Genes Flashcards
(152 cards)
1
Q
What genetic principles account for the transmission of traits from parents to offspring?
A
•”blending” hypothesis
- “particulate” hypothesis of inheritance: the gene idea
2
Q
One possible explanation of (blank) is a “(blank)” hypothesis
A
Heredity, blending
3
Q
The idea that (blank) (blank) contributed by two parents mixes in a manner (blank) to the way blue and yellow paints blend to make green
A
Genetic, material, analogues
4
Q
An alternative to the blending model is the “(blank)” hypothesis of inheritance: the (blank)(blank)
A
Particulate, the gene idea
5
Q
An alternative to the blending model is the “particulate” hypothesis of inheritance: the gene idea
- Parents pass on (blank) (blank) (blank), genes
A
Discrete heritable units
6
Q
Documented a particulate mechanism of inheritance through his experiments with garden peas
A
Gregor Mendel
7
Q
Who is Gregor Mendel
A
Documented a particulate mechanism of inheritance through his experiments with garden peas
8
Q
Concept 14.1:
A
Mendel used the scientific approach to identify two laws of inheritance
Mendel discovered the basic principles of heredity
9
Q
Mendel discovered the basic principles of heredity by doing what
A
By breeding garden peas in carefully planned experiments
10
Q
Mendel’s Experimental, (blank) (blank)
A
Quantitative approach
11
Q
Why did Mendel choose to work with peas?
A
-Because they are available in many varieties
- Because he could strictly control which plants mated with which
12
Q
Crossing pea plants
APPLICATION
A
By crossing (mating) two true-breeding varieties of an organism, scientists can study patterns of inheritance. In this example, Mendel crossed pea plants that varied in flower color.
13
Q
Crossing Pea plants
Technique
A
Step
1.
2.
3.
4.
5.
14
Q
Crossing pea plants
Results
A
When pollen from a white flower fertilizes eggs of a purple flower, the first-generation hybrids all have purple flowers. The result is the same for the reciprocal cross, the transfer of pollen from purple flowers to white flowers.
15
Q
a heritable feature, such as flower color
A
Character
16
Q
a variant of a character, such as purple or white flowers
A
Trait
17
Q
Mendel chose to track
- Only those characters that varied in an “blank- blank” manner
A
‘either- or”
18
Q
Mendel also made sure that
- He started his experiments with varieties that were “blank-blank”
A
True breeding
19
Q
In a (blank) breeding experiment
- Mendel mated two (blank), true-breeding varieties, a process called (blank)
A
Typical, contrasting, hybridization
20
Q
The true-breeding parents
- Are called the (blank) (blank)
A
P generation
21
Q
The hybrid offspring of the P generation .
- Are called the (blank) (blank)
A
F,1 generation
22
Q
When F, individuals (blank-blank) .
- The (blank) (blank) is produced
A
Self-pollinate, F₂ generation
23
Q
• When Mendel crossed contrasting, true- breeding white and purple flowered pea plants
- All of the offspring were purple
• When Mendel crossed the F, plants
- Many of the plants had purple flowers, but some had white flowers
A
The Law of Segregation
24
Q
What is The Law of Segregation?
A
Mendel’s law of segregation states that: “During the formation of gamete, each gene separates from each other so that each gamete carries only one allele for each gene.”
25
When Mendel crossed contrasting, true- breeding white and purple flowered pea plants
- All of the offspring were purple
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When Mendel crossed the F, plants
- Many of the plants had purple flowers, but some had white flowers
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Mendel discovered
- A ratio of about three to one, purple to white flowers, in the (blank) (blank)
F₂ generation
28
Mendel Discovered
Expirement
True-breeding purple-flowered pea plants and white-flowered pea plants were crossed (symbolized by x). The resulting F, hybrids were allowed to self-pollinate or were cross- pollinated with other F, hybrids. Flower color was then observed in the F, generation.
29
Mendel Discovered
Results
Both purple-flowered plants and white- flowered plants appeared in the F generation. In Mendel's experiment, 705 plants had purple flowers, and 224 had white flowers, a ratio of about 3 purple: 1 white.
