

A
  • specific characteristic of an individual
  • purple flower or white flower
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3
Q

define gene

A
  • basic unit of heredity passed from one generation to the next
  • region of DNA encoding a product
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4
Q

define allele

A
  • different versions of the same gene
  • different sequence of nucleotides
  • each individual has two for each gene
  • P and p
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5
Q

define phenotype

A
  • physical appearance of an organism
  • purple flower or white flower
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6
Q

define genotype

A
  • genetic makeup of an organism
  • what alleles you have
  • PP, Pp, pp
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7
Q

define locus

A
  • specific locations on a chromosome where a gene is found
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8
Q

define monohybrid cross

A
  • cross between two true-breeding parents that express different traits for one characteristics
  • PP x pp
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9
Q

define dihybrid cross

A
  • cross between two true-breeding parents that express different traits for two characteristics
  • PPYY x ppyy
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10
Q

define test cross

A
  • cross between dominant expressing organism whose genotype you don’t know and a homozygous recessive organism for the same characteristic
  • determines the genotype of the dominant expressing parent
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11
Q

define reciprocal cross

A
  • paired cross in which respective traits of the female and female in one cross become respective traits of the female and male in the next cross
  • phenotype switches genders
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12
Q

define discrete

A
  • characteristics that are in a either/or manner
  • one or the other
  • white OR purple
  • yellow OR green
  • wrinkled OR smooth
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13
Q

define true-breeding

A
  • organisms that always pass a specific phenotype to the next generation
  • homozygous
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14
Q

define P generation

A
  • true-breeding parents
  • both homozygous for different traits (PP x pp)
  • manually crossed
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15
Q

define F1 generation

A
  • offspring of P generation
  • hybrids
  • heterozygous (Pp)
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16
Q

define F2 generation

A
  • offspring of F1 generation from self-pollination
  • all genotypes expressed (PP, Pp, pp)
  • creates 3 to 1 ratio of phenotypes
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17
Q

define dominant

A
  • allele that is expressed over recessive allele
  • PP or Pp
  • purple flower color was dominant in mendel’s experiments
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18
Q

define recessive

A
  • allele expressed only in absence of dominant allele
  • pp
  • white flower color was recessive in mendel’s experiments
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19
Q

define continuous variation

A
  • range of difference among individuals for a characteristic
  • offspring look like a blend of their parents
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20
Q

define discontinuous variation

A
  • each individual shows one of two (or few) easily distinguishable and distinct traits
  • what mendel observed
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21
Q

who is known as the father of genetics

A

gregor mendel

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22
Q

what did gregor mendel do

A
  • set principles of genetics: principle of heredity and mechanism of inheritance
  • did experiments through pea plant model system
  • discovered 2 laws of inheritance
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23
Q

