Unit 7A: Genetics and DNA

I. Vocabulary a.DNA: Deoxyribonucleic Acid—the “instruction manual” for an organism b.Double Helix: shape of DNA—looks like a twisting ladder c.Gene: small section of DNA that codes for a specific trait d.Chromosome: tightly wound, coiled DNA

II. The Genetic Code a.The Beginning i. James Watson and Francis Crick published the DNA structure in ii. They discovered that DNA was in a Double Helix Shape

II. The Genetic Code b. DNA Structure i. The two sides of the DNA double helix are made of sugars, called deoxyribose, and phosphates 1. This is called The Sugar-Phosphate Backbone of DNA ii. The “rungs” of the ladder are made of Nitrogen Bases iii. There are four different nitrogen bases 1. Adenine (A) 2. Thymine (T) 3. Guanine (G) 4. Cytosine (C)

II. The Genetic Code iv. These bases are paired 1. Adenine and Thymine 2. Guanine and Cytosine v. This means that in the genetic code an adenine will only ever pair with a thymine vi. Even though they pair with the same nitrogen base, every gene has a different order of A,T,C,G’s. vii. Diagram

III. DNA Replication a.Purpose: cells must replicate or copy their DNA when the cells wants to go through Mitosis (cell reproduction) b.Happens in the Nucleus c.Uses an Enzyme called DNA Helicase: Acts like a zipper d.What you end with: Two identical strands of DNA e.STEPS

Warm Up #1 Use your notes to help you answer these questions 1. What did Francis Crick and James Watson do to advance genetics? 2. Explain the structure of DNA. What is it made of? What shape is it? 3. What are the four different nitrogen bases and how do they pair?

IV. Heredity a.Passing of traits from parent to offspring b. Vocabulary i. P generation: parent generation ii. F1 generation: offspring of p generation iii. F2 generation: offspring of F1 generation iv. Alleles: different form of a gene or trait—an organisms traits are controlled by the alleles it has v. Dominant Allele: trait that will always show up if present in the organism shown by capital letter vi. Recessive Allele: trait that is hidden when Dominant allele is present shown by lowercase letter vii. Hybrid: organism that has two different alleles for a trait (1 dominant, 1 recessive)

IV. Heredity c. Gregor Mendel: Known as the “Father of Genetics” i. Studied pea plants and wondered why do pea plants vary in looks ii. He noticed some of these differences 1. Height of plant (tall or short 2. Color of seed (green or yellow) 3. Pod color (green or yellow) 4. Flower color (purple or white)

IV. Heredity iii. Mendel’s Experiment 1. He crossed pea plants with different characteristics. 2. He used a process called fertilization 3. He started with purebred pea plants 4. He then took notes of the following traits that he saw appear in the offspring a. seed color, pod color, flower color and a number of other things

IV. Heredity 5. Example of his cross (Tall Plant (TT) with short plant (tt)) a. Step one: b. Step two: c. Step three: 6. Mendel’s experiment showed the presence of dominant and recessive genes and that traits will always come from what their parents traits

Warm Up #2 Complete Note page 62.

V. Probability of Heredity a. Punnett Squares: Shows crosses between organisms i. They show the probability of what traits will be passed down 1. Probability: the likeliness that a specific outcome will occur ii. The whole Punnett square makes 100% of the options, so each individual box is 25% of the options

V. Probability of Heredity b. Vocabulary: i. Phenotype: the physical characteristics that organism possesses ii. Genotype: the genetic make-up of an organism—the type of alleles it has iii. Heterozygous: both alleles are different (Tt) iv. Homozygous: both alleles are the same v. Homozygous Dominant: Both alleles code for the dominant trait (TT) vi. Homozygous Recessive: Both alleles code for the recessive trait (tt)

V. Probability of Heredity c. Example 1: If Mendel took a plant with a homozygous white flower pea plant and crossed it with a homozygous purple flower pea plant, what is the probability that Mendel will get a Purple Flower? i. What other information do you need to know before you can start this cross? You would also need to know which flower color is dominant: purple is dominant