30
Mendel Discovered
Photo
P generation explanation
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Mendel reasoned that (1)
- In the F, plants, only the purple flower factor was affecting flower color in these hybrids
32
Mendel reasoned that (2)
Purple flower color was dominant, and white flower color was recessive
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Mendel observed the same pattern in many other (blank) (blank) (blank)
pea plant characters
34
•Mendel developed a hypothesis
- To explain the 3:1 inheritance pattern that he observed among the F₂ offspring
•Four related concepts make up this model
Mendel's model
35
Mendel developed a hypothesis
- To explain the (sentence blank)
3:1 inheritance pattern that he observed among the F₂ offspring
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Mendel's model
First, ( blank sentence)
alternative versions of genes
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First, alternative versions of genes
- Account for variations in inherited characters, which are now called (blank)
Alleles
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Mendel's Model
Second, (blank sentence)
for each character
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Second, for each character (1)
- An organism inherits two alleles, one from each parent
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Second, for each character (2)
A genetic locus is actually represented twice
41
Mendel's Model
Third, (blank sentence)
if the two alleles at a locus differ
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Third, if the two alleles at a locus differ (1)
Then one, the dominant allele, determines the organism's appearance
43
Third, if the two alleles at a locus differ (2)
The other allele, the recessive allele, has no noticeable effect on the organism's appearance
44
Mendel's model
Fourth, (blank sentence)
the law of segregation
45
Fourth, the law of segregation
- The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
46
Does Mendel's segregation model account for the 3:1 ratio he observed in the F₂ generation of his numerous crosses?
- We can answer this question using a Punnett square
47
Mendel's law of segregation, (blank) and the (blank) (blank)
Probability, punnett square
48
Useful Genetic Vocabulary
• An organism that is (blank) for a particular gene
- Has a pair of identical alleles for that gene - Exhibits true-breeding
homozygous
49
Useful Genetic Vocabulary
• An organism that is homozygous for a particular gene (1)
Has a pair of identical alleles for that gene
50
Useful Genetic Vocabulary
• An organism that is homozygous for a particular gene (2)
- Exhibits true-breeding
51
Useful Genetic Vocabulary
An organism that is (blank) for a particular gene
- Has a pair of alleles that are different for that gene
heterozygous
52
Useful Genetic Vocabulary
An organism that is heterozygous for a particular gene (1)
- Has a pair of alleles that are different for that gene
53
Useful Genetic Vocabulary
- Is its physical appearance
An organism's phenotype
54
Useful Genetic Vocabulary
- Is its genetic makeup
An organism's genotype
55
Phenotype versus genotype (explain)
The genotype refers to the genetic material passed between generations, and the phenotype is observable characteristics or traits of an organism.
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In pea plants with purple flowers
- The genotype is not immediately obvious
The Testcross
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In pea plants with purple flowers
- The (blank) is not immediately obvious
genotype
58
- Allows us to determine the genotype of an organism with the dominant phenotype, but unknown genotype
- Crosses an individual with the dominant phenotype with an individual that is homozygous recessive for a trait
A testcross
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A testcross (1)
Allows us to determine the genotype of an organism with the dominant phenotype, but unknown genotype
60
A testcross (2)
- Crosses an individual with the dominant phenotype with an individual that is homozygous recessive for a trait
61
The testcross
APPLICATION
An organism that exhibits a dominant trait,
such as purple flowers in pea plants, can be either homozygous for the dominant allele or heterozygous. To determine the organism's genotype, geneticists can perform a testcross
62
The testcross
Technique
in a testcross, the individual with the
unknown genotype is crossed with a homozygous individual expressing the recessive trait (white flowers in this example). By observing the phenotypes of the offspring resulting from this cross, we can deduce the genotype of the purple-flowered parent.
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The testcross photo analysis
analyzation
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•Mendel derived the law of segregation
By following a single trait
•The F, offspring produced in this cross
- Were monohybrids, heterozygous for one character
The Law of Independent Assortment
65
Mendel derived the law of segregation by (blank sentence)
following a single trait
66
The Law of Independent Assortment
The F, offspring produced in this cross
- Were (blank), (blank) for one character
monohybrids, heterozygous
67
Mendel identified his second (blank) of (blank)
Law of inheritance
68
Mendel identified his second law of inheritance
- By (blank sentence)
following two characters at the same time
69
Crossing two, (blank-blank) parents differing in two characters
- Produces (blank) in the F, and generation, (blank) for both characters
true-breeding, dihybrids, heterozygous
70
How are two characters transmitted from parents to offspring?
