Intro Exam 2 Flashcards
Zygote
a fertilized egg
Mitosis process
- one cell–>two
-both cells get exact copy of genetic material from parent cell
Meiosis
- genetic material halved
-diploid complement is reformed by fertilization
-Gamete formation in animals
Which species has most and fewest pairs of chromosomes
Poultry=most
Swine=fewest
Mitosis steps
Prophase, Metaphase, Anaphase, Telophase
Where does meiosis occur
Primordial germ cells
The doubled pairs in meiosis come together through:
Synapsis
What are the cells called in meiosis
-primary spermatocyte
-primary oocyte
Spermatogenesis
when each meiosis produces 4 equally sized sperm cells
What are homologous Chromosome
Chromosomes paired in diploid cells
DNA Bases
- Adenine (A) pairs with Thymine (T)
-Guanine (G) pairs with Cytosine (C)
Protein Synthesis Steps
1) Transcription (synthesis of RNA from DNA in the nucleus by matching base sequences)
2) Transfer RNA/tRNA (tRNA gets coded by DNA in the nucleus then moves to the cytoplasm where it identifies and connects w/ an amino acid)
3) These amino acids formed then go down to the ribosome where peptide bonds form btwn the amino acids
4) tRNA gets released and there’s a newly formed protein
Who determines sex of offspring
Male
Linear Interaction
When genes in the same chromosome interact
Allelic interaction
When corresponding genes interact in a homologous chromosome
Epistatic Interaction
When a gene/gene pair alters or masks the expression of genes on another chromosome (nonhomologous chromosomes)
Overdominance
where the heterozygous animals are superior to either of the homozygous conditions
Hybrid Vigor
the greater vigor/productivity of crossbreds
Somatotropin
protein hormone produced in anterior pituitary gland to stimulate growth
Qualitative traits
-only 1-4 pairs of genes control 1 trait
-simple inheritance
-descriptive/subjective
Quantitative traits
-ones that are economically important
-many pairs of genes affect one trait
-objectively measured
Pleiotropy
when genes have effect on more than one trait
P=G+E
phenotype=genotype+environment
What is a contemporary group
a group of animals with the same:
-herd -sex -birth szn -weigh dates -breed/breed type
Ratio=
(individual measurements/avg. group measurement)x100
Adjusted Data
Adjustments: age of dam/age of calf
205-day WW=
((actual WW-BW)/weaning age in days)x205
then +BW
What’s an EPD
(expected progeny difference) is a prediction of future progeny performance relative to some standard
How is reliability of an EPD expressed
accuracy
genetic change/year=
(accuracy x intensity x genetic variability)/generation interval
Tandem method
-select only one trait at a time in sequence
-effective if requires rapid change in a single trait
Independent culling levels
-Est. minimum cull standards and select simultaneously (but independently) for each character
-most prevalent method of selection!!
-WEAKNESS: individual can be culled for lacking only 1 trait
Selection index
-formula set up assigning a weighting factor for each trait; all important values are combined into one overall value
-individuals are organized in order of net genetic worth
-DISADVANTAGE: index=difficult to come up with
Inbreeding
-Mating of animals closer related than avg. of breed/population they came from
-increases the # of pairs of genes that are homozygous (reduces genetic variation within lines)
- why do it: fix a specific trait, get heterosis when inbred lines are crossed
Inbreeding disadvantage
-disadvantage: may uncover recessive genes (undesirable) which will then show up at a higher frequency
-disadvantage: overall performance is decreased in inbred lines
Linebreeding
- a form of inbreeding
- an attempt to concentrate the inheritance of 1+ outstanding ancestors in a pedigree
- used by producers who have high level of genetic superiority
Outbreeding
-mating of individuals that aren’t related
-increases heterozygosity
Outcrossing
-mating unrelating individuals of the same breed
-most widely used breeding system
Rotational cross
-crossbred female x male of third breed
-crossbred female x breed of sire present in her genetic makeup in lowest %
Terminal cross
-all offspring are sold
Primary male sex organ
testis (gonad)
Function of testis
- produce sperm
- produce testosterone
What is the Scrotum
-sac that contains testes
-regulates temp of testes for sperm production
Tunica dartos muscle
-where: scrotum
-what: pushes testes upward to body for warmth/relaxes to cool
Cremaster muscle
-where: scrotum
-what: helps regulate temp of testes
Which animal has highest concentration of sperm
ram
What’s the heritability estimates for repro traits
5-15%
Which species testes are vertical
- Ram
- Bull
Which species testes are horizontal
- Stallion
- Boar
What are the accessory sex glands and their functions?
-seminal vesicles: supply nutrients for sperm following ejaculation/deposition into female
-prostate gland: clean/lubricate the urethra ahead of sperm
-cowper’s: clean/lubricate urethra
Species variation in glans penis
- bull: tapers to end
- ram: filiform (tubular) appendage
- boar: spiral
- stallion: bloated end
Which animals have a sigmoid flexure
-ruminants
-boar
Seminiferoud tubules
-produce sperm
-approx. 90% of testes mass
-spermatogenesis occurs in lumen
Sertoli Cells
-provide nourishment for developing sperm
-located within semi tubules
Interstitial cells (leydig)
-produce testosterone
-located btwn semi tubules
Where is sperm produced in the testicle and what two types of cells are found there
-produced in seminiferous tubules
-cells=steroli and interstitial
Which cell is inside tubules and which is between?
-in=steroli
-btwn=interstitial
How many functional sperm are produced from one primary spermatocyte
4
What’s contained in the head of the sperm?
genetic material
What does the tail of sperm allow
Sperm to be motile
Endocrinology definition
study of hormones, their effects, and glands that secrete them
How are hormones transported in the body
through blood circulation, gets carried to a target tissue in body where they have effect
What are the 2 lobes of the pituitary
anterior and posterior
What are the functions of testosterone
-stimulate growth, development, and secretory activity of accessory glands
-stimulate growth of repro tract at puberty
-initiate spermatogenesis
-necessary for sperm survivak
-responsible for secondary sex characteristics
List 3 secondary sex characteristics in male
-voice
-muscle development
-libido
