What is DNA short for?

1. What is DNA short for?

2. What is DNA short for? deoxyribonucleic acid

6. DNA Discovery • Modelled in 1953 by James Watson & Francis Crick. • Awarded Nobel Prize in Physiology or Medicine in 1962 to Watson, Crick and Wilkins. Franklin’s “Photograph 51” Watson & Crick’s ball and stick model

7. Use the information in the text to produce the DNA Discovery Timeline. • EXT: Put the discoveries in order of importance, in terms of their contribution to the work of Watson and Crick. Rosalind Franklin Franklin’s “Photograph 51” Watson & Crick’s ball and stick model

8. Answer These: • Which discovery contributed the most to the work of Watson & Crick? • Why was Erwin Chargoff’s work an important contribution to the deduction of the structure of DNA? • Why was the structure of DNA seen as such an important scientific development?

9. Accepting the Facts • Rosalind Franklin – never nominated for Nobel Prize. • Watson & Crick discovery made in 1953, Nobel Prize awarded in 1962. • Charles Darwin reported his ideas on Evolution in 1859, his theories were not accepted until the 1870’s. Why does it take the community so long to accept scientific discoveries?

10. Charles Darwin – religion. Rosalind Franklin – sexism? Watson and Crick – verification time!

13. The Bases Base pairs hold the two strands of the DNA helix together. The sequence of these bases along a DNA molecule forms the genetic code

14. DNA is made up of Purines and Pyrimidines. Purines: • Adenine (A) • Guanine (G) Pyrimidines: • Thymine (T) • Cytosine (C)

16. Unzipping the DNA

17. Replication new DNA molecules

19. Mendel’s 7 Experiments

21. Pure bred plants are those that consistently produce offspring the same as the parents for a particular trait. For example, yellow-pod plants that always produce more yellow-pod plants would be considered to be true-breeding. Mendel cross pollinated true-breeding plants with contrasting traits. For example, he took the pollen from a plant with round seeds and placed it on the flower of a plant with wrinkled seeds. He found that all the offspring (called the F1 generation) were like one of their parents. When these offspring were cross-pollinated among themselves, their offspring (the F2 generation), showed both traits

22. What does F1 and F2 stand for? • F1 = First cross generation from pure bred parents • F2 = offspring of the F1 generation

23. When the F1 generation was crossed with F1 generation (e.g. round seed(F1) & round seed(F1) crossed), both round and wrinkled seeds were produced. This tell us about that traits are determined by two different allelles, one dominant and one recessive.

24. Heredity : the passing of traits from parent to offspring Traits are controlled by genes, SO what is GENETICS? Genetics: The study of how traits are inherited.

25. WHAT ARE ALLELES? Are ONE FORM of a gene (there can be more than one form) -Sex cells have one form of a gene on their chromosomes Body cells have two forms or ALLELES for a single gene (you got one from Mom and one from Dad) One may be dominant over another. If this happens, the dominant gene is the one expressed. If not, the recessive trait is expressed.

26. DOMINANT AND RECESSIVE A Dominant trait: will always be expressed and will “mask” a recessive trait A Recessive trait: can only be expressed if there are nodominant alleles present.

27. Example: Eyecolor—Brown color is dominant and blue is recessive. A person can have a brown allele and a blue allele but still have brown eyes because the brown allele is dominant and “hides” the blue allele.

28. Example:R= dominant r = recessive • Generally, dominant alleles are represented with a capital letter, and recessive alleles are represented with a lower case letter.

29. Each organism is represented by TWOletters, one for each allele.

30. “Purebred” species have two alleles of the same trait Represented by two of the same letters. This is called homozygous. For instance: BB or bb. Species with two different alleles or two different forms of the gene would be “hybrid” Represented by two different “letters” and by called “heterozygous”. For instance: Bb The alleles present in the organism are referred to as its genotype. For instance, BB, Bb, or bb.

31. The PHYSICAL trait that shows, regardless of genotype is called a PHENOTYPE. For instance, Blue or Brown Eyes.

32. PROBABILITY Helps predict thechancethat something will happen Example: the probability of throwing heads or tails on a coin is 50%(1/2 chances) Your predictions become more accurate with the more trials you run!

33. Steps for using the Punnett square: • One parent’s alleles (genotype) go along the top • The other parent’s alleles go down the side. • You fill in the squares like doing the communicative property of multiplication. B b B b BB Bb Bb bb

34. Steps for using the Punnett Square: Let’s say the parents are Bb and Bb (the same genotype). What would be their phenotype? Brown Eyes B b So you would predict: ¼offspring to be BB, or Brown Eyes 2/4 or 1/2 to be Bb, or Brown Eyes and ¼to be bb or Blue eyes B BB Bb b Bb bb

35. GENEticS Rap