- As a package?
- Independently?
71
- Illustrates the inheritance of two characters
A dihybrid cross
72
Produces four phenotypes in the F₂2 generation
A dihybrid cross
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A dihybrid cross
Produces four (blank) in the (blank) (blank)
phenotypes, F₂2 generation
74
A dihybrid cross
Experiment
Two true-breeding pea plants-
one with yellow-round seeds and the other with green -wrinkled seeds were crossed, producing dihybrid F, plants. Self-pollination of the F, dihybrids, which are heterozygous for both characters, produced the F generation. The two hypotheses predict different phenotypic ratios. Note that yellow color (Y) and round shape (R) are dominant.
75
A dihybrid cross
Conclusion
The results support the hypothesis of independent assortment. The alleles for seed color and seed shape sort into gametes independently of each other.
76
A dihybrid cross
Photo analysis
Analyzes
77
Concept (blank): The laws of probability govern Mendelian inheritance
14.2
78
Concept 14.2:
The laws of probability govern Mendelian inheritance
79
Reflect the rules of probability
Mendel's laws of segregation and independent assortment
80
The (blank) and (blank) Rules Applied to (blank) (blank)
Multiplication, addition, Monohybrid Crosses
81
- States that the probability that two or more independent events will occur together is the product of their individual probabilities
• The multiplication rule
82
Can be determined using this rule
Probability in a monohybrid cross
83
- States that the probability that any one of two or more exclusive events will occur is calculated by adding together their individual probabilities
The rule of addition
84
Solving Complex Genetics Problems with the (blank) of (blank)
Rules of Probability
85
- To predict the outcome of crosses involving multiple characters
• We can apply the rules of probability
86
- Is equivalent to two or more independent monohybrid crosses occurring simultaneously
A dihybrid or other multicharacter cross
87
In calculating the chances for various (blank) from such (blank)
- Each character first is considered separately and then the individual probabilities are (blank) together
genotypes, crosses, multiplied
88
Concept 14.3:
Inheritance patterns are often more complex than predicted by simple Mendelian genetics
89
Inheritance patterns are often more complex than predicted by simple Mendelian genetics
Concept 14.3:
90
Concept 14.3: (2)
The relationship between genotype and phenotype is rarely simple
91
Extending (blank) (blank) for a Single Gene
Mendelian Genetics
92
Extending Mendelian Genetics for a Single Gene
• The inheritance of characters by a single gene
-(sentence)
May deviate from simple Mendelian patterns
93
The Spectrum of Dominance
Occurs when the phenotypes of the heterozygote and dominant homozygote are identical
Complete dominance
94
The Spectrum of Dominance
Two dominant alleles affect the phenotype in separate, distinguishable ways
In codominance
95
The Spectrum of Dominance
- Is an example of codominance
The human blood group MN
96
The phenotype of F, hybrids is somewhere between the phenotypes of the two parental varieties
In incomplete dominance
97
The Spectrum of Dominance
The Relation Between (blank) and (blank)
Dominance, Phenotype
98
-Do not really "interact"
- Lead to synthesis of different proteins that produce a phenotype
Dominant and recessive alleles
99
Dominant and recessive alleles (1)
-Do not really "interact"
100
Dominant and recessive alleles (2)
Lead to synthesis of different proteins that produce a phenotype
101
The Spectrum of Dominance
Frequency of (blank) (blank)
Dominant Alleles
102
- Occurs when the phenotypes of the heterozygote and dominant homozygote are identical
Complete dominance
103
- Are not necessarily more common in populations than recessive alleles
Dominant alleles
104
Most genes exist in populations
Multiple Alleles
105
Most genes exist in populations
- In more than two (blank) (blank)
allelic, forms
106
Is determined by multiple alleles
The ABO blood group in humans
107
A gene has multiple phenotypic effects
pleiotropy
108
In pleiotropy, A gene has multiple (blank) effects
phenotypic
109
Some traits
- May be (blank sentence)
determined by two or more genes
110
- A gene at one locus alters the phenotypic expression of a gene at a second locus
In epistasis
111
In epistasis
- A gene at one (blank) alters the (blank) expression of a gene at a (blank) locus
locus, phenotypic, second
112
example of epistasis
what
113
Polygenic Inheritance (1)
Many human characters
114
Polygenic Inheritance
• Many human characters
- Vary in the population along a (blank) and are called (blank) (blank)
