Genetics Class Notes PDF

Genetics Class Notes Go to the slideshow that should be on Brightspace and take notes on them for later studying that will be on tests in the future. Ask questions in the notes and then provide the answers as a fun twist this time. Genetics System Review ⇓ DNA Structure Summary Notes:...

Genetics Class Notes Go to the slideshow that should be on Brightspace and take notes on them for later studying that will be on tests in the future. Ask questions in the notes and then provide the answers as a fun twist this time. Genetics System Review ⇓ DNA Structure Summary Notes: It's a double helix structure that is made with a chain of compose nucleotides. Nucleotide is made of a Sugar, Phosphate group and nitrogen base, there are four names, adenine, the mine, guanine, or cytosine. Cytosine always bonding with the Guanine making two hydrogen bonds Adenine and Thymine always bond together creating three hydrogen bonds. A molecule of DNA is made of two polynucleotide chains held by hydrogen bonds between the bases. Erwin Chargaff's Rule with DNA: In DNA the proportion f A is equal to T and the proportion of G is equal to C Therefore the equation is, A + G = T + C A=T & G=C Also A + G Divide by T + C = 1 DNA Study Facts & Review: Genes in DNA determine the characteristics of organisms. Alternation in the DNA is called a mutation. Mutation sometimes is caused by chemical agents, natural causes or radiation. Mutation also can occur during the DNA replication process. A Chromosome has a telomere (which are the ends of each arm) it also has a centromere which is the middle part of one and then it has the Chromatid (one half of the two arms). DNA Replication Notes: The structure of DNA is the optimal shape and makes it easy to be copied. The DNA molecule “unzips” each side and serves as a template. On each half of the molecule a new complementary half is built. The two new DNA molecules are identical to each other. Cell Division Review ⇓ Dna Replication and Cell Division Notes: DNA must replicate so that when cell division happens new cells receive a complete set of genetic information Cell divide for the Asexula reproduction one sells organisms basically, Growth and Healing and tissue repair. Mitosis Review Summary Notes: It occurs when the parents divide into the identical daughter cells. Mitosis if diving of the nuclear material cytokinesis refers to the separation of the cytoplasm and its own contents into equal parts. Interphase is where it spends most of its time, has three mini phases, first is called dG1 which is the cell growth, second is called S phase where the DNA is replicated and the third is called G2 where it prepares of mitosis the DNA is visible in the nucleus as stands called chromatin. Prophase the centrioles move the the opposite poles of the cell they help determine the location of where the material in the cell goes in mitosis, after that is the chromatin condense and shorterns into chromosomes, spindle fiber from between the centrioles and the nuclear membrane starts to dissolve along with the sound fibers attaching to the centromeres of the chromosomes. Metaphase, spindle fiber attaches to the centrioles and pulls the chromosomes into place, the chromosome lines up across the equator of the cell and the centromere holds the chromium perpendicular to the spindle fibers. Anaphase, the chromatids which are single stranded chromosomes at this point are separated at the centromere, chromatids are pulled away to opposite parts of the cell by the spindle fibers. Two nuclear envelopes form, single stainless chromosomes uncoil to become chromatin, cytokinesis occurs after telophase where the organelles are distributed between the two daughter cells and the cell membrane pinches inwards. Asexual vs Sexual Reproduction ⇓ Mitosis vs Meiosis Review: Purpose of Mitosis