Intro to Animal Science Exam 3

Mendel’s Laws

Principle of Independent Assortment and Principle of segregation

what is the principle of dependent assortment

inheritance of one trait has no effect on the inheritance of another trait, genes for different traits assort independently of one another in gamete production

what is the principle of segregation?

2 members of a gene pair segregate from each other in formation of gametes, half of the gametes carry one allele and the other half carry the other allele. Each gene has 2 copies(alleles) and a parent will give one copy to a child, the other parent will give one-thus giving 2

what is genetics?

the study of structure, composition, and function of genes. a science which deals with the principles of heredity and variation

what is heredity

those traits or characteristics which are transmitted from generation to generation, can be physical, eye color, blood type, disease.

what is the chromosome? structure of chromosome?

strands of DNA (genetic material for all living organisms) located in cell nucleus, genes in linear order(not numerical), characteristic number fixed with species, originate in pairs.

what are the different types of chromosomes

autosomes, sex chromosomes

what are autosomes

chromosomes other than sex chromosomes

what are sex chromosomes

carry material to determine secondary sex characteristics/ gamete production

sex chromosomes in mammals

x chromosome and y chromosome

what are females? (sex chrom)

homogametic XX

what are males? (sex chrom.)

XY heterogametic

how do sex chromosomes in mammals work?

all normal egg cells carry one X and ½ normal sperm cells carry one X and the other ½ normal sperm cells carry one Y

diversity of sex determination

the sexual differentiation triggered by a main gene (a sex locus) with a multitude of other genes following in domino effect

sex determination systems?

z/w system (females are heterogametic, males homogametic; birds, reptiles, etc) x-0 system (females have 2 copies of sex chromosome (xx) but males only have one(x0) sex is determined by number of genes expressed across 2 chromosomes) haplo-diploid system(females are diploid and developed from fertilized eggs, 2 sets of chromosomes, males are haploid and develop from unfertilized egg, one set

what are alleles

a variant of a gene controlling the same trait, 2 forms of alleles exist: dominant allele and recessive allele

relationship with dominant and recessive

dominant will always express over recessive. dominant: capital letters, recessive lower case

dominant

will always be displayed even in a heterozygous with recessive allele, complete dominance

recessive

only shown in homozygous

homozygous

condition which both members of allele pair are indetical

heterozygous

allele pair are NOT identical

genotype

genetic makeup of an organism

phenotype

physical features/appearance of organism: expression of genotype, not only produced by genotype but also interaction between genotype and environmental factors

codominance

both alleles are expressed in phenotype when present in heterozygous state, roan both are seen

incomplete dominance

condition in the heterozygote where both genes are expressed in a way that differs from either homozygous condition, mixed, pink rose

what is a punnett square

a tool that allows you to see different gene combinations that are possible when two parents have offspring

what is hybridization

process of crossing two genetically different individuals

what is a hybrid

the progeny(offspring) of hybridization ex: coyote dog, puma

types of hybrids

monohybrid, dihybrid

what is a monohybrid

an organism which is heterozygous with respect to only ONE pair of allele at a locus under study

what is a dihybrid

an organism which is heterozygous with respect to TWO pairs of alleles at two loci under study

why might you want to crossbreed?

to take advantage of heterosis/hybrid vigor, to produce animals which blend characteristics of two or more breeds into a more desirable combination not available in any one breed, produce foundation stock for developing new breed

what is a reciprocal cross

two reverse crosses in which the sexes of the parents are interchanged, if the traits are autosomal the reciprocal cross always yields the same, if sex chromosome it gives different results

what is a breeding system?

set of management practices that are used by producers to ensure the transmission of certain traits from parent to offspring

what does a successful breeding systems need to consider? these factors can also affect these plans

environment, economical factors and technology

what to consider when finding what plan is best for you

climate conditions, types of market, knowledge of genetics, size of operation, personal preference, available resources, goals of breeder

what is random mating

individuals are selected for breeding, they may be managed in one breeding group with one or multiple sires, ultimately, there is no action taken to determine which animals from the selected group mate. animals choose who they mate with in group

what is pedigree mating

implies that all individuals in a genetic population are related to some extent

what is inbreeding?

closed herd, closely related breeding which may increase genetic uniformity but reduce performance especially fertility and survival

when to use inbreeding

when wanting to keep offspring pure, used more in purebred operations

what is phenotypic mating

plans are based on performance or visual appearance, not pedigree, and are called assortative

what is assortative mating and difference between positive and negative

breeding where individual with similar traits or genotypes tend to mate with each other. positive pairing is similar phenotypes/genotypes use to mate best to best and negative is pairing dissimilar phenotypes/genotypes use to mate worst to best to correct problems

what is crossing breeding

two different breeds, usually both purebreds, hybrid vigor: superior traits that come from crossbreeding causing offspring to have better traits than parents=heterosis

hybrid vigor

hybrid vigor: superior traits that come from crossbreeding causing offspring to have better traits than parents=heterosis

straight breeding/purebred breeding

registered purebred male crossed with a female of the same breed

what is grading up

mating purebred male (sire) to grade or unregistered or crossbred female (dam) to improve herd

benefits of grading up

improves quality, develops uniformity, increased performance in offspring

what is outcrossing

mating animals within the same breed but having no common ancestors on either side

what is linebreeding?

