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ZZZ - General Zoology > Mendel and the Gene Idea > Flashcards

Mendel and the Gene Idea Flashcards

1
Q

What genetic principles account for the transmission of traits from parents to offspring?

A
  1. “Blending” Hypothesis
  2. “Particulate” Hypothesis of inheritance: the gene idea
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2
Q

the idea that genetic material contributed by two parents mixes in a manner analogous to the way blue and yellow paints blend to make green

A

Blending hypothesis

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3
Q

Hypothesis which states that parents pass on discrete heritable units, genes

A

Particulate Hypothesis of Inheritance: The Gene Idea

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4
Q

documented a particulate mechanism of inheritance through his experiments with garden peas

A

Gregor Mendel

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5
Q

What approach did Mendel use to identify the two laws of inheritance?

A

scientific approach

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6
Q

How did Mendel discover the basic principles of heredity?

A

By breeding garden peas in carefully planned experiments

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7
Q

Why did Mendel choose to work with peas?

A
  1. Available in many varieties
  2. Could strictly control which plants mated which
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8
Q

By crossing (mating) two true-breeding varieties of an organism, scientists can study __ __ __

A

patterns of inheritance

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9
Q

Results: When pollen from white flower fertilizes eggs of purple flower, the first generation hybrids all have ___ flowers

A

Purple

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10
Q

a heritable feature

A

character

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11
Q

example of a character

A

flower color

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12
Q

a variant of a character

A

trait

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13
Q

example of a trait

A

purple or white flowers

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14
Q

What characters did Mendel chose to only track?

A

characters that varied in an “either-or” manner

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15
Q

What did Mendel make sure when starting the experiments?

A

His varieties were true-breeding

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16
Q

What do you call the process where Mendel mated two contrasting, true-breeding varieties?

A

Hybridization

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17
Q

The true-breeding parents are called?

A

P generation

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18
Q

The hybrid offspring of the P generation are called?

A

F1 generation

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19
Q

What do you call the offspring when F1 individuals self-pollinate?

A

F2 generation

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20
Q

Law states that hybrid offspring will only inherit the dominant characteristics in the phenotype. The alleles that suppress a trait are recessive traits, whereas the alleles that define a trait are known as dominant traits.

A

Law of Dominance

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21
Q

The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes

A

Law of Segregation

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22
Q

What is the first law of inheritance?

A

Law of Dominance

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23
Q

What is the second law of inheritance?

A

Law of Segregation

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24
Q

When Mendel crossed the F1 plants, he discovered a ratio of about __ to __, __ to __ flowers, in the F2 generation

