Genetics The Science of Heredity

1. Genetics The Science of Heredity

2. Unit Vocabulary Heredity Passing of traits from parent to offspring. Traits Different physical characteristics Genes Factors that control traits. Different forms of a gene. Always two for each trait. One from each parent. Alleles

3. Alleles Dominant Allele Recessive Allele The trait that is always exhibited or “shows up.” (Tt) Heterozygous two different alleles for a trait (hybrid) Homozygous two identical alleles for a trait (purebred) The trait that is masked or covered up when a dominant allele is present. A recessive allele will show up only if there are two recessive alleles (tt) (ss) Homozygous 2 identical recessive alleles (tt) (ss)

4. Monohybrid Dihybrid A dihybrid is produced by crossing parents that are heterozygous for two alleles, so that each gene is represented by two different forms of alleles. (Tt) A hybrid produced by crossing parents that are homozygous for two alleles. (TT) (tt) Phenotype – The physical appearance or visible traits (green eyes, brown hair, shape of face) Genotype – The genetic makeup or allele combinations (Tt, TT, tt) Symbolic representation

5. Co dominance - a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together. (chicken with white and black feathers) Incomplete Dominance - a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits. (flower - white and red= pink)

6. Punnett Square - is a chart that is used to show possible combinations of a genetic cross, and to determine the probability of a particular outcome. ***created by geneticist named Reginald Punnett

7. Mendelian GeneticsGregor Mendel (1822 – 1884) was an Austrian monk whose studies of the inheritance of traits in pea plants helped to lay the foundation for the later development of the field of genetics. He is often called the "father of genetics." His studies showed that there was particulate inheritance of traits according to basic laws of inheritance. The significance of Mendel's work was not recognized until the turn of the twentieth century.Living as a monk, he raised and monitored more than 20,000 pea plants inside the walls of his monastery. Particulate inheritance - traits that insures a species survival.

9. Mendel’s Pea Plant Experiments Mendel’s 1st Experiments • Mendel used purebred plants PP, pp • PP for all purple flowers and tt for white flowers • He called the offspring from each cross First/F1 Generation plants • Each of the offspring had purple flowers with an heterozygous allele combination Pp Mendel’s 2nd Experiment • Mendel allowed the first generation to self-pollinate • The white flower reappeared. • 3:1 Ratio

10. Probability • Probability - (or likelihood) is a measure or estimation of how likely it is that something will happen. • Probability is often written as a fraction or a percentage. • If you flip a coin the probability of flipping heads is 50% or ½.

11. Meiosis • Meiosis 1 • At the end of Meiosis 1 there are two daughter cells with a full set of chromosomes that are identical to the parent cell. • The two cells are called daughter cells. • During meiosis II the chromosomes are not copied • Four (sex cells) called gametes are produced. Egg cells for females and sperm cell for males. • Each gamete has half the number of chromosomes than the original cell.

12. Mitosis Vs. Meiosis • One large cell makes two smaller cells with same number of chromosomes; allows organisms to grow, develop and repair. • Before Mitosis begins the chromosomes copy themselves. • The two new cells are called daughter cells. • Both new daughter cell have a full set of chromosomes. • Cell division for reproduction • One large cell will produce four smaller cells called gametes. Each cell will have half the normal number of chromosomes. • DNA does not duplicate during meiosis 2. • Cells produced will fuse together during sexual reproduction. • The egg cell and sperm cell will combine (fertilization) to form zygote (new organism) with a complete set of chromosomes.

13. DNA - DEOXYRIBONUCLEIC ACID • The double helix model was discovered by a group of scientists named Watson, Crick and Franklin • The steps of the double helix is made of nucleotides. • Four nitrogen bases: Adenine always pairs with Thymine (AT) and Guanine always pairs with Cytosine (GC) • Alternating bands of sugar and phosphates make up the sides of the double helix.

14. DNA Continued Humans sex cells normally have 23 pairs of chromosomes, for a total of 46 after the egg cell and sperm cell combine. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair is called the sex chromosomes and differs between males and females. Females have two copies of the X chromosome or XX, while males have one X and one Y chromosome. DNA lies within the nucleus of all cells in humans and other living organisms. Most of the DNA is placed within the nucleus and is called nuclear DNA. However, a small portion of DNA can also be found in the mitochondria and is called mitochondrial DNA or mtDNA. • DNA stores all the genetic information for an organism, and it can replicate itself and be transmitted to all the organism's offspring. • DNA is located in the nuclei of cells, which make up the body. • DNA can be considered one of the building blocks of the body. • Genes are hereditary material that lies within the cell nucleus. Genes, which are made up of DNA, act as instructions to make molecules called proteins.

15. The DNA can make copies of itself. Both the strands of the DNA open up and make a copy of each and become two DNA stands. DNA consists of 2 strands in a twisted ladder structure called the Double Helix.

16. Karyotype – A picture of all the chromosomes in a cell lined in pairs. Female

17. Male

18. Pedigrees • Pedigrees are one tool that geneticists use to trace the inheritance of traits in humans. • A pedigree chart or “family tree” that tracks which members of a family have a particular trait. • The trait recorded in a pedigree can be for an ordinary trait such as a widows peak, or it could be a sex link traits such as color blindness or hemophilia.

