Single-Gene Inheritance Patterns Chapter 2 1/26/17

Review Questions In many species, there are two representatives of each chromosome. In such species, the characteristic number of chromosomes is called ___________. It is usually symbolized as ____________. Haploid; n Haploid; 2n Diploid; n Diploid; 2n

Review Question Genetics is the study of___________. Heredity and variation Mutation and recession Transcription and translation Variation of metagenomics analysis.

Chapter 2: Single Gene Inheritance Wild type vs Mutants Mutations arise heritable changes in the gene’s DNA Genotypes vs Phenotypes Polymorphisms Coexistence of two or more common phenotypes of a biological property Wild type is the most common form found in nature and heritable variations observed are mutants

Gene Discovery 4 Steps to Gene Discovery 1. Collect mutants affecting a biological property Genetic dissection and forward genetics 2. Cross the mutants to Wild type to see if their descendants show ratios of wild type to mutant that are characteristic of single-gene inheritance 3. Determine the gene function at the molecular level 4. Determine how the gene interacts with other genes to produce the biological property

The seven phenotypic pairs studied by Mendel A a R r I i Y y L l or S s P p G g

Remember of Mendelian Genetics © 2015 W. H. Freeman and Company

Complete 2 punnett squares starting with two pure peas, one with purple flowers peas and one with white flowers. Then self-cross for the F1 and F2. What are the three ratios of phenotype and genotype?

Quick concept check: What is Mendels 1st law? Law of Segregation What does this law state? During the production of gametes the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent

Introduce some terminology Zygote a fertilized egg, the first cell that develops into a progeny individual Homozygous dominant, heterozygous, and homozygous recessive AA, Aa, aa Monohybrid heterozygous for one gene is monohybrid Monohybrid cross Yy x Yy Zygote- a fertilized egg, the first cell that develops into a progeny individual Monohybrid – heterozygous for one gene is monohybrid

Mitosis Somatic cells Programmed stage Any non-sex cell Germ-line cells = Gametes = Sex cells Programmed stage One progenitor cell -> 2 genetically identical cells 2n  2 daughter cells that are both 2n (Diploid cells) 2n  4n  2n n  2n  n

Stages of the asexual cell cycle M – Mitosis G1 – Growth stage 1 S – DNA synthesis G2 – Growth stage 2 M G2 G1 GROWTH 1 -growth -increase in size -new proteins and organelles made Growth 2 preparation for cell division (lower Surface Area to V so the cell can become bigger) S What is the difference between G1 and G2?

Meiosis Specialized diploid cells call meiocytes (sex cells progenitors) Two sequential cell divisions take place Meiosis I and Meiosis II 2n (Diploid)  n + n + n + n (4 haploid cells) 2n  4n  2n + 2n  n + n + n + n

3 cells of the meiotic tetrad abort in females GP gametophyte Female – mega gametophyte Male – microgametophyte Transient diploid cells only survive for a short time

Key stages of meiosis and mitosis

Pass Me A Taco Cytokinesis

More on Meiosis Each meiotic division (both I and II) is formally divided into: Prophase Metaphase Anaphase Telophase Prophase I is the most complex and lengthy Made up of 5 parts

Stages of Meiosis

Stages of Meiosis

Stages of Meiosis

Stages of Meiosis

Stages of Meiosis Linda zipped ping-pongs down Delaware

Mitosis and Meiosis Anyone confused on the steps still? IPMATC LZPDD Quick Review What are the stages of Mitosis? What are the 5 stages of Prophase in Meiosis?

Mitosis takes place in haploid cells only. diploid cells only. haploid or diploid cells. bacterial cells only.

Meiosis takes place in haploid cells only. diploid cells only. haploid or diploid cells. somatic cells.

During meiosis I homologous chromosomes align and are joined to one another (during synapsis). homologous chromosomes align individually at the “equatorial plane,” similar to what occurs during mitosis. homologous chromosomes align and are held together only at their centromeres. sister chromatids separate and are drawn to opposite ends of a cell.

Good morning my fellow geneticists. This is Lecture for January 26th Good morning my fellow geneticists. This is Lecture for January 26th. I have broken lecture into three parts today to allow you and myself to take breaks between the concepts we are going to cover today. To start off with we are going to discuss single gene inheritance in haploids. We covered single gene inheritance of diploids on Thursday.

Nuclear division at the DNA level PART 2

Molecular Basis for Mendelian Inheritance Patterns What causes different alleles?

PKU: Case Study Phenylketonuria disease Phenylalanine tyrosine Phenylalanine Hydroxylase (PAH) Phenylalanine tyrosine Phenylpyruvic acid Phenylpyruvic acid interferes with the development of the nervous system, leading the mental retardation. Babies tested at birth, if the deficiency is detect, phenylalanine is withheld from the diet

Mutant sites in the PKU gene Mutations in black are in exons (expressed) Mutations in green are in introns(interrupt) Most are null mutations – make a non-functioning protein (typically a truncated protein) Others are leaky mutations – makes a functional protein but it lacks the full function of the wt gene