The Secret Code of Life: DNA (Deoxyribonucleic Acid)

The true story about the discovery of the structure of DNA

To sum up: –Rosalind Franklin-helped in the discovery of the double-helix shape of DNA. –James Watson, Francis Crick, and Maurice Wilkins-Won Nobel Prize, based on Franklin’s work made a model of the DNA structure and little has been changed about it.

DNA DNA is where all the information for the make up of your body is stored. A blueprint that contains all of the directions that control the functions of your body. All of this information is stored into this tiny, tiny space and exact copies are made and passed on to new cells constantly through cell division. When a cell divides, the DNA makes an exact copy of itself!

The Shape of DNA The Double Helix! DNA is like a miniature ladder with two sides and rungs connecting the sides. The sides twist around each other like a spiral staircase with ten rungs for each turn.

DNA Make-up DNA is made up of three substances: Phosphate (P) Deoxyribose (D)- a sugar 4 bases- There are four nitrogen bases present in DNA: Adenine(A), Cytosine(C), Guanine(G), Thymine(T) The genetic code determines the kinds of inherited traits! P-D-P-D-P-D-P-D-P-D-P-D-P-D-P A T C G A G T TA G C T C A P-D-P-D-P-D-P-D-P-D-P-D-P-D-P

What about chromosomes, genes, and alleles? Chromosomes are the individual DNA strands. Genes determine the trait and are located on the Chromosomes! You have two genes for every trait. One from yo momma & one from yo daddy! Alleles are the different variations of genes that depending on the combination determines the trait.

Chromosomes come in Pairs!!! Humans have 46 chromosomes or 23 pairs of chromosomes in each set of DNA Cats: _____ Goats:____ Dogs: ____ Chicken:____ Gold Fish: ____ Rat:____ Sweet Potato:___90 Sage:___ 14 Daisy:___18

Twenty-two of the pairs of chromosomes are similar in males and females. The 23rd pair is different. A female has two X chromosomes and a male has an X and a Y chromosome. Because they are different in males and females, we call the X and Y, sex chromosomes.

When a cell divides the DNA is copied!!!! Two types of cell division are: Mitosis -for growth and repair! Meiosis -for the reproduction of the organism. It’s how babies are made!! The cell that forms the new organism (baby) has a full set of DNA that is made up of two halves DNA. One half is from Dad and the other half is from Mom!!

Mitosis

Pairs Split! 23-pairs

Why do Chromosomes come in pairs? You start out as one body cell! That cell has a set of DNA that is a combination of your parents DNA! During fertilization, when the sperm gamete combines with the egg gamete, the ½ set of DNA from mom combines with the ½ set of DNA from Dad to create that first body cell One set of chromosomes is a copy of the chromosomes from your mom and the other set of chromosomes is a copy of the chromosomes from your dad!!!!!

Babies! Two reproductive cells combine to make a zygote which is the first body cell, that cell divides through mitosis and makes an… Embryo-a multicellular organism

Gregor Mendel Mendel was the first person to describe how traits are passed from one generation to the next. –He learned this by studying Pea (yes, I said Pea) Plants for 8 years! He was able to observe 9 generations in a short time because pea plants grow and reproduce quickly.. –He was able to observe why certain traits including tallness/shortness, color green/yellow, smooth/wrinkled seed coats and so on by using probability.

Dominant vs. Recessive When your parents pass one gene down to you, the gene can either be dominant or recessive.

Dominant allele/gene- an allele who’s trait always shows up in the organism when the allele is present. If this gene gets passed to you, the trait that gene represents will show! Recessive allele/gene- An allele that is masked or hidden when a dominant allele is present. If this gene gets passed to you, the trait that gene represents will not show unless both genes that you get are recessive!

Genotypes vs. Phenotypes Genotype- An organism’s genetic makeup, or allele combination. It’s the coding of the genes that was passed to you from your parents. It shows which gene your mom passed to you and which gene your dad passed to you. Coding- DD or Dd or dd

Phenotype- An organism’s physical appearance of a trait; the visible trait. –Example of a phenotype would be brown hair. It is what we will actually see in the organism. So…  Genotype is the code: Tt  Phenotype is the physical appearance: Tall

Every person has two genes for the traits they show. One from mom and one from dad. We record which gene was passed from mom and which gene was passed from dad in the genetic coding called the genotype.

Purebred vs. Hybrid Purebred for the trait: –When both genes passed to the offspring are both dominant or both recessive. Example: DD (Pure Dominant) or dd (Pure Recessive) –When the pair of alleles are the same like they are above, we call that a homozygous pair of alleles! We say they are Purebred for the trait and have a homozygous pair of alleles in the genotype!

Hybrid for the trait: –When one of the genes passed to the offspring is dominant and the other is recessive. Example: Dd (Hybrid Dominant) –When the pair of alleles are different like they are above, we call that a heterozygous pair of alleles! We say they are Hybrid for the trait and have a heterozygous pair of alleles in the genotype!

Punnett Squares A fun tool used to calculate the probability of getting certain traits passed from parents to offspring.

You must have a Key: Analysis of Punnett Square: Genotype Phenotype Probability (%) Purebred/Hybrid (describe the trait) Dominant/Recessive B- b- Hair Color

Analysis of Punnett Square: Genotype Phenotype Probability (%) Purebred/Hybrid (describe the trait) Dominant/Recessive Key: __________ ___

Gender Linked Traits: Also known as Gender linked traits! These traits are determined by the genes located on the X and Y chromosomes. The genes located on the X chromosome don’t necessarily match the genes on the Y chromosome. In other words, there are certain genes that are only found on the X and certain ones only found on the Y. For example, Color Blindness- color vision is a gene only located on an X chromosome (XC or Xc)

Blood Typing There are three different alleles for human blood type, A, B, and O: Each of us has two A B or O blood type alleles, because we each inherit one blood type allele from our biological mother and one from our biological father.

The positive and negative side to blood: Most people also have an another inherited protein of the red blood cells known as the Rh factor, or antigen D. When the D antigen is present, a person's blood type is designated Rh positive. When antigen D is missing, the blood type is classified Rh negative. In general, Rh negative blood is given to Rh negative patients and Rh positive blood to Rh positive patients

Type You Can Give Blood To You Can Receive Blood From A+A+ AB+A+ A- O+ O- O+O+ A+ B+ AB+O+ O- B+B+ AB+B+ B- O+ O- AB+ Everyone A-A+ A- AB+ AB-A- O- O-EveryoneO- B-B+ B- AB+ AB-B- O- AB-AB+ AB-AB- A- B- O- If your blood type is...

Twins? Remember: Two reproductive cells combine to make a zygote which is the first body cell, that cell divides through mitosis and makes an embryo….a multicellular organism Identical twins: one fertilized egg splits and develops two babies with exactly the same genetic information. Fraternal twins: where two eggs are fertilized by two sperm and produce two genetically unique children.

Incomplete Dominance When the two alleles present in the genotype are both dominant. Neither one is dominant over the other, so they blend. For example: For flowers, the color white is considered a dominant trait, but so is Red. –If the genotype for the color of the petals has one gene for Red and one gene for White they will blend because neither one is dominant over the other. The result will be pink petals.