form of inbreeding to produce offspring with deserved characteristics, one selected parent should have one or more common ancestors in the pedigree in the last 5 generations

negatives of inbreeding

decrease reproductive efficiency, decrease vigor, decrease survivability and physical abnormalities

most important traits for selection

reproductive performance(highest economic value), maternal ability(milk), growth and efficiency(weaning, post weaning), market price, temperament(cattle) flocking instinct(sheep), longevity

what is EPD

expected progeny differences:the prediction of how future progeny of each animal are expected to perform relative to progeny of other animals in the database. expressed in units of measure for the trait, plus or minus(closer to 1,0 indicates higher reliability)

how to select without genetic data

use visual appraisal: structural soundness, breeding soundness, udder capacity, indicators of productivity and adaptability and visible factors affecting market price

what are 2 major phases with development

before birth/hatch(pre-natal) and after birth/hatch(post-natal)

pre-natal

from formation of embryo, through development of fetus to parturition

post-natal

begins immediately after birth

what is the most critical period

first 6 weeks

what are the four essential stages in early animal development

fertilization, cleavage, gastrulation, organogenesis

what do gastrulation and organogenesis contribute to together

morphogenesis-the biological process that results in organism’s shape and body organization

fertilization

the process of single sperm cell combining with single egg cell to form a zygote

cleavage

rapid, multiple rounds of mitotic cell division where the overall size of the embryo does not increase. the developing embryo is called a blastula following completion of cleavage

gastrulation

occurs after implantation, dramatic rearrangement of cells in blastula to create the embryonic tissue layers. these tissue layers will go on to produce the tissues and organs of adult animal

blastula

developing embryo

organogenesis

the process of organ and tissue formation via cell division and differentiation

important outcomes of gastrulation

1. formation of 3 germ layers,2 formation of embryonic gut(archenteron), 3appearance of major body axes

what are the 3 germ layers

ectoderm, mesoderm, endoderm; process of the tissues and organs that are formed by the developing embryo

ectoderm

gives rise to nervous system the skin epidermis and epithelial lining of mouth and rectum

mesoderm

gives rise to muscle cells and skeletal cells, the circulatory system and reproductive organs

endoderm

gives rise to many internal organs such as liver and pancreas and epithelial lining of digestive and respiratory system

what forms the organs

the continuous development of 3 different germ layers

organogenesis

process of organ and tissue formation via cell division and differentiation

tissue

group of similar cells that work together on specific task

organs

structures made up of two or more tissues organized to carry out a particular function

organ system

group of organs with related functions make up

tissue types

epithelial tissues, connective tissues, muscle tissue, nervous tissue

epithelial tissue

form covering of all body surfaces, their functions include protection, secretion, absorption, excretion, filtration, diffusion and sensory reception

connective tissue

connects and supports other tissues and the function is supporting organs and cells, transporting nutrients and wastes, defending against pathogens, storing fat and repairing damaged tissues

muscle tissues

essential for keeping the body upright, allowing it to move and even pumping blood and pushing food through digestive tract

nervous tissues

involved in sensing stimuli and processing and transmitting info

how does growth occur

hypertrophy(increase in cell size) hyperplasia (increase in cell number, before birth), accretion (a growth or enlargement by gradual build up)

3 tissue types that grow post natal

muscle, bone(matures first), and fat (adipose)

determined growth

mammals, grow to given size(set at birth), growth rate effected by environment

indeterminate growth

fish, lizards, snakes, no predetermined size, unlimited growth, will grow to available nutrients and environment; largely dependent on environmental factors

what makes muscle unique

ability to contract, protein filaments(myosin and actin) and multi-nucleated

what is myogenesis

the process of muscle tissue formation

how do muscles mature

embryonic precursor cells called myoblast fusing to form multinucleated muscle fibers

what determines the number of muscle fibers in an animal

length of gestation(slow pre-natal growth rate=large cell #) small versus large animals (large animal have slow growth at cellular level, rapid growth for live weight gain)

hyperplasia

condition where there is increased number of cells in a tissue or organ, longer gestation = more hyperplasia

what is the humane methods of slaughter act

requires humane treatment and handling of food animals at slaughter plant and providing quick and effective death passed august 27 1958 and was amended 1978 to stop slaughter activities if they believe an animal is being handled inhumanely

why is welfare and handling critical when moving animals

moving animals can be stressful and this should be limited

flight zone

animal’s safety zone which animal will move if human enters this zone

point of balance

imaginary point on animals body(shoulder) where if approached from front or rear, animal will move forward of backward

what is lairage

resting areas in packing plant where animals are contained until slaughter

why is proximity to processing plant important

less time traveling less time in lairage

what is the maximum time animal can be contained

no more than 28 hours

ante-mortem inspection

initial step in detection of any signs of disease, distress, injury of animals when they arrive at plant for slaughter occurs before slaughter. conducted 12-14 before slaughter by qualified vets. examine general behavior, reflexes, fatigue, excitement, gait, posture

ante-mortem inspection letters

u-unfit for slaughter, p-postpone slaughter and treat, s-handle as suspect, d- destroy and dispose, cu-conditionally unfit

immobilization/stunning techniques

mechanical(captive bolt), electrical, chemical (co2), renders animal unconscious and insensible to pain, prepares animal for exsanguination (bleeding)

what is exsanguination

sticking, removal of blood, essential for quality. severing carotid arteries and jugular veins

mechanical stunning

immobilized animals by eliciting trauma to head, captive bolt common in beef