Ch 1 Overview of Genetics PDF

Because learning changes everything. ® Chapter 1 Overview of Genetics https://www.researchgate.net/figure/Triangle-base-knowledge-of-gene--protein--function_fig1_271766207 https://www.researchgate.net/figure/Triangle-base-knowledge-of-gene--protein--function_fig1_2717...

Because learning changes everything. ® Chapter 1 Overview of Genetics https://www.researchgate.net/figure/Triangle-base-knowledge-of-gene--protein--function_fig1_271766207 https://www.researchgate.net/figure/Triangle-base-knowledge-of-gene--protein--function_fig1_271766207  Topics Review of general terms and concepts How genes control traits Fields of genetics Causes of genetic variation Gender vs sex https://www.eurekalert.org/news-releases/992769 https://www.eurekalert.org/news-releases/992769 © McGraw Hill 2  Figure 1.1 Protein (composed of amino acids) Access the text alternative for slide images. © McGraw Hill 3  Introduction Human Genome Project Started 1990 Completed sequence published in 2003 ~ 3 billion nucleotides https://www.genome.gov/human-genome-project Accuracy > 99.99% 1000 Genomes Project -to catalog human genetic variation Sequencing of 2,500 genomes described in Nature in 2015 Study of the human genome How many genes we have How cells develop into complex tissue How defective genes cause disease © McGraw Hill 4  Examples of genetic technologies (a) GFP expressed in mice Figure 1.2 Figure 1.3a © McGraw Hill (Left): ©R. Scott Horner KRT/Newscom; (Right): ©Eye of Science/Science Source 5  The Molecular Expression of Genes Genetics = the study of heredity and variation Gene = classically defined as a ‘unit’ of heredity Modern definition = a segment of DNA that produces a functional product such as a polypeptide. Genes determine the traits of an organism Traits = observable characteristics of an organism https://www.khanacademy.org/test-prep/mcat/behavior/behavior-and-genetics/a/genes-environment-and-behav https://www.khanacademy.org/test-prep/mcat/behavior/behavior-and-genetics/a/genes-environment-and-behavior © McGraw Hill 6  Living Cells are Composed of Biochemicals Nucleic acids Proteins Carbohydrates Lipids Macromolecules © McGraw Hill 7  Molecular Organization of a Cell Nucleotide - building block of DNA DNA associates with proteins → form chromosomes. Chromosomes are contained within the nucleus. https://microbenotes.com/nucleotide/ https://microbenotes.com/nucleotide/ © McGraw Hill (inset) ©Biophoto Associates/Science Source 8  Overview of DNA Structure 5' end 3' end P phosphate pyrimidine base purine base S S P P P S S 5' end 3' end P P P S S 5' 2' 3' S 1' 1' 4' P 4' S P 3' 2' 5' S S P 5' P C P O S S 4'C S C 1' P C C 3' 2' deoxyribose 3' end 5' end a. Double helix b. Ladder structure c. One pair of bases © McGraw Hill 9  Proteins Determines Cell Structure and Function Polypeptide - composed of a linear sequence of amino acids Protein is composed of one or more polypeptides Characteristics of a cell dependent on proteins All of the proteins that a cell makes at a given time = proteome https://www.peptidesciences.com/information/peptides-vs-proteins/ © McGraw Hill 10  Functions of Proteins Structural proteins Play role in cell shape and movement Transport proteins Aid in the transport of ions and small molecules across the cell membrane Enzymes Catabolic Break down of large molecules into small → provide energy Anabolic Large molecules synthesized from smaller ones → components for construction of cell © McGraw Hill 11  DNA Stores the Information for Protein Synthesis DNA (deoxyribonucleic acid) - the genetic material in all living organisms Some viruses use RNA DNA encodes information → cellular proteins Each nucleotide contains one nitrogenous base Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Genetic information is stored in the linear sequence of bases © McGraw Hill 12  DNA Stores the Information for Protein Synthesis The genetic code directs the order of amino acids-three base code for each: DNA Sequence: ATG GGC CTT AGC Amino Acid Sequence: Met Gly Leu Ser DNA Sequence: TTT AAG CTT GCC Amino Acid Sequence: Phe Lys Leu Ala © McGraw Hill 13  DNA Stores the Information for Protein Synthesis DNA in living cells → contained within chromosomes Human cells - 46 chromosomes Chromosome = DNA + proteins Average human chromosome: >100 million nucleotides per DNA strand ~1,000 different genes © McGraw Hill 14  Figure 1.5 Micrograph of the 46 chromosomes found in a cell from a human male © McGraw Hill ©Kateryna Kon/Shutterstock 15  Gene Expression Two steps Transcription (DNA →RNA) The genetic information in DNA is copied into a nucleotide sequence of ribonucleic acid (RNA) Translation (RNA →protein) The nucleotide sequence in RNA provides the information (using the genetic code) to make the amino acid sequence of a protein © McGraw Hill 16  Figure 1.6 © McGraw Hill 17  Genes and Traits Trait = any characteristic that an organism displays Morphological traits Appearance Example: Color of flower Physiological traits Function of the organism Example: Ability to metabolize a sugar Behavioral traits The ways an organism responds to the environment Example: Mating calls of bird species © McGraw Hill 18  Molecular Expression of Genes Four levels of biological organization Genes are expressed at the molecular level Proteins function at the cellular level Traits are often observed at the organism level Genes/traits within a particular species can also be studied at the population level © McGraw Hill 19  Relationship between genes and traits 1 The relationship between genes and traits at four levels of biological organization Highly functional Poorly functional pigmentation pigmentation enzyme enzyme (a) Molecular Level (a) Molecular Level Figure 1.7a © McGraw Hill 20  Relationship between genes and traits 2 Lots of pigment made Little pigment made (b) Cellular level (b) Cellular level Figure 1.7b © McGraw Hill 21  Relationship between genes and traits 3 Dark butterfly Light butterfly (c) Organism level (c) Organism level Figure 1.7c © McGraw Hill 22  Relationship between genes and traits 4 Dark butterflies are usually Light butterflies are usually in forested regions. in unforested regions. (d) Population level (d) Population level Figure 1.7d © McGraw Hill 23  Inherited Differences in Traits are due to Genetic Variation Genetic variation = differences in inherited traits among individuals within a population For example: In petunias, white versus purple flowers In some cases, genetic variation is very striking Members of the same species may be misidentified as belonging to different species Figure 1.8 Contrasting forms within a single species are termed morphs © McGraw Hill 24  Genetic Variation and Molecular Level Changes 1 Genetic variation is a result of various types of changes to DNA at the molecular level 1. Gene mutations Differences in gene sequences Lead to two or more expression forms or alleles of the same gene 2. Changes in chromosome structure Large segments of a chromosome may be lost, duplicated or reattached to another chromosome © McGraw Hill 25  Genetic Variation and Molecular Level Changes 2 3. Changes in chromosome number Single chromosomes may be lost or gained A person with Down syndrome has 47 rather than 46 chromosomes A whole extra set of chromosomes may be inherited Cultivated wheat has 6 sets of chromosomes Figure 1.9 © McGraw Hill (a): ©Stockbyte/Alamy; (b): ©Pixtal/age fotostock 26  Genes and by the Environment Traits are a result of the interaction between genes and the environment Example: diet and height/weight In some cases, the environment dictates whether a disease is manifested in an individual or not Example: Phenylketonuria (PKU) Inability to metabolize phenylalanine properly Newborns are now routinely screened for PKU Individuals with the disease are put on a strict dietary regimen © McGraw Hill 27  Reproduction Process During reproduction, genes are passed from parent to offspring © McGraw Hill 28  Human Chromosome Composition Humans - 46 chromosomes 23 homologous pairs (Diploid) Note: The X and Y chromosomes of human males are not homologous (a) Chromosomal composition found in human somatic cells of females (46 chromosomes) © McGraw Hill 29  Human Gamete Chromosome Composition Gametes Sperm and egg cells are haploid Have one set of 23 chromosomes (b) Chromosomal composition found in human gamete (23 chromosomes) © McGraw Hill 30  Fields of Genetics Transmission Genetics inheritance patterns of traits as they are passed from parents to offspring Molecular Genetics how the molecular features of DNA underlie gene expression Gene organization and function Detailed analysis of DNA, RNA and proteins Population Genetics genetic variation and its role in evolution mathematical theories to explain the prevalence of certain alleles © McGraw Hill 31  Fields of Genetics Researchers often times study model organisms so they can compare their research results. (a): Source: Peggy S. Hayes & Elizabeth H. White, M.S./CDC; (b): ©Science Photo Library/Alamy; (c): ©Janeff/Getty Images; Figure 1.12 (d): ©Sinclair Stammers/Science Source; (e): ©G.K. & Vikki Hart/ Getty Images; (f): ©WILDLIFE GmbH/Alamy © McGraw Hill 32  Genetics is an Experimental Science The scientific method underlies scientific research It is a standard process that provides a way to validate (or invalidate) hypotheses about the natural world Textbook Examples: One to two experiments that have been “dissected” into five parts “See” the experimental process from start to finish © McGraw Hill 33 34 Gender Identity Versus Sex Gender - socially constructed characteristics of men and women Can include social norms, roles, and expectations. Many cultures recognize more than two genders. Gender identity - how individuals perceive themselves. Sex - designation assigned at birth. based on presence of external body parts and internal structures associated with reproduction. determined by the type of gamete (eggs or sperm) an individual can produce. based on chromosome composition; females have two X chromosomes while males have one X and one Y chromosome. Intersex - individuals have characteristics that are different from the two common patterns classified as males or females. © McGraw Hill 34  Ch 1 Study Guide Review definitions of the following terms: Gene Allele Trait Codon Proteome Haploid Genetic code Diploid Describe the purpose of the Human Genome Project Identify four types of macromolecules Describe the structural components and composition of DNA and proteins Describe the main cellular functions of proteins Identify the number of chromosomes in human cells Identify the two main processes of gene expression and identify the product of each process Describe 3 types of traits and recognize examples Describe 4 levels of biological organization Describe 3 types of changes to DNA that can cause genetic variation Describe 3 fields of genetics Review the steps of the scientific method © McGraw Hill 35