V. Probability of Heredity ii. Choose your Alleles 1. Dominant: __________ 2. Recessive: __________ iii. Write the genotype for each parent allele 1. White Flower: __________ 2. Purple Flower: __________

V. Probability of Heredity iv. Next step is to draw your Punnett Square, fill in the parents, and cross them

Probabilities. 1.What is the probability that you will get a flower with a heterozygous genotype? _______________________ 2.What is the probability that you will get a homozygous recessive genotype? _______________________ 3.What is the probability that you will get a homozygous dominant genotype? _______________________ 4.What is the probability that you will get a flower with a phenotype of purple? _______________________ 5.What is the probability that you will get a flower with a phenotype of white? _______________________

V. Probability of Heredity d. Example 2. Try this one with your partner Bunnies can have black fur or they can have white fur. Black fur is dominant and white fur is recessive. What would happen if you crossed a heterozygous black fur bunny with a homozygous recessive white fur bunny?

Examples 1. What is the probability that you will get a black bear if black is recessive color and you cross a heterozygous bear with another heterozygous bear.

Examples 2. If Green shoots are dominant to yellow shoots in beans, and you cross two beans with yellow shoots, what is the probability that you will get a bean with green shoots?

Examples 3. What is the probability of getting a homozygous dominant genotype if you cross a heterozygous Dominant with a homozygous recessive?

Examples 4. Red hair is recessive to Blonde hair. What is the probability that a cross between a red haired female and a homozygous blonde hair male will result in a blonde haired child?

Examples 5. What are the genotypic probabilities if you cross a heterozygous blue monster with a homozygous recessive purple monster?

Examples 6. What are the phenotypic probabilities if you cross a heterozygous four eyed monster with a homozygous recessive 8 eyed monster.

Examples 7. What is the probability that I will get a recessive phenotype if I take two heterozygous organisms and cross them.

Examples 8. What is the probability that I will get a genotype with a recessive allele if I take two heterozygous organisms and cross them.

VI. Inheritance a.Walter Sutton: In the 1900’s, he looked at grasshopper cells. i. He wanted to understand how sperm and egg form ii. This would help to understand inheritance iii. He hypothesized that chromosomes were the key to how parents pass down their traits iv. He found that sex cells have half the number of chromosomes as body cells

VI. Inheritance b. What Sutton found true in grasshoppers is true for all organisms. i. Each parent passes down half their genetic information c. Chromosomes in Humans i. Humans have 46 chromosomes ii. These 46 chromosomes make 23 pairs iii. Each human parent gives 23 chromosomes iv. Each chromosomes carries between 20,000 and 25,000 genes. v. Chromosomes from parents

VI. Inheritance d. The creation of sex cells to get ready for the passing of traits happens during Meiosis i. Meiosis is similar to Mitosis but not exactly the same ii. Basic Definition: The chromosome pairs separate into two different cells. The sex cell that forms later has only half as many chromosomes as the organisms body cells iii. Right before Meiosis occurs, the chromosomes or DNA is Copied 1. Diagram

VI. Inheritance v. At the end of Meiosis you end with four different sex cells 1. This gives four different possible combinations of genes/traits

What Phase?

Draw Telophase 1

What Phase?

Draw Telophase 2

VII. Sexual vs. Asexual Reproduction a.Sexual Reproduction requires the female egg to be fertilized by the male sperm i. This produces an organism with a combination of physical traits that will resemble the physical traits of the parents

VII. Sexual vs. Asexual Reproduction b. Asexual Reproduction one parent produces an identical offspring i. In other words, the parent and the child have identical DNA ii. Sponges, and hyrda’s go through Asexual Reproduction iii. Hydra’s use a process called budding 1. Budding is when a new organism/offspring grows on the parent and then when it is mature enough it breaks off iv. Some animals divide into two

VII. Sexual vs. Asexual Reproduction c. They both have their advantages and disadvantages Asexual ReproductionSexual Reproduction Advantages Disadvantages