CAs1 topic biology adfdffgfdggfgfdg.pptx

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1. Keywords: DNA, chromosome, gene, genetic material LOb: Understand the structure of DNA and how it was discovered. Did you know… Everyone has DNA that is unique to them. However, identical twins have the same DNA. Learning Outcomes: Describe the structure of DNA Describe how scientists worked together to discover the structure of DNA

2. An Introduction to DNA DNA is sometimes mentioned in the news, in social media and on our TV screens. DNA is really important - but what is it? DNA can be used to solve crimes that were committed many years ago. It can be used to identify people. It can be used to trace members of a family.

3. What Is DNA? DNA is the short name for deoxyribonucleic acid. It is a structure that carries information about any living thing. DNA in humans determines what colour our eyes are, if our hair is straight or wavy, how our lungs work and much, much more. Each piece of information is carried on a different part of the DNA. Each of these parts are called genes. People once thought that our characteristics were passed on through our blood. However, red blood cells have no DNA! Did You Know...? All the DNA in the human body could stretch from the Sun to Pluto and back – 17 times!

4. Where Can DNA Be Found? Cells are the basic building blocks of all living things. The human body is made up of trillions of cells. DNA can be found in almost every cell of every living thing. Cell Chromosome DNA DNA is found in structures called chromosomes inside a cell. If we wanted to look at the DNA in a chromosome, we’d have to use an extremely powerful microscope. They are very, very small!

5. Activity: Watch and make notes about DNA

6. DNA is made up of two strands joined together by four different chemicals which are bases. A T C G The shape of DNA is called a double helix. Phosphate backbone

7. DNA bases join together in a particular order. A T C G

8. Activity: We are going to make our own model of DNA.

9. Keywords: DNA, chromosome, gene, genetic material Learning Outcomes: Describe the structure of DNA Describe how scientists worked together to discover the structure of DNA LOb: Understand the structure of DNA and how it was discovered. Did you know… Everyone has DNA that is unique to them. However, identical twins have the same DNA.

10. 1953 was the year the world found out about the structure of the DNA molecule. The story is a sad one for Rosalind Franklin.

11. Activity: Complete this sheet as you watch the video 1. What did Rosalind franklin use to study DNA? 2. Rosalind’s colleagues were… 3. What year did she take the most famous DNA picture, p hoto 51 ? 4. What did Wilkins do with Rosalind’s photo 51? 5. Where did the journal put Rosalind Franklin’s manuscript? 6. Why didn’t Rosalind get a N ob el prize? Friendly Not friendly 1943 1953 1962 1972 Secretly destroyed it Stole it and showed Watson and Crick Last in the journal Before Watson and Cricks They didn’t publish it She died They ignored her The award could only be given to thre e people Microscopes X –rays Bunsen Burners

12. Review 1. What did Rosalind franklin use to study DNA? 2. Rosalind’s colleagues were… 3. What year did she take the most famous DNA picture, p hoto 51 ? 4. What did Wilkins do with Rosalind’s photo 51? 5. Where did the journa l put Rosalind Franklin’s manuscript? 6. Why didn’t Rosalind get a N ob el prize? Friendly Not friendly Secretly destroyed it Stole it and showed Watson and Crick Last in the journal Before Watson and Cricks They didn’t publish it She died They ignored her The award could only be given to thre e people Microscopes X –rays Bunsen Burners 1943 1953 1962 1972

13. Story recap Review Rosalind was working to discover the structure of DNA using x-rays. She produced photo 51. Wilkins stole photo 51 and showed it to two other scientists working to discover the structure, Watson and Crick. The photo helped them prove their idea on the structure. They published their ideas in 1953. Rosalind Franklin also published but they put her ideas behind the other Scientists. Rosalind died without her knowing they had seen the picture. Watson and Crick won a Nobel prize.

14. Discussion Time: I will put some questions up and we will discuss them. What were all the bad things that happened in the story? What would have happened if Wilkins didn’t steal photo 51? Why did male scientists have a unfriendly attitude to Rosalind? Should Rosalind Franklin get a Nobel prize? Write 3 bullet points about the story. The story is a sad story because… Wilkins was wrong/right to steal the picture because… Rosalind should/shouldn’t get a Nobel prize because…

15. Keywords: DNA, chromosome, gene, genetic material Learning Outcomes: Describe the structure of DNA Describe how scientists worked together to discover the structure of DNA LOb: Understand the structure of DNA and how it was discovered. Did you know… Everyone has DNA that is unique to them. However, identical twins have the same DNA.

16. DNA is made of two strands joined together by four different chemicals called bases. A – T The strands of DNA twist together to form a C – G double helix shape. Scientists worked together to discover the structure of DNA. The last major achievement was the human genome project of 2003. The double helix structure was discovered by Watson, Crick, Wilkins and Rosalind Franklin (No Nobel prize )

17. Plenary Rules In one minute explain to your partner, what you have learnt today. Try to use all of the key words. Keywords: DNA Double helix Bases Watson Crick Wilkins Franklin Genome project

18. Plenary One key word that is stuck in your mind from today A picture to describe todays learning A sentence to describe your learning today

19. Gene Mutations Sickle Shaped Red Blood Cells

20. What is a gene mutation? Mutations are changes in genetic material – changes in DNA code – thus a change in a gene(s) In gene mutations, the DNA code will have a base (or more) missing, added, or exchanged in a codon.

21. How common are mutations? Mutations occurs at a frequency of about 1 in every 1 billion base pairs Everybody has about 6 mutations in each cell in their body!

