2.  Gene – segment of DNA. Carries genetic information that codes for a trait.  Chromosome - compact packages of DNA. Inside nucleus.  Sperm – male sex cell (gamete)  Egg – female sex cell (gamete)

3.  Karyotype – arrangement of chromosomes. A picture.  Autosome - any chromosome that is not a sex chromosome

4.  Genotype = the genes of an organism; for one specific trait we use two letters to represent the genotype. ◦ A capital letter represents the dominant form of a gene (allele) ◦ A lowercase letter is the abbreviation for the recessive form of the gene (allele). Example: V = dominant v = recessive

5.  Dominant: a gene that is expressed, regardless of whether its counterpart allele on the other chromosome is dominant or recessive. ◦ Ex: VV or Vv = Long wings  Recessive : gene that produces its characteristic phenotype only when its allele is identical; vv= short wings

7.  Phenotype = the physical appearance of a trait in an organism ◦ BB, Bb = brown eyes ◦ bb = blue eyes

8.  Allele: different versions of the same gene occupying a given position on a chromosome Chromosome from Mom Chromosome from Dad

9.  Organisms that have 2 identical alleles for a particular trait are called homozygous (TT or tt).  Organisms that have 2 different alleles for a particular trait are called heterozygous (Tt).

10.  The use of a microscope to analyze cells during mitosis shows condensed chromosomes  Scientists cut pictures of these chromosomes out in and arrange them into a karyotype (right). =The number and visual appearance of the chromosomes in the cell nuclei of an organism or species

11.  2 haploid gametes (egg and sperm) join together during fertilization.  The result is a fertilized egg called a zygote which is diploid.  Humans have 46 chromosomes

14.  Two of the 46 chromosomes are sex chromosomes because they determine whether the zygote will develop into a male or female  Females have XX chromosomes  Males have XY chromosomes

15.  The 44 chromosomes that are not sex chromosomes are called autosomes.

16.  Because of the way sex chromosomes segregate, there is a 50:50 chance of both males and females being born  All human egg cells carry a single X chromosome, but only half of sperm cells carry an X while the other half carries a Y Which parent determines the sex of the baby?

17.  To identify an inherited trait controlled by a single gene, first we need to determine if that the trait is inherited and not a result of environmental influences. Then, we have to study how it’s passed from one generation to the next

18.  A pedigree chart shows the relationships within a family and how particular traits are passed from one generation to the next

19.  Nope. Unfortunately, many traits are polygenic, meaning they are controlled by many genes. ◦ Example: eye or ear shape  Additionally many traits are influenced by the environment ◦ Example: genetics determines a person’s maximum possible height, nutrition also plays a role in whether or not that height is ever reached

20.  While it’s important to consider environmental effects on expression of genes…  Environmental effects on genes expression ARE NOT INHERITED!!! ◦ Analogy: Just because someone’s arm gets cut off doesn’t mean their child will be born missing an arm!

21. Recessive aaAa aa Aa

22.  Dominant alleles will be expressed even if the recessive allele is present  Codominance: both alleles of a gene pair in a heterozygote are fully expressed, with neither one being dominant or recessive to the other R = Red flower W = White flower RW = Red & White spotted flowers

23.  Incomplete Dominance: both alleles of a gene are expressed in the phenotype- resulting in combined phenotype red flowers crossed with white flowers = pink flowers

24.  The trick is to recognize when you are dealing with a question involving incomplete dominance.  There are two steps to this: 1) Notice that the offspring is showing a 3rd phenotype. The parents each have one, and the offspring are different from the parents. 2) Notice that the trait in the offspring is a blend (mixing) of the parental traits.

25.  When meiosis goes wrong and homologous chromosomes fail to separate its called nondisjunction. This means “not coming apart.”  When this happens abnormal numbers of chromosomes end up in gametes and a disorder of chromosome numbers may result. ◦ Examples: Down Syndrome, Turner’s Syndrome, Klinefelter’s Syndrome

26.  If 2 copies of an autosomal chromosome fail to separate in meiosis an individual may be born with 3 copies of a chromosome. This is known as “trisomy”  Down Syndrome is the most common form of this, called Trisomy 21.

28. Child with Downs Syndrome The extra chromosome causes problems with the way the body and brain develop.

29.  In females, nondisjunction can lead to Turner’s Syndrome ◦ She inherits only 1 X (45, X) ◦ Sterile and sex organs don’t develop at puberty  In males, nondisjunction can lead to Klinefelter’s Syndrome (47, XXY) ◦ Extra X interferes with meiosis and usually prevents individuals from reproducing ◦ Estimated 1 in every 500-600 males ◦ XXXY and XXXXY have been found!

30.  The Human Genome Project may help in finding cures for genetic disorders through gene therapy.  Gene therapy is the process of changing a gene that causes a genetic disorder. An absent or faulty gene is replaced by a normal, working gene.

31.  The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene in order to replace a mutated gene.  Today, most gene therapy studies are aimed at cancer and hereditary diseases linked to a genetic defect

33.  If scientists can find ways to cure genetic diseases is it okay if they also start engineering taller people, or their hair color, skin color, sex, blood group or appearance??????  What are the kinds of ramifications (effects) gene therapy in this way could have on human populations in the world?

