ANSC 612 Exam 1

Genetics

The study of variation and heredity in living organisms

Genotype

The genetic makeup of an organism

Domestic animal

an animal that is no longer wild, but has been bred or tamed by humans to perform various functions

Wild animal

an animal that lives independently of people, in natural conditions and with natural characteristics

Captive animal

animals kept in zoos or wild animal parks

Domestication

The process whereby a population is changed at the genetic level through generations of selective breeding, to accentuate traits that ultimately benefit humans

Animal Breeding

A branch of animal science that addresses the evaluation of the genetic value of livestock. The selection of breeding animals with superior growth rate, egg, meat, milk, or wool production, or with other desirable traits.

Phenotype

An organism's physical appearance, or visible traits

Evolution

The gradual change in a species over time

Commensals

Animals adapted to human niche

Prey

Animals used for food

Targeted

Animals used for Draft and Nonfood resources

Natural =

Domestication (wild to tame)

Experimental =

Domestication (wild to tame)

Reverse =

Fertilization (tame to wild)

Cattle Ancestor =

Auroch

Wildlife

Undomesticated animal species, now includes all organisms that grow or live wild in an area without being introduced by humans

Population

A group of individuals that belong to the same species and live in the same area

Trait

A characteristic that an organism can pass on to its offspring through its genes

Predicting Phenotype

P = G + E

Plasticity

The ability of one genotype to produce more than one phenotype when exposed to different environments

Important Concept:

Genotypes must be different due to evolution and not just raised or trained differently

Genetic Diversity

The range of genetic material present in a gene pool or population of a species

Biodiversity

the variety of life in the world or in a particular habitat or ecosystem

Biodiversity: Variation in

- Ecosystems

- Species

- Populations within species

- Genetic Diversity within species

Genes

Chemical instructions for building proteins

Locus

Psychical location of a gene on a chromosome

Diploid Cell (2n)

two sets of chromosomes

Haploid cell (1n)

A cell containing only one set of chromosomes (n)

Allele

Each version of a gene

Homozygous

An organism that has two identical alleles for a trait (AA)

Heterozygous

An organism that has two different alleles for a trait (Bb)

- Dominant allele= B

- Recessive allele= b

Homozygous dominant

AA

Homozygous recessive

aa

Genetic Diversity: A measure of

1.) How many different versions (forms) of genes exist across a genome among individuals in a population.

2.) How frequently they occur

Nucleotide Diversity

comparing the nucleotide sequences of DNA samples from two individuals then pooling the data from many such comparisons of two individuals

Why is genetic diversity important?

- Diverse gene pool gives a population more flexibility to survive in a changing environment

- The more genetically diverse a population, the more ways it has to adapt and survive

10 ways to use genetics in conservation effects:

1.) Decrease extinction rates by reducing inbreeding and the resultant loss of GD

2.) Identify species/populations at risk for reduced GD

3.) Resolving fragmented population structures

4.) Resolving taxonomical uncertainty

5.) Defining management within a species

6.) Detecting hybridization

7.) Non-intrusive sampling method for genetic analysis

8.) Defining Sites for reintroduction

9.) Forensic investigations

10.) Understanding species biology

Homologous Chromosomes

Chromosomes that have the same sequence of genes and the same structure

Centromere

Area where the chromatids of a chromosome are attached

Telomeres

DNA at the tips of chromosomes

Telocentric Chromosome

Centromere is at tip

Acrocentric Chromosome

centromere is close to tip

Submetacentric Chromosome

Centromere is off center

Metacentric Chromosome

centromere is in the middle

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape

Chromosome Theory of Heredity (1902) Sutton-Boveri Theory

- Heredity "factor" is in nucleus

- Chromosomes only part of nucleus that are equally divided

- Chromosomes occur in pairs

- Chromosomes separate at meiosis

- Members of chromosome pair appear to segregate independently

Female sex chromosome

XX

Male sex chromosome

XY

Ideogram

A schematic representation of a chromosome

Cytogenetics

1.) Genetics subdiscipline that focuses on chromosome variations

2.) Abnormal gene or chromosome copy numbers can lead to genetic abnormalities

Molecular Cytogenetics and Genomics Laboratory:

- Services: Karyotyping

- "Our Lab specializes in performing karyotyping analysis for a variety of animals like cattle,

horse, sheep, goat, pig, dog, cat and even exotic species"

Chromosomes are only visible about __ of the time.

5%

Karyotypes are visualized when the cell is in _________.

Metaphase

The four phases of mitosis:

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

How the cytoplasm divides: Cytokinesis

- Begins toward end of anaphase

- Finishes after telophase

- Cleavage furrow forms

- Microfilaments pull plasma membrane inward around the cell

- Pinches the cell in two

Meiosis

- Single DNA replication

- Two divisions of cytoplasm

Meisosis I = Reductional division

- Separation of homologs

- Reduces chromosomes to haploid (n)

- Haploid: one set of chromatids

Meisosis II = Equational division

Sister chromatids of haploid cells are separated

Species Crossing

crossing animals of different species; ex: Liger or Tigon

Aneuploidy

Embryo does not have an exact multiple of the number characteristic of that species (part of the set is wrong).