is to maintain the growth repair and asexual reproduction by keeping the number of chromosomes in each daughter cell making sure that they stay the same. This is called Genetic continuity. Purpose of Meiosis is to produce gametes which are sex cells which unite during sexual reproduction, in each sex cell is half of a parent cell. Asexula reproduction involves mitossi and sexual reproduction involves meiosis. Asexual Reproduction: Single parents makes the offspring that are genetically identical to the original parents (clones) Examples include the budding of yeast, spore formation by ferns and binary fission of Amoeba. Like making skin cells, you wouldn't want them to be different otherwise you would have constantly changing skin all the time which would not be pleasant so they are meant to do the same job as before. Sexual Reproduction: Genetic information from two parents is combined to produce a new organism that is genetically différent from the parent and requires more time and energy than asexual reproduction. Some benefits of sexual reproduction is that the organism is able to adapt to changing environments better because of the différent between their mother and father for natural selection. The recombination of the chromosomes allows this to happen. They will become more adapted and will survive and have more biological fitness most of the time. Meiosis & Mitosis Reproduction ⇓ Meiosis Purpose and Steps Review: Meiosis goes through diving twice, Interphase Meiosis I and Meiosis II Each division follows PMAT, Hereditary material is exchanged and the number of humans chromosomes is 46, therefore each gamete cell the sex cell with care egg and sperm is half which would equal 23. Interphase Cell Review: -​ Occurs before meiosis starts -​ Uncondensed Chromosomes -​ Once replicated the chromatin begins to condense. Meiosis Prophase I Review: -​ Chromosomes are created by shortened chromatin -​ Homologous chromosomes are paired -​ In late Prophase I the crossing over occurs of the chromosomes Crossing Over Review: -​ Homologous chromosomes switch portions resulting in offspring that have different DNA and genes than the parents and from each other as well. This happens through the process of synapsis. Meiosis Metaphase I: -​ Pairs of Homologous line up across the middle of the cell. -​ Random Assortment of the homologous pairs occurs making sure that they are all different. Meiosis Anaphase I: -​ Homologous pairs separate and move along the spindle fibers towards the poles of the cell. Meiosis Telophase I & Cytokinesis: -​ Divisions of the cell into two daughter cells occurs -​ Random assortment of the maternal and paternal cells into the each daughter cell -​ Cell is divided into two daughter cells each with their own random special genetic material half from the father which is paternal and half from the mother which is maternal. Meiosis Prophase II: -​ Nuclear membrane dissolves and the spindle fibers begin to form. Meiosis Metaphase II: -​ Chromosomes line up across the middle of the cell Meiosis Anaphase II:  -​ The centromeres split and the sister chromatids separate and move to the opposite poles of the cell and then the chromatids are now called single stranded chromosomes. Telophase / Cytokinesis II: -​ Formation of 4 cells meiosis over each of these prospective germ cells carries half of the number of chromosomes than other body cells. The reason it's only half is because there are four cells now. Bonus Notes Meiosis: Sperm formation 4 sperm are produced like normal however with the egg there are still four cells that are produced however three of them are polar bodies that degrade and don't do anything but the Ootid develops into the ovum which is the egg that is a massive cell 100,000 times bigger than the sperm. Also when it's comes to the chromosomes, the x looking one is