Genitics and inheritance
- 1. Genetics Adam Cleaver
- 2. Cell division DNA Genes Chromosomes DNA (deoxyribose nucleic acid) molecules are large and complex. DNA (deoxyribose nucleic acid) molecules are large and complex. They carry the genetic code that determines the characteristics of aaliving thing. They carry the genetic code that determines the characteristics of living thing. Genes - -A gene is aashort section of DNA. Each gene codes for aaspecific protein Genes A gene is short section of DNA. Each gene codes for specific protein by specifying the order in which amino acids must be joined together. by specifying the order in which amino acids must be joined together. Chromosomes - -The cell’s nucleus contains chromosomes made from long DNA Chromosomes The cell’s nucleus contains chromosomes made from long DNA molecules. molecules.
- 3. Cell division - Mitosis 1 Mitosis produces two new Mitosis produces two new cells that are identical to cells that are identical to 2 each other, and to the each other, and to the 3 parent cell. parent cell. 1) Parent cell. 1) Parent cell. 4 2) Chromosomes make identical copies of 2) Chromosomes make identical copies of themselves. themselves. 3) They line up along the centre. 3) They line up along the centre. 4) They move apart. 4) They move apart. 5) Two daughter cells form with identical 5) Two daughter cells form with identical chromosomes to the parent cell. chromosomes to the parent cell. 5 Mitosis is Asexual reproduction
- 4. Interphase Prophase Metaphase Anaphase Telophase Cytokinesis - 2 identical cells formed
- 5. Mitosis mini plenary Q4: How many times does the nucleus divide during mitosis? Q3: At whatproduces cells that are...... Q1: Mitosis stage is this image? Q2: What happens during Anaphase? A) They line up across the middle of the cell A) They line up across the middle of the cell B) They start to move to opposite poles B) They start to move to opposite poles Q:5 How many gametes does mitosis produce? C) The chromatids pair up to form chromosome C) The chromatids pair up to form chromosome
- 6. Cell division – Sexual reproduction Gametes Gametes Gametes & Gametes are sex cells. The male gametes are the Gametes are sex cells. The male gametes are the sperm, and the female gametes are the eggs. sperm, and the female gametes are the eggs. Fertilisation Gametes contain one set of genetic information, Gametes contain one set of genetic information, while body cells contain two sets of genetic while body cells contain two sets of genetic information. information. Fertilisation Fertilisation Gender Gender Fertilisation is the joining or fusion of aamale Fertilisation is the joining or fusion of male Human body cells have 23 pairs of Human body cells have 23 pairs of gamete and aafemale gamete. The new cell gamete and female gamete. The new cell chromosomes in the nucleus. One of chromosomes in the nucleus. One of that is formed divides over and over again by that is formed divides over and over again by these pairs controls the inheritance of these pairs controls the inheritance of mitosis. This creates the many cells that mitosis. This creates the many cells that gender - -whether offspring are male gender whether offspring are male eventually form aanew individual. eventually form new individual. or female: or female: In males, the two sex chromosomes are different. They are XY. In females, the two sex chromosomes are the same. They are XX
- 8. Cell division - Sexual reproduction - Meiosis Gametes are formed from cells in the reproductive Gametes are formed from cells in the reproductive organs by aatype of cell division called meiosis organs by type of cell division called meiosis The cells that are formed by meiosis have half as The cells that are formed by meiosis have half as many chromosomes as the cell that formed them. many chromosomes as the cell that formed them. Human body cells contain 23 pairs (46) of Human body cells contain 23 pairs (46) of chromosomes, while human gametes contain 23 chromosomes, while human gametes contain 23 single chromosomes. single chromosomes. The main features of meiosis are: The main features of meiosis are: the chromosomes are copied the chromosomes are copied the cell divides twice, forming four gametes the cell divides twice, forming four gametes
- 9. Meiosis MAKE KEY NOTES ON VIDEO!! Video to show the process of meiosis:
- 10. A slightly clearer clip on meiosis as the one in lesson may not have been very clear
- 11. Meiosis mini plenary Meiosis mini plenary 1) How many chromosomes are in the body? 2) Meiosis involves how many divisions of the nucleus? 3) Which of the following are examples of gametes? Testes Eggs Sperm Ovaries 4)How many gametes are produced by meiosis?
