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County Interim Exam – spring 2015 DNA/Meiosis/Genetics focus

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1 County 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 roles 9b. 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 law 9d. 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 situations 9f. examine the use of DNA technology in forensics, medicine, and agriculture 9g. apply the principles of Mendelian genetics to predict probabilities of offspring

2 Building 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,G RNA – bases are A,U,C,G

3 Nucleic 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

4 Figure 5.29 The components of nucleic acids

5 Figure 16.6 Base pairing in DNA

6 Unnumbered Figure (page 292) Purine and pyridimine
Why does A always pair with T (or U), and G with C?


8 DNA Replication….a review
Where happens? Nucleus What are you making? DNA  DNA When happens? During S phase of Interphase (Synthesis) Enzymes? Helicase, ligase, DNA polymerase, gyrase

9 Figure 16.7 A model for DNA replication: the basic concept (Layer 4)
Gyrase – enzyme that winds the double helix back into shape Semi-conservative process…

10 Protein Synthesis 2 stages: Transcription and Translation
Transcription occurs in the nucleus DNA  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 ribosome mRNA  protein (using tRNA and rRNA)

11 Figure 17.3 The triplet code

12 Figure 5.28 DNA ->RNA -> protein: a diagrammatic overview of information flow

13 The Genetic Code Section 12-3 Go to Section:

14 Figure 17.4 The dictionary of the genetic code

15 Working with the Code – use the box from your textbook
Given TACGGGCCCCAAACT a. what is the mRNA made? b. what is the tRNA needed for translation? c. what is the protein made? (amino acid chain) 2. Given TACGCACATAATACT do a, b, and c as above…

16 Working with the Code – use the box from your textbook
Given TAC GGG CCC CAA ACT a. what is the mRNA made? AUG CCC GGG GUU UGA b. what is the tRNA needed for translation? UAC GGG CCC CAA ACU c. what is the protein made? (amino acid chain) Methionine – Proline – Glycine -- Valine

17 Mendel 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

18 Today 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” B b

19 Mendel’s Conclusions….
Biological inheritance is determined by “factors” that are passed from one generation to a next – today, called genes Principle 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 eyes This one deals with MORE than one trait, so brings us to dihybrid crosses….

20 Meiosis 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…)

21 Meiosis starts with ONE diploid cell, ends with 4 haploid cells
Fig. 13-8 Meiosis starts with ONE diploid cell, ends with 4 haploid cells Prophase I Metaphase I Anaphase I Telophase I and Cytokinesis Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis Centrosome (with centriole pair) Sister chromatids remain attached Centromere (with kinetochore) Sister chromatids Chiasmata Spindle Metaphase plate Sister chromatids separate Haploid daughter cells forming Homologous chromosomes Homologous chromosomes separate Cleavage furrow Fragments of nuclear envelope Microtubule attached to kinetochore Figure 13.8 The meiotic division of an animal cell The gametes can be involved in fertilization later…but don’t HAVE to be used! 


23 Figure 13.7 The stages of meiotic cell division: Meiosis II

24 Figure 13.8 A comparison of mitosis and meiosis: summary

25 Mutations – 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…) OR Due to presence of mutagens – substances or agents that can cause changes in DNA Ex. Chemicals, radiation, x-rays, viruses

26 Point mutations vs. Chromosome mutations
Point mutation: change in single base pair of DNA Chromosome mutation: change in a large portion of an entire chromosome – effects MANY genes

27 Point 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



30 Sexual vs. Asexual reproduction
link to Learn Genetics Living 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.

31 Punnett Square Device for predicting the results of a genetic cross between individuals of a known phenotype. Developed by R.C. Punnett Rules: 1.must predict possible gametes first 2. male gametes are written across top, female gametes on left side 3. Capital letters come first, then obey alphabetical order 4. when read Punnett, start in upper left corner and read as if a book – WRITE OUT GENOTYPES IN ORDER

32 Monohybrid crosses – only one character considered
Steps to do: Write out genotypes of parents Write out possible gametes produced Draw 4 box Punnett square Put male gametes on top, female on left side Fill in boxes with two letters in EACH box, one from each parent READ boxes like a book – start in the upper left corner, go across, then down to next line as needed Determine 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)

33 Dihybrid cross – 16 box Punnett Square (two traits are being considered at once…)
Write out genotypes of parents Write out gametes produced – “hop-scotch method” 1st with 3rd, 1st with 4th, Ex. RrTt – RT, Rt, rT, rt 2nd with 3rd, 2nd with 4th WILL HAVE 2 alleles (2 letters) IN EACH GAMETE THIS TIME!!! Draw 16 box Punnett square Put male gametes on top, female on left side Fill in boxes – WILL HAVE 4 LETTERS IN EACH BOX *follow alphabetical order first *then put capitals in order Determine 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.

34 Beyond Mendel…know how to identify and work out genetics problems with:
Sex determination – XX and XY Sex linked traits – use of super scripts XCXc Incomplete dominance – blending Codominance – no blending Multiple alleles (blood typing) Pedigrees

35 DNA technology and Forensics
PCR Gel electrophoresis DNA fingerprinting

36 DNA technology and Medicine
Amniocentesis and Karyotyping Gene therapy – cystic fibrosis treatment Biotechnology (make medicines by splicing needed genes into new organisms – ex. gene for insulin and human growth hormone inserted into bacteria) Cloning – stem cell research

37 DNA technology and agriculture
GMO’s – genetically modified organisms Bt corn and Bt cotton = pest resistant Tomatoes & 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

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