Presentation on theme: "County Interim Exam – spring 2015 DNA/Meiosis/Genetics focus"— Presentation transcript:
1County Interim Exam – spring 2015 DNA/Meiosis/Genetics focus 9. analyze how biological traits are passed on to successive generations (GPS, HSGT)9a. distinguish between DNA and RNA; including the differences in types of sugar, nitrogen bases, number of strands, locations and roles9b. explain the role of DNA in storing and transmitting cellular information including replication, transcription, translation, and gene expression (central dogma of biology)9c. explain the role of meiosis in reproductive variability (crossing over, non- disjunction) using Mendel’s law9d. describe the relationship between changes in DNA and potential appearance of new traits including alterations during replication, insertions, deletions, and substitutions and mutagenic factors that can alter DNA (high energy radiation and chemical)9e. compare the advantages of sexual reproduction and asexual reproduction in different situations9f. examine the use of DNA technology in forensics, medicine, and agriculture9g. apply the principles of Mendelian genetics to predict probabilities of offspring
2Building blocks of nucleic acids are nucleotides *phosphate group, pentose sugar, and a nitrogenous base (A,T,C,G,U)DNA – bases are A,T,C,GRNA – bases are A,U,C,G
3Nucleic Acids *sugar is deoxyribose *never leaves nucleus Exist as 2 types : DNA and RNA*DNA *double stranded (entire code)*sugar is deoxyribose*never leaves nucleus*bases are A,T,C,G*involved in replication and protein synthesis*RNA *single stranded (partial code)*sugar is ribose*mobile – nucleus and cytoplasm*bases are A,U,C,G*involved in Protein Synthesis
8DNA Replication….a review Where happens? NucleusWhat are you making? DNA DNAWhen happens? During S phase of Interphase (Synthesis)Enzymes? Helicase, ligase, DNA polymerase, gyrase
9Figure 16.7 A model for DNA replication: the basic concept (Layer 4) Gyrase – enzyme that winds the double helix back into shapeSemi-conservative process…
10Protein Synthesis 2 stages: Transcription and Translation Transcription occurs in the nucleusDNA mRNA(this is only PART of the entire DNA molecule – ONLY the part that codes for the specific proteins needed at that time)Translation occurs in the cytoplasm at a ribosomemRNA protein(using tRNA and rRNA)
15Working with the Code – use the box from your textbook Given TACGGGCCCCAAACTa. what is the mRNA made?b. what is the tRNA needed for translation?c. what is the protein made?(amino acid chain)2. Given TACGCACATAATACTdo a, b, and c as above…
16Working with the Code – use the box from your textbook Given TAC GGG CCC CAA ACTa. what is the mRNA made?AUG CCC GGG GUU UGAb. what is the tRNA needed for translation?UAC GGG CCC CAA ACUc. what is the protein made?(amino acid chain)Methionine – Proline – Glycine -- Valine
17Mendel studied 8 different pea plant traits… Trait – a specific characteristic that varies from one individual to another(ex. Seed color, height, hair color)Mendel’s studied traits had two contrasting characters or “alleles” -- different forms of a gene
18Today we know that there are 2 ways of describing organisms – Phenotype and Genotype Phenotype is the physical appearance – green, tall, purple, round, etc.Genotype describes the letter combo used when represent alleles – capital letters are called “dominant” and lower case letters are called “recessive”Bb
19Mendel’s Conclusions…. Biological inheritance is determined by “factors” that are passed from one generation to a next – today, called genesPrinciple of Dominance: where there are two or more forms of a gene for a single trait, some alleles are dominant and other alleles are recessive (some show, others do not and are hidden)Law of Segregation: alleles separate from each other during the process of meiosis (gamete formation)________________________________________________________He also had one more:Principle of independent assortment: genes for different traits can separate independently during the formation of gametes --Ex. Blondes do not all have blue eyes, brunettes do not all have brown eyesThis one deals with MORE than one trait, so brings us to dihybrid crosses….
