Additional Study Material for Final Exam Flashcards
What is a phenotype?
The physical appearance of an animal
What is a genotype?
The genetic makeup of an animal
What is a genome?
The entire genetic material of an animal
What are genes?
The functional units of inheritance
What is the DNA composition?
Deoxyribose, phosphate, and nitrogenous base (A,G,C,T)
What sugar is present in RNA?
Ribose
What nitrogenous bases are present in RNA?
A, G, C, U
What are the bonding pairs in DNA?
A with T and C with G
What is replication?
The production of an exact replica of DNA
What is a mutation?
When replication is not exact due to chemical changes in DNA
What is migration?
Bringing new genotypes through breeding stock into a population
What is selection?
Using some animals as parents more than others
What are the two types of selection?
Natural and artificial
What information is included in DNA?
Directions for organization and metabolism of cells
How are amino acids coded for?
Through triplet codons of RNA
What are the two types of chromosomes?
Sex chromosomes and autosomes
What is the role of RNA?
To “read” the information on DNA and direct protein synthesis
What is transcription?
The synthesis of an mRNA strand by copying a DNA segment
What is translation?
Production of amino acids from RNA codon sequences
What is messenger RNA?
RNA that carries information about particular proteins and directs amino acid/protein synthesis
What is ribosomal RNA?
RNA that is essential for ribosomal structure and function
What is transfer RNA?
RNA that identifies codons in mRNA and moves amino acids into the proper place in the polypeptide chain
What is the locus?
The location of particular gene on a chromosome
What are homologous chromosomes?
Chromosomes with the same loci and structure
What are alleles?
Different forms of the same gene
What does homozygous mean?
Genes are alike for a particular trait (same allele)
What does heterozygous mean?
Genes are not alike for a particular trait (different alleles)
What is a dominant allele?
An allele that overpowers and prevents the expression of another allele
What is a recessive allele?
An allele that is expressed only when the animal is homozygous for non-dominant allele
Which cells are diploid?
Body cells
Which cells are haploid?
Gametes
What are the characteristics of qualitative inheritance?
- Controlled by a single gene
- Phenotypes are easily described
- Phenotypes are discontinuous (one or the other)
What is codominance?
When two alleles are both expressed in the heterozygote
What is incomplete dominance?
When three distinct phenotypes are possible due to the heterozygote being an intermediate
What is the homogametic sex in mammals?
Female
What is the homogametic sex in birds and reptiles?
Male
What is sex-linked inheritance?
Some genes are located on only the X chromosomes and are only expressed in the heterogametic sex
What are the characteristics of quantitative inheritance?
- Many genes involved
- Phenotypes described by measurements
- Continuous distribution of phenotypes
What are allelic interactions?
Interactions that occur between corresponding genes on homologous chromosomes
What is heterosis?
Heterozygotes show better results than either homozygote
What are the other two names for heterosis?
Overdominance and hybrid vigor
What are common environmental effects on phenotype?
Feed supply, temperature, housing, light
What is the formula for genetic progress?
genetic gain/year = (heritability x selection differential)/generation interval in years
What is heritability (h^2)?
The proportion of an animal’s appearance that is due to genetics and can be passed on
What is the selection differential?
The difference in a trait between the population mean and the average of the animals selected from the population for production purposes
Which quantitative traits are medium to high heritability traits?
Weight or weight gain related traits
Which quantitative traits are low heritability traits?
Health and repro traits
What is the generation interval?
The average age of the parents when offspring are born
What is the tandem selection method?
Selection for one trait at a time, then selection for a second trait once desired level fo the first trait is achieved
What is the independent culling levels selection method?
Minimum acceptable levels are assigned for each trait
What is the downfall of the independent culling levels method?
Outstanding animals in one trait may not meet the cut due to a poor secondary trait
What is the selection index method?
Several traits are evaluated and expressed as a total score
Which breeding selection method is typically most effective?
Selection index
What is a pedigree?
A chart that traces the lineage of a purebred animal
What is the difference between graded and registered animals?
Registered animals are recorded in a breed association and meet all organization standards; graded animals have similar genetics but typically do not meet one or more standards
What are scrubs?
Animals that look like representatives of a species but have an unknown ancestry
What is inbreeding?
The mating of animals that are more related than the general population
What are the effects of inbreeding?
Increased homozygosity, potential for lower growth and repro performance, higher susceptibility to stress and disease
What is line-breeding?
A milder form of inbreeding that tends to emphasize one outstanding ancestor
What is outbreeding?
The mating of males to unrelated females
What is a species cross?
The widest possible form of outbreeding, where animals of two species are mated
What is crossbreeding?
Mating two animals within the same species, but from different breeds
What is outcrossing?
Mating unrelated animals within the same breed
Which sex can be more intensively selected for and why?
Males, because one male can fertilize multiple females
What does a positive correlation indicate?
Traits that are directly related
What does a negative correlation indicate?
Traits that are inversely related