a duplicated chromosomes and you only coin the one centromere in the middle of it however the single strand thing is called a single chromosome so both are still chromosomes you only it a chromatid when they are together. Karyotype Practice Study Questions ⇓ What is a Karyotype Test? ​ A genetic test that examines chromosomes in a cell. ​ Look at the size, shape, and number of chromosomes. ​ Chromosomes are located in the nucleus of cells and contain genes made of DNA. ​ Normal chromosome count: ○​ 46 chromosomes (23 pairs). ○​ Half from each parent. Purpose of Karyotype Testing 1.​ Check for: ○​ Missing chromosomes or pieces. ○​ Extra chromosomes or pieces. ○​ Structural changes (e.g., broken or rearranged chromosomes). 2.​ Diagnose genetic conditions: ○​ Down syndrome (extra chromosome 21). ○​ Turner syndrome (missing X chromosome). 3.​ Identify issues caused by chromosome changes, including: ○​ Birth defects. ○​ Infertility. ○​ Miscarriages. ○​ Certain cancers. When is it Used? 1.​ Before or during pregnancy: ○​ Check parents for genetic disorders they may pass on. ○​ Test an unborn baby for chromosome problems, especially if: ​ Parents are 35 or older. ​ Abnormal results from prenatal screening tests. ​ Family history of genetic disorders. 2.​ Reproductive issues: ○​ Infertility (difficulty having children).  ○​ Multiple miscarriages or stillbirths. 3.​ Cancer diagnosis and treatment: ○​ Detect chromosomal changes linked to: ​ Leukemia. ​ Lymphoma. ​ Multiple myeloma. ​ Anemia. 4.​ Symptoms of genetic disorders: ○​ Used to confirm diagnosis. How is the Test Done? ​ Unborn baby: 1.​ Amniocentesis: ​ Takes amniotic fluid (contains baby’s cells). ​ Done in 15–20 weeks. 2.​ Chorionic Villus Sampling (CVS): ​ Samples placental tissue. ​ Done in 10–13 weeks. ​ Other methods: 1.​ Blood test (most common): ​ Small blood sample from arm vein. 2.​ Buccal (cheek) swab: ​ Rubs inside of the cheek to collect cells. 3.​ Bone marrow test: ​ Takes marrow from hip bone (used for cancer testing). Preparation for the Test ​ Amniocentesis/CVS: ○​ May need a full bladder (drink water beforehand). ​ Blood test or cheek swab: ○​ No preparation needed. ​ Bone marrow test: ○​ Ask your doctor for specific instructions. Risks ​ Amniocentesis/CVS: ○​ Mild stinging/cramping. ○​ Slight risk of miscarriage. ​ Blood test: ○​ Minor bruising or pain. ​ Cheek swab: ○​ No risks. ​ Bone marrow test: ○​ Soreness or stiffness; rare serious risks. Results ​ Normal result (Negative): ○​ 46 chromosomes without abnormalities. ​ Abnormal result (Positive): ○​ Changes in chromosome number or structure detected.  ○​ Results vary depending on specific chromosome changes. ○​ Discuss with your doctor for full understanding. Additional Information ​ Chromosome problems can be: ○​ Present from birth. ○​ Develop later in life (e.g., cancer-related changes). ​ Talk to a genetic counselor if: ○​ You’re considering a karyotype test. ○​ You receive abnormal results. Genetic Mendelian & Monohybrid Crosses ⇓ Key Terms 1.​ Homozygous Trait ○​ Definition: Both genes (alleles) for a trait are the same. ○​ Analogy: Think of a homozygous trait like a matching pair of shoes—both shoes are identical. ○​ Example: A pea plant with two tallness genes (TT) is homozygous for tallness. 2.