DNA MUTATIONS & GENETICS

LEWIS BIOLOGY 2013

CONCEPTS COVERED THIS UNITMutations (Point and Frame-shift)Diseases caused by MutationsSickle Cell Anemia and Point MutationsGenetics and HeredityGregor Mendel and the Pea PlantsMonohybrid CrossingAllelesMendelian GeneticsNon-Mendelian GeneticsDominance vs. RecessiveCo-DominanceIncomplete DominanceMultiple Alleles & Blood TypingSex-Linked TraitsPedigree Analysis

Chapters 10 & 12-13 are a good resource to use for this unit! Please read ahead

TERMS YOU WILL ENCOUNTER THIS UNIT (AT SOME POINT YOU WILL NEED THIS VOCABULARY IN YOUR NOTES)

Heredity TraitGeneticsGameteFertilizationZygotePollinationHybridAlleleDominant RecessivePhenotypeGenotype

HomozygousHeterozygousCrossing overDiploidHaploidEggHomologous chromosomesMeiosisNondisjunctionSpermSexual reproductionCarrierFetuspedigree

Co-dominanceIncomplete dominanceMultiple allelePolygenic inheritanceSex chromosomeSex linked traitKaryotype

DISEASES COVERED THIS UNIT

Please research and read ahead about the following genetic disorders:Kleinfelter’s DiseaseTurner’s SyndromeCystic FibrosisSickle Cell AnemiaTrisomy 21 (Down Syndrome)

THE EXAM FOR THIS UNITThe exam for this unit will be held between October 30-31st.This will be considered your Midterm Examination. Most of the material will cover: DNA, RNA, Protein Synthesis and Genetics—although older material will be on the exam.The midterm will be weighed twice (as two test grades)Please study ahead of time as it is comprehensive and cumulative.

As a resource, utilize Chapters 10 & 12 in the Blue Glencoe Textbook

DNA MUTATIONSThere are two general types of mutationsPoint and Frame-ShiftMutagen: something that causes a mutation

Point Mutations: a genetic mutation in which only one of the nitrogenous bases is substituted (changed) to another). Only one amino acid is changed

Frame-shift Mutations: a genetic mutation in which one of the bases is added or deleted. This causes the rest of the DNA sequence to shift, changing the ENTIRE DNA/AMINO ACID SEQUENCE. THIS IS THE MOST DANGEROUS MUTATION

EXAMPLES OF POINT MUTATION

Sickle cell anemia is caused by a point mutation. A single base is changed, causing the disease to occur(FYI, those who have sickle cell are resistant to Malaria)

Normal Hemoglobin (blood) GGG-CTT-CTT-TTT

Sickled Hemoglobin (blood) GGG-CAT-CTT-TTT

Only one(1) of the amino acids will change

EXAMPLES OF FRAME-SHIFT MUTATIONS

One of the bases in a DNA sequence is either inserted or deleted, therefore causing the entire sequence to shift. This will change the entire DNA sequence, thusly changing the entire AMINO ACID SEQUENCE.THIS CAN BE LETHAL

NORMAL SEQUENCE: ATC – GAT – TTA – AAG

THE A WILL BE DELETED, AND THE REST OF THE BASES WILL SHIFT TO FILL ITS PLACE

MUTATED SEQUENCE: ATC – GTT – TAA –AG…..

ASSIGNMENT #1: MUTATIONS WORKSHEET

Complete the mutations worksheet on my website. This is to be completed on your own paper.The answers will be discussed on today’s meet www.todaysmeet.com (please remember guidelines for appropriate commentary) Lets not allow for immaturity to ruin the privileges of those who follow rules.

Be sure to read the section on your worksheet about Sickle Cell Anemia.

GENETICS & HEREDITYCHAPTERS 10 &12

FATHER OF GENETICSGregor Mendel is the father of genetics (hence the term Mendelian Genetics).

• Mendel was an Austrian monk studied heredity (how traits are passed from parent to offspring)

• He was the first to be able to predict the outcome of one’s traits.

• This led to the field of genetics (branch of biology that studies heredity)

• He studied heredity using garden pea plants using the sex organs (yes, plants reproduce sexually..)

