Unit #5 (Genetics) Notes PDF

Unit #5 (Meiosis & Genetics)  Which parent do you look “ like more? Do you have siblings? Do you look like them or totally different? 2 At the cellular level, How does this diversity in siblings occur? Meiosis Circle the one that is a sperm/egg ce...

Unit #5 (Meiosis & Genetics)  Which parent do you look “ like more? Do you have siblings? Do you look like them or totally different? 2 At the cellular level, How does this diversity in siblings occur? Meiosis Circle the one that is a sperm/egg cell. 5 Meiosis ▪ Meiosis produces sex cells (gametes) with half the genetic information from the parent cell. ▫ Parent cell (somatic cell)=Diploid (2n)=46 chromosomes ▫ Daughter cells (gametes)=Haploid (n)=23 chromosomes ▪ Meiosis creates gametes (created by germline cells) ▫ Eggs or Ovum in Females ▫ Sperm in males 6 Meiosis (con’t) The combining of two gametes produces a 46-chromosome zygote (fertilized egg) Zygote divides through mitosis to create an organism. 7 What must happen to a gamete to make it different? Meiosis (Crossing Over) ▪ While paired up the chromosomes intertwine and exchange genetic material. ▫ This mixes up the genetic material between Generations ▪ Crossing over is the reason for genetic diversity 9 Meiosis (con’t) Meiosis has the same stages as Mitosis: (PMAT) but has two sets of those phases. For example, there is a Prophase 1 and a Prophase 10  What is the purpose of “ meiosis? 11  Which of the following “ describes a sex cell (sperm/egg) created during meiosis? 12 The study of Genetics  Which organism would “ be the easiest for geneticists to study? 14 History of Genetics- Gregor Mendel Watch the following video on the father of genetics: Gregor Mendel 15 Genes and Dominance Some traits are dominant and some are recessive Trait: A specific characteristic that varies from one individual to another. Dominant: A gene or trait that prevents a recessive trait from appearing. Dominant traits are represented by an uppercase letter. Recessive: A gene or trait that only appears when a dominant trait is not present. Recessive traits are represented by a lowercase letter. For each trait or characteristic, an individual carries 2 factors (genes) One inherited gene from each parent 16  If you have a dominant “ trait in your genetics, then you will express that trait. 17 18 Mendel’s Experiments Conclusion: Tall is the dominant trait in pea plants Short is the recessive trait in pea plants And.. A trait can be hidden in some individuals, but can reappear in their offspring. 19 20 Fill in the punnett square (write in each square if the plant will be tall or short) T= Tall t=Short T (Tall) T (Tall) t (short) t (short) 21 Segregation During Meiosis, alleles (forms of a gene) segregate (separate) independently For each trait or characteristic, an individual carries 2 genes One inherited gene from each parent The two genes of each pair segregate from each other End up in separate gametes (sex cells 22 Determine the characteristics of an offspring Genotypes Genotype: Genetic makeup Alleles: The different forms of a gene Represented by letters Capital letters Dominant allele Lowercase letters Recessive allele Example: Tall-T and Short- t 23 Types of Genotypes Heterozygous or Hybrid individual: Two different alleles for the same trait 1 uppercase (dominant) and 1 lowercase (recessive) letter Example: Tt, tT Homozygous or pure line individual: Two identical alleles for a particular trait 2 uppercase (dominant) or 2 lowercase (recessive) letters for a trait 24 Example: TT, tt Phenotypes Phenotype: Physical characteristics of an organism Example: All tall plants 25 Place a red dot on phenotypes and blue on genotype Short Tt Red RR Green eyes 26 Genotype vs. Phenotype The plants have different genotypes (TT and Tt), but they have the same phenotype (tall) 27 Given the same cross, what is the probability that the offspring will have white flowers. Fill in the punnett square below with the appropriate alleles. If R is dominant