Genetics Final study cards

2 benefits of cloning

1. There’s a smaller generation interval
2. increased uniformity

DNA factors (2)

It replicates prior to cell division during mitosis

It’s composed of two parallel chains held together by weak hydrogen bonds

Meiosis factors (2)

The second stage (Called Meiosis II) consists of division of haploid cells

In the case of males, it results in 4 functional sperm cells

RNA factors (2)

It’s involved in both transcription and Translation

MRNA carries genetic information from DNA, out of the nucleus into the cytoplasm

Gene linkage factors (2)

Crossing over involves the reciprocal exchange of chromosome segments between homologs and may disrupt the linkage of two genes

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Recombination involves new allelic pairings of genes

Hardy-Weinberg (2)

States that genotypic and phenotypic frequencies remain constant through time if the qualifying conditions are met

Is a mathematical formula that describes genotypic frequencies in terms of phenotype

Factors of post-transcriptional RNA modification (3)

The Addition of a 7-methylguanosine cap

Addition of a poly a tail to primary transcript

Splicing of introns

In Hardy-weinberg 2pq represents

Heterozygotes

AaBb x aabb is an illustration of: (2)

A Dihybrid cross

A Test cross

Benefits of alternative splicing

Different proteins can be generated from a single gene

Variations of stop codon (3)

UAA

UGA

UAG

If a strong negative change in mature weight is observed along with a positive change in meat tenderness then the two traits have:

Strong negative correlation

The most important genetic parameter for an individual

Breeding value

The degree of heterosis in the offspring can be affected by (2)

The heritability of the trait

Genetic relationship of the parents

Correlation (3)

It’s unitless

Is the same for X and Y and Y and X

It ranges from -1 to 1

In Non-random mating (2)

The expected proportion of homozygous and heterozygous is derived from Hardy-weinberg (H-W)

Assignment of mates can be based on genetic relationship and phenotypic similarity

Inbreeding depression (2)

It is the opposite of heterosis

Results from poor gene combination value

byx (3)

It represents the regression of Y on X

There’s an assumption of cause and effect

Represent variation in trait X that influences the variation in trait Y

Effects of Outbreeding

An increase in heterozygosity

What is NOT an example of extensive/major use of crossbreeding

Crossing of two dairy breeds such as holstein and jersey

Environmental correlation (2)

Measures of strength of relationship between the environmental effect of one trait over another

Is often used for management purposes

Heterosis (2)

Results from an increase in heterozygosity

Gene combinations are not transmitted to progeny

{On test this was A, C remember the terms those}

The Rate of genetic change with selection depends on: (3)

Selection differential

Generation interval

Heritability

Accuracy of individual performance is: (3)

Based on an individual’s records

Higher heritability equaling higher accuracy

Accuracy equaling the square root of heritability

Reasons why pedigree information is valuable for selection decision (2)

It can be used for traits expressed later in life

It’s cheap and is valuable for sex-limited traits

The major objective for progeny testing for a qualitative trait

To help determine if an animal is a carrier for a detrimental recessive allele

Independent culling method (2)

An animal must meet the standard for each trait in order to be saved for breeding purposes

It has the potential to cull an animal that’s outstanding in a trait

BLUP: (3)

Method of genetic selection when performance data comes from genetically diverse groups

Is an extension of selection index

simultaneous solution of a number of equations using matrix algebra

Across breed EPD adjustments (3)

It’s useful to commercial producers purchasing bulls for crossbreeding

The accuracy of across-breed EPD is dependent on the accuracy of within-breed EPD for the bull

Useful in estimating divergence of birth-weight EPD for bulls to breed to first calf heifers

Problems in determining heritability in equine selection (3)

Tremendous environmental variation

Data bias

Limited information resulted from analyzing only the best

In Dairy selection, the selection is primarily based on the sire because: (3)

Sires produce more progeny the dams

Artificial insemination allows for more progeny

Lower cost with keeping few or no bulls

Beef infrasture (3)

Purebred

Cow/calf operations

Stocker

The inheritance of a type of horn growth in cattle that’s dominant in males but recessive in females

Sex-influenced trait

Parents with normal vision produce daughters with normal vision, but if the dam is a carrier, half of the sons will be color-blind

Sex-linked trait

An allele in horses that gives rise to the overo coat pattern, that along with white coloration, has an effect on homozygosity where the foal develops anganglionsis and dies a few days after birth

Lethal gene action

Three consecutive bases with DNA or RNA (nucleotide triplets) that code a specific amino acid

Genetic code

A situation where heterozygous is superior to both homozygous in performance and disease resistance

Overdominance

An autosomal gene where DD individuals have normal skin, Dd individuals have freckled normal skin, and dd individuals have freckles that ulcerate under UV light; this condition is fatel before puberty

Semi-lethal gene action

When the phenotypic effect of a gene at one locus is dependent on what allele is present at another

Epitasis

Traits that can only be expressed in one sex due to anatomical difference and lack of penetrance/ or the gene simply being turned off the the other sex

Sex-limited

Relatively common disorders that can be split into grades based on increasing severity

ex: congenital heart disease of kees-hounds

Variable expressivity

Group of individuals within a species that can potentially inbreed and share a common genepool

Population

The measure of strength between breeding value for one trait and breeding value for another trait

Genetic correlation

The measure of how well two breeds compliment each other for a specific trait

Specific combining ability

A mating system where the best male is mated to the best female for and with the same trait

Assortative mating

Animals with the same alleles from a common ancestor

Identical by descent

A system of mating where genes of a common ancestor is concentrated in an individual