​ Heterozygous Trait ○​ Definition: Both genes (alleles) for a trait are different. ○​ Analogy: A heterozygous trait is like wearing one sneaker and one flip-flop—two different “styles” in one pair. ○​ Example: A pea plant with one tall gene and one short gene (Tt) is heterozygous for tallness. Genotype vs. Phenotype ​ Genotype: ○​ The genetic makeup of an organism (what’s in the DNA). ○​ Tip to remember: "Geno" sounds like "Gene," so it's what’s in the genes. ○​ Example: A pea plant’s genotype might be TT, Tt, or tt. ​ Phenotype: ○​ The physical appearance or traits that you can see. ○​ Tip to remember: "Pheno" sounds like "Photo"—what you see in a picture. ○​ Example: A tall plant (phenotype) might have the genotype TT (pure tall) or Tt (hybrid tall). Dominant and Recessive Traits ​ Dominant: ○​ Always expressed if present. Represented by a capital letter (e.g., T for tallness). ○​ Example: If T (tall) is dominant, any genotype with a T (like Tt) will result in a tall plant. ​ Recessive:  ○​ Only expressed when both alleles are recessive. Represented by a lowercase letter (e.g., t for shortness). ○​ Example: A plant is short only if its genotype is tt. Punnett Squares: Predicting Traits Like a Pro! A Punnett square is a visual tool to predict genetic outcomes. Think of it as a “genetic calculator” where you mix parental genes to see possible offspring. Steps to Use a Punnett Square: 1.​ State the Key ○​ Use a capital letter for the dominant trait (e.g., T = tall). ○​ Use a lowercase letter for the recessive trait (e.g., t = shirt). 2.​ Write the Cross ○​ Write the parent genotypes and the gametes they produce. ○​ Example: If the parents are Tt and Tt, their gametes are T and t from each parent. 3.​ Draw the Punnett Square ○​ Create a grid with the gametes from one parent on the top and the other parent on the side. ○​ Tip to visualize: Think of it as a “genetic bingo” card! 4.​ Fill in the Grid ○​ Combine the letters (alleles) from the top and side for each box. 5.​ Interpret the Results ○​ Count how many boxes show each genotype (e.g., TT, Tt, tt). ○​ Determine the phenotypic ratios (e.g., tall vs. short). Example Punnett Square Parent Genotypes: Tt × Tt T t T TT Tt t Tt tt Results: ​ Genotypes: ○​ 1 TT (homozygous tall) ○​ 2 Tt (heterozygous tall) ○​ 1 tt (homozygous short) ​ Phenotypes: ○​ Tall: 3/4 (75%) ○​ Short: 1/4 (25%) How to Remember It All ​ Homozygous vs. Heterozygous: ○​ “Homo” = same, like twins. ○​ “Hetero” = different, like opposites. ​ Genotype vs. Phenotype: ○​ Geno = Genes, Pheno = Physical. ​ Punnett Squares: ○​ Imagine you're baking cookies: one parent's traits are on the left, the other's traits are on top, and the offspring traits “mix” inside the boxes! Basically there is the genotype and phenotype and the phenotype is the ratio of the trait so like there actual trait let's say monkey and rolling tongues their phenotype would be for this example 50% tongue roller and 50% Non tongue rollers. Then the genotype is the more terminological way of saying it, so you can have the homo and hetero and the homo means the same like RR or pp and the hetero means different like Rp. So then for this example it would be 50% Hetero Dominant which would be Rp and Rp for two boxes or 50% of the table and then it would also be 50% recessive which is pp, you don't put hetero or homo for recessive because if it's different than it would be dominant in the mix. So then you have 0% Homo Dominant which would be RR. Dihybrid Crosses Biology Notes ⇓ Finding the possible Gametes you should be using the foil method which is similar to expanding factored from brackets but isn't the exact same, here is an image of the foil method: Before you even do this you should be able to figure the code from a word problem. When you find all your possibilities you can make your table to figure out the percentage of the chances. Dihybrid Crosses: In-Depth Study Notes Key Concepts: 1.​ Dihybrid Cross: A genetic cross between parents differing in two traits, each with two alleles (dominant and recessive). 2.​ Mendel’s Second Law: Law of Independent Assortment – genes located on separate chromosomes assort independently during gamete formation. 3.