for red flower color and r is recessive for white flower color. R r R r 28 Which of the following is true? Which is an example of Homozygous alleles? Which is an example of heterozygous alleles? If G:green fur and g: is purple fur. Then what color fur would an individual have with the genotype Gg? Inheritance/Heredity DNA Fingerprinting No two people are alike. ◦ Unless identical twins. Scientist can use DNA, or genes to identify a person. ◦ Repetitive sequences that are highly variable from person to person. Genes are found on chromosomes 34 Human Karyotype Karyotype: pictures of chromosomes Humans have 46 chromosomes ◦ 44 are autosomal chromosomes ◦ 2 are sex chromosomes ⚫ XX = female ⚫ XY = male 35 Finish this punnett square dealing with fertilization X X X Y 36 Complexity in human genes Human traits are not always determined by simple dominance and recessiveness. Factors that affect human traits. ◦ 1. Multiple alleles ◦ 2. Multiple genes ◦ 3. Sex linkage ◦ 4. Sex limited traits ◦ 5. Sex influenced traits 37  Do you know your blood “ type? If so, what is it? 38 Multiple Alleles Genes that occur in several different forms Example: Blood Type has 3 possible alleles ◦ A,B,O ◦ A and B are dominant ◦ O recessive Results: More than 2 possible phenotypes ◦ A O and AA = A blood type ◦ B O and BB = B blood type ◦ A B = AB blood type: universal recipient ◦ O O = O blood type: universal donor 39 40 Multiple Genes Polygenic traits: traits determined by more than one gene. Examples: Eye and skin color Results: Wide range of variation 41  Do you think height is a “ single-trait or a polygenic trait? Explain. 42 Sex-Linked Genes Genes located on X or Y chromosome ◦ Most are on X chromosome Examples: Color blindness, Hemophilia, Duchenne Muscular Dystrophy Results: ◦ Males are most likely to exhibit these traits since they only have one X. ◦ Females need to have the trait on both of her X 43 chromosomes 44 45 Sex Limited Traits Genes appear in autosomal chromosomes but only in one sex Example: Heavy beard, facial hair Results: ◦ Females may possess the genes but are not expressed 46 Sex Influenced Traits Differences in body chemistry cause some genes to be dominant in one sex and recessive in the other. Example: Baldness Results: Baldness is dominant in males and recessive in females. B = baldness b = normal Male Female BB Bald Thin Bb Bald Normal bb Normal Normal 47 Exploring Mendelian Genetics Independent Assortment ❧ Two-Factor Cross ❧ Mendel determine if the segregation of one pair of alleles affects the segregation of another pair of alleles ❧ Two-Factor Cross: F1 ❧ Crossed true-breeding plants ❧ Round yellow peas (genotype RRYY) X wrinkled green peas (genotype rryy). ❧ F1 Offspring 49 ❧ All round yellow peas (RrYy). 50 Two-Factor Cross: F2 ❧ Crossed ❧ Heterozygous F1 plants (RrYy) with each other to determine if the alleles would segregate in the F2 generation. ❧ RrYy × RrYy ❧ Produced ❧ 9:3:3:1 ratio 51 Beyond Dominant and Recessive Alleles ❧ Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes. 52  What is different about “ the Punnett Square below? 53 Incomplete Dominance ❧ Incomplete Dominance: ❧ One allele is not completely dominant over another ❧ The heterozygous phenotype is somewhere in between the two homozygous phenotypes. ❧ Example: Pink flowers 54  Describe what is “ happening with the example below: 55 Codominance ❧ Codominance: ❧ Both alleles contribute to the phenotype. ❧ Example: ❧ Chickens ❧ The allele for black feathers is codomiant with the allele for white feathers ❧ Roan Cow ❧ The allele for white hair is codominant with the allele for red hair 56 SKIP MULTIPLE ALLELES AND POLYGENIC 57  Something that has a wide variety of outcomes Something that would be has a wide considered variety which of following? of the outcomes would be considered which of the following? In sex-linked diseases such as colorblindness, which sex is the carrier of the disease and which sex expresses the disease. Why is blood type considered “multiple allele”?