ANSC 1000

Entero-

intestine

What is antrum?

Where estrogen is produced

Myo-

muscle

Mitosis (2)

* simple division of one cell into two
* the two daughter cells receive an exact copy of genetic material of the parent cell

Meiosis (2)

* genetic material halved so that diploid complement is reformed by fertilization
* in animals, this is gamete formation

Chromosome background info (5)

* in the nucleus
* called "colored body" with staining
* X where the two chromosomes come together is the centromere
* come in pairs, and all along the chromosome are genes
* when cells divide, chromosomes do as well

Which livestock species has the most chromosomes?

poultry

Which livestock species has the least chromosomes?

swine

How many chromosomes do humans have?

46 (23 pairs)

End result of mitosis

mother and daughter cells have exactly the same genetic components

4 stages of mitosis

* prophase
* metaphase
* anaphase
* telophase

Gametogenesis

production of gametes

Meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell (gamete)

How any chromosome pairs do gametes have?

one

Spermatogenesis

production of sperm

Oogensis

production of egg

Where does meiosis occur for spermatogenesis?

in the primordial germ cells near the outer wall of the seminiferous tubules of each testicle

Where does meiosis occur for oogenesis?

near the surface of each ovary

In meiosis, each chromosome pair comes together through \_____________

synapsis

What is the name of the cell that divides during meiosis? (2)

* primary spermatocyte
* primary oocyte

Spermatogensis

process in make where each meiosis produces 4 equally sized sperm cells

Cells from \________ produce primary spermatocyte

testes

Spermatid (2)

* most lose a lot of cytoplasm and develop a tail to become a sperm
* mature into sperm by spermatogenesis

Both primary spermatogenesis and oogensis contains a. . .

tetrad

Polar body

haploid cell produced during meiosis in the female of many species; these cells have little more than DNA and eventually disintegrate

Second maturation division of meiosis produces. . . (2)

* ovum
* polar body

During fertilization, each gamete contributes. . .

one chromosome

Fertilization

the union of the sperm and ovum along with the establishment of the paired condition of chromosomes

Gametogenesis reduces number of chromosomes in a cell to half (diploid/haploid), fertilization reestablishes this (diploid/haploid)

* haploid
* diploid

Locus

location of gene on a chromosome

DNA

deoxyribonucleic acid

DNA contains. . . (3)

deoxyribose sugar, phosphate, one of 4 bases

Nucleotide

monomer of nucleic acids made up of a deoxyribose sugar, a phosphate, and a nitrogenous base

Nucleotides come together to form what?

half of the DNA molecule

During mitosis/meiosis, chromosomes replicate by. . .

* unwinding the DNA strands and forming a new strand alongside
* form 2 double stranded molecules from 1

What do genes code for?

proteins

What are proteins made out of?

amino acids (20)

What codes for amino acids?

* DNA triplet sequence
* 3 nucleotides

What are the three steps of protein synthesis?

transcription, translation, replication

Transcription (4)

* first step
* synthesis of RNA from DNA in the nucleus by matching the sequences of bases
* involves messenger RNA
* transcribes encoded message and leaves the nucleus to the ribosome, where protein synthesis occurs

Translation (4)

* involves transfer RNA
* tRNA is coded by DNA in the nucleus and moves out to the cytoplasm
* identifies and unites w one amino acid
* contains anticodon complementary to mRNA (mRNA UUC attaches to tRNA AAG)

Replication (4)

* mRNA attaches to ribosome for translation of message into a protein
* begins at one end of mRNA and continues along the length
* fully formed protein dissociates

XX

female

XY

male

Does the sire or dam determine sex?

sire bc he contributes Y chromosome too

In birds, does the sire or dam determine sex?

the dam bc the hen is XY and the rooster in XX

Allels

genes that occupy corresponding loci in homologous chromosomes, but that affect the same character in different ways

Genotypic ratios

differences in the genetic makeup of the animal

Phenotypic ratios

the physical appearance of the animal

3 Types of Gene Interactions

* Linear
* Allelic
* Epistatic

Linear Interaction

interaction with another gene in the same chromosome

Allelic Interaction

interaction with its corresponding gene in a homologous chromosome

When unlike genes occupy corresponding loci . . .

complete dominance may exist

Epistatic Interaction (2)

* when a gene or gene pair alters or masks the expression of genes on another chromosome
* interactions with genes in nonhomologous chromosomes (non allelic)

Epistatic Interaction example

* horse coat color!
* extension gene = determines the base color. ee makes chestnut, Ee and EE make black
* agouti gene = determines if foal is bay (AA and Aa) or solid black (aa)
* some horses also have a white gene that masks all other colors (dominant gene is W, WW homozygous state is lethal, and w allows other color genes to express themselves)

External factors that may interact genes (3)

* nutrition
* temp
* amount of light
* the environment in general!!!

