ANTH 101 Chapter Two: Genetics
ANTH 101 Chapter Two: Genetics ANTH 101 - 001
Popular in INTRO TO BIOLOGICAL ANTH
Popular in Biological Anthropology
This 8 page Class Notes was uploaded by Tera Notetaker on Monday October 3, 2016. The Class Notes belongs to ANTH 101 - 001 at Portland State University taught by Amiee Potter (P) in Fall 2016. Since its upload, it has received 47 views. For similar materials see INTRO TO BIOLOGICAL ANTH in Biological Anthropology at Portland State University.
Reviews for ANTH 101 Chapter Two: Genetics
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: 10/03/16
I. Genetics A. Gene: term coined by Danish botanist Wilhelm Johannsen in early 1900s; particulate unit of inheritance; 20 c saw increased understanding of how heredity works; gene evolved from theoretical unit to well-described biochemical entity. B. THE STUDY OF GENETICS 1. In complex animals, genetics can be approached from different levels, depending on aspect of interest: a) Cellular and molecular genetics: study at cellular level; most fundamental level of genetic transmission (DNA molecule) b) Classical or Mendelian genetics: involves looking at pedigree (shows transmission of a genetic trait over generations of a family); observable traits c) Population genetics: examine genetic variation within and b/t populations (at both molecular level and observable traits); insight into evolutionary history of populations and species as a whole d) Phylogenetics: concerned with determining evolutionary relationships b/t species; treelike diagrams indicate how closely or distantly related species are to one another. e) Behavioral genetics: involves trying to understand how behavior of animals & humans is influenced by genetics; controversial field; behavior is complex and result of multiple influences 2. Biological anthropology concerned w/ evolution of human species in all aspects; each approach is relevant; also concerned with biological variability (genetic and environmental influences); often work at intersection of biological (genetic) and environmental (cultural) sciences to understand human variation and its evolution. C. GENETIC METAPHORS: BLUEPRINTS, RECIPES, OR WHAT? 1. Homunculus: what is passed b/t generations 2. “Blueprint” implies construction and potential deconstruction—cannot unbuild a body by breaking it down into original component parts. 3. Homeotic (Hox) genes: underlines development of basic body structure in both invertebrates and vertebrates; modified by evolution to produce range of animal bodies. 4. Genes more akin to a recipe than a blueprint; includes: a) List of ingredients b) Instructions of what to do w/ ingredients 5. Recipe for converting energy and a host of essential components into a body; difference b/t genes and recipe: environments in which genes exist cannot be controlled; humans can modify environment to suit the genes they carry 6. Genes thought of as information storage; not just info but are part of essential machinery of living body. II. The Cell A. “Basic building block of life”; microscopic organic entity in which genetic material and other structures are separated from surrounding environment by semipermeable membrane. B. Life forms that can be seen w/ naked eye are multicellular; protozoans (bacteria) are single cell C. Basic division of life not b/t single and multi-cell but: 1. Prokaryote: single-celled organism, such as bacteria, in which genetic material is not separated from rest of cell by nucleus. 2. Eukaryote: Cell that possesses a well-organized nucleus: a) Part of cell in which the genetic material is separated from rest of cell (cytoplasm) by a plasma membrane b) Cytoplasm: region within cell membrane that surrounds nucleus; contains organelles which carry out essential functions of cell (i.e. energy production, metabolism, protein synthesis D. Somatic cell are the cells of body that are not gametes: 1. Gametes: sex cells; sperm in males & eggs (ova) in females E. Stem cells: undifferentiated cells found in developing embryo that can be induced to differentiate into a variety of cell types or tissues; found in adults but adult stem cells not as totipotent (capable of giving rise to any cell type) as embryonic stem cells F. CELL ANATOMY 1. Deoxyribonucleic acid (DNA): double-stranded molecule that is carried of genetic info. Each strand composed of linear sequence of nucleotides; the two strands are held together by hydrogen bonds that form b/t complementary bases. 2. Proteins: complex molecules formed from chains of amino acids (polypeptide) or from a complex of polypeptides. Function as structural molecules, transport molecules, antibodies, enzymes, and hormones. 