​ Genotype vs Phenotype: ○​ Genotype: The genetic makeup (e.g., RrYy) ○​ Phenotype: The physical traits (e.g., round yellow seeds) Step-by-Step Guide to Dihybrid Crosses 1. Set up the Parental Cross (P1 x P2) ​ Choose Two Traits: ○​ Example: Seed shape and seed color in pea plants ​ Seed Shape: ​ R = Round (dominant) ​ r = Wrinkled (recessive) ​ Seed Color: ​ Y = Yellow (dominant) ​ y = Green (recessive) ​ Determine Parental Genotypes: ○​ Parent 1: RRYY (Round, Yellow seeds) ○​ Parent 2: rryy (Wrinkled, Green seeds) 2. Determine Gametes for Each Parent ​ Parent 1 (RRYY): ○​ Gametes: Only RY (since both alleles are homozygous) ​ Parent 2 (rryy): ○​ Gametes: Only ry (since both alleles are homozygous) 3. F1 Generation Cross ​ Cross: RRYY × rryy ○​ F1 generation: RrYy (All heterozygous for both traits) Using FOIL to Determine Gametes ​ FOIL: This method helps when both parents are heterozygous for both traits. It stands for: ○​ F = First (first alleles in each gene pair) ○​ O = Outside (outer alleles of the two gene pairs) ○​ I = Inside (inner alleles of the two gene pairs) ○​ L = Last (last alleles in each gene pair) ​ Example: RrYy × RrYy (both parents are heterozygous for both traits): ○​ F1 Genotype: RrYy ○​ FOIL the alleles for each parent: ​ First: R and R → RR ​ Outside: R and Y → RY ​ Inside: r and Y → rY ​ Last: r and y → ry ○​ Gametes: RY, Ry, rY, ry (Each parent produces these four possible gametes) 4. F2 Generation Cross ​ F2 Generation Cross: Cross the F1 generation (RrYy × RrYy) ○​ Gametes: RY, Ry, rY, ry × RY, Ry, rY, ry ​ Punnett Square for F2 Generation: ○​ Set up a 4x4 Punnett square. Fill in all possible combinations from the gametes: RY Ry rY ry RY RRYy RRYy RrYY RrYy Ry RRYy RRyy RrYy Rryy rY RrYY RrYy rrYY rrYy ry RrYy Rryy rrYy rryy 5. Genotype Ratio: ​ Genotype count from Punnett square: ○​ 9 Round, Yellow (R_ Y_) ○​ 3 Round, Green (R_ yy) ○​ 3 Wrinkled, Yellow (rr Y_) ○​ 1 Wrinkled, Green (rr yy) ​ Genotype Ratio: 9:3:3:1 6. Phenotype Ratio: ​ Phenotype count from Punnett square: ○​ 9 Round, Yellow ○​ 3 Round, Green ○​ 3 Wrinkled, Yellow ○​ 1 Wrinkled, Green ​ Phenotype Ratio: 9:3:3:1 7. Percentage of Each Genotype and Phenotype ​ Genotype Percentages: ○​ 9 Round, Yellow (R_Y_): 9/16 = 56.25% ○​ 3 Round, Green (R_yy): 3/16 = 18.75% ○​ 3 Wrinkled, Yellow (rrY_): 3/16 = 18.75% ○​ 1 Wrinkled, Green (rryy): 1/16 = 6.25% ​ Phenotype Percentages: ○​ Round, Yellow: 9/16 = 56.25% ○​ Round, Green: 3/16 = 18.75% ○​ Wrinkled, Yellow: 3/16 = 18.75% ○​ Wrinkled, Green: 1/16 = 6.25% Example 2: Fur Length and Fur Color in Cats Traits and Alleles: ​ Fur Length: ○​ F = Short (dominant) ○​ f = Long (recessive) ​ Fur Color: ○​ G = Grey (dominant) ○​ g = Orange (recessive) Parental Genotypes: ​ Parent 1: FfGG (Short, Grey fur) ​ Parent 2: FFgg (Short, Orange fur) Gametes: ​ Parent 1 (FfGG) → FG, Fg ​ Parent 2 (FFgg) → Fg F1 Generation: ​ Cross: FfGG × FFgg ​ Possible Genotypes: FFGg, FFGg, FfGg, FfGg Genotype Ratio (F1 Generation): ​ 1:1 ratio of FFGg : FfGg Phenotype: ​ All kittens will have short grey fur (because both traits are dominant in the F1 generation). Study Tips for Dihybrid Crosses: 1.​ FOIL Method: ○​ Use FOIL to determine all possible gametes for heterozygous parents. This is critical for understanding how to combine alleles correctly. 2.​ Punnett Squares: ○​ For dihybrid crosses, remember to set up a 4x4 Punnett square. ○​ Include all possible allele combinations from both parents. 3.​ Genotype vs Phenotype: ○​ Genotype refers to the genetic makeup (homozygous or heterozygous), while phenotype refers to the visible trait. ○​ Genotype Ratios: Focus on the numbers of each genotype in the Punnett square. ○​ Phenotype Ratios: Focus on the physical traits that result from the genetic makeup. 4.