GENETICS AND LIVESTOCK IMPROVEMENT Flashcards
the branch of biology that deals with the principles of heredity and variation in all living things
genetics
important contributors to the field of genetics
- gregor mendel (1866)
- hugo de vries 1901
- carl correns 1901
- erick von tshermark 1901
- william bateson (1906)
- johannsen (1909)
- james watson (1956)
- francis erick (1956)
father of genetics;
austrian monk who conducted breeding experiments on garden peas (pisum sativum L.);
formulated his hyphothesis about inheritance of characteristics in plants;
discovered that heriditary characteristics were determined by elementary factors (called GENES)
gregor mendel (1866)
independenty rediscovered the works of mendel in 1901
hugo de vries (netherlands)
carl correns (germany)
erick von tshermark (austria)
english biologist, studies inheritance of certain characteristics of the chicken;
showed that the mendelian laws applied also in animals
william bateson (1906)
danish biologist, coned the term GENE to refers to the particulate factor that mendel hyphothesized as the basic unit of inheritance
Johannsen (1909)
two young scientists of cambridge, university of england;
hyphotesized by the chemical nature and function of the gene w/c is now iniversally accepted
james watson and francis crick (1956)
improvement with the performance of the animals brought about by selection assuming that the environment is favorable
genetic improvement
primary genetic material of all cells;
biochemical compound consisting of chain of nucleotides
DNA deoxyribonucleic acid
chain of nucleotides;
each nucleotides consists of phosphate (P), sugar (S) and base (B)
polynucleotide
threadlike structures found in the nuclei of the cell
chromosome
the building blocks of proteins;
specific combinations of 3 bases;
20 of w/c are normally found in proteins are referred to as esential amino acids
amino acids
segment of DNA w/c determines the base sequence of nucleotide in the messenger ribonucleic acid (m-RNA) that makes up the code for a certain biological function
gene
the mechanism of cell division by w/c the genetic and chromosome composition of a cell is faithfully reproduced in each of the daughter cells;
means of growth and replacement in multicellular organisms
mitosis
special kind of cell division in sexually reproducing organisms whereby the chromosomes number of the cells is reduced to half
meiosis
process by w/c the germinal cells divide to produce haploid cells each carrying only one-half of the genetic complement of the individual
meiosis
genetic materials is transmitted from parent to offspring is made possible through the reduction division of the germinal cells and subsequent union of the gametes
meiosis
cell, tissue, or organism that contains two genomes or chromosome set
diploid
cells that contain half as many chromosome as the somatic cells
haploid
mechanics by w/c the gene i avle to synthesize protein in the cell underlies the realationship among G, and E in the formation of phenotype (P) of the organism
the G x E interaction
refers to the specific combination of genes that are associated w/ particular chracteristic of indivudual;
genotype
totality of non-genetic factors affecting the indivudual
environment
the observable manifestation of a given character of an individual; this can be change but the genotype remains
phenotype
may be active only when they occur in pairs of alleles during the diploid phase
gene action
one of two or more alternative forms of a gene w/c are usually recognizable by the phenotype
allele
directly responsible for the synthesis of a certain biochemical products during cell metabolism
structural genes
control or regulate the function of other genes; may function in terms of quantity, quality or timing of the activity of certain structural genes
regulator genes
action of genes as they influence genotypic values (3)
- additive
- dominance
- epistasis
pair of allelic genes contribute independently to the genotypic value
- additive
corresponding trait determined by an alle w/c is manifested in the heterozygote form
- dominance
taken from the greek word w/c means “to stand upon”
interaction of between two or more genes so that one of them (epistatic gene
) interfers w/ or even inhibits the phenotypic expression of the other gene (hypostatic gene)
- epistasis
allows the flow of the genetic material from generation to generation; involves two process
animal production
two process of animal production
- gametogenesis
2. fertilization
process of producing reproductive cells
- gametogenesis
gametogenesis (2)
- spermatogenesis
2. oogenesis
process of differenciation of a mature sperm cell from an undifferentiated germ line cell, including meiosis;
male produces sperm cells
- spermatogenesis
process of differentiation of mature egg cell from an undifferentiated germ line cell, including meiosis;
female produces eggs
- oogenesis
mature reproductive cell capable of fusing w/ similar cell of the opposite sex to form a zygote; also called sex cell
gamete
male gametes of animals
spermatozoa
female gamete
ovum
the fusion of two gametes of opposite sexes to form a zygote or an embryo
- fertilization
process of segregation and recombination of genes is giverned purely by chance and that the occurrence of each new combination may be predicted according to the rules of probability