A

3:1, purple:white

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25
Mendel reasoned that in F1 plants, purple flower color was __, and white flower color was __
purple = dominant white = recessive
26
Four (4) concepts that make up the Mendel's model
1. Alternative versions of genes 2. An organism inherits two alleles, one from each parent, and a genetic locus is represented twice 3. If the two alleles at a locus differ, the dominant allele determines the organism's appearance 4. Law of segregation
27
An organism that is homozygous for a particular gene has a pair of ___ alleles for that gene and exhibits ____
Identical alleles Exhibits True-breeding
28
An organism that is heterozygous for a particular gene has a pair of alleles that are ___ for that gene
Different
29
its physical appearance
phenotype
30
its genetic makeup
genotype
31
allows us to determine the genotype of an organism with the dominant phenotype
testcross
32
How do you testcross?
cross an individual with the dominant phenotype with an individual that is homozygous recessive for a trait
33
The F1 offspring produced in the testcross were __, __ for one character
monohybrid, heterozygous
34
How did Mendel derive the law of segregation?
by following a single trait
35
How did Mendel derive his second law of inheritance?
by following two characters at the same time
36
Crossing two, true-breeding parents differing in two characters produces __ in the __ generation, __ for both characters
dihybrids; F1; heterozygous
36
illustrates the inheritance of two characters
dihybrid cross
37
dihybrid cross produces __ phenotypes in the F2 generation
four
38
How did Mendel develop the law of independent assortment?
using the information from a dihybrid cross
39
each pair of alleles segregates independently during gamete formation
Law of Independent Assortment
40
The physical site or location of a specific gene on a chromosome.
locus
41
The laws of __ govern Mendelian inheritance
probability
42
states that the probability that two or more independent events will occur together is the product of their individual probabilities
Multiplication Rule
43
The probability in a monohybrid cross can be determined using what rule?
Multiplication Rule
44
states that the probability that any one of two or more exclusive events will occur is calculated by adding together their individual probabilities
Rule of Addition
45
The rules of probability can be applied to predict the outcome of crosses involving __ __
multiple characters
46
equivalent to two or more independent monohybrid crosses occurring simultaneously
dihybrid or other multicharacter cross
47
each character first is considered separately and then the individual probabilities are multiplied together
Calculating chances for various genotypes from such crosses
48
Inheritance patters are often more complex than predicted by simple Mendelian genetics
relationship between genotype and phenotype is rarely simple
49
Inheritance of characters by a single gene may deviate from ____ ____ ____
simple Mendelian patterns
50
occurs when the phenotypes of the heterozygote and dominant homozygote are identical
Complete Dominance
51
two dominant alleles affect the phenotype in separate, distinguishable ways
Codominance
52
Example of codominance
human blood group MN
53
the phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties
Incomplete Dominance
54
Dominant and recessive alleles do not really __; lead to ____
- do not really "interact" - lead to synthesis of different proteins that produce a phenotype
55
Frequency of Dominant Alleles
Dominant alleles are not necessarily more common in populations than recessive alleles
56
most genes exist in populations in more than two allelic forms
Multiple alleles
57
The __ __ __ in humans is determined by multiple alleles
ABO blood group
58
- a gene has multiple phenotypic effects - the phenomenon of a single gene affecting multiple traits
pleiotropy
59
a gene at one locus alters the phenotypic expression of a gene at a second locus
epistasis
60
Example of epistasis
albinism
61
occurs when one characteristic is controlled by two or more genes
polygenic inheritance
62
Example of polygenic inheritance
height, skin color, eye color, weight
63
usually indicates polygenic inheritance
quantitative variation
64
when the phenotype of a character depends on environment as well as on genotype
Nature and Nurture: The Environmental Impact on Phenotype
65
is the phenotypic range of a particular genotype that is influenced by the environment
The norm of reaction
66
are those that are influenced by both genetic and environmental factors
Multifactorial characters
67
An organism's phenotype
- physical appearance - internal anatomy - physiology - behavior - reflects overall genotype and unique environmental history
68
- family tree that describes the interrelationships of parents and children across generations - can also be used to make predictions about future offspring
Pedigree
69
can be traced and described using pedigrees
inheritance patterns of particular traits
70
Many genetic disorders are inherited in a __ manner
recessive
71
Recessively inherited disorders show up only in individuals __ for the allele
homozygous
72
Carriers are __ individuals who carry the recessive allele but are phenotypically normal
heterozygous
73
caused by a defective gene that makes the body produce abnormally thick and sticky fluid, called mucus
cystic fibrosis
74
Examples of inherited disorders due to recessive genes
1. Cystic fibrosis 2. Sickle-cell Disease
75
a group of conditions in which red blood cells are not shaped as they should be
Sickle-cell Disease
76
How many African-Americans are affected with sickle-cell disease?
one out of 400
77
Symptoms of cystic fibrosis
- mucus buildup in some of the internal organs - abnormal absorption of nutrients in the small intestine
78
Symptoms of sickle-cell disease
- physical weakness - pain - organ damage - paralysis
79
- can increase the probability of the appearance of a genetic disease
matings between relatives
80
matings between relatives are called __ __
consanguineous matings
81
Some human disorders are due to __ alleles
dominant
82
Example of inherited disorders due to dominant genes
1. Achondroplasia 2. Huntington's disease
83
form of dwarfism that is lethal when homozygous for the dominant allele
Achondroplasia
84
degenerative disease of the nervous system
Huntington's disease
85
Huntington's disease has no obvious phenotypic effects until about ____ of age
35-40 years
86
human diseases have both genetic and environment components
multifactorial disorders
87
Examples of multifactorial disorders
1. heart disease 2. cancer
88
can provide information to prospective parents concerned about a family history for a specific disease
genetic counselors
89
can identify whether your baby is more or less likely to have certain birth defects, many of which are genetic disorders.
fetal testing
90
the liquid that bathes the fetus is removed and tested
amniocentesis
91
sample of the placenta is removed and tested
chorionic villus sampling (CVS)

ZZZ - General Zoology (23 decks)

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