34.  There have been NO incidences in which an individual lacks an X chromosome all together  This suggests that the X chromosome contains genes that are vital for the survival and development of an embryo

35. 1. Single Allele Dominant 2. Single Allele Recessive 3. Sex Linked (X-Linked) 4. Multiple Alleles 5. Polygenic Traits

36.  Regular traits that are either determined by a dominant or recessive allele on an autosome 1. Autosomal Dominant examples: a. Huntington’s Disease b. Achondroplasia (dwarfisim) c. Polydactyly (extra fingers and toes) 2. Autosomal Recessive examples: a. Albinism b. Cystic Fibrosis c. Sickle Cell Anemia

37. Huntington’s Disease (HD)  Results in loss of muscle control and mental deterioration  No signs are shown until 30’s  Brain degeneration  Treatment: No cure, but drug treatments are available to help manage symptoms.

38. Achondroplasia  Dwarfism  Person grows no taller than 4’4

39. Polydactyly  The presence of more than the normal number of fingers or toes.  Can usually be corrected by surgery.

40. Albinism  Lack of pigment in skin, hair, and eyes  Mutation in one of several genes which provide the instructions for producing one of several proteins in charge of making melanin.

41. Cystic Fibrosis (CF)  Caused by recessive allele on chromosome 7  Small genetic change (removes one Amino Acid)  changes protein  Results in: Excess mucus in the lungs, liver and digestive tract, gets infection easily, and early death unless treated.

42. Sickle Cell Disease  Red blood cells are bent and twisted  Get stuck in capillaries  damage tissues  Results in weakness, damage to brain and heart

44. How do we determine the sex of an individual?  through sex chromosomes  Sex Chromosomes: X and Y Female: XX Male: XY  Who is responsible for gender determination in the child? The father because he gives an X or Y to the gametes. The mother only gives an X to the gamete  Which sex chromosome is bigger?  the X chromosome (y is much smaller)

45.  X-linked genes are genes found on the X chromosome, symbolized by X r, X R, Y 0.  Y-linked genes are found on the Y chromosome, symbolized by X 0, Y R, Y r  Thomas Morgan experimented with the eye color of fruit flies (Drosophilia) to determine X- linkage

46. 1. Color Blindness 2. Muscular Dystrophy 3. Hemophilia 4. Icthyosis simplex (scaly skin)

47.  Turns out, there’s a special pattern of inheritance for genes located on the X or Y chromosome.  Because these chromosomes determine sex, genes located on them are termed sex-linked

48.  About 1 in 10 males is color blind, while 1 in 100 females are color blind in the U.S.  Colorblindness is X-linked. This means that the genes for color vision are located on the X chromosome.  Since females have 2 Xs they have a better shot at color vision, while males only have 1 X which means all X-linked alleles are expressed even if they are recessive.

50.  A person with normal color vision sees a number seven in the circle above.  Those who are color blind usually do not see any number at all.

51.  RED-GREEN COLORBLINDNESS:  People with red-green color blindness see either a three or nothing at all.  Those with normal color vision see an 8.

52.  Sex-linked  Results in progressive weakening and loss of skeletal muscle  1 in 3,000 U.S. males is born with it

53.  Males only get one copy of the X chromosome, so what happens to the extra one in females?  One X is randomly turned “off”. This is called X-Chromosome Inactivation. It forms a dense region in the nucleus called a Barr Body

54.  One X chromosome may have the allele for orange spots while the other X may have the allele for black spots  In cells in different parts of the body one X may be turned on while the other X is turned on elsewhere  The cat’s fur will have a mixture of orange and black spots  Fact: If a cat has 3 colors, it’s female. Males can only have 2 colors (unless they have genetic disorder)!

55. Hemophilia- Lacking in the ability to clot blood ◦ There is a gene on the “X” chromosome that controls blood clotting ◦ People who have hemophilia are missing the protein to clot blood ◦ They can bleed to death by a minor cut.

56. - Results in weakening/loss of muscles - Caused by defective version of gene that codes for muscle

57.  Sex-Influenced traits are those that are on autosomes, but occur because of the sex hormones in male and female bodies.  Examples: Facial hair Baldness

58. Multiple Alleles – any gene that has 3 or more alleles (not just 1 dominant and 1 recessive) Example: Blood type has 3 alleles: Example: Blood type has 3 alleles: I A = Type A blood (dominant) I B = Type B blood (dominant) I B = Type B blood (dominant) i = Type O blood (recessive) i = Type O blood (recessive)

59. GenotypesPhenotypes I A I A or I A iType A I B I B or I B iType B IAIBIAIB Type AB iiType O

60.  If you have I A I B as your genes, you have both Type A and Type B blood, also known as Type AB  If you have I A i, i is recessive to I A, so you have type A blood  Q. When would you have Type O blood?  A. When you have ii as your genotype.

61.  Usually show a wide range of phenotypes  Ex: Skin color, eye color, foot size, height  Wide range of skin colors because there are more than 4 genes that control this trait.  These may also be influenced by the environment, for example height. If not given the proper nutrition as a child, they might not be as tall as their genes dictate.