ANSC 4395-Animal Breeding & Genetics Test 2 QUESTIONS
WITH COMPLETE ANSWERS
Gregor Mendel: Correct Answer: -Augustinian priest and scientist
-"Father of Genetics"
-Mid 19th century
-Performed breeding experiments with peas
-Determined basic rules of inheritance by observing the outcomes of his matings
Gene: Correct Answer: -Basic unit of inheritance
-Segments of DNA
-Relatively short segments of chromosomes
Chromosomes: Correct Answer: -Long strands of DNA & associated proteins present in the
nucleus of every cell
-Present in pairs (one from the sire & one from the dam-# of pairs depends on the species)
Homologs: Correct Answer: Pair of chromosomes having corresponding loci
Locus: Correct Answer: The specific location of a gene on a chromosome
At each locus, there is a pair of genes: Correct Answer: -One on the maternal chromosome and
one on the paternal chromosome
The genes at a locus are denoted by: Correct Answer: -A single letter or combination of letters
and/or symbols
-A locus = A and a (These are called alleles)
If one letter of the gene at a locus is uppercase and the other lowercase, this implies... Correct
Answer: a chemical and functional difference
Allele: Correct Answer: An alternative form of a gene
Although there are only two genes at any particular locus, the two may be part of a... Correct
Answer: larger series of alternative forms of a gene
(Multiple alleles)
Multiple Alleles: Correct Answer: -More than two possible alleles at a locus
-If there are 4 possible alleles, you may have: B b b' b"
In dogs, the E locus affects coat color: Correct Answer: E - full extension of pigment
E^br - brindling or tigerstriping
e - inhibits pigment
-Any dog can have a maximum of two of these color alleles in the E series
, The combination of genes at a particular locus is called a... Correct Answer: genotype
If J and j are the only possible alleles at the J locus, then three genotypes are possible: Correct
Answer: JJ Jj jj
Homozygous: Correct Answer: A one-locus genotype containing functionally identical genes
(EX: AA bb DD gg ff)
Heterozygous: Correct Answer: A one-locus genotype containing functionally different genes
(EX: Jj Aa Bb Gg)
Law of Segregation (Mendel's 1st Law): Correct Answer: In the formation of a germ cell or
gamete, the two genes at a locus in the parent cell are separated, only one gene being
incorporated into each germ cell
-Meiosis
-Entire homologous chromosomes are separated
Germ cells contain: Correct Answer: Half the number of chromosomes and half the number of
genes as normal body cells
The number of gametes that can be obtained from a parental genotype depends on: Correct
Answer: How the genotype is
-Two locus genotypes: JJBB JJBb JjBb
Law of Independent Assortment (Mendel's 2nd Law): Correct Answer: Genes assort
independently during meiosis if all possible gametes are formed in equal proportions
For the Law of Independent Assortment (Mendel's 2nd Law) to happen: Correct Answer: A
given gene from a locus must have an equal probability of being present in a germ cell with
either of the two genes from some other locus
Example for the "Law of Independent Assortment": Correct Answer: -JjBb individuals can
produce four different gametes:
JB Jb jB jb
-If all four genotypes appear in equal proportions, then these genes have assorted independently
-If only JB and jb occur, or they occur at much higher frequencies, then the law has been violated
Example for the "Law of Independent Assortment" continued: Correct Answer: It would appear
that J and B are stuck together, or j & b are stuck together
-Not all genes assort independently, but they are exceptions to the rule, not the rule
-Exceptions to the "Law of Independent Assortment" are due to linkage
Linkage: Correct Answer: The occurrence of two or more loci of interest on the same
chromosome
WITH COMPLETE ANSWERS
Gregor Mendel: Correct Answer: -Augustinian priest and scientist
-"Father of Genetics"
-Mid 19th century
-Performed breeding experiments with peas
-Determined basic rules of inheritance by observing the outcomes of his matings
Gene: Correct Answer: -Basic unit of inheritance
-Segments of DNA
-Relatively short segments of chromosomes
Chromosomes: Correct Answer: -Long strands of DNA & associated proteins present in the
nucleus of every cell
-Present in pairs (one from the sire & one from the dam-# of pairs depends on the species)
Homologs: Correct Answer: Pair of chromosomes having corresponding loci
Locus: Correct Answer: The specific location of a gene on a chromosome
At each locus, there is a pair of genes: Correct Answer: -One on the maternal chromosome and
one on the paternal chromosome
The genes at a locus are denoted by: Correct Answer: -A single letter or combination of letters
and/or symbols
-A locus = A and a (These are called alleles)
If one letter of the gene at a locus is uppercase and the other lowercase, this implies... Correct
Answer: a chemical and functional difference
Allele: Correct Answer: An alternative form of a gene
Although there are only two genes at any particular locus, the two may be part of a... Correct
Answer: larger series of alternative forms of a gene
(Multiple alleles)
Multiple Alleles: Correct Answer: -More than two possible alleles at a locus
-If there are 4 possible alleles, you may have: B b b' b"
In dogs, the E locus affects coat color: Correct Answer: E - full extension of pigment
E^br - brindling or tigerstriping
e - inhibits pigment
-Any dog can have a maximum of two of these color alleles in the E series
, The combination of genes at a particular locus is called a... Correct Answer: genotype
If J and j are the only possible alleles at the J locus, then three genotypes are possible: Correct
Answer: JJ Jj jj
Homozygous: Correct Answer: A one-locus genotype containing functionally identical genes
(EX: AA bb DD gg ff)
Heterozygous: Correct Answer: A one-locus genotype containing functionally different genes
(EX: Jj Aa Bb Gg)
Law of Segregation (Mendel's 1st Law): Correct Answer: In the formation of a germ cell or
gamete, the two genes at a locus in the parent cell are separated, only one gene being
incorporated into each germ cell
-Meiosis
-Entire homologous chromosomes are separated
Germ cells contain: Correct Answer: Half the number of chromosomes and half the number of
genes as normal body cells
The number of gametes that can be obtained from a parental genotype depends on: Correct
Answer: How the genotype is
-Two locus genotypes: JJBB JJBb JjBb
Law of Independent Assortment (Mendel's 2nd Law): Correct Answer: Genes assort
independently during meiosis if all possible gametes are formed in equal proportions
For the Law of Independent Assortment (Mendel's 2nd Law) to happen: Correct Answer: A
given gene from a locus must have an equal probability of being present in a germ cell with
either of the two genes from some other locus
Example for the "Law of Independent Assortment": Correct Answer: -JjBb individuals can
produce four different gametes:
JB Jb jB jb
-If all four genotypes appear in equal proportions, then these genes have assorted independently
-If only JB and jb occur, or they occur at much higher frequencies, then the law has been violated
Example for the "Law of Independent Assortment" continued: Correct Answer: It would appear
that J and B are stuck together, or j & b are stuck together
-Not all genes assort independently, but they are exceptions to the rule, not the rule
-Exceptions to the "Law of Independent Assortment" are due to linkage
Linkage: Correct Answer: The occurrence of two or more loci of interest on the same
chromosome