what are the 2 laws of inheritance that gregor mendel discovered

A
  • law of segregation
  • law of independent assortment
24
Q

why did gregor mendel study peas

A
  • available in many varieties
  • easy to control mating of plants
  • used them to feed a monastery
25
describe mendel's pea experiments
- manually cross-pollinated pea plants - worked with thousands of plants over 8 years - looked at many characteristics: flower color, seed color, seed texture, plant height, etc - worked with discrete characteristics - mated contrasting true-breeding parents (hybridization)
26
what 4 concepts helped to explain the 3:1 phenotypic ratio mendel obseved
- concept of alleles - each characteristic has multiple alleles and each individual has 2 - individuals can have differing alleles, heterozygotes - law of segregation
27
define mendel's law of segregation
- alleles/chromosomes segregate during meiosis - gametes have equal change of receiving either allele/chromosome - only one allele/chromosome is carried in a particular gene
28
how did mendel discover the law of segregation
following a single characteristic
29
define mendel's law of independent assortment
- each pair of alleles/chromosomes segregates without influence of other alleles/chromosomes - random combinations of alleles into gametes - gamete with R allele has equal chance of also have Y or y
30
how did mendel discover the law of independent assortment
following two characteristics at the same time, dihybrid cross
31
what do results of a test cross tell you
- genotype of dominant expressing parent (PP or Pp) - all offspring expressing dominant phenotype mean parent in homozygous dominant - offspring express dominant and recessive phenotype in 1:1 ratio means parent is heterozygous
32
how many boxes will a punnett square have for 1, 2, 3, 4, and 5 genes
- 1: 4 - 2: 16 - 3: 64 - 4: 256 - 5: 1024
33
define probability
- fraction or decimal equivalent over a range of 0 to 1 or out of a percentage 0% to 100%
34
what does a probability of 0 and a probability of 1 mean
- 0: event will not happen, not due to chance - 1: event will happen, not due to chance
35
define chance
- anything that ranges between 0 and 1 - ex: chance of flipped coin landing on head = 0.5
36
what is the multiplication rule of probability
- 2 or more independent events will occur together - product of individual probabilities - AND - chance of rolling a 5 on the first die AND a 4 on the second = 1/6 x 1/6 = 1/36
37
what is the addition rule of probability
- probability that one event or the other will occur - adding individual probabilities - OR - chance of rolling a 4 OR a 5 = 1/6 + 1/6 = 1/3
38
what are the rules of probability used for
- predicting outcome of crosses - can be used together for complex events
39
how do you calculate the chances of various genotypes
- each character/gene is calculated separately - individual probabilities then multiplied together
40
what is the probability that an individual offspring has the genotype AaBBCCDd with both parents being AaBbCcDd
- calculate probability of each allele combination using punnett square: Aa= 1/2, BB= 1/4, CC= 1/4, Dd= 1/2 - multiply individual probabilities together: 1/2 x 1/4 x 1/4 x 1/2 = 1/64
41
define complete dominance
- phenotypes of heterozygote and dominant homozygote are identical - dominant trait masks recessive - purple flowers
42
define incomplete dominance
- phenotype of F1 hybrids are between the phenotypes of two parents - 3 phenotypes are usually seen - blended mix
43
define codominance
- 2 dominant alleles affect phenotype in separate but distinguishable ways - human blood type - unblended mix
44
define multiple alleles
- genes with more than 2 alleles (very common) - each organisms can only have 2 - wide variety in phenotypes - some alleles are dominant to others and recessive to others - blood type in humans determined by 3 alleles (A, B, O)
45
define pleiotropy
- many influencing - a gene has multiple phenotypic effects - an allele causes multiple characteristics
46
define polygenic
- many genes - opposite of pleiotropy - characteristic determined by 2 or more genes
47
define quantitative inheritance
- human characteristics that vary in the population - indicates polygenic inheritance: additive effect of 2 genes on single phenotype
48
define epistasis
- a gene at 1 locus alters the phenotypic expression of a gene at another locus
49
define multifactorial
- influences by both genetics and environmental factors - includes heart disease and cancer
50
examples of human characteristics that follow mendelian inheritance patterns
- earlobe attachment - tongue rolling - photic sneezing - marfan syndrome - huntington's syndrome
51
what things did mendel's experiments suggest
- two types of alleles exist for every gene - alleles maintain their integrity for each generation (no blending) - dominant allele always masks the recessive allele
52
do the fundamental principles of mendelian genetics still hold true
- yes - but we know more complexity exists
53
are dominant alleles aways more common in a population
- no - polydactyly is dominant but still rare
54
define lethality
- some alleles are so non-functional that they lead to death of the individual - can be dominant or recessive
55
example of lethality in manx cats
- MM are normal housecats - MML are manx - MLML results in early embryotic death
56
example of pleiotropy in humans
- red hair color gene - codes for red hair, increased pain tolerance, requiring more anesthesia, lower UV protection
57
example of polygenic trait/epistasis in dogs
- coat color in labs - B locus: determines color of pigment produced - E locus: determines if pigment is deposited in hair follicles