2What is a DNA?A nucleic acid that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine. The sequence of nucleotides determines individual hereditary characteristics.
3What is a Nucleotide?A single molecule of DNA comprised of 2 basic parts made from 3 distinct molecules.Sugar/Phosphate BackboneNitrogenous Base
4Sugar/Phosphate Backbone Comprised of deoxyribose sugar and a simple phosphate moleculeForms a strong bond that creates the backbone of a DNA strandEXACTLY THE SAME IN ALL DNA
5Nitrogenous BaseBond with complimentary bases in other nucleotides to form the rungs of the DNA ladder (zip DNA together)Only 4 types in all DNA-Adenine, Cytosine, Guanine, and ThymineAdenine and Thymine bond only with each otherCytosine and Guanine bond only with each other
6DNA formDNA nucleotides combine in cells to form long strands in the shape of a double helix (looks like a twisted ladder)
7DNA Form Nucleotides bond at two spots Sugar/Phosphate molecules form the backbone (outside rails)Nitrogenous bases bond in the middle by hydrogen bonds (steps or rungs)Hydrogen bonds between nitrogenous bases are MOST EASILY BROKEN
8DNA FormThe order of the nucleotides is the determining factor in the expression of genes in organisms.
10DNAAccounts for all genetic variation between different individuals and organisms by the use of different:Sequences of nitrogenous basesLengths of DNA segmentsNumbers of Chromosomes and amounts of DNA in an organismThe amount of DNA in an organism DOES NOT relate to the size or complexity of an organism.
11DNA ReplicationThe process through which cells copy DNA for transmission to daughter cells during cell division.The double helix structure allows DNA to easily unzip down the center between nitrogenous bases.Free floating nucleotides attach to each of the separated DNA strands forming 2 new strands of DNA, each an exact copy of the original.
12MutationsA mutation is an unexpected change in a DNA sequence, usually occurring during the replication/cell division.Mutations are common in most organisms (especially simple organisms) though only a small percentage produce noticeable changes in organisms.
14Genetic HierarchyA group of nucleotides=a gene/allele= base pairsA group of genes=1 strand of DNASeveral condensed strands of DNA=1 chromosome2 chromosomes=1 chromatid pairAll possible gene forms in a population=Genome
15Gene MappingMapping the genome of a species allows scientists to identify beneficial and harmful genes in a population, and is the first step in determining the location of specific genes on chromosomes.Changes in the genome of a species occur slowly in response to environmental changes.
16Transferring of DNADNA is passed to offspring during sexual reproduction through single chromosomes.
17Human Genetics Almost all humans have 46 chromosomes. Individuals with Down Syndrome have one extra chromosome.Humans generally differ from each other by approximately 3 million nitrogenous base pairs, or 0.1% of the total gene sequence.
19Genetic DisordersDiseases or other problems resulting from errors in the transmission of genetic information, or the expression of certain negative gene sequences.
20Genetic DisordersMost genetic disorders are recessive, and thus cannot be predicted without genetic analysisRecessive disorders are transmitted by carriers-parents with one dominant gene (normal) and one recessive gene (disorder)Example-Tt
21Genetic DisordersCertain disorders are more common in certain populationsExample: The occurrence of sickle cell in African Americans.
22Common Genetic Disorders Inherited DisordersExamples: Tay-Sachs, Sickle Cell Anemia, HemophiliaMutationsCancer-uncontrolled division of abnormal cellsTreatment must destroy mutated cells
23Genetic MutationsSudden unexpected changes in the genetic code of an organism which appear most often during the process of replication
24Genetic MutationsOften result from increased levels of stress on cells just prior to or during cell divisionStresses include-radiation, UV rays, environmental, etc.
25Genetic MutationsAlmost all mutated cells die immediately, or never impact living organismsMost mutations in humans are harmful such as cancerA small fraction of noticeable mutations are beneficial, such as Chimeras which are used to give us variegated plants.
