BIOLOGY1001 - Biology For Science I

Repair of Damage in DNA Not all changes to DNA are mutations: mutations are double-stranded changes Changes in only one strand are DNA damage: includes replication errors resulting in wrong base pairs, chemical reactions that add chemical groups to bases 3 types of repair mechanisms: Proofreading: for errors by DNA polymerase Mismatch repair: for errors made during replication that escape proofreading Excision repair: for various kinds of DNA damage (chemicals, radiation, etc) Correction of erro

Microevolution Pt. 1 Microevolution: change in a population’s genetic makeup from one generation to the next Phenotypic variation: differences in appearance or function (weight, physiology, etc) Heritable variation is a driver of natural selection Quantitative variation: individuals differ in small + incremental ways Qualitative variation: polymorphism (exist in 2+ discrete states and intermediate forms are absent) Phenotypic variation can be due to genotypic variation and/or environmental facto

Genetic recombination Many types of reproduction Octopi: reproduction is occasional, preceded by courtship involving intermingling tentacles Slipper limpet: reproduction is a lifelong group activity Both genetic alikeness and difference are necessary for evolution Mutation is the main source of genetic diversity: usually from errors in DNA replication, need more diversity so other mechanisms (e.g. genetic recombination) exist Genetic recombination: widespread in nature; part of meiosis Needs two

Viruses, Viroids, and Prions Understanding viruses is important bc it can help us deal with virus outbreaks and tracking global migration to improve quality of life and prevent illnesses Viruses aren’t always bad; we can use viruses’ properties for our own purposes (e.g. gene therapy) Viruses aren’t considered to be living organisms because they lack many of the properties of life, and are infectious biological particles Can’t reproduce on their own No metabolic system to provide energy Structur

Cell Cycles Cell division occurs bc of: DNA replication, a dynamic cytoskeleton, and cell cycle checkpoints Prokaryotic/simple eukaryotic cell division can give us clues abt ancestral cell division Early 1900s: scientists know all life on Earth made of cells + cell products, all cells come from pre-existing cells New progeny cells needed for increasing population of single-celled organisms, multicellular tissue growth, asexual reproduction, replacement of lost cells (e.g. shedding skin, virus in

Sexual Selection Pt. 1 Sexual selection is caused by drive to reproduce, competition for mates, mate choices Sexual dimorphism: one gender is larger and more colourful than the other, may be due to sexual selection Males often compete for females: larger, may have ornaments and weapons (horns, antlers, tail feathers, etc) for attracting females and fighting rival males (may be both at the same time) Exaggerated structures are to show to females that the male is healthy, can harvest resources eff

The Chromosomal Basis of Mendelian Inheritance Gregor Mendel (1860s): used traits in generations of garden peas to study pattern of inheritance  Shows how rigorous scientific work is done: observation, hypotheses, experiments His techniques and conclusions were so advanced for the time that they weren’t appreciated until later: chromosomes and meiosis were yet to be discovered  Was also lucky that the characters he analyzed all segregate independently (none are near each other on the chromosomes

Cycle 1 Viruses, Viroids, and Prions Understanding viruses is important bc it can help us deal with virus outbreaks and tracking global migration to improve quality of life and prevent illnesses Viruses aren’t always bad; we can use viruses’ properties for our own purposes (e.g. gene therapy) Viruses aren’t considered to be living organisms because they lack many of the properties of life, and are infectious biological particles Can’t reproduce on their own No metabolic system to provide energy