​ Genetic Ratios:  ○​ After completing your Punnett square, calculate the genotype and phenotype ratios by counting the different combinations and dividing by the total number of outcomes. Blood Cells Genetics Review ⇓ Human Blood Type? ​ One gene can become multiple blood types, three different alleles IA, IB, i ​ Ia and Ib are co-dominant and i (type o) is recessive. ​ 6 possible genotypes, 4 possible phenotypes Phenotypes include the following: Genotypes include the following: ​ Type A ​ IAIA or IAi ​ Type B ​ IBIB or IBi ​ Type AB ​ IAIB ​ Type O ​ ii Blood type compatibility? Type of Blood Can give blood to… Can receive blood from… A A,AB A,O B B,AB B,O O A,B,AB,O O AB AB A,B,AB,O Blood type Compatibility and Rh Factor ​ Rhesus (Rh) factor is an inherited protein found on the surface of red blood cells. ​ If you blood has the protein you are Rh positive ​ If you blood doesn't have the protein you are Rh negative ​ Rh positive is the most common blood type Mendelian Genetics: The Blueprint of Heredity 1. Laws of Inheritance:  ​ Law of Segregation: Each organism carries two alleles for each trait, and these alleles segregate during gamete formation. Every gamete receives one allele. ​ Law of Independent Assortment: Genes for different traits are inherited independently of each other (assuming they are on different chromosomes). ​ Law of Dominance: In a pair of alleles, one may mask the expression of the other—this is the "dominant" allele overpowering the "recessive" one. Mendel's Legacy: Dominance Unraveled ​ Dominant & Recessive Alleles: ○​ Dominant: The “loud” allele that covers the quieter recessive allele. ○​ Recessive: The “shy” allele that gets overshadowed by the dominant one. ​ Complete Dominance: In Mendel’s experiments, only one allele seemed to speak up—leading to the offspring resembling only one parent. ○​ Example: Pea plants show either tall (dominant) or short (recessive), never a blend. Non-Mendelian Genetics: The Rainbow Beyond Dominance 1.​ Incomplete Dominance: ○​ Imagine two colors mixing to make a new shade, like red and white mixing to form pink. ○​ Neither allele is completely dominant, so they blend to create a third phenotype. ○​ Example: Cross a red snapdragon (RR) with a white snapdragon (WW). ​ F1 Generation: All offspring will be RW (Pink Snapdragons). ​ Phenotypic ratio: 100% pink. ​ Genotypic ratio: 100% RW. ○​ Other Examples of Incomplete Dominance: ​ Rabbit Fur Length: Long x Short = Medium Fur. ​ Dog Tail Length: Long x Short = Medium Tail. ​ Hair Texture: Straight x Curly = Wavy Hair. ​ Horse Coat Color: Red x Cream = Golden Coat. 2.​ Codominance: ○​ Here, both alleles share the spotlight. Neither allele is dominant, and both are expressed simultaneously. ○​ Example: A red camellia (RR) crossed with a white camellia (WW) results in RW offspring, showing both red and white flowers together. ○​ Phenotypic ratio: 100% Red and White. ○​ Genotypic ratio: 100% RW. ○​ Other Examples of Codominance: ​ Speckled Chickens: ​ BB (Black), WW (White), and BW (Speckled). ​ Roan Cattle: ​ RR (All red hairs), WW (All white hairs), and RW (Roan, red and white hairs mixed). ​ Appaloosa Horses: ​ GG (Gray coat), HH (White coat), and GH (Gray with white spots). Practice Problems for Non-Mendelian Genetics 1.​ Incomplete Dominance Practice: ○​ Red x White Snapdragon Cross: ​ P1: Red (RR) x White (WW) → F1: 100% Pink (RW). ○​ F2 Generation: ​ Red x Pink Snapdragon: 50% Red, 50% Pink. ​ White x White Snapdragon: 100% White. ​ Pink x Pink Snapdragon: 25% Red, 50% Pink, 25% White. 2.​ Codominance Practice:  ○​ Red Cow x Roan Cow (RR x RW): ​ F1 Generation: 50% Red, 50% Roan. ○​ Roan Cow x Roan Cow (RW x RW): ​ F1 Generation: 25% Red, 50% Roan, 25% White. Metaphors and Literary Techniques for Retention: ​ Law of Segregation: Think of alleles as actors in a play. When the curtain rises (gamete formation), each actor steps out with one role (allele), and the rest are hidden backstage. ​ Law of Independent Assortment: Imagine genes as ingredients in a recipe. Just because you add sugar doesn’t mean you automatically add flour. Each ingredient (gene) adds its unique flavor to the mix. ​ Law of