Ansc 1000, Week Four Notes
Ansc 1000, Week Four Notes ANSC 1000
Popular in Introduction to Animal Sciences
Popular in Animal Science and Zoology
This 7 page Class Notes was uploaded by Olivia Schweikart on Thursday January 21, 2016. The Class Notes belongs to ANSC 1000 at Auburn University taught by Dr. Carolyn Huntington in Spring 2016. Since its upload, it has received 60 views. For similar materials see Introduction to Animal Sciences in Animal Science and Zoology at Auburn University.
Reviews for Ansc 1000, Week Four Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 01/21/16
Genetics Week Four Notes Cell Division Cell division is an ongoing body process o Ex) Helping tissues develop, heal wounds, etc. Cells All cells have certain structures in common, yet outer appearances vary greatly o Nuclei hold different shapes o DNA identical in all body cells even though they may function and look different Background Which genes inherited by offspring depend on how the cells divide o Results in a mixture of different traits Species and Chromosomes The number of chromosomes varies greatly with different species o Example) Horses have 32 pair and humans have 23 o Pairs are different than number of chromosomes, humans may have 23 chromosome pairs, but have 46 chromosomes Mitosis Interphase o The cell is not actively dividing Prophase o DNA within the cell must replicate o Sister chromatids join together at centromere o Spindles begin to form within the cell Metaphase o Chromosomes line up along the mitotic plate down the center of the cell o Spindles migrate to opposing sides and attach fibers to the sister chromatids Anaphase o Sister chromatids are pulled apart to opposite sides of the cell Telophase o Cytokinesis begins and the cell becomes fully divided, resulting in two fully-functioning cells Meiosis Functions similar to mitosis, however in the first part to meiosis the pairs of chromosomes are lined up (X X) instead of just the sister chromatids (X) o After the first cell division, in the second half of meiosis the sister chromatids of the freshly divided cell will line along the center and be pulled apart again resulting in 4 daughter cells Crossing over is unique to meiosis These cells will contain half of the genetic material as a somatic (normal body) cell Gametogenesis- the production of sex cells o For males, this production occurs in the seminiferous tubules o For females, this process occurs at the outer area of the ovary Reason for being near the edge is it is easier to send the eggs outward the closer they are to the surface After the first stage of meiosis, these gametes are referred to as the primary spermatocyte and the primary oocyte Spermatogenesis When cells first divide, they are incapable of fertilizing an egg Need flagella to move around Results in 4 functioning gametes Oogenesis Only one functioning oocyte, and three supporting polar bodies o Polar bodies will die and be reabsorbed into the body after fully supporting the primary oocyte After the primary oocyte matures, it can become a secondary oocyte, which can then divide further to become an ovum Fertilization The process of the sperm meeting the egg Haploid refers to a cell containing half the original number of chromosomes Diploid refers to a cell containing the full set of chromosomes DNA DNA located within the chromatin of the nucleus o These further condense to chromatids which can then pair Sugar-Phosphate bonds on the DNA result in a double-helix structure Where a gene is located on a chromosome is referred to as a locus o A gene is a certain portion of a chromosome, which in turn is a second of DNA Contains four bases o Adenine (A) o Guanine (G) o Thymine (T) o Cytosine (C) Combinations of either A-G-T-or-C, a deoxyribose sugar and a phosphate group form a nucleotide When replicating DNA, the created strand will prove to be a mirror image of the original DNA strand o Example) Existing strand: AGTTGC Replicated strand: TCAACG Genes and Chromosomes In a dividing cell, chromosomes pair up, therefore genes also pair up In terms of livestock, a large concern is rate of growth o Two parents with faster growing rates will be paired in order to produce an idealistic offspring Genes code for proteins which are made of amino acids o There are 20 amino acids that are coded by triplet DNA sequences Example) TTT codes for alanine Protein Synthesis Transcription begins the process by synthesizing RNA o This results from matching the bases on DNA strands in the nucleus Transfer RNA will then travel to a ribosome which transcribes the RNA to build peptide bonds, thus forming protein chains The formed protein chain will then detach and go perform specified function Sex Chromosomes Male and female sex chromosomes get their name (X and Y) based on their microscopic shapes Male chromosomes tend to be shorter than female Male are the determining factor to the offspring’s gender o Female only able to contribute X Birds are the exception to the commonality o Females determine sex of offspring due to females being XY and males XX Homozygous and Heterozygous Homozygous refers to the offspring containing two of the same genes from the parents o These matching genes are known as identical alleles Heterozygous refers to the offspring containing two different parental genes o These differing genes are known as alleles May be expressed in different ways B B B (example: black and white (dom. coat coloring) ) When b an allele is dominant, it will (rec.) overpower other alleles B BB BB Similarly, when an allele is (dom. recessive it will be ) b Bb Bb overpowered by the b dominant allele (rec.) Genotypic vs. B BB Bb Phenotypic An animal’s b Bb bb phenotype refers to the outside appearance of the animal The genotype refers to the genetic combination of the animal o Ex) BB, Bb, bb Phenotype = genotype plus the environment o Genes can be influenced by environmental conditions Example: Nutrition Infertility due to Cross Crossing of different species most often results in infertile offspring due to mismatching chromosome numbers from the parents o Example: Crossing of a Jack and a Mare to form a Mule Punnett Squares Used to determine possible genotypic outcomes Example: A cross between a black homozygous dominant male and a black heterozygous female o Outcome: Two homozygous dominant and two heterozygous offspring combinations o Genotypic ratio is 1:1 (homozygous dominant: heterozygous dominant) o Phenotype of offspring: black Example: A cross between a black heterozygous male and a black heterozygous female o Outcome: One homozygous dominant, two heterozygous, and one homozygous recessive offspring o Genotypic ratio is 1:2:1 (homozygous dominant: heterozygous: homozygous recessive) o Phenotypic ratio is 3:1 (three offspring will appear black, and the homozygous recessive offspring will appear red) Multiple Gene Pairs When dealing with multiple genes, find the genotypic ratios and multiply through Example: A possible outcome results in genotypic ratios of 3:1 black to red and 3:1 polled to horned Black Polled Offspring (3x3) = 9 Black Horned Offspring (3x1) = 3 Red Polled Offspring (1x3) = 3 Red Horned Offspring (1x1) = 1 Gene Interactions Genetically, the phenotype can be altered by changing the environment o Example: if two identical twin bovine are separated and one is placed in a good environment while the other is in a lesser environment, they will not grow to the same standard (the one in the greater environment will much likely be larger in stature) Linear interactions occur when genes interact with other genes along the same line of chromosome o Have not been seen in livestock, focused more on animals such as fruit flies, etc. Allelic interactions occur when genes interact with other genes along a homologous chromosome o While the genes may have the same loci, they address situations differently o Can sometimes be known as dominance interactions due to the dominant gene being the gene expressed o Complete dominance Example: If a BB is crossed with a bb, all offspring will be black due to the dominant B being present Because of the allelic interactions this B will be expressed over the recessive allele o Lack of dominance Considered a half-way point between the parents of the offspring Example: If a sheep that is earless is crossed with one that has long ears, the resulting offspring may have short ears, meeting the two parents in the middle in terms of phenotype Also known as additive gene action, due to each gene having its own phenotypic effect on the animal Example: If animals with different daily gain rates are crossed, the resulting offspring may be in the middle of the two rates o Resulting offspring: DD (0.2 lb./day) Dd (0.15 lb./day) Dd (0.10 lb./day) o Overdominance This occurs when offspring have better characteristics than the parents, in other words, the heterozygous offspring outperform the homozygous parents Heterosis- occurs when an animal tends to have better characteristics than the parents and outperform Hybrid vigor- term for more productivity arising from crossbreds o In the beef industry, a lot of crossbreeding occurs, however in the dairy industry it is not a common occurrence o Partial dominance The heterozygous offspring looks more similar to the homozygous dominant parents, however does exhibit some intermediate phenotypic expression HYPP (hyperkalemic periodic paralysis) Occurs when an animal has too much potassium, which results in temporary paralysis Epistatic interactions occur when genes interact with other genes along a non-homologous chromosome (another chromosome) o Will alter or mask the expression of another gene Example: White coat color will mask other coat colors (the WW results in albino horse which dies) Can be lethal depending on genotype o Example: EEWW, EeWW, eeWW, (notice all contain the dominant form for the white coat—albino) are lethal o Those containing just the recessive form of the white coat are non-lethal to the animal (EeWw, and eeWw) Example: EEww (black coat) Eeww (black coat) eeww (chestnut coat) o In horses, the extension gene is what determines the basic coat color Example: EE and Ee result in black color expression, while ee results in chestnut expression o The agouti gene determines coat color in foals Example: AA and Aa result in bay color expression, while aa results in solid black coat expression Black coat color in the horse industry is relatively uncommon Bay coat color refers to the body being a chestnut color (or lighter) with black points on the body, be it the tail, legs, etc. Temperature, along with many other environmental factors can affect the genetics of an animal o Example: Infertility due to excess heat o Example: Lack of light can alter breeding pattern
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'