7 Jan • Opening question: • Welcome back! Check out the new calendar for the next three weeks. • Agenda: • Intro to unit 6 • Genetics discussion questions • Pedigree Basics • Video Clip • Class activity • HW: Read 8.11 and 8.12 + GQs
Genetics Discussion Questions • Where do you get your traits? • How do you get your traits? • Are your traits just a blend of your parents’? • Is it possible to have a trait that neither of your parents have? • Besides function, what is the difference between sex cells (sperm & egg) and body cells (skin, liver, brain)? • Can humans reproduce asexually?
Pedigree basics • Male/female • Marriage line • Offspring line • Generations • Shading • Questions: • How many males? • How many marriages? • How many generations? • How many kids were made from 2nd generation? • How many people with the disease? • Does the disease have a pattern?
Pedigree Class Regroup • Does this disease affect males more than females? • If the parent has this disease, does that mean the kids are going to have it? • If the parents don’t have it, can their kids have it? • Any ideas on how this disease is passed on through families by their genes?
8 Jan • Opener: • How does DNA of a sex cell compare to the DNA of the parent? • Agenda • Review Pedigrees • Meiosis • Meiosis puzzle • Meiosis drawing • Homework • Read 2.6 + GQs
Human female karyotype 2n diploid = 2 copies 46 chromosomes 23 pairs XX
Human male karyotype 2n diploid = 2 copies 46 chromosomes 23 pairs XY
Do we make egg & sperm by mitosis? No! What if we did, then…. + 46 92 46 egg sperm zygote Doesn’t work!
Meiosis • Meiosis • special cell division in sexually reproducing organisms • reduce number of chromosomes • Diploid (2 sets of chromosomes haploid or monoploid (1 set ) • makes gametes- sex cells • sperm, eggs
46 46 23 23 46 23 23 How do we make sperm & eggs? • Must reduce 46 chromosomes 23 • must halve the number of chromosomes • haploid zygote egg meiosis fertilization sperm gametes
46 23 46 23 Meiosis makes sperm & eggs • 46 chromosomes to 23 chromosomes • halve the number of chromosomes egg meiosis diploid haploid sperm
Steps of meiosis • Cell copies its DNA • Chromosomes that code for the same information pair-up and some of their information is transferred (crossing-over) • Cell divides once, yielding 2 cells • Each of the 2 cells divide again, yielding 4 gametes.
9 Jan • Opener • Think about the pedigrees from yesterday. When can we tell someone’s genetic make-up by observing them? • Agenda: • Review Meiosis • Why sex? • Sources of variation • Homework • Read 8.10 + GQs
Meiosis Review • http://media.pearsoncmg.com/bc/bc_0media_bio/bioflix/bioflix.htm?8apmeiosis
10 Jan • Opener • Agenda • Generation of Variation • Meiosis Review • Pop Beads • White Board • Participation Quiz • Homework • Formative Quiz Tomorrow
Natural selection Charles Darwin Where does the Variation come from? There is heritable variation within populations More offspring are born than can survive This leads to a competition for limited resources Some survive/reproduce based on favorable adaptations
Generation of variation Where does that variation in offspring come from? • Mutations & Epigenetics • Crossing over • Independent assortment of chromosomes into gametes • Random fertilization or combination of gametes
On your whiteboard… • Show the complete process of meiosis from parent cell to gamete. • Pretend your organism’s diploid number of chromosomes is six. • Be sure to have a small, medium and large set of homologous chromosomes. • Make sure to include the following terms: • Diploid • Haploid • Gamete • Crossing over • Homologous pair
Participation Quiz • What is the main advantage of sexual reproduction over asexual reproduction? • What type of cells are produced via meiosis? • In meerkats, a diploid cell contains 36 chromosomes. How many chromosomes does a meerkat egg contain? • T/F: All the gametes produced from meiosis are genetically identical to one another. • How many chromosomes did you get from your mother?