3. Protein synthesis: The assembly of proteins from amino acids, which occurs at ribosomes in the cytoplasm and is based on info carried by mRNA 4. Ribonucleic acid (RNA): single-stranded nucleic acid that performs critical functions during protein synthesis and comes in three forms: messenger RNA, transfer RNA, and ribosomal RNA 5. Mitochondria: organelles in cytoplasm of cell where energy production for the cell takes place; “powerhouse of the cell”. Contains its own DNA. 6. Endoplasmic reticulum (ER): organelle in cytoplasm consisting of a folded membrane. Provides increased surface area within cell for metabolic reactions to take place. Some has knobby appearance. a) “knobs” are ribosomes: structures composed primarily of RNA, which are found on ER. Site of protein synthesis. III. DNA Structure and Function A. Has to be able to do three things: 1. Replicate (make copies of itself) so it can be passed from generation to generation 2. Make proteins, the most important components of cells 3. Coordinate the activity of proteins to produce bodies; have some way to translate info it carries about making bodies into growing actual bodies B. DNA STRUCTURE I: THE MOLECULAR LEVEL 1. Basic unit of DNA (and RNA) is a nucleotide: molecular building block of nucleic acids DNA and RNA; consists of a phosphate, sugar, and base. a) Base: variable component of the nucleotides that form the nucleic acids DNA and RNA. (1) In DNA bases are: adenine, guanine, thymine, and cytosine. (2) In RNA: uracil replaces thymine b) Purines: adenine (A) and guanine (G) c) Pyrimidines: cytosine (C) and thymine (T) 2. Two separate strands, each made up of a chain of nucleotides; sugar of one nucleotide bonds to phosphate group of the next; each side of ladder composed of alternating sugar and phosphate molecules. Bases point toward the center of ladder and form rungs (formed by two bases, one projecting from each side of ladder) 3. Purine is always opposite a pyrimidine. 4. RNA—similar to DNA except it is single stranded; ribose replaces deoxyribose as sugar in nucleotide; thymine not found in RNA—replaced by another pyrimidine base, Uracil (U)—bonds to adenine. C. DNA FUNCTION I: REPLICATION 1. DNA molecule, or portion, divides into two separate strands. After separation, the strands act as templates for assembly (nucleotide by nucleotide) of new complementary strands of DNA. Each completed are made up of one original side and one newly synthesized side. Each step of replication is mediated by a particular enzyme a) Enzyme: complex protein molecule that mediates a chemical or biochemical reaction; catalyst for chemical processes in body D. DNA FUNCTION II: PROTEIN SYNTHESIS 1. Structural tissues (i.e. bone & muscle) composed primarily of protein a) Workhorse molecules of biological organisms & most common large molecules found in cells 2. Hemoglobin: protein found in red blood cells, that transports oxygen, and other transport proteins facilitate movement of molecules across cell membranes 3. Some function as hormones natural substance produced by specialized cells in one location of the body that influences activity or physiology of cells in a different location. 4. Enzymes are largest class of proteins in the body; lower the activation energy of countless biochemical reactions in cells; essential for life 5. Amino acidsmolecules that form basic building blocks of protein; 20 different amino acids: a) 9 are essential amino acids; cannot be synthesized by body & must be obtained from protein in diet. Nonessential amino acids can be synthesized from the essential amino acids. 6. Polypeptide molecule made up of a chain of amino acids; sequence of amino acids governs how the chain may be folded in space or how it associates w/ other polypeptide chains to form larger more complex protein 7. Genetic code system whereby the nucleotide triplets in DNA and RNA contain the info for synthesizing proteins from the 20 amino acids a) Codons: a triplet of nucleotide bases in mRNA that specifies an amino acid or the initiation or termination of a polypeptide sequence b) Gene: fundamental unit of heredity; sequence of DNA bases that carries the info for synthesizing a protein (or polypeptide) & occupies a specific chromosomal locus location of gene on a chromosome; identified by the number of the chromosome on which it is found and its position on the chromosome 8. Messenger RNA (mRNA)strand of RNA synthesized in the nucleus as a complement to a specific gene (transcription). It carries the info for the sequence of amino acids to make a specific protein into the cytoplasm, where it is read at a ribosome and a protein molecule is synthesized (translation) 9. Transfer RNA (tRNA)RNA molecules that bind to specific amino acids & transport them to ribosomes to be used during protein synthesis. E. DNA STRUCTURE II: CHROMOSOMES AND CELL DIVISION 1. Chromatin diffuse form of DNA as it exists during the interphase of the cell cycle; condenses and coils into larger, tightly wound, discrete structures called chromosomes 2. Two processes of cell division or replication: a) Mitosis: Somatic cell division in which a single cell divides to produce two identical daughter cells b) Meiosis: cell division that occurs in the testes and ovaries that leads to the formation of sperm and ova (gametes) 