Near the cells where oxygen is used, its chemical potential is significantly lower than near the lungs. Even though there is no gaseous oxygen near these cells, it is customary to express the abundance of oxygen in terms of the partial pressure of gaseous oxygen that would be in equilibrium with the blood. Using the independent-site model just presented, with only oxygen present, calculate and plot the fraction of occupied heme sites as a function of the partial pressure of oxygen. This curve is called the Langmuir adsorption isotherm (“isotherm” because its for a fixed temperature). Experiments show that adsorption by myoglobin follows the shape of this curve quite accurately.
Section 4: Genetic and Molecular Biology Chapter 11 (Notes) Sexual reproduction and meiosis Meiosis • Meiosis: type of nuclear division which results in half as many chromosomes as the parent cell (Reduction division). ◊ Leads to formation of eggs and sperm (gametogenesis) • Fertilization: process when sperm and egg unite sperm and egg ◊ Leads to offspring that are genetically distinct from each other and from their parents ◊ Each cell produced by meiosis receives a different gene combination • Genes are located on chromosomes ◊ Mistakes during meiosis result in cells containing the wrong number of chromosomes Chromosomes and autosomes • Karyotype: number and types pf chromosomes present in an organism (basically a picture of someone’s chromosomes) • Sex chromosomes: The 23 chromosome which determine the sex of the individual. (1 pair) ◊ All other chromosomes are autosomes (22 pairs) • Humans have 46 chromosomes in every cell except their gametes • Chromosomes carry genes ◊ Gene: a section of DNA that influences one or more hereditary traits in an individual • Different types of genes are called alleles EXAMPE: Eye shape (gene) Narrow or round eyes (alleles) Homologous chromosomes • Homologous chromosomes: Chromosomes of the same type (also called homologs) ◊ Homologs carry the same genes in the same locations but each one may contain different alleles. Concept of ploidy • Ploidy: number of each type of chromosome present (n, 2n, 3n, etc.) ◊ Haploid (n): Organism whose cells contain just one of each type of chromosomes (ex: gametes) ◊ Diploid (2n): organisms whose cells contain two versions of each type of chromosome (one paternal chromosome and one maternal chromosome) ◊ Polypoid (3n,4n, etc..): Organisms with three or more versions of each type of chromosomes