Transcript Heredity
Heredity It’s in the genes! What is heredity? Heredity is the passing of traits from parent to offspring. You inherit traits from your parents What are traits? Eye Color Hair Color Height Weight Body Structure Facial Features Skin Color http://www.dance-classes.ca/photos/faces/faces_2004W_comp1.jpg More Traits – Video Clip What traits did you inherit from your parents? Complete the genetic scavenger hunt with the people at your table. List any unusual traits that your group members have on the back of the paper. You have 5 minutes to complete this assignment. Be ready to share with the class. How traits are passed When organisms reproduce, traits are passed from parent to offspring. These traits are carried in DNA, the genetic material found in a cell’s nucleus. DNA acts like a blueprint. How are traits passed? publications.nigms.nih.gov http://www.healthsystem.virginia.edu/internet/huntdisease/i mages/DNA.gif http://www.geocities.com/Heartland/Bluffs/1958/notech1.html Dominant and Recessive Each parent has two genes (or letters) for a trait. These letters are called alleles. Capital letters are called Dominant alleles. When these alleles are present, they take over or show. They are the “stronger” alleles Lower case letter are recessive alleles and are the “weaker” of the alleles. http://naturalsciences.sdsu.edu/classes/lab2.4/trait.jpg Punnett Squares Using Punnett Squares allow us to show what the offspring could look like Allows us to calculate probability of certain genotypes and phenotypes to occur http://www.math.utep.edu/Faculty/mleung/probabilityandstatistics/probapps2.html Punnett Squares- Video Clip Gender Female – XX Male –XY Male determines the sex of the baby Practice Punnett Squares 10 examples Dominant/Recessive Capital letters are called Dominant alleles. When these alleles are present, they take over or show. They are the “stronger” alleles Lower case letter are recessive alleles and are the “weaker” of the alleles. Dominant B – brown eyes T – tall C – curly hair W – widows peak F – freckles D – dark skin Recessive b – blue eyes t – short s – straight hair w – no widows peak f – no freckles d – light skin Genotype and Phenotype Genotype – the inherited alleles (letters) Phenotype – what the alleles look like when inherited. http://www.phschool.com/atschool/science_images/human_punnett_square.jpg http://www.bbc.co.uk/schools/gcsebitesize/img/bigenopheno.gif Genotype/Phenotype Genotype Bb bb TT tt Cc cc Ff ff Phenotype Brown Eyes Blue Eyes Tall Short Curly Hair Straight Hair Freckles No Freckles Homozygous and Heterozygous IF the genes are the same, they are homozygous – “homo” means same IF the genes are different, they are heterozygous – “hetero” means different http://discover.edventures.com/images/termlib/h/homozygous/support.gif Homozygous/Heterozygous RR Rr rr Tt tt BB Bb Drop and Drag Genetics http://www.zerobio.com/drag_gr11/mono.ht m Punnett Square Practice Complete part 2 of the worksheet that we completed yesterday. Bell-work Complete the practice Punnett Square sheet on the counter (T’s). Class Survey http://www.phschool.com/atschool/science_ activity_library/survey_of_traits.cfm Bell-Work Get a half sheet of paper off of the counter and answer the following questions. 1. Explain how two brown-eyed parents could have a blue eyed child. 2. Suppose H=curly hair and h=straight hair. Using a Punnett square, show a cross between a parent that is heterozygous for curly hair and a parent that is homozygous for straight hair. Bell Work In order for the child to have blue eyes, the parents would both have to pass on a ________________ gene. The probability of the child having blue eyes is _________. Assignment Complete the Alien Genetics activity (2 aliens) After you cut out your aliens, make sure your name is on the back of each and turn in. Complete the Monsters Inc. Heredity worksheet and turn in. The study of heredity started with the work of Gregor Mendel and his pea plant garden Gregor Mendel is considered to be the father of genetics Who was Gregor Mendel Gregor Mendel was born in 1822 in Austria. He grew up on his family’s farm and was able to learn a lot about flowers and fruit trees. After going to college, he joined a monastery. At the monastery, he worked in the garden where he studied how traits were passed form parent to offspring. Why?? Mendel noticed that some patterns of inheritance made sense and other did not. For example, Mendel noticed that when he crossed a purple flowered pea plant with a white flowered pea plant, that all of the offspring had purple flowers. He then noticed that if he crossed two of these offspring, then one out of every four offspring had white flowers. Mendel wanted to know why. http://www.mentalfloss.com/store/files/d_219.jpg WHY??? What did Mendel Do? Mendel looked at 7 traits of pea plants. Mendel crossed pea plants with two different forms of each trait (for example, smooth/wrinkled peas or yellow/green peas) to determine which raits would appear and how often. Mendel was then able to determine which of the 7 traits were dominant and which were recessive. What traits do you see? http://www2.edc.org/weblabs/Mendel/Mend elMenu.html How?? The flowers of pea plants are self pollinating which means that they contain both male and female reproductive structures. Pollen from one flower or plant can fertilize the eggs of the same plant or another plant. http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/Seed%20Plants/Lily_flower.jpg HOW??? Mendel cut off the anthers of one flower and used the pollen from these anthers to fertilize the stamen on another plant. For example, he used the pollen from a plant that produced wrinkled seeds to fertilize the plant that produced round seeds. The stigma of the flower actually turns into seeds (peas). These seeds/peas are then planted in the ground to produce more pea plants. Steps of Mendel's Experiment Mendel Clip