- 12. Inheritance
- 13. Inheritance Inheritance The resemblance of children to their parents is The resemblance of children to their parents is the result of genetic information passed on in the result of genetic information passed on in gametes (sex cells). gametes (sex cells).
- 14. Your set of books has about 25000 chapters Chapter 451 Chapter 451 Instructions Instructions for blue eyes: for blue eyes: Lorem ipsum dolor sit amet, consectetur Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint fugiat nulla pariatur. Excepteur sint Set 1, Book 17, chapter 451 Set 2 Book 17, chapter 451 (from mother) (from father) If each book is aachromosome, then each chapter is aagene, consisting of aaset of If each book is chromosome, then each chapter is gene, consisting of set of instructions for an aspect of the organism. .--The person in this example will have instructions for an aspect of the organism The person in this example will have blue eyes. blue eyes.
- 15. Chapter 451 Instructions Chapter 451 for blue eyes: Instructions Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna for brown aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. eyes: Lorem ipsum dolor sit amet, consectetur Duis aute irure dolor in reprehenderit in adipisicing elit, sed do eiusmod tempor voluptate velit esse cillum dolore eu incididunt ut labore et dolore magna aliqua. fugiat nulla pariatur. Excepteur sint Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure Set 1, Book 17, chapter 451 Set 2 Book 17, chapter 451 (from mother) (from father) In this example, the two corresponding chapters are not in agreement. In some cases like this, the In this example, the two corresponding chapters are not in agreement. In some cases like this, the body compromises between the two sets of instructions with eye colour, one set of instructions is body compromises between the two sets of instructions with eye colour, one set of instructions is more dominant than others. With eye colour, brown eyes are dominant, so although this person more dominant than others. With eye colour, brown eyes are dominant, so although this person carries instructions for both brown and blue eyes, the blue eye instructions are overridden and the carries instructions for both brown and blue eyes, the blue eye instructions are overridden and the person has brown eyes. person has brown eyes.
- 16. Chapter 451 Chapter 451 Chapter 451 Chapter 451 Instructions Instructions Instructions Instructions for blue eyes: for brown for blue eyes: for brown eyes: eyes: My mother My father Chapter 451 Chapter 451 Instructions Instructions for blue eyes: for blue eyes: Me SEE? There is aa25% chance of this happening, and aa75% There is 25% chance of this happening, and 75% chance of having aabrown-eyed child. chance of having brown-eyed child.
- 17. Alleles Out there in the human population there are many versions of each chapter (gene). These versions Out there in the human population there are many versions of each chapter (gene). These versions are called alleles. In the case of eye colour, there is aablue version, aabrown, green, etc. For blood are called alleles. In the case of eye colour, there is blue version, brown, green, etc. For blood type there are three: A, BBand O. For some chapters (genes) there are hundreds of versions (alleles) type there are three: A, and O. For some chapters (genes) there are hundreds of versions (alleles) out there in the human population. out there in the human population.
- 18. Alleles Alleles are dominant or recessive: Alleles are dominant or recessive: the characteristic controlled by aadominant allele develops ififthe allele is present on one or both the characteristic controlled by dominant allele develops the allele is present on one or both chromosomes in aapair chromosomes in pair the characteristic controlled by aarecessive allele develops only ififthe allele is present on both the characteristic controlled by recessive allele develops only the allele is present on both chromosomes in aapair chromosomes in pair
- 19. Where are the ‘books’ kept? We now start to look closely at cells, to see where the ‘books’ (chromosomes) are kept. We now start to look closely at cells, to see where the ‘books’ (chromosomes) are kept. Every single cell contains aaset, within the nucleus (with aafew exceptions, such as red blood Every single cell contains set, within the nucleus (with few exceptions, such as red blood cells, which have no nucleus). cells, which have no nucleus). Here are some human cheek cells in which you can see the nuclei. Here are some human cheek cells in which you can see the nuclei.
