Genetics and Heredity

DNA D.N.A. - Deoxyribonucleic Acid Molecule made of: 1. Deoxy Sugar 2. Combination of four nitrogen bases Either: a. Guanine b. Cytosine c. Thymine d. Adenine COOL FACT!: The sum total of combinations that these four bases are capable of creating are greater than all the stars visible in the night time sky!!

DNA Nitrogen bases pair up Pairing creates a ladder shape Cytosine & Guanine Thymine & Adenine Pairing creates a ladder shape Angle of bonds creates a twist Ladder and Twist produces the famous “Double Helix”

DNA DNA resides in all cells Each strand forms a chromosome Nucleus Cell DNA resides in all cells Inside the nucleus Each strand forms a chromosome DNA

DNA DNA is found in all living cells It controls all functions inside a cell It stores all the genetic information for an entire living organism Single cell like an amoeba Multi cell like a human

Why do we study DNA? We study DNA for many reasons: its central importance to all life on Earth medical benefits such as cures for diseases better food crops. About better food crops, this area is controversial. There is a Dr. Charles Arntzen who is working on bioengineering foods with vaccines in them. People in poor countries could be immunized against diseases just by eating a banana, for instance.

Chromosomes and DNA Chromosomes are made up of genes. Genes are made up of a chemical called DNA. {Ask students where the chromosomes are in this picture. Or ask them where the DNA is. Remind them that the mitochondria also have DNA.}

One Strand of DNA The backbone of the molecule is alternating phosphate and deoxyribose, a sugar, parts. The teeth are nitrogenous bases. phosphate deoxyribose {Point to the 3-D mode, if you have one, to show the parts as you discuss them.} bases

Nucleotides O -P O O One deoxyribose together with its phosphate and base make a nucleotide. O -P O O Nitrogenous base C O Phosphate {Ask students where they have seen a similar molecule before in this class. Answer: ATP . Emphasize that nucleotides are the basic building blocks or units of a DNA molecule and that a single molecule has many millions of nucleotides.} C C C Deoxyribose ribose O

Do Now! Where is DNA located? What does it look like? What are its bases? Why do you think DNA is located there?

DNA by the numbers Each cell has about 2 m of DNA. The average human has 75 trillion cells. The average human has enough DNA to go from the earth to the sun more than 400 times. DNA has a diameter of only 0.000000002 m. The earth is 150 billion m or 93 million miles from the sun. If you unravel all the DNA in the chromosomes of one of your cells, it would stretch out 2 meters. If you did this to the DNA in all your cells, it would stretch from here to sun more than 400 hundred times!

What’s the main difference between DNA and RNA

RNA In RNA Thymine is replaced by Uracil A-U (RNA) not A-T (DNA)

IF the DNA strand is GTACCAGATTAGC What would the RNA strand be?

Transcription When a secretary transcribes a speech, the language remains the same. However, the form of the message changes from spoken to written

Transcription Transcription- RNA is made from a DNA template in the nucleus. This type of RNA is called messenger RNA or mRNA When a reporter transcribes a speech, the language remains the same. However, the form of the message changes from spoken to written

Transcription DNA is protected inside the nucleus. mRNA carries the message of DNA into the cytoplasm to the ribosome's

Translation To translate English into Chinese requires an interpreter. Some person must recognize the worlds of one language and covert them into the other.

tRNA Transfer RNA The cells interpreter tRNA translated the three-letter codons of mRNA to the amino acids that make up protein.

Codon The flow of information from gene to protein is based on codons. A codon is a three-base word that codes for one amino acid

Information Flow: DNA to RNA to Protein

Genetics The study of heredity, how traits are passed from parent to offspring or x = or

What is it?! Genetics is the study of genes. Inheritance is how traits, or characteristics, are passed on from generation to generation.