Dominance: The dominant allele is like the lead actor who commands attention, while the recessive allele plays a supporting role in the background, rarely seen unless there’s no lead actor (dominant allele) around. ​ Incomplete Dominance: Picture mixing two paints—red and white. Instead of one overpowering the other, they blend into a new shade (pink), creating something entirely unique. ​ Codominance: Think of two distinct voices in a choir. Instead of blending into one sound, both voices sing clearly and equally, creating a harmonious yet distinct melody. Recap: Key Takeaways ​ Mendel’s World: Dominant traits shout louder, recessive traits stay quiet unless both alleles are recessive. ​ Beyond Mendel: ○​ Incomplete dominance creates blended traits (like mixing paints). ○​ Codominance shows both traits clearly side by side (like two singers in a duet). ​ Genetics Unfolds Like a Story: In this tale of inheritance, sometimes the characters (alleles) cooperate, sometimes they clash, and sometimes they work together to create something new. Sex Linked Inheritance Notes 1.Sex Chromosomes: ​ 1-22 Chromosomes: They are responsible for all the traits that are non sexual, however the 23rd chromosomes are the sex chromosomes which change sex related traits. ​ Sizes of the Chromosomes: Y chromosomes are small and the X chromosomes are larger , nearly 100 genes that control non sexual characteristics. Example: “The X chromosome carries the gene for colour blindness. B = normal vision​ ​ b = colour-blind B B ​ X X = female with normal colour vision ​ XBXb = female who carries gene for colour-blindness (but has normal colour vision) ​ XbXb = colour-blind female ​ XBY = male with normal colour vision ​ XbY = colour-blind male *Note* males cannot be a carrier, only females can be a carrier.  Chromosomal Mutations Notes 1.​ Karyotypes Review: ​ It's a picture of the person's chromosomes to test and examine them and it can help identify genetic problems by counting the number of chromosomes or looking for structural changes that are unnatural or different. Can be tested in almost any tissue ​ Mistakes in Separation: Aneuploidy, Error during meiosis, separation of chromosomes doesn't take place properly results in cells having too many or too few chromosomes. ​ Caused by Nondisjunction, failure of the homologous chromosomes to separate in meiosis I ​ Failure of the sister chromatids to separate in meiosis II Examples: Monosomy: Sex cell missing one chromosome. Polysomy: Condition where there are more chromosomes than required Polyploidy: Nondisjunction of all the chromosomes in a gamete that unites with a haploid gamete to produce 3 sets of chromosomes (3n) Mistakes in Crossing Over: Pieces of genetic information are exchanged but do not re-attach properly 1.​ Deletion: When exchanged information does not reattach to the chromosome 2.​ Inversion: Segment of DNA reattaches to chromosome but in the reverse order 3.​ Duplication/Insertion: The exchanged information is repeated on the chromosome 4.​ Translocation: Movement of information from one chromosome to a non-homologous chromosome Background of Genetic Disorders: ​ Genetic disorders can be caused by chromosomes or genes ​ Inherited disorders is caused by a gene passed from parent to child ​ Inherited disorders can be: ○​ Dominant - a trait that will appear in the offspring if ONE parent donates it ○​ Recessive - must be contributed by BOTH parents to appear in the offspring; recessive traits can be carried in a person’s genes without appearing in that person X-Linked / Sex Linked Disorders: ​ X-linked disorders are caused by genes on the X chromosome ​ This is because of size difference x being bigger thant he y ​ X-linked disorders are generally seen in males. ○​ Males have only one X chromosome, therefore, no dominant gene to cancel out recessive gene