- 20. Mendel – genetic inheritance Gregor Mendel (1822-1884) studied the inheritance Gregor Mendel (1822-1884) studied the inheritance of different characteristics in pea plants. He found of different characteristics in pea plants. He found that when he bred red-flowered plants with white- that when he bred red-flowered plants with white- flowered plants, all the offspring produced red flowered plants, all the offspring produced red flowers. flowers. If he bred these offspring plants (g1) with each If he bred these offspring plants (g1) with each other, most of the offspring (g2) had red flowers, but other, most of the offspring (g2) had red flowers, but some had white. This was because the allele for red some had white. This was because the allele for red flowers is dominant, and the allele for white flowers flowers is dominant, and the allele for white flowers is recessive. Genetic diagrams help to show how this is recessive. Genetic diagrams help to show how this works. works. Original parents G1 = 1st generation of new offspring G2 = 2nd generation See family tree for further clarification. The difference between the Simpson family tree G1 and the pea plants is that the original parent’s offspring were mated together and Marge obviously isn’t Abe and Mona’s daughter. – But you get the idea! G2
- 21. Mendel – genetic diagrams In aagenetic diagram, you show all of the possible alleles for aa In genetic diagram, you show all of the possible alleles for particular characteristic. There will be two alleles from one parent, particular characteristic. There will be two alleles from one parent, and two from the other parent, making four altogether. You then and two from the other parent, making four altogether. You then draw lines to show all the possible ways that these alleles could be draw lines to show all the possible ways that these alleles could be paired in the offspring. There will be four possible ways, but some or paired in the offspring. There will be four possible ways, but some or all of them could be repeated. all of them could be repeated. In genetic diagrams, the dominant allele is shown as a capital letter, while the recessive allele is G1 shown as a lower- case letter.
- 22. G1 G2 Have a go with eye colour. Parent one has Bb parent two has brown Bb
- 23. Can also be drawn as a punnett square Can also be drawn as a punnett square B b B BB Bb b Bb bb
- 24. Inheritance of disease – Huntinton’s Huntington’s disease Huntington’s disease ••Huntington’sdisease is an inherited disorder Huntington’s disease is an inherited disorder that affects the nervous system. that affects the nervous system. ••Affectsmuscle coordination and leads to Affects muscle coordination and leads to cognitive decline and dementia. cognitive decline and dementia. ••Itis caused by aadominant allele. It is caused by dominant allele. ••Thismeans it can be passed on by just one This means it can be passed on by just one parent if they have the disorder. parent if they have the disorder.
- 25. Cystic Fibrosis Cystic fibrosis is an inherited disorder that affects the cell membranes, causing the production of thick and sticky mucus. It is caused by a recessive allele. This means that it must be inherited from both parents. Notice that the offspring with Ff are labelled 'carriers'. A carrier has one copy of the faulty allele, but Notice that the offspring with Ff are labelled 'carriers'. A carrier has one copy of the faulty allele, but does not have the disorder themselves. In this example above, both parents are carriers. They may does not have the disorder themselves. In this example above, both parents are carriers. They may not know they are, but there is aaone in four chance of them producing aachild who has cystic not know they are, but there is one in four chance of them producing child who has cystic fibrosis. It is possible to screen embryos to see ififthey carry alleles for genetic disorders. fibrosis. It is possible to screen embryos to see they carry alleles for genetic disorders.
- 26. Cystic Fibrosis In the example, one parent is aacarrier, while the In the example, one parent is carrier, while the other does not carry the allele for cystic fibrosis. other does not carry the allele for cystic fibrosis. They cannot produce aachild with the disorder, but They cannot produce child with the disorder, but they can produce children who are carriers. they can produce children who are carriers.
- 27. Plenary • Try to complete the mini lesson test • Fill out exit card and return to me
Editor's Notes
- #16: If each book is a chromosome, then each chapter is a gene, consisting of a set of instructions for an aspect of the organism. The chapters correspond between the two sets of books. Here is an example, with made-up chapter numbers (bearing in mind that it is usually more complicated than a one gene / one characteristic correspondence – even eye colour is in fact more complicated than this model suggests). It may so happen that two corresponding chapters are the same, in which case it is fairly obvious what the organism will be like. The person in this example will have blue eyes.
- #17: In this example, the two corresponding chapters are not in agreement. In some cases like this, the body compromises between the two sets of instructions (as in, say, a dog with ‘brown fur’ instructions from one parent, and ‘white fur’ instructions from the other, being brown and white). In other cases, such as with eye colour, one set of instructions is more dominant than others. With eye colour, brown eyes are dominant, so although this person carries instructions for both brown and blue eyes, the blue eye instructions are overridden and the person has brown eyes.
- #18: Here is how two brown-eyed people can have a blue-eyed child. (There is a 25% chance of this happening, and a 75% chance of having a brown-eyed child.)