Chromosomes are made up of genes, which are made up of DNA. Genetic material (genes, chromosomes, DNA) is found inside the nucleus of a cell. Gregor Mendel is considered “The Father of Genetics"

Genetics Small sections of DNA are responsible for a “trait”. These small sections are called “Genes”. Gene - A segment of DNA that codes for a specific trait Trait - A characteristic an organism can pass on to it’s offspring through DNA Gene

Genetics Hair color is a perfect example of a trait What color hair should their children have? Prince Charming is blond Snow White has dark hair

Genetics There are three basic kinds of genes: Dominant - A gene that is always expressed and hides others Recessive - A gene that is only expressed when a dominant gene isn’t present Codominant - Genes that work together to produce a third trait

Genetics Dominant and Recessive Genes A dominant gene will always mask a recessive gene. A “widows peak” is dominant, not having a widows peak is recessive. If one parent contributes a gene for a widows peak, and the other parent doesn’t, the off- spring will have a widows peak. Widows Peak

T,t TT, tt Tt, Gg TERMS TO KNOW ALLELES HOMOZYGOUS HETEROZYGOUS DIFFERENT FORMS OF A TRAIT THAT A GENE MAY HAVE T,t HOMOZYGOUS AN ORGANISM WITH TWO ALLELES THAT ARE THE SAME TT, tt HETEROZYGOUS AN ORGANISM WITH TWO DIFFERENT ALLELES FOR A TRAIT Tt, Gg

Tt, Gg T OR G t or g TERMS TO KNOW HYBRID DOMINANT RECESSIVE SAME AS HETEROZYGOUS Tt, Gg DOMINANT A TRAIT THAT DOMINATES OR COVERS UP THE OTHER FORM OF THE TRAIT REPRESENTED BY AN UPPERCASE LETTER T OR G RECESSIVE THE TRAIT BEING DOMINATED OR COVERED UP BY THE DOMINATE TRAIT REPRESENTED BY A LOWER CASE LETTER t or g

TERMS TO KNOW PHENOTYPE TALL, SHORT, GREEN, WRINKLED GENOTYPE THE PHYSICAL APPEARANCE OF AN ORGANISM (WHAT IT LOOKS LIKE) TALL, SHORT, GREEN, WRINKLED GENOTYPE THE GENE ORDER OF AN ORGANISM (WHAT ITS GENES LOOK LIKE) TT, GG, Tt, gg Gg, tt RATIO THE RELATIONSHIP IN NUMBERS BETWEEN TWO OR MORE THINGS 3:1, 2:2, 1:2:1

Gregor Mendel Austrian Monk. Experimented with “pea plants”. Used pea plants because: They were available They reproduced quickly They showed obvious differences in the traits Understood that there was something that carried traits from one generation to the next.

Mendel’s Pea Plants Mendel based his laws on his studies of garden pea plants. Mendel was able to observe differences in multiple traits over many generations because pea plants reproduce rapidly, and have many visible traits such as: Pod color Seed Color Plant Height Green Yellow Green Yellow Seed Shape Short Pod Shape Tall Wrinkled Round Smooth Pinched

What is meant by “true breeding?” To test the hypothesis, Mendel crossed true-breeding plants that had two distinct and contrasting traits—for example, purple or white flowers. What is meant by “true breeding?” Mendel cross-fertilized his plants by hand. Why is it important to control which plants would serve as the parents?

Mendel’s Experiments Mendel noticed that some plants always produced offspring that had a form of a trait exactly like the parent plant. He called these plants “purebred” plants. EXAMPLE: -purebred short plants always produced short offspring purebred tall plants always produced tall offspring. X Short Offspring Purebred Short Parents X Purebred Tall Parents Tall Offspring

Mendel’s First Experiment Mendel crossed purebred plants with opposite forms of a trait. He called these plants the parental generation , or P generation. For instance, purebred tall plants were crossed with purebred short plants. X Parent Short P generation Parent Tall P generation Offspring Tall F1 generation Mendel observed that all of the offspring grew to be tall plants. None resembled the short short parent. He called this generation of offspring the first filial , or F1 generation, (The word filial means “son” in Latin.)

Mendel’s Second Experiment Mendel then crossed two of the offspring tall plants produced from his first experiment. Parent Plants Offspring X Tall F1 generation 3⁄4 Tall & 1⁄4 Short F2 generation Mendel called this second generation of plants the second filial, F2, generation. To his surprise, Mendel observed that this generation had a mix of tall and short plants. This occurred even though none of the F1 parents were short.

Mendel studies seven characteristics in the garden pea

Martin Sheen Charlie Sheen How is it possible to maintain such genetic continuity? Kirk Kirk Douglas Michael Emilio Estevez