dna mutations & genetics
DESCRIPTION
DNA Mutations & Genetics. Lewis Biology 2013. Concepts Covered this unit. Mutations (Point and Frame-shift) Diseases caused by Mutations Sickle Cell Anemia and Point Mutations Genetics and Heredity Gregor Mendel and the Pea Plants Monohybrid Crossing Alleles Mendelian Genetics - PowerPoint PPT PresentationTRANSCRIPT
DNA MUTATIONS & GENETICS
LEWIS BIOLOGY 2013
CONCEPTS COVERED THIS UNITMutations (Point and Frame-shift)
Diseases caused by Mutations
Sickle Cell Anemia and Point Mutations
Genetics and Heredity
Gregor Mendel and the Pea Plants
Monohybrid Crossing
Alleles
Mendelian Genetics
Non-Mendelian Genetics
Dominance vs. Recessive
Co-Dominance
Incomplete Dominance
Multiple Alleles & Blood Typing
Sex-Linked Traits
Pedigree Analysis
Chapters 10 & 12-13 are a good resource to use for this unit! Please read ahead
TERMS YOU WILL ENCOUNTER THIS UNIT (CHAPTERS 10 AND 12 IN BLUE BOOK; DO NOT USE INTERNET DEFINITIONS!)
Heredity
Trait
Genetics
Gamete
Fertilization
Zygote
Pollination
Hybrid
Allele
Dominant
Recessive
Phenotype
Genotype
HomozygousHeterozygousCrossing overDiploidHaploidEggHomologous chromosomesMeiosisNondisjunctionSpermSexual reproductionCarrierFetuspedigree
Co-dominanceIncomplete dominanceMultiple allelePolygenic inheritanceSex chromosomeSex linked traitKaryotype
DISEASES COVERED THIS UNIT
Please research (and TAKE NOTES) and read ahead about the following genetic disorders:
Symptoms, causes, treatment, etc..
1. Klinefelter’s Disease
2. Turner’s Syndrome
3. Cystic Fibrosis
4. Sickle Cell Anemia
5. Trisomy 21 (Down Syndrome)
6. Phenylkentonuria (PKU)
ENVIRONMENTAL OR GENETIC??
The following list contains diseases that are either caused by environmental factors (smoking, diet, etc.) or because of mutated genes that are passed along by parents. Determine if each disease is caused by an environmental factor or genetic factor (mutation)—or both
1. Skin cancer
2. Lung cancer
3. Diabetes
4. PKU
5. Heart Disease
THE EXAM FOR THIS UNIT
The exam for this unit will be held between April 29-30.
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, & 13 in the Blue Glencoe Textbook
DNA MUTATIONS
There are two general types of mutations
Point and Frame-Shift
Mutagen: 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. Potentially lethal
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…..
GENETICS & HEREDITYCHAPTERS 10 &12
FATHER OF GENETICS
Gregor 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 PLANTS
IN 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 TERMS
Phenotype= 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 #2
Complete 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
HOW WE MAKE GAMETES (SPERM AND EGGS)
…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 chromosomes
46 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 MITOSIS
Organism 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 material
Nondisjunction: where the chromosomes fail to separate during Meiosis, this causes Trisomy 21 (Down Syndrome)
Crossing over
TO BE CONTINUED…NON-MENDELIAN GENETICS