THE BIRDS & THE BEES…WELL JUST THE PLANTSIN PLANT FERTILIZATION, THE MALE GAMETE UNITES WITH THE FEMALE GAMETE. THIS RESULTS IN A ZYGOTE

ZYGOTE

TERMS & ABBREVIATIONS

• Monohybrid cross: aka the ‘Punnett Square’, used to predict the traits of offspring

• P1: Parent generation (mom & dad)

• F1, F2, ..: Filial generations (the offspring, grandchildren etc.)

• Homozygous Dominant: AA• Homozygous recessive: aa (this is the ONLY time recessive traits are

shown)• Heterozygous: Aa (the dominant trait is still expressed)• Dominant: trait that is shown or expressed• Recessive: trait that is hidden or disappears in the mating• Alleles: forms of a gene

…MORE TERMSPhenotype= the Physical appearance (color, size, shape, etc.)Genotype = the gene or allele (Aa, AA, aa)

Example: 75% of the Offspring were Heterozygous Aa (genotype), meaning, they have Yellow eyes (phenotype)25% of the offspring were Homozygous recessive aa (genotype), meaning they have white eyes (phenotype)

Joke: You’ve got some good jeans! Haha…Get it??

BASICS OF THE PUNNETT SQUARE: TRY THIS EXAMPLE

Alleles: Brown eyes: BB, Bb Blue Eyes: bb

Problem:Mom has blue eyes, and Dad is Heterozygous for Brown eyes.

Complete the Punnett Square and give the phenotype and genotype of the offspring

A a

a

a

BASICS OF THE PUNNETT SQUARE: ANSWER

Aa aa

Aa aa

Alleles: Brown eyes: BB, Bb Blue Eyes: bb

Problem:Mom has blue eyes, and Dad is Heterozygous for Brown eyes.

Complete the Punnett Square and give the phenotype and genotype of the offspring A a

a

a

Answer: Phenotype: 50% will have brown eyes50% will have blue eyes

Genotype: 50% Aa (heterozygous)50% (homozygous recessive)

ASSIGNMENT #2Complete the Monohybrid Cross worksheet on my website. The worksheet has been upload, you may write your answers on your own paper OR print it at home!

Do not forget the rules of Mendelian Genetics!!!

If there is a capital letter (A, B, C…), this means the gene is dominant, and will mask (cover) the recessive gene (a, b, c)

MEIOSIS…NOT SEXUAL REPRODUCTION

REMEMBER…We covered Meiosis when we talked about Mitosis.Meiosis is a cell division of gametes…

In other words---it’s how guys make sperm, and ladies make eggs (ladies, you’re born with the eggs you have ) Guys continue Meiosis until they’re old…yuck

Meiosis is NOT SEXUAL REPRODUCTION

MEIOSISIn Meiosis, it’s a way of taking a person’s 46 chromosomes, and dividing them in half—so that parents only pass 23 chromosomes onto their offspring.You’re the perfect blending of both of your parents.46 chromosomes in dad’s sperm / 2 (meiosis) = 23 chromosomes46 chromosomes in mom’s eggs / 2 (meiosis) = 23 chromosomes

23 chromosomes + 23 chromosomes = YOU

REVIEW: MITOSIS VS. MEIOSISMitosis Meiosis

Number of Divisions 1 2 (Meiosis I & Meiosis II)

Number of daughter cells 2 4

Purpose Making new body cells (liver, hair, skin, etc.)“somatic cells”

Making new sex cells “gametes” (sperm & eggs)

Chromosome # Diploid (2n) Haploid (n) -half

MEIOSIS VS MITOSISOrganism Somatic cell (Mitosis)

Diploid (2n)

Gamete (meiosis)Haploid (n)

Fruit fly 8 4

Garden pea 14 7

Corn 20 10

Tomato 24 12

Leopard frog 26 13

Apple 34 17

Human 46 23

Chimpanzee 48 24

Dog 78 39

Adder’s tongue fern 1260 630

EVENTS IN MEIOSISCrossing Over: Occurs in Prophase I, where the chromosomes break, and exchange genetic materialNondisjunction: where the chromosomes fail to separate during Meiosis, this causes Trisomy 21 (Down Syndrome)

Crossing over

TO BE CONTINUED…NON-MENDELIAN GENETICS