Which interaction is known to exist in lower animals, but NOT in farm animals?

Linear Interactions

Each gene occupying the same locus on homologous chromosomes may influence the trait differently. What does it depend on?

Dominance/recessive

Allelic interactions may also be called. . .

dominance interactions

When unlike themes occupy corresponding loci, \___________ \___________ may exist

complete dominance

complete dominance

a relationship in which one allele is completely dominant over another

Lack of Dominance (Incomplete Dominance)

the heterozygous animal shows a different phenotype than either a homologous (dominant or recessive) animal

Lack of Dominance example

* sheep ear length
* LL have long ears, ll are earless
* Ll heterozygous sheep have short ears (meaning it's intermediate)

Additive gene action occurs when. . .

* when each gene has an expressed phenotypic effect
* think the ADG problem on the worksheet

Overdominance

condition where the heterozygous animal outperforms the homozygous dominant and homozygous recessive parent

Heterozygotes of breed crosses are (more vigorous/weaker) than straight-bred parents

more vigorous

Hybrid vigor

greater vigor or productivity of crossbreds

Quick types of dominance review (3)

* Complete Dominance: Aa and AA are indistinguishable
* Lack of Dominance: Aa is intermediate between AA and aa
* Overdominance: Aa outperforms AA and aa

Partial Dominance

the heterozygote expresses intermediate phenotype BUT it most likely resembles the homozygous dominant parent

What is the most important interaction between genes and environment?

* feed supply
* easy keepers: breed that can survive when feed is in short supply for long periods of time and can eat anything they can
* hard keepers: the opposite

When the environment has a large effect on production traits, genetic improvement is (low/high)

- low

Biotechnology examples (7)

* use of living organisms to improve, modify, or produce industrially important products (microorganisms in dairy)
* genetic engineering
* DNA research and manipulation
* superovulation
* sexing of semen
* cloning
* embryo transfer

Genetic engineering

removing, modifying, and/or adding genes to DNA

Superovulation

* producing greater than normal number of eggs
* breed donor and flush uterus
* transfer to surrogate
* reverse AI

"genetic scissors" that cut DNA at designated places

enzymes

quantitative traits (3)

* objectively measured (can be measured by something)
* usually ones of economic importance
* ex: ADG, FE, WW, muscling, etc

qualitative traits

descriptive, subjective (color, big or small, etc)

Pleiotrophy

* when some genes may have an effect on more than one trait
* can work for or against you

equation for phenotype

p \= g + e

"What we see or measure"

phenotype

"True breeding value"

genotype

"Smoke screen"

environment

Contemporary group (2)

* a way to make the environment the same
* a set of animals raised under similar environmental and management conditions

Contemporary group examples (6)

* herd
* sex
* breed/type
* birth season
* weigh dates
* management

What makes animals different from each other?

genes or environment

Environmental differences (8)

* nutrition
* health
* weather
* injury
* management
* fertility of parents
* time of mating during the heat period
* season of the year

Environmental effects can be \_____________ or \________________

known or unknown

Known environmental effects

have an average/predictable effect on individuals

Unknown environmental effects

random in nature and more difficult to control

Management uses \______________ \________________ to record known/unknown environmental effects

adjusted records

Weaning weight adjustment

205-day WW \= (actual WW - birth weight)/weaning age in days) x 205 days + birth weight + correction factor

EPDs

Expected Progeny Differences

What is an EPD?

a prediction of future progeny performance relative to some standard

What do EPDs do?

help compare animals to each other

How are EPDs calculated?

using statistical procedures that take into account large amounts of information

ex: individual's record, ancestor/progeny records, heritablility of the trait, etc

Can you compare EPDs across breeds?

NO, because different breeds have different standards

Heritability (H2)

The portion of the phenotypic (observed) variation in a trait which can be attributed to transmissible genetic effects (i.e, additive genetic effects)

Reproductive traits are (lowly, moderately, highly) heritable

low

Growth traits are (lowly, moderately, highly) heritable

moderately

Carcass traits are (lowly, moderately, highly) heritable

highly