Polyploidy

Embryo has three, four, or more sets of chromosomes (complete set duplicated).

Triploid

A chromosomal mutation where an organism has three sets of chromosomes (3n) instead of two (2n)

Tetraploid

4 sets of chromosomes

Result of unreduced gamete (2n) + normal gamete (n):

- Two sperm fertilize one egg

- Haploid sperm + diploid egg

Four F's When Selecting Wild Animals to Domesticate:

- Feedable - should look for herbivores that aren't picky and will eat something that's everywhere that we can't eat (like a cow eats grass and then provides meat).

- Friendly - domesticating animals that aren't super dangerous and or won't easily scare/try to run away will make it easier.

- Fecund - animals that are willing to reproduce, don't have preferences that might make them incompatible to captivity (like pandas do), and don't have a long reproduction process will make for easier breeding.

- Families - horses are better then zebras because zebras are dangerous (kick and bite), hard to lasso, and lack family structure. While horses have a horse herd hierarchy and by capturing the lead male we become the head horse and create a family structure. I'm conclusion, horses are just more family friendly than zebras.

Chromosome Nondisjunction

Failure of the chromosomes to separate properly during meiosis or mitosis

Nondisjunction of Autosomes

- One or more pairs of chromosomes fails to separate during cell division

- Probability increases with age

- If such a gamete is fertilized: Trisomy and Monosomy

Trisomy

a condition in which an extra copy of a chromosome is present in the cell nuclei, causing developmental abnormalities

Monosomy

Chromosomal abnormality consisting of the absence of one chromosome from the normal diploid number

Deletions

- Permanent loss of genetic material

- Causes: spontaneous, viral, irradiation, chemical, or environmental

Terminal Deletion

Deletion close to chromosome end

Interstitial Deletion

Deletion within chromosome arm

Arthrogryposis Multiplex (Curly Calf Syndrome)

Joints are fixed in abnormal positions at birth. Lethal genetics in angus cattle

Duplications

- Gene sequences that are repeated

- Very few genetic disorders have been linked with this

Structure Abnormalities

Larger regions of deletion or duplication increase the likelihood that there will be an associated phenotype.

Ex: Chromosome 15 duplication in humans

Ring Chromosomes

- Break in both arms of chromosome

- Terminal ends (telomeres) are lost

- Broken arms fuse together as a ring

- May form following genetic damage, but 99% arise spontaneously

- Phenotypes associated with the loss of genetic material

Inversion

Segment of chromosome reversed

Translocation

two chromosomes arms exchanged in part or entirely

Griffith Experiment

demonstrated the transforming principle, converting non-virulent bacteria into virulent bacteria by exposure to heat-killed virulent bacteria

Chromosome =

DNA + protein

What they already know:

- T2 Phages consist of ~ 50/50 Protein:DNA

- DNA contains lots of phosphorus but no sulfur

- Protein contains sulfur and very little phosphorous

- Infection is initiated by adsorption of the phage by its tail fibers to the bacterial cell

- The production of a new virus occurs within the bacterial cell

Phoebus Levene

DNA made of nucleotides

Erwin Chargaff

Discovered that DNA composition varies, but the amount of adenine is always the same as thymine and the amount of cytosine is always the same as guanine

DNA is a double helix

- Maurice Wilkins & Rosalind Franklin

- The clue from photo 51

- X-ray diffraction indicated DNA is a helix

Hydrogen bonds

weak attraction between a hydrogen atom and another atom

The Central Dogma

DNA (replication) --> (transcription) RNA --> (translation) Protein

In Vitro Replication: Arthur Kornberg

DNA needs to be sequenced, primer needed to start reaction, DNA polymerase needed, dNTPs needed

Transcription

DNA serves as a template for RNA synthesis

RNA polymerase

- Begins at "promoter" region

- Adds nucleotides until a stop codon is reached

Transcription

1. Ribosomal RNA (rRNA)

- Forms the ribosomes (with protein)

2. Messenger RNA (mRNA)

- Carries the code for protein synthesis (codons) mRNA is eventually translated into a protein

3. Transfer RNA (tRNA)

- Picks up amino acid for the growing polypeptide chain (anticodons)

rRNA = Ribosome Building Blocks

- 2 subunits built in the nucleus from

- Shipped to the cytoplasm, combines with protein

- Combine into ribosomes during translation

MRNA molecule is assembled on a ___ ________.

DNA template

Codons

- Three nucleotide bases on mRNA transcript

- 64 codons make up the genetic code

- Most amino acids have > one codon

•redundancy of the genetic code

•Example: proline codons = CCU, CCC, CCA, CCG

Start Codon

AUG; establishes the "reading frame"

Stop Codons

UAA, UAG, and UGA

Codons in mRNA

It is a three-nucleotide DNA sequence that codes for specific amino acids in the protein chain or that signifies a start signal or a stop signal.

The Genetic Code consists of mRNA "words" called ______.

Codons

tRNA translates the genetic code:

- Has a "hook" for the attachment of an amino acid

- Anticodon base pairs with the codon on mRNA

Protein Synthesis

The formation of proteins by using information contained in DNA and carried by mRNA

RNA Splicing

Process by which the introns are removed from RNA transcripts and the remaining exons are joined together