continuum, quantitative, characters
115
Polygenic Inheritance
- An additive effect of two or more genes on a single phenotype
Quantitative variation usually indicates polygenic inheritance
116
Nature and Nurture: The Environmental Impact on (blank)
Phenotype
117
Another departure from simple (blank) (blank) (blank)
- When the phenotype for a character depends on environment as well as on genotype
Mendelian genetics arises
118
- Is the phenotypic range of a particular genotype that is influenced by the environment
The norm of reaction
119
- Are those that are influenced by both genetic and environmental factors
Multifactorial characters
120
- Are those that are influenced by both genetic and environmental factors
Multifactorial characters
121
Integrating a (blank) View of (blank) and (blank)
Mendelian, Heredity, Variation
122
- Includes its physical appearance, internal anatomy, physiology, and behavior
- Reflects its overall genotype and unique
environmental history
An organism's phenotype
123
An organism's phenotype (1)
- Includes its physical appearance, internal anatomy, physiology, and behavior
124
An organism's phenotype (2)
- Reflects its overall genotype and unique environmental history
125
Even in more complex (blank) (blank)
- Mendel's fundamental laws of (blank) and (blank) (blank) still apply
inheritance patterns, segregation, independent assortment
126
Concept 14.4:
Many human traits follow Mendelian patterns of inheritance
127
Many human traits follow Mendelian patterns of inheritance
Concept 14.4:
128
(Blank) are not convenient subjects for genetic research
- However, the study of (blank) (blank) continues to advance
Humans, human genetics
129
- Is a family tree that describes the interrelationships of parents and children across generations
A pedigree
130
Inheritance (blank) of particular traits
- Can be traced and described using (blank)
patterns, pedigrees
131
Can also be used to make predictions about future offspring
Pedigrees
132
Many genetic disorders
- Are inherited in a (blank) (blank)
recessive manner
133
- Show up only in individuals homozygous for the allele
Recessively inherited disorders
134
Recessively inherited disorders
- Show up only in individuals (blank) for the (blank)
homozygous, allele
135
- Are heterozygous individuals who carry the recessive allele but are phenotypically normal
Carriers
136
Symptoms of cystic fibrosis include:
- Mucus buildup in the some internal organs
- Abnormal absorption of nutrients in the small intestine
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-Affects one out of 400 African-Americans
- Is caused by the substitution of a single amino acid in the hemoglobin protein in red blood cells
Sickle-Cell Disease
138
Sickle-Cell Disease
Is caused by the (blank) of a single (blank) (blank) in the (blank) (blank) in red blood cells
substitution, amino acid, hemoglobin protein
139
Sickle-Cell Disease
Symptoms include
- Physical weakness, pain, organ damage, and even paralysis
140
Matings between relatives
- Can increase the (blank sentence)
probability of the appearance of a genetic disease
141
Mating of Close Relatives
Are called (blank) (blank)
consanguineous matings
142
Some human disorders
- Are due to (blank) (blank)
dominant alleles
143
Dominantly Inherited Disorders
Example: A form of dwarfism that is lethal when homozygous for the dominant allele
achondroplasia
144
Dominantly Inherited Disorders
- Is a degenerative disease of the nervous system
-Has no obvious phenotypic effects until about 35 to 40 years of age
Huntington's disease
145
Multifactorial Disorders
Many human diseases
- Have both (blank) and (blank)
components
genetic, environmental
146
Many human diseases
- Have both genetic and environment
components
• Examples include
Heart disease and cancer
147
Genetic Testing and Counseling
- Can provide information to prospective parents concerned about a family history for a specific disease
Genetic counselors
148
Counseling Based on Mendelian Genetics and Probability Rules
- Genetic counselors help couples determine the odds that their children will have genetic disorders
Using family histories
149
Tests for Identifying Carriers
- Tests are available that identify carriers and help define the odds more accurately
For a growing number of diseases
150
Fetal Testing
- The liquid that bathes the fetus is removed and tested
In amniocentesis
151
Fetal Testing
A sample of the placenta is removed and tested
In chorionic villus sampling (CVS)
152
Some genetic disorders can be detected at birth
- By simple tests that are now routinely performed in most hospitals in the United States
Newborn Screening
