Genetics Flashcards
Genetic terms, the role of G+E on the P expression,
gene action, the mechanics of inheritance, the Mendelian
inheritance, genes in population.
Genetics
Objectives of animal breeding, systems of
breeding, inbreeding and crossbreeding.
Animal Breeding
Reproduction and rate of genetic improvement,
animal reproductive biotechnologies
Reproduction
A branch of biology that deals with heredity and variations of
organisms.
Genetics
Transmission of traits from generation to the next generation.
Heredity
Deals with the genetic differences
between organisms
Variation
Deals with the transmission of genes from generation to generation.
Mendelian Genetics
Study of heredity in groups of individuals.
Population Genetics
Three main areas in Animal Genetics
Mendelian Genetics
Population Genetics
Quantitative or Biometrical Genetics
Smallest unit of inheritance, found as segments of DNA on a chromosome.
Gene
Play a central role in determining various traits and characteristics of an
organism, including its physical appearance, physiological processes, and
susceptibility to diseases.
Gene
Store and transmit genetic
information from cell to cell and
from parent to offspring.
Genes
Copy or replicate itself with great
consistency and precision
Genes
Undergo mutation or error in
copying which would subsequently
copied and replicated.
Genes
Cound in the nucleus of the cell, and forms
the backbone of chromosome.
Deoxyribonucleic acid (DNA)
In Deoxyribonucleic acid (DNA) the spiral or double helix structure composed
of ?
nucleotides (deoxyribose sugar,
phosphate, and N base). The N bases are
adenine (A), thymine (T), guanine (G) and
cytosine (C).
DNA itself is wound up into a thin fiber which is wrapped around proteins called?
Histones
The histones and DNA structure forms a beadlike structure known as?
Nucleosome
Slender, thread-like strands that
contain the units of inheritance
(genes).
Chromosomes
How many sister chromatids?
2 sister chromatids
It is made of
protein and a single molecule of DNA
(chromatin).
Chromosomes
Genes occupying corresponding loci
on homologous chromosomes that
affect the same trait but in a
different way.
Alleles
Genes on the same locus controlling
a trait in the same way are called “homozygous”, and if they contrast
in controlling the trait, they are called “heterozygous”.
Alleles
Specific location of a gene on a
chromosome.
Loci
Having identical genes (one from
each parent) for a particular
characteristic.
Homozygous
Having two different genes for a
particular characteristic.
Heterozygous
Genes on the same locus controlling
a trait in the same way are called?
“homozygous”,
If they contrast
in controlling the trait.
“heterozygous”.
The allele of a gene that masks or
suppresses the expression of an
alternate allele; the trait appears in
the heterozygous condition.
Dominant
An allele that is masked by a
dominant allele; does not appear in
the heterozygous condition, only in
homozygous.
Recessive
The combination of alleles in an
individual The genetic makeup of an organism
Genotype
Any behavioral, biochemical,
morphological, or physiological
manifestation of the genotype
Phenotype
The genetic makeup of an organisms
Genotype
What is the meaning P = G + E (GxE)
- Genotype (G)
- Environment (E)
- Phenotype (P)
The genetic makeup of an organisms
Genetics
Fixed at conception and expressed until death (except for possible mutation)
Genetics
Reflects the action of genes in different combinations within the individual
Genetics
Causes variations other than heredity (e.g. disease, nutrition)
Environment
Affects the phenotypic expression of quantitative traits (production and
reproduction)
Environment
May be defined as the interaction between the genotype of the
individual and the environment under which it is raised.
GxE
Any behavioral, biochemical, morphological, or physiological manifestation of the
genotype
Phenotype
Visible or measurable traits
Phenotype
Differences in individuals which are measured by means of senses (e.g. litter size, color)
Phenotype
Dominance
Epistasis
Nonadditive gene action
determined at the time of conception, but the degree to which the potential is reached
during the animal’s life is determined by environment.
Genetic potential
The phenotypic expression of one gene doesn’t necessarily add to the
phenotypic expression of the other.
Nonadditive gene action
Kinds of Nonadditive gene action
Dominance and Epistasis
When a gene suppresses the expression of its allele, the former is called
the dominant gene while the latter is referred to as the recessive gene.
Dominance
Intra-allelic interaction (interaction of genes in the same locus)
Dominance
Different exceptions to Mendel’s principle
- Complete dominance
- Incomplete/partial/Codominance
- Overdominance
Form of dominance in which heterozygous and homozygous dominant genotypes
have the same phenotypic expression.
Complete dominance
Pp and PP (genotype) are polled cattle; pp (genotype) is horned cattle is an example of what kind of form of dominance.
Complete dominance
Dominance is absent and the progeny does not resemble any of its parents.
Incomplete/partial dominance
The Aa heterozygote is almost as valuable as the AA homozygote.
Incomplete/partial dominance
both alleles at a particular gene locus are fully expressed in the heterozygous
condition.
Codominance
neither allele is dominant or recessive to the other, and both contribute to the
phenotype independently.
Codominance
The heterozygote exceeds the phenotypic measurements of the homozygous
parents.
Overdominance
The heterozygote is more valuable than either homozygous genotype.
Overdominance
Inter-allelic interaction (interaction between genes at different loci)
Epistasis
An interaction among genes at different loci such that the expression of
genes at one locus depends on the alleles present at one or more other
loci.
Epistasis
Type of Epistasis
Recessive Epistasis
Dominant Epistasis
True or false. Multiple genes= one phenotype
True
The phenotypic ratio is 9:3:4
Recessive epistasis
One gene completely masks another gene
Recessive epistasis
Coat color in Mice = 2 separate genes
Recessive epistasis
When dominant allele ‘A’ masks the
expression of ‘B’, ‘A’ is epistatic
gene of ‘B’
Dominant epistasis
A’ can express itself only in the
presence of ‘B’ or ‘b’ allele
Dominant epistasis
‘B’ expresses only when ‘aa’ is
present Ratio is 12:3:1
Dominant epistasis
The effect of dominant gene ’Y’ is
masked by the dominant gene ’W’
(epistatic gene)
Dominant epistasis
The effect of one gene contributed to the
effect of another gene in the expression
of the same phenotype
Additive gene action
Thus, if more genes contribute to the
same phenotype, then the expression of
the trait in an individual is more intensive
Additive gene action
The laws of Gregor Mendel described
how the hereditary material is passed on
from parent to offspring as evidenced by
the physical appearance of the offspring.
The Mendelian inheritance
The two laws of Gregor Mendel.
Law of Independent Segregation
Law of Independent Assortment
Law that states that the alleles of a gene pair
separate completely and cleanly from
each other during meiosis.
Law of independent segregation
Can be illustrated using a monohybrid
cross.
Law of independent segregation
Monohybrid cross is a cross between
homozygous individuals that are different
from each other at one gene locus.
Law of independent segregation
States that genes for different characters
are inherited independently of the other
pairs
Law of independent assortment
Can be illustrated using a dihybrid cross.
Law of independent assortment
Dihybrid cross is a cross between two
homozygous individuals that are different
from each other at two gene loci
Law of independent assortment