3. Centromerecondensed & constricted region of chromosome that is of critical importance during cell replication; size determined by the size of DNA molecule that makes up the chromosome 4. Total number of chromosomes in each somatic celldiploid number a) In diploid cell, the members of each pair of chromosomes homologous chromosomes 5. Sex cells (gametes) have half as many chromosomes as somatic cells; total number of chromosomes haploid number 6. Allelesalternative versions of a gene; distinguished from one another by their differing effects on the phenotypic expression of the same gene a) Homozygous: having the same allele at the loci for a gene on both members of a pair of homologous chromosomes (autosomes) b) Heterozygous: Two different alleles at the loci for a gene on a pair of homologous chromosomes (autosomes) 7. Zygotefertilized egg 8. Crossing over: exchange of genetic material b/t homologous chromosomes during the first prophase of meiosis; mechanism for genetic recombination a) Recombination: rearrangement of genes on homologous chromosomes that occurs during crossing over in meiosis. The source of variation arising out of sexual reproduction; important for increasing rates of natural selection 9. Karyotype: the complete chromosomal complement of an individual; usually based on a photograph of the chromosomes visualized under the microscope 10. Autosomes Any of the chromosomes other than the sex chromosomes rd a) Sex chromosomes 23 pair of autosomes; In mammals, X and Y chromosomes, w/ XX producing females and XY producing males 11. Nondisjunction errorfailure of homologous chromosomes (chromatids) to separate properly during cell division. When occurring during meiosis, it may lead to the formation of gametes that are missing a chromosome or have an extra copy of a chromosome (Down syndrome & Turner syndrome) IV. Molecular Tools for Bioanthropological Research A. Understanding genetics is critical to understanding evolutionary phenomena such as adaptation & the biological histories of populations & species. Biological anthropologists use variety of molecular genetics techniques to study natural history of people& other primates B. INDIRECT VERSUS DIRECT RESEARCH METHODS 1. Ultimate indirect method look at anatomy & physiology of an organism; individual organisms are result of complex interactions b/t genes & the environment 2. Problem w/ molecules very small & difficult to see; visual representation did not have to be exact replication but had to provide enough info so that inferences about structure can be made; concern was to find techniques to provide info about variation in molecular structure w/o worrying about exact structure a) 1960s-70s, bio. Anthropologists made use of indirect techniques to study evolutionary relationships (i.e. protein immunology or DNA hybridization) (1) Allowed protein or DNA structures from diff species to be compared w/o determining amino acid or base pair sequences 3. Protein electrophoresis most commonly used indirect method; a) Proteins vary by electrical charge, not only size; determined by the amino acid composition; useful for detecting protein & allelic variation. 4. DNA sequencing determining actual base sequence of a gene or stretch of DNA; most widely used tool in molecular anthropology a) Most direct kind of evidence about genetic makeup; can yield insights about both coding and noncoding regions of genome sum total of all genes carried by an individual b) Development in 1970s-80s; made “molecular revolution” of 20 century possible (1) Human Genome Project (1980s); goal of determining sequence of all the bases in a single human genome (completed in 2003); payoff immense for study of development, physiology, medicine, & evolution C. PCR, MITOCHONDRIAL DNA, & ANCIENT DATA 1. Polymerase chain reaction (PCR), another essential tool of molecular rev. a) Small amnt of DNA can be used to make millions (or billions) of copies of specific DNA segment b) Depends on specialized enzyme (Taq polymerase); causes extension of single DNA strand. c) Process DNA containing target sequence, base pair nucleotides (A,T, C, &G), two primers, & Taq polymerase placed in test tube. Heated to point where DNA strands separate (95 C). Cooled to ~55 C; allows primers to attach to single DNA strands at positions flanking DNA segment of interest. Temp raised to ~75C; Taq poly. Works to extend target segments strands starting at primer positions. Copies of target DNA being made. Process repeated 25-30 times 2. Mitochondrial DNA Small loop of DNA found in mitochondria. Clonally and maternally inherited. 3. Ancient DNA PCR is essential in recovering ancient DNA sequences b/c DNA in bone is usually fragmentary or degraded. Easier to amplify mtDNA than nuclear DNA; thousands of copies of mtDNA per cellmore individual copies of mtDNA than nuclear DNA in bony remains. a) Recent advances in molecular tech make possible the recovery of nuclear DNA as well as mtDNA
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'