26Genetic MutationsMost mutations occur in developed plants and animals, affecting isolated groups of cells.Mutations are most devastating when the occur in the early development of organisms. (STEM CELL STAGE)
27Types of Mutations Point mutation Frameshift A mutation that changes DNA at a single point, substituting one nucleotide pair.FrameshiftNucleotides are inserted or deleted, altering the entire DNA sequence after the mutation
29What is Mitosis? The process of cell division in all diploid cells Constantly occurs in cells throughout plants and animals at all timesMuscle cellsSkin cellsStem cellsCambium cellsResults in two diploid daughter cells
30Stages of Mitosis Interphase Prophase Metaphase Anaphase Telephase Cytokinesis
31InterphaseThe period of cell growth and function prior to the beginning of true mitosis, in which the cells store energy for cellular divisionThe cell replicates DNA and produces chromatid pairsThis is the longest period in the life of a cell
32Prophase The first true stage of mitosis The nuclear membrane dissolves, centromeres form, and centrioles move toward opposite ends of the cell
33Metaphase The second and shortest stage of mitosis Chromatids align in the center of the cell and spindle fibers attach to centromeres from centrioles
34Anaphase The third stage of mitosis Chromatids are separated and pulled towards opposite ends of the cell by spindle fibersErrors in the transmission of genetic information are most likely to occur at this stage
35Telephase The final and longest stage of mitosis Chromosomes reach opposite ends of the cell, and new nuclear membranes form for each new daughter cell
36CytokinesisThe actual division of daughter cells at the end of mitosisA cleavage furrow forms pinching apart cells in animalsIn plant cells, a cell plate forms between daughter cells, dividing cells and forming the new section of the cell wall.
38What is Meiosis?The specialized form of cell division that occurs only in haploid cellsSpermEggPollenOvumVery similar in process to mitosis, except with two cycles, producing 4 haploid daughter cells (23 chromosomes each)
39Spermatogenesis Production of male sex cells through meiosis Produces 4 sperm
40Oogenesis Production of female sex cells through meiosis Usually produces 1 viable egg-other 3 abort
41Stages of Meiosis Interphase Meiosis I Meiosis II The stages of Meiosis I and Meiosis II are identical to the stages of Mitosis, but with different cells for a different purpose
42InterphaseSame as mitosisPeriod of growth and function
43Meiosis I Prophase I Metaphase I Anaphase I Telephase I Cytokinesis Reduction process-changes cells from diploid to haploid
44Meiosis II Prophase II Metaphase II Anaphase II Telephase II Prophase II is responsible for aligning chromosomes for the final divisionMetaphase IIAnaphase IITelephase IICytokinesis
46DNA ExtractionThe process of isolating nucleic acids (DNA) from organic material.DNA can be extracted from almost any intact cellular tissue (more cells make it easier)Skin, blood, saliva, semen, mucus, muscle tissue, bone marrow, etc.DNA cannot be extracted from hair, unless skin is attached at the bottomMitochondrial DNA can often be extracted long after nuclear DNA has degraded.
47Simple DNA ExtractionFor observation only, not feasible for analyzing DNAWorks well with fruit (Example: Strawberries)
48Simple DNA Extraction Step 1 Step 2 Step 3 Step 4 Physically break apart plant material, usually fruitsStep 2Use a detergent to break apart the cell membraneStep 3Treat with ethyl alcohol to isolate DNA from remaining proteins and sugarsStep 4Spool using a glass rod to view a large clump of nucleic acids (DNA)
49Advanced DNA Extraction The organism to be tested is chosen, and a sample is taken from which DNA can be extracted.Detergents are used in simple DNA extraction procedures to break down cell membranes, blending the contents of the cell.
50Advanced DNA Extraction The DNA sample is treated with enzymes to isolate nucleic acids, usually both DNA and RNAEnzymes dissolve proteins, sugars, and other materialsExamples: protease, amylase, etc (enzymes end with the suffix –ase)A second enzyme may be applied to cut DNA into gene segments for analysis
51Restriction Digests and Enzymes Restriction enzymes are used to cut extracted DNA into smaller gene sequences.Make analysis easier during the process of gel electrophoresis.Enables scientists to isolate specific genes with specific enzymes for use in genetic engineering.
52Restriction Digests and Enzymes Cuts the gene from the chromosome making a sort of gene soup after the removal of proteinsLeaves the ends of gene segments “sticky” with usually 3 exposed nucleotides on one side of the double helix, so that ends may be rejoined later.
53Methods of DNA Analysis There are several simple methods used for analyzing DNAPaternity TestingGel ElectrophoresisAdvanced MethodsPolymer Chain Reaction (PCR)Amniocentesis
54Paternity TestingSimple method of DNA analysis that compares the DNA of an offspring, plant or animal, with a known mother and suspected father.
55Paternity Testing Process DNA sample taken usually from saliva or blood in animals and leaf or callus tissue in plants. (Hair does not contain DNA, but the hair follicle does.)DNA isolated in sample through the use of protein “eating” enzymes.