11 Jan • Opener • Have you ever heard of Hereditary Hemochromatosis? • Agenda • Parts of the cell game • Parts of the cell drawing • Homework
14 Jan • How do you study? • Where are you? • Do you have music/t.v./computer on? • How long do you study at one time? • Agenda • Studying • Note cards/ foldables • Peer quiz • HH ppt • Homework • Study for the final
Mr. Gotlund’s study tips • Study for short periods of time (15-30 min) followed by a timed break (5- 10 min) • Avoid distractions: turn off music, close computer windows, T.V., etc. Go somewhere else (different room, library) • When possible study during daylight or early evening hours. • Set goals for your study sessions. Base them on content, not clock. • Study actively: read it, say it, write it, hear it.
22 Jan • Opener: • If a couple (of humans) were going to have a baby, what are the chances of them having a girl? How do you know? • Agenda • New Seats • Genetics Vocab • Coin Flipping • Punnett Squares • Homework • Punnett Square Problems
Genetics vocabulary • Allele- different versions of a gene • Dominant- an allele that masks the effects of another. Only need one copy to show the trait. Usually represented as a capital letter • Recessive- need two copies to show the trait. Usually represented with a lower case letter • Homozygous- two copies of the same allele (dominant or recessive) • Ex. RR, tt, EE, qq • Heterozygous- one copy of each allele. Also, called carriers • Ex. Rr, Tt, Ee, Qq
Genetics Vocab (cont.) • Genotype- an organism’s genetic make-up • ex. Tt, rr, Qq • Phenotype- the physical trait- “what is seen” • Ex. Attached earlobes, blood type, eye color You can’t always tell a genotype by looking at the phenotype
In pea plants, Yellow seeds (Y) are dominant over green (y) seeds. • What are the possible genotypes for a yellow- seeded plant? • green-seeded? • If two heterozygotes were crossed, what could be the possible outcomes? YY or Yy yy Use a Punnett Square Punnett square : a chart that shows the predicted outcomes of a genetic cross
Y y Y y Punnett squares Yy x Yy male / sperm Now try: YY x yy Yy x yy YY Yy female / eggs Yy yy
Solving genetic problems • Write out genotypes • Write out cross • Make a Punnett square • Answer the question
Let’s try a problem… • In a certain species of daisy, purple flowers are dominant to white flowers. A heterozygote and a homozygous recessive plant are crossed. What percent of their offspring would you expect to be white? P= purple flowers p= white 2. Pp x pp P p p 3. p 4. 2/4= 50%
23 Jan • Opener: • Agenda • Finish Punnett Squares • Practice Problems • Non-mendelian genetics • Homework • Participation Quiz tomorrow
25 Jan • Opener: In lynx, striped fur is dominant over solid fur. If you were presented with a striped lynx, how could you determine its genotype (without doing a genetic test)? • Agenda • Participation quiz • Non-Mendelian Genetics • Homework • none
Participation Quiz • In a certain species of daisy, purple flowers are dominant to white flowers. A heterozygote and a homozygous recessive plant are crossed. • Write a key for this problem • Show the cross • Draw the Punnett square. • If 36 offspring are produced from this cross, how many of their offspring are expected to be purple?
What traits in humans obey Mendel’s Law of Dominance? Tongue curling- dominant Free Ear lobe- dominant Widow’s peak- dominant Hitchhiker’s thumb- recessive Shorter big toe than 2nd toe- dominant
Breaking the Law of Dominance According to the law of dominance what should happen when you cross a purebred/homozygous white snapdragon plant with a purebred/homozygous red snapdragon?
Incomplete Dominance • Heterozygotes show a blending of the two parental traits • Red is incompletely dominant over white so pink snapdragons are produced
According to the Law of Dominance what should happen when you cross a red and white horse?
CODOMINANCE- Both parental phenotypes are shown in heterozygotes White and red color in horses are codominant so a white and red horse is produced.
Multiple Alleles • Many genes have more than just two alleles • If there are three or more alleles for a trait, it is called multiple alleles • Example: Human Blood type Alleles: • IA=A gene • IB=B gene • i=O gene
Polygenic inheritance • Some phenotypes determined by additive effects of 2 or more genes on a single character • phenotypes on a continuum • human traits • skin color • height • weight • intelligence • behaviors
Example of a polygenic trait • Eye color • There are genes for • Tone of pigment (what color it is) • The amount of pigment • Position of pigments (look at people’s eyes- there are many different patterns in the iris)