the medelian inheritance
states that the unit of hereditary chracters occur in pairs, and that in the information of gametes during meiosis, these separate from each other so that only one member of the pair goes into the paricular gamete;
each parent must have contributed equally to the progeny;
it is a matter of chance wheter the gamete gets the dominant or the recessive allele
LAW OF SEGREGATION
states that the genes for the different characters are inherited independently from each other and randomly combine during meiosis
LAW OF INDEPENDENCE
the medelian inheritance (2)
- law of segregation
2. law of independence
the inheritance of some characters did not follow the mendelian laws;
deviations were due to chromosomal phenomena
non-mendelian inheritance
measure of the tendency of some genes to be inherited as a group rather than individually because of the proximity of their loci in the chromosome
linkage
place at w/c particular gene resides on genetic or linkage map
locus (plural. loci)
carry genetic material but do not determine sex
autosomes
determine the sex of the individual
sex chrosomes
sex chromosome pair of mammal
Male = XY Female = XX
sex chromosome pair of bird
Male = ZZ Female = ZW
genes that are located in the sex chromosomes
sex linked genes
the inheritance of certain characteristics that are associated w/ one sex or the oher because the genes controlling them are located in the sex chromosomes;
the heterogametic offspring could only receive the gene from its homogametic parent while the homogametic offspring receives the allelic genes from the parents;
the distribution of the genotypes in the male and female progeny is not the same when reciprocal crosses are made between pure recessive and dominant genotypes
sex linkage
non-nuclear inheritance (2)
- cytoplasmic inheritance
2. maternal influence
occurs in plants; chlorophyll - bearing plastids are carried in the cytoplasm;
rare in animals;
there are some evidences it is affecting milk production may be present in cattle
- cytoplasmic inheritance
other than the genetic materials in the chromosomes and the possibility that there may be genetic materials in the cytoplasm, the mother could further influence the characteristics of her offspring because of the material care she provides to her young;
forms part of the total environment of the individual
- maternal influence
the totality of the genes that could potentially be trasnmitted by individuals in a population to the next generation
gene pool
group of individuals sharing a common gene pool;
community of sexually interbreeding or potentially interbreeding individuals;
characterized by the frequencies in w/c the genes and genotypes occur in them
population
state when no chage may occur;
equilibrium population
stating that in an indefinitely large population undergoing random mating, the gene and genotypic frequencies will remain constant from the generation to generation provided that there are no selection, migration, and mutation.
hardy-weinberg equilibrium
who formulated hardy-weinberg equilibrium principle
formulated independently by british mathematician hardy and german physician weinberg in 1908
factors affecting the genetic compisition of a population: (4)
- selection
- migration
- mutation
- non-random mating
process in w/c certain genotypes contribute more progeny in the next generation than other genotypes
selection
process in w/c individuals from one population transfer to another population;
change in genetic composition in the host population after migration is directly proportional to the 2 factors.
migration
factors in the chnage in genetic composition (2)
- the number of migrants in proportion to that of the resulting population after migration
- the difference in the gene frequencies between the migrants and the natives
spontaneous change in the biochemical structure of the gene resulting in an entirely different phenotypic effect;
if it occurs in the somatic cells (as in the cancer), it is not heritable;
if it occurs in the germinal cells, then it could be transmitted to the next generation.
mutation
occurs when some individuals do not have the same clhances of mating w/ individuals of the opposite sex;
only changes the genotypic frequency in the population
non-random mating
important forms of non-random mating (3)
- assortative
- disassortative matings
- inbreeding
individuals that are more phenotypically similar tend to mate more often;
tend to drive the population toward homozygous
- assortative
individuals w/c are less phenotypically similar tend to mate more other together than would be expected by chance;
tend to maintain the production of more heterozygotes at the expense of homozygotes
- disassortative matings
individuals that are related by descent tend to mate more often than under random mating; also tend to drive the population towards the increase in the frequency of homozygotes
- inbreeding
sex dimorphism in mammals where only the mating between XX and XY genotypes is successful
complete disassortative matings
record of an individual’s ancestors related to it through its parents;
ancestral relationships among individuals of a family over two or more generations
pedigree
