Patterns of Inheritance (Chapter 12) Flashcards
Father of modern genetics
Gregor Mendel
Gregor Mendel’s hypothesis of transmission of traits are now considered _____.
laws of inheritance
Mendel’s genetic hypothesis
Each parent contributes to its progeny distinct elements of heredity (factors/genes).
Factors remain unchanged as they pass through generations.
Mendel’s experiments used the organism _____.
garden pea
Pisum sativum
True-breeding varieties
Self-fertilized plants produce only progeny like themselves
Cross-pollination / cross-fertilization
Pollen transferred from varieties exhibiting alternative character forms
The observed trait is called _____.
dominant
The masked trait is called _____.
recessive
Mendel’s First Law of Segregation
Each plant possesses two distinct separable units (alleles) for each trait inherited from each parent.
Gametes contain _ allele for each trait.
1
The unit (allele) does not disappear; it may be present but _____.
hidden
Principle of Segregation
Two alleles for a gene segregate during gamete formation and are rejoined at random (one from each parent) during fertilization.
5 element model (1)
Parents transmit discrete factors (genes)
5 element model (2)
Each individual receives one copy of a gene from each parent
5 element model (3)
Not all copies of a gene are identical
5 element model (4)
Alleles remain discrete – no blending
5 element model (5)
Presence of allele does not guarantee expression
Homozygous
2 of the same allele
Heterozygous
different alleles
Genotype
total set of alleles an individual contains
Phenotype
physical appearance
Most common phenotype in the general population
wildtype phenotype
When the phenotype is different from the wildtype, it is called a _____.
mutant phenotype
The most frequent allele associated with the common phenotype is the _____.
wildtype allele
The allele associated with the mutant phenotype is the _____.
mutant allele
Mendel’s Second Law of Independent Assortment
Two genes on different chromosomes segregate their alleles independently.
The inheritance of an allele of one gene does not influence which allele is inherited at a second gene.
Principle of independent assortment
Independent alignment of different homologous chromosome pairs during metaphase I leads to the independent segregation of the different allele pairs.
In a dihybrid cross, parents with _____ are crossed.
two differing traits
Mode of Inheritance
Indicates the patterns with which the mutant
phenotype is associated
Most common modes of inheritance (3)
Autosomal recessive
Autosomal dominant
X-link recessive
_____ is used to track inheritance patterns in families.
Pedigree analysis
Human autosomal traits are located on _____.
the non-sex chromosomes (1-22)
Heterozygotes exhibit _____.
the affected phenotype
Albinism
A condition in which the pigment melanin is not produced.
Do autosomal dominant inheritance traits skip generations?
No
Mendel’s model of inheritance assumes that (1-3)
Each trait is controlled by a single gene.
Each gene has only 2 alleles.
There is a clear dominant-recessive relationship between the alleles.
continuous variation
The greater the number of genes influencing a character, the more continuous the expected distribution of character variation will be.
pleiotropic effects
Individual alleles often have more than one effect on the phenotype.
Incomplete dominance
Heterozygotes are intermediate in color.
Environmental effects
Degree of allele expression may depend on the environment.
Epistasis
one gene interferes with the expression of another gene.
Polygenic inheritance
The phenotype is an accumulation of contributions by multiple genes.
Pleiotropy
Refers to an allele which has more than one effect on the phenotype
Incomplete dominance
indicates the heterozygous phenotype is distinct from either homozygous phenotype.
Each individual can only have _ alleles.
2
Epistasis
When one gene affects the expression of a second gene.
the H gene is _____ to the ABO gene.
epistatic
All ABO genotypes appear as _____.
type O
Codominance
No single allele is dominant, and each allele has its own effect.
ABO blood groups
Human gene that encodes enzyme that adds sugar molecules to lipids on the surface of red blood cells
I^B adds:
galactose
I^A adds:
galactosamine
i adds:
no sugar
Codominant alleles are observed _____.
simultaneously
The ABO gene encodes a _____.
cell surface protein
Allele A makes (ABO):
A protein
Allele B makes (ABO):
B protein
Allele O makes (ABO):
no protein
Alleles A and B (ABO) are _____.
codominant
Allele O is _____ to both A and B alleles.
recessive
Blood type A receives _____ and donates to _____.
A, O
A, AB
Blood type B receives _____ and donates to _____.
B, O
B, AB
Blood type O receives _____ and donates to _____.
A, B, AB, O
AB
Blood type AB receives _____ and donates to _____.
O
A, B, AB, O