56Paternity Testing Process Sample run on gels or through a gene sequencer to indicate the presence of certain genes.Comparison of genes-anything present in the child MUST BE PRESENT IN EITHER THE MOTHER OR THE FATHER. 13 genes present in the child that are not in the mother, but present in the father make a 99% match.
57Polymer Chain Reaction (PCR) Method used in forensic science to amplify genetic material for identification or analysis.Newer technique used only in advanced laboratories.Only a few cells are needed with this technique.
58AmniocentesisMethod used to analyze the DNA of a mammal (occasionally other animals) prior to birth.Used widely in humans to predict the expression of lethal genes or genetic disorders in high-risk pregnancies.Gaining favor in high expense animal breeding (Ex. Race horses)
59Gel ElectrophoresisMethod used to analyze extracted DNA through the distribution of genetic markers on an agar media.Smaller genes travel further distances on the gel. Samples extracted through the same process can be easily compared on a single gel.
60Gel Electrophoresis Process An agar gel is placed into a mold to dry, then placed into an electrophoresis chamber.DNA extraction is placed in small wells at one end of the agar gel. Each well represents a different sample or individual.
61Gel Electrophoresis Process Low voltage direct current is run through a buffer solution surrounding the agar gel distributing DNA fragments across the gelFragments separated by the size of the gene segment; smaller move faster than largerNegative charged DNA fragments are repelled away from the negatively charged wells to the positive charged end.
62Gel Electrophoresis Process Buffer solution provides a means of transmission for electrical current, but also keeps DNA samples in place in wells in the gel.Buffer is heavier than DNA
63Gel Electrophoresis Process Strength of the electrical current determines the speed at which DNA moves across the gel.Ethidium Bromide or another Bromine based solution is applied at the end of the electrophoresis process to stain DNA for better viewing under certain bands of light.
65Natural Selection Mechanism for evolution in natural populations Organisms with best traits suited to the environmental factors affecting a population are most likely to survive and reproduce.Results in the inheritance of the same well-suited traitsImportant traits in natural selection-disease resistance, size, color pattern/camouflage, etc.
67Stabilizing Selection Individuals with the average or norm for a trait have an advantage over other forms of the traitExample: gray moths (norm) are favored over black and white moths
68Directional Selection Individuals with one extreme or less common version of a trait are favored over other forms of the trait.Example: Black moths are favored over gray or white moths
69Disruptive SelectionMultiple extremes or alternative forms of a trait are favored over the normExample: Black moths and white moths are favored over gray moths
70Selective BreedingMethod of breeding plants and animals utilized in agriscience to produce offspring that possess certain characteristics desirable to agriculturistsUtilized for generations-produced the first domestic animals in early civilizations
71Selective Breeding Used to select for a variety of traits including: Muscling/SizeFat contentBreeding CapabilityColorSpeed/AgilityTemperamentMilk Production
72Selective Breeding Methods for selective breeding: Artificial inseminationPen/field breedingIsolation Breeding-inbreedingMechanical pollination of plantsHybridization of plants and animals
73Selective BreedingSelective breeding is accomplished much quicker in plants than animals due to growth rates and ease of propagation/production
75Observe Patterns of Heredity The occurrence of genetic disorders in offspring or parents is an indicator that the parent may have a recessive gene for the disorderThough genetic recombination is random, some animals are more likely to transmit genes than othersKeeping careful breeding records improves effectiveness
76Select Animals Carefully Animals used in selective breeding should be:Healthy-old injuries or illnesses are not a factor unless they are a result of genetic propensities or impair breeding capabilitiesCarefully monitored-nutrition levels, pests and stress can all reduce breeding viability. Some very good specimens are completely isolated.
77Select Animals Carefully Hybrids should be avoided, since traits expressed in the organism are rarely transmitted to offspringThe process of inbreeding isolates genes for only a single generation, as many are recessive.
78Carefully Plan Breeding Crosses Plants can be crossed not only within species (interspecific), but also within genus (intergeneric), and even, in rate cases family (interfamilial)Animals are usually limited to crosses within the same species
79Methods for Producing Selective Breeding Programs
80Inbreeding Crossing organisms that are genetically related Crossing two plants to produce an f1 generation, then crossing two of the f1 offspring to create an f2 generation
81BackcrossingCrossing offspring from a cross with one of the previous parents, or a similar organism, to maximize the expression of certain traits.Often used after intergeneric crosses to produce offspring that possess more characteristics from one genus.