19. Hemophilia Hemophilia is the name of a genetic disorder which means the body's inability to control bleeding. It is called a sex linked disorder because it is carried on the x chromosome.

20. The charts below show the most common types of color blindness. If a certain pigment is missing in your eyes, you may have trouble seeing blue-yellow colors. People with blue-yellow color blindness usually have problems identifying reds and greens, too. Color Blindness

21. Mutations Deletion – a base pair is left out. Insertion –an extra base is added Substitution - the wrong base is used. (most common) A genetic disorder is an abnormal condition that a person inherits through genes or chromosomes. Some occur in sex cells during meiosis, and are passed down from the parent’s cells. These abnormal conditions are called mutations. There are three types of mutations.

22. Genetic Disorders This adorable child has a genetic disorder called down syndrome. A person with down syndrome has an extra copy of chromosome 21. The extra chromosome is the result of an error made during meiosis. People with down syndrome have a distinctive physical appearance and some degree of mental or cognitive problems. Heart defects are also common but can be treated.

23. Klinefeltersyndrome is a disorder that affects only males. Males normally have an X chromosome and a Y chromosome (XY). But males who have Klinefelter syndrome have an extra X chromosome (XXY), This called an insertian giving them a total of 47 instead of the normal 46 chromosomes. • People with this disorder develop as males with subtle characteristics that become apparent during puberty. They are often tall and usually don't develop secondary sex characteristics, such as facial hair or underarm. The extra X chromosome primarily affects the testes, which produce sperm cells and the male hormone testosterone.

24. Genetic Disorders cont. • Turner Syndrome • Normally, females inherit one X chromosome from their mother and one X chromosome from their father. But females who have Turner syndrome are missing one of their X chromosomes. (omission) • Women with Turner syndrome are usually sterile and cannot have children.

25. Other Genetic Disorders • Albinism is a congenital disorder in which there is little or completely no production of melanin in hair, skin and iris of the eyes. Hence people suffering from albinism have light-colored skin, hair and eyes. • Color Blindness - refers to the inability to differentiate among certain colors. Color blindness is most commonly the result of mutations in the X chromosome. However, research has shown that mutation in 19 different chromosomes can cause color blindness. • Cystic Fibrosis - is an inherited disease of the glands that secrete mucus and sweat. Cystic fibrosis causes the mucus to become thick, sticky. The mucus clogs various organs of the body, that results in other complications. It mostly affects lungs, liver, pancreas, sinuses, intestines and sex organs. At present, there is no cure for cystic fibrosis.

26. Hemophiliais the name of a genetic disorders which mean the body's inability to control bleeding. The bleeding might be exterior, if the skin is broken by a cut, scrape, or abrasion, or it can be interior, into joints, muscles, or organs which are hollow. The result can be visible on the skin or subtle (e.g., brain bleeding). Muscular Dystrophy is a genetically inherited disorders of progressive degeneration of skeletal muscles. It also causes defects in muscle proteins and death of muscle cells and tissues. These disorders vary in severity and the extent and distribution of muscle weakness. Although the skeletal muscles are primarily affected, muscular dystrophy may impair functions of other systems of the body as well. Sickle cell disease or sickle cell anemia is a blood disorder. A mutation causes sickling of the red blood cells that may lead to a number of complications.

27. Genetic Counseling If a couple has a family history or concern about a genetic disorder they may seek help from a genetic counselor. Genetic counselors help couples understand their chances of having a child with a particular genetic disorder. They use tools such as karyotyping, pedigree charts and Punnett squares to help them in their work.

28. Genetic Engineering Genetic engineering is sometimes called “gene splicing” because a DNA molecule is cut open and a gene from another organism is spliced into it. Genetic engineering can improve medicines, improve food crops, and may cure many human genetic disorders. In the last few decades geneticists have developed a powerful technique for producing organisms with desired traits. This process is called genetic engineering. In genetic engineering genetic information is transferred from one organism to another organism.

29. Genetic Engineering in Bacteria Researchers had their first success with genetic engineering when they inserted DNA from another organism into bacteria. Once the DNA is spliced into the bacteria, for example, insulin all of that bacteria's offspring will contain this human gene. In this case the human code for insulin. Why are bacteria used for gene splicing? Because bacteria reproduce quickly, and large amounts of insulin can be produced in a short amount of time. Then the insulin can be collected and used to treat people with diabetes.

31. Gene Therapy This process involves inserting working copies of a gene directly into the cells of a person with a genetic disorder. For example, people with cystic fibrosis do not produce a protein that is needed for proper lung function. With gene therapy scientists can insert copies of the gene into the harmless virus. The engineered virus can then be sprayed into the lungs of patients with cystic fibrosis.