20Meiosis Type of cell division where one diploid somatic cell produces four haploid gametes(these are the FINAL result, will not divide again…will join egg/sperm or sperm/egg to make a zygote…)
21Meiosis starts with ONE diploid cell, ends with 4 haploid cells Fig. 13-8Meiosis starts with ONE diploid cell,ends with 4 haploid cellsProphase IMetaphase IAnaphase ITelophase I andCytokinesisProphase IIMetaphase IIAnaphase IITelophase II andCytokinesisCentrosome(with centriole pair)Sister chromatidsremain attachedCentromere(with kinetochore)SisterchromatidsChiasmataSpindleMetaphaseplateSister chromatidsseparateHaploid daughter cellsformingHomologouschromosomesHomologouschromosomesseparateCleavagefurrowFragmentsof nuclearenvelopeMicrotubuleattached tokinetochoreFigure 13.8 The meiotic division of an animal cellThe gametes can be involved in fertilization later…but don’t HAVE to be used!
23Figure 13.7 The stages of meiotic cell division: Meiosis II
24Figure 13.8 A comparison of mitosis and meiosis: summary
25Mutations – Changes in DNA clip to review of variations Can affect entire chromosome (chromo mutations) or can change the proteins produced by a DNA code (point mutations)Mutations can happen spontaneously (no reason they occurred…)ORDue to presence of mutagens – substances or agents that can cause changes in DNAEx. Chemicals, radiation, x-rays, viruses
26Point mutations vs. Chromosome mutations Point mutation: change in single base pair of DNAChromosome mutation: change in a large portion of an entire chromosome – effects MANY genes
27Point mutations*if does not effect the length of the code, MIGHT just change the amino acid in that position – SUBSTITUTION(be aware, though, that due to the multiple codes that code for most amino acids, there may NOT be a change in the amino acid…)*if does change the length of the code, the point shift mutation is called a frameshift mutation, and are two types of this:INSERTIONS AND DELETIONS
30Sexual vs. Asexual reproduction link to Learn GeneticsLiving things use lots of different strategies for producing offspring, but most strageties fall neatly into the categories of either sexual or asexual reproduction.Asexual reproduction generates offspring that are genetically identical to a single parent.In sexual reproduction, two parents contribute genetic information to produce unique offspring.
31Punnett SquareDevice for predicting the results of a genetic cross between individuals of a known phenotype.Developed by R.C. PunnettRules:1.must predict possible gametes first2. male gametes are written across top, female gametes on left side3. Capital letters come first, then obey alphabetical order4. when read Punnett, start in upper left corner and read as if a book – WRITE OUT GENOTYPES IN ORDER
32Monohybrid crosses – only one character considered Steps to do:Write out genotypes of parentsWrite out possible gametes producedDraw 4 box Punnett squarePut male gametes on top, female on left sideFill in boxes with two letters in EACH box, one from each parentREAD boxes like a book – start in the upper left corner, go across, then down to next line as neededDetermine genotypes by reading Punnett starting from top left(fraction of boxes, percent, letter combination, word description of letters)Determine phenotypes by reading from genotype list(fraction of genotypes, percent, what it looks like to your eye)
33Dihybrid cross – 16 box Punnett Square (two traits are being considered at once…) Write out genotypes of parentsWrite out gametes produced – “hop-scotch method”1st with 3rd, 1st with 4th, Ex. RrTt – RT, Rt, rT, rt2nd with 3rd, 2nd with 4thWILL HAVE 2 alleles (2 letters) IN EACH GAMETE THIS TIME!!!Draw 16 box Punnett squarePut male gametes on top, female on left sideFill in boxes – WILL HAVE 4 LETTERS IN EACH BOX*follow alphabetical order first*then put capitals in orderDetermine Genotypes -- Read Punnett square from top left as if reading a book. Report fractions, percent, letter combinations, and descriptions of the letter combinations…Determine Phenotypes – Read the GENOTYPES and report the phenotypes in order from top to bottom. Report fractions, percent, and descriptions of the physical appearance.
34Beyond Mendel…know how to identify and work out genetics problems with: Sex determination – XX and XYSex linked traits – use of super scriptsXCXcIncomplete dominance – blendingCodominance – no blendingMultiple alleles (blood typing)Pedigrees
35DNA technology and Forensics PCRGel electrophoresisDNA fingerprinting
36DNA technology and Medicine Amniocentesis and KaryotypingGene therapy – cystic fibrosis treatmentBiotechnology (make medicines by splicing needed genes into new organisms – ex. gene for insulin and human growth hormone inserted into bacteria)Cloning – stem cell research
37DNA technology and agriculture GMO’s – genetically modified organismsBt corn and Bt cotton = pest resistantTomatoes & Strawberries – inserted a gene to make them not freeze (frost resistant…using genes from Arctic Fish)Induction of Polyploidy – chemicals disrupt meiosis – bigger fruit or seedless fruit