Line-breeding

Mating purebred males to non purebred females in an attempt to create a purebred population

Top-Crossing

Combining the desirable characteristics of 2 or more breed (or lines) into the same offspring

Line-breeding

Animal model which combine all information known about an individual and it’s relatives to create a genetic profile of the animal’s merit (mainly in meat breeding)

Expected progeny difference

Expectation of a squared deviation from its mean

Variance

The superiority of the offspring from outbred mating in comparison to the average phenotypic merit of offspring from purebred mating contributing to the cross

Heterosis

Term used for alleles in individuals that happen to look alike but don’t share a common ancestor

Indentical by state

The ability of the parent to impress its hereditary characteristics on its progeny because of increased homozygosity

Prepotency

The probability that 2 alleles at a locus in an individual are identical by descent

Inbreeding coefficient

Average age of parents when the animals that replace them are born

Generation interval

A selection method that selects for one trait at a time

Tandem selection

A measure of how good and close a calculated estimate of an animal’s genetic value is compared to the unknown true genetic value

Accuracy

One of the markers associated with meat tenderness

Calpastatin

A genetically similar group of animals born in and raised under the same management and environmental conditions

Contemporary group

Changes in ranking of performance of genotypes in different environments

Genotype-Environmental interaction

The evaluation of an individual’s genotype using the performance of its progeny

Progeny test

The difference between the average for a trait in replacement animals and the average of the group the replacements were picked from

Selection differential

A single number that predicts the breeding value of an individual for weighted combination of traits

Selection index

A developmental duplication with high embryonic death among homozygous recessive individuals with incomplete penetrence

Polymelia

An autosomal recessive gene that is usually selected against in beef cattle production. It’s characterized by severe lethal deformities in calves

Tibial Hemimelia

In equine selection, taking the fastest winning times at a particular distance for the past 3 years at a given track

Speed index

An inherited disease in horses caused by a defect in the voltage-gated sodium channels of muscle cells

HYPP: Hyperkalemic periodic paralysis

A condition where foals cannot properly store/metabolise glucose leading to abnormal polysaccharides in cells

Glycogen branching deficiency

An important economic trait in sheep relating to live and carcass traits

Dressing percentage

The systematic collection of comparative production information of an individual

Performance testing

The selection differential measured in phenotypic standard deviation units of the selected trait

It’s inversely proportional to the proportion of available replacement

Selection intensity

A recorded trait that has been standardized for a given effect such as age or environmental factors

Adjusted trait

A collection of information that has been systematically organized for easy access and analysis

Database

Refers to the ability of a breeding animal to remain in the breeding herd

Stayability

Linear descriptive traits that can affect milk production in cows

Type traits

An inherited disease in fairy where the animal shows bilateral hind leg weakness between the ages of 6 to 18 months resulting in a weaving gait

Bovine progressive degenerative myeloencephalopathy

An inherited disease in dairy where animals have soft tissues, low appetite, chronic pneumonia and diarrhea

BLAD

If the template is the sense strand what is the mRNA it would produce? (2)

The sense strand is the complementary strand of DNA with the same sequence as the mRNA

Whatever the sense strand is a complementary Antisense strand will be coded

3 Types of modification mRNA goes through and the role the modification plays

1. Splicing: Removes the introns & joins exons together
2. Capping: Protects RNA from decay
3. polyadenylation: protects from degradation, aids in transcription, exports mRNA from nucleus

Describe the process and function of each enzyme involved in DNA Replication

1. Polymerase 3: Produces new strands of complementary DNA
2. Polymerase 1: Fills in gaps between newly synthesized okazaki segments
3. DNA Helicase: Unwinds double Helix
4. Single strand binding protein: Keeps Helix Open
5. Primase: Creates RNA primer to initiate synthesis
6. Ligase: Welds together okazaki fragments

Steps of translation and roles of mRNA. tRNA, and rRNA

1. Initiation: rrna initiates catalyst, mRNA is started after ribosomal subunits bind to it. tRNA binds start codon to mRNA
2. Elongation: tRNA starts translation, each codon is translated and amino acids are added to the chain until all have been read by rRNA. rRNA binds mRNA to begin translation
3. Termination: MRNA employs stop codon to stop tRNA’s processes

When an allele that is dominant is influenced by a dilation gene which alters the appearance of offspring

Non-dominance epistasis

Describe the experiments of Avery, Mcleod, and Mccarty’s that prove DNA is genetic material

Their experiments involved isolating strains of bacteria and watching the DNA transform another strain with its characteristics.

4 major differences between DNA replication and RNA transcription

1. Replication copies two strands of DNA
2. One strand of DNA becomes 2 daughter strands
3. RNA transcription strands only produce a single identical strand
4. Replication occurs before cell division, transcription happens before protein translation

Phenotype

Observable characteristics in an organism

Alleles

Alternate forms of a gene

Independent assortment

Alleles of one gene separate into gametes randomly with respect to alleles of other genes

Gametes

Reproductive cells containing only one copy of each gene

Gene

The heritable entity that determines a characteristic

Segregation

The separation of two alleles of a gene into different gametes

Heterozygote

An individual with two different alleles of the same gene

Dominant

The allele expressed in the phenotype of a heterozygote

F1

Offspring of the (Parent) P generation

Test Cross

The cross of an individual of an ambiguous genotype with a homozygous recessive individual

Penetrence

Proportion of individuals carrying a particular variant of a gene that also expresses an associated phenotype

Recessive

The allele that does not contribute to the phenotype of the heterozygote

Breed standards

The description of how an animal should look and behave

Homozygote

Having to identical alleles of a given gene

Genotype

The alleles an individual has