32. Selective BreedingTheir are two types of selective breeding called inbreeding and hybridization Inbreeding Inbreeding involves cross breeding two individuals that have identical or similar sets of alleles. As a result organisms have offspring that are very similar to those of their parents. For example, breeders produce pure breed dogs such as golden retrievers and other dog breeds. Unfortunately, because of inbreeding the offspring have a greater chance of inheriting alleles that lead to genetic disorders such as hip problems, cataracts and certain types of cancers.

33. Hybridization Hybridization – breeders cross two genetically different individuals. The hybrid organism that results is bred to have the best traits from both parents. For example, a farmer might cross corn that produces many kernels with corn that is resistant to disease. The result is corn plants with both of the desired traits. Today, most crops grown on farms and in gardens were produced by hybridization.

34. Cloning Cloning Plants – A cutting is one way to clone a plant. A small stem or leaf is cut from a plant and an entire new plant will grow. The new plant will be identical to the plant is was cut from. A clone is an organism that is identical to the organism from which it was produced. This means that a clone has exactly the same genes as the organism from which it was produced.

35. Cloning Animals – Dolly was the first clone of an adult mammal ever produced. To create Dolly scientists followed these steps: • First – researcher removed an egg cell from one sheep. • Second – the cell’s nucleus was replaced with the nucleus from a six year old sheep. • Third – the egg was then implanted into the uterus of a third sheep. • Five months later Dolly was born. Dolly was genetically identical to the six year old sheep that supplied the nucleus. Since Dolly, scientist have cloned pigs and calves. Scientists hope that cloning animals will help humans live healthier lives. For example, pigs that are being cloned have genes the will make their organs suitable for organ transplant into humans.

36. Biotechnology Biotechnology is the use of biological processes, organisms, or systems to manufacture products intended to improve the quality of human life. A few examples of modern biotechnology are tissue cultures, genetic engineering, recombinant DNA techniques, mutagenesis, drugs, antibiotics, antibodies, pesticide free crops, breeding , hybridization, and cloning.

37. Bioethics Bioethics is a group of principles that help people determine what is right and what is wrong in biological and medical investigations. When scientist conduct investigations they follow these guidelines: In the laboratory they must follow all safety instructions and wear safety equipment. In the field they must respect all living organisms, their habitats and their environment. During any testing with humans or animals, subjects should not be harmed unnecessarily. Human test subjects should be informed of possible consequences of the test before they agree to take part. Lastly, all subjects should be treated humanly.

38. Sexual and Asexual Reproduction Sexual Reproduction - Reproduction that involves two parents. Asexual Reproduction – Reproduction that involves one parent.

39. Reproduction of Bacteria Bacteria – When bacteria are living in the suitable conditions (lots of food, stable temperature) they can reproduce every 20 minutes. Binary Fission – (asexual) a type of reproduction in which one cell divides into two identical cells. Conjugation – (sexual) one bacterium transfers some of its genetic material into another bacterial cell through a thin, thread-like bridge that joins the two cells. Conjugation results in bacteria with a new combination of genetic material.

40. Reproduction in Protist • Protist also reproduce through binary fission (asexual) and multiple fission to make more than two offsprings from one parent • Conjugation (sexual)are in single cell organisms.

41. Reproductionin Fungus Sexual or Asexual • Asexual Reproduction– 2 ways • The hyphae break apart and each new piece becomes a new fungus. • Production of spores - spores are small reproductive cells that are protected by a thick cell wall. Spores are light and can spread by the wind. When conditions are right the spore will grow into a fungus. • Sexual Reproduction – happen when special structures form to make sex cells. The sex cells join to produce sexual spores that grow into new cells. Hyphae are threadlike filaments made of cells that have openings that allow cytoplasm to move freely between cells.

42. Reproduction in Plants Stamens the male reproductive parts where pollen is produced . Pistils the female reproductive parts . The base of the pistil contains ovary which has one or more ovules. First pollen falls on a stigma. Next the sperm cell and the egg cell join together in the flower ovule. The zygote develops into the embryo part of the seed.

43. Reproduction in Animals Invertebrates Fragmentation - In this type of reproduction, the body of the parent breaks into distinct pieces, each of which can produce an offspring. Planarians exhibit this type of reproduction. Regeneration - In regeneration, if a piece of a parent is detached, it can grow and develop into a completely new individual. Echinoderms exhibit this type of reproduction. (starfish, worms) Budding – when part of an organism breaks off and forms a new organism (hydra, sponge)

44. Vertebrates • Sexual Reproduction – Two parents. • Internal Reproduction – Egg cell and sperm cell fertilize inside the organism. ex, humans, cats, dogs and manatees. • External Reproduction – Egg cell and sperm fertilize outside of the organism – • ex. amphibians and fish.

45. Advantages of Asexual and Sexual Reproduction • Asexual • Asexual reproduction does not require any meeting of two gametes which means that it can reproduce many individuals very quickly. • But with this it means that there will be very little variations in the offspring. • Asexual reproduction contain the identical genetic information from their parents as they are essentially a clone. • Less energy required for reproduction. Sexual • With sexual reproduction there are lots of variations because they have a different cell from each parent. • Sexual reproduction is very slow. • Purges the species of mutations. Since most mutations. • Less population growth • Requires long-term energy use