22. If I have that many mutations, why don’t I look weird? Mutations are not always seen. The affected gene may still function. Mutations may be harmful . Mutations may be beneficial . Mutations may have no effect on the organism .

23. Mutations are a major source of genetic variation in a population increasing biodiversity. Some variations may help them to survive better . How do mutations affect a population?

24. Only mutations in gametes (egg & sperm) are passed onto offspring. Mutations in body cells only affect the organism in which they occur and are not passed onto offspring . How are mutations inherited?

25. Types of Gene Mutations Point mutation occurs when the base sequence of a codon is changed. (ex. GCA is changed to GAA) There are 3 types: Also called frameshift mutations Substitution Deletion Insertion

26. What will happen to the amino acids? Normal DNA: CGA – TGC – A TC Substitution Mutations Mutated DNA: CGA – TGC – T TC Alanine – Threonine - stop Alanine – Threonine - Lysine This is a substitution mutation The adenine was replaced with thymine What has happened to the DNA?

27. Substitution Mutations Mutated DNA: CGA – TGC – T TC Alanine – Threonine - Lysine This is a substitution mutation . A single nitrogen base is substituted for another in a codon. It may or may not affect the amino acid or protein. Normal DNA: CGA – TGC – A TC Alanine – Threonine - stop

28. TRY THIS! On your notebook paper write: The cat ate the rat Change one letter in the sentence to represent a substitution mutation. Think-Pair-Share

29. Analogy 3 letter words because codons are 3 letters The cat ate the rat. SUBSTITUTION Th c cat ate the rat. May have little effect. You still have the idea like a typo on a test. The h at ate the rat. Changes the thought of the sentence.The effect Depends on where the substitution happens

30. This is an insertion mutation, also a type of frameshift mutation. Normal DNA: CGA – TGC – ATC Insertion Mutations Mutated DNA: CGA – T A G – CAT – C Alanine – Threonine – stop Alanine – Isoleucine – Valine What will happen to the amino acids? An adenine was inserted thereby pushing all the other bases over a frame. What has happened to the DNA?

31. Insertion Mutations Mutated DNA: CGA – T A G – CAT – C Alanine – Leucine - Valine This is an insertion mutation . A nitrogen base is inserted/added to the sequence. It causes the triplet “frames” to shift . It always affects the amino acids and, consequently, the protein. Normal DNA: CGA – TGC – ATC Alanine – Threonine - stop

32. TRY THIS! On your notebook paper write: The cat ate the rat. Insert a letter into any word above. Rewrite the sentence . Each word must have only 3 letters to represent the codon. Discuss the effects on the insertion. Think-Pair-Share

33. Analogy Insertion The cat ate the rat. The c ca tat eth era t. Inserting the c causes a FRAMESHIFT THE SENTENCE NO LONGER MAKES SENSE!! Insertions may have huge effects.

34. What will happen to the amino acids? Mutated DNA: CGA – TCA- TC A guanine was deleted, thereby pushing all the bases down a frame. Alanine – Threonine – stop Alanine – Serine Deletion Mutations Normal DNA: CGA – TGC – ATC This is called a deletion mutation, also a type of frameshift mutation. What has happened to the DNA?

35. Deletion Mutations This is a deletion mutation . A nitrogen base is deleted/removed from the sequence. It causes the triplet “frames” to shift . It always affects the amino acids and, consequently, the protein. Mutated DNA: CGA – TCA- TC Alanine – Threonine – stop Alanine – Serine Normal DNA: CGA – TGC – ATC

36. TRY THIS! Write the sentence on your paper: The cat ate the rat. Delete one letter from any word. Rewrite the sentence. Remember: each word can only have 3 letters. Think-Pair-Share

37. Analogy DELETION Th e cat ate the rat. Thc ata tet her at FRAMESHIFT The sentence no longer makes sense!! Deletions can have huge effects.

38. Gene Mutations Substitution has the least affect because it changes only one amino acid or it may change no amino acid . Which mutation would have the least affect on an organism? Mutated DNA: CGA – TGC – AT T Alanine – Threonine - stop Normal DNA: CGA – TGC – AT C Alanine – Threonine - stop Mutated DNA: CGA – TGC – AT G Alanine – Threonine - Tyrosine

39. Gene Mutations An example of a substitution mutation is sickle cell anemia . Only one amino acid changes in the hemoglobin. The hemoglobin still functions but it folds differently changing the shape of the rbc. Sickle Shaped Red Blood Cells Normal Red Blood Cells

40. Gene Mutations Which mutation would have the most affect on an organism? Insertion and deletion mutations have the most effect on an organism because they affect many amino acids and consequently the whole protein . Mutated DNA: CGA – TCA- TC Alanine – Threonine – stop Alanine – Serine Normal DNA: CGA – TGC – ATC Mutated DNA: CGA – T A G – CAT – C Alanine – Leucine - Valine

41. Gene Mutations Huntington’s Disease is caused by an insertion mutation. People with this disorder have involuntary movement and loss of motor control. They eventually have memory loss and dementia. The disease is terminal. Huntington Disease Located on chromosome 4 First Gene Disease Mapped

42. Gene Mutations When does a gene mutation have the greatest affect on an organism? When it occurs in the gamete (egg or sperm) or early in embryonic development (in stem cells or first few days). Four cell Zygote Embryo Egg being fertilized

43. Mutagens What causes mutations? natural errors or an environmental event What is a mutagen ? something that causes the DNA code to change (mutate) – x-ray, chemicals, UV light, radiation, etc What happens to a person who has a mutation?

44. Gene Mutations Change in the nucleotide sequence of a gene May only involve a single nucleotide May be due to copying errors , chemicals , viruses , etc.