genetics STAAR review

Incomplete/codominance video Genetics video Incomplete/codominance video https://www.youtube.com/watch?v =qIGXTJLrLf8 Monohybrid tutorial: https://www.youtube.com/watch?v =swXg3FJhYoY Dihybrid tutorial: https://www.youtube.com/watch?v= qRxyIc4vMgA http://www.youtube.com/watch?v =jdJNFFVj4h8 Sex linked video: https://www.youtube.com/watch? v=jLfOBc-PVtc

Gregor Mendel worked with pea plants to learn the basic patterns of inheritance. Phenotype – what the organism looks like Genotype – the gene (letter) combination – either Homozygous (TT or tt) or Heterozygous (Tt) Homozygous (aka: pure breeding, true breeding) Homozygous dominant- HH (shows dominant trait) Homozygous recessive- hh (shows recessive trait) Heterozygous (aka: hybrid)- Ht (shows dominant trait) Monohybrid Cross – follows 1 trait through several generations Dihybrid cross – follows two traits Simple Genetics

Simple Genetics- monohybrid cross P(parental) TT x tt F1 generation T T T t t geno- all Tt T geno – ¼ TT, ½ Tt, ¼ tt (1:2:1 geno. ratio) t pheno – all tall t pheno – ¾ Tall; ¼ short (3:1 pheno. ratio) F2 generation T t T t T geno- ½ TT; ½ Tt (1:1 geno. ratio) t geno – ½ Tt; ½ tt (1:1 geno. ratio) T pheno – all Tall t pheno– ½ Tall; ½ short (1:1) Tt TT Tt tt TT Tt Tt tt Simple Genetics- monohybrid cross

Dihybrid Cross BbEe x BbEe B- brown b- white E- short ears e- long ears 9 brown and short ears 3 brown and long ears 3 white and short ears 1 white and long ears Dihybrid Cross

Complex Genetics Incomplete Dominance – blended/mixed phenotype Ex) snap dragons  Red (RR) X White (R’R’)  all Pink R R R R’ R’ geno- all RR’ R’ geno- ¼ RR; ½ RR’; ¼ R’R’ R’ pheno-all pink R’ pheno- ¼red; ½ pink; ¼ white Codominance – both parental phenotypes show up in offspring Ex) Chickens  Black x White Black and White feathers Multiple Allelism – trait with 3+ alleles ex) A, B, O blood types Complex Genetics RR’ RR RR’ R’R’

Complex Genetics Sex Linked – genes carried on sex chromosomes Ex) hemophilia, color blindness Cross shows a carrier female and a normal male. For a female to inherit the trait the father must have it and the moth must at least be a carrier Karyotypes – show if it is a boy or girl and if there is too many or too few chromosomes Ex) Down’s Syndrome (aka Trisomy 21) Complex Genetics

Vocab review game

Term: genotype Term: sex-linked Definition: genetic make- up; letters Ex. AA, Aa, aa Definition: traits controlled by the X chromosome XRXr XrY

Term: Heterozygous Term: dominant Definition: hybrid; two different alleles for a trait Ex. Aa Definition: trait that is observed; masks/hides the recessive Ex. A

Term: homozygous Term: nondisjunction Definition: pure; two of the same alleles for a trait Ex. AA or aa Definition: when chromosome pairs fail to separate during Meiosis

Term: incomplete dominance Term: karyotype Definition: neither allele is dominant; hybrid is a blend of the alleles Ex. red x white = pink Definition: picture of paired chromosomes Definition: picture of paired chromosomes

Term: recessive Term: phenotype Definition: trait that is masked Definition: physical appearance based on alleles

Term: codominant Term: blood type Definition: both alleles are dominant; hybrid shows both alleles Ex. roan cow Definition: trait you get with a combination of these alleles- IA, IB,i

What am I game

Incomplete dominance Gregor Mendel Inheritance when blue X yellow = green Who discovered how some things are inherited

genotype heterozygous Homozygous dominant hybrid Homozygous recessive

phenotype genotype When you look and see a watermelon has stripes BB

Practice eoc questions

Purple flowers are dominant over white flowers Purple flowers are dominant over white flowers. A pure purple flowered plant is crossed with a homozygous recessive plant. What percent of the offspring are homozygous? A. 0% B. 25% C. 50% D. 100% A

If red snapdragon flowers are crossed with white snapdragons, pink snapdragon flowers are produced. If two pink snapdragons are crossed what are the expected phenotypic results? A. ¼ red, ½ pink, ¼ white B. ¾ red, ¼ white C. ¼ red, ¾ white D. ½ red, ½ white A

A boy with blood type A has a sister with blood type B A boy with blood type A has a sister with blood type B. What are the possible blood types of their parents? Type O and type O Type AB and type O Type AA and type B Type A and type A B

A. Chromosomes of different lengths B. Two X chromosomes When viewing a karyotype to detect genetic disorders, which of the following would be a concern? A. Chromosomes of different lengths B. Two X chromosomes C. Twenty-three pairs of chromosomes D. Three chromosomes in any one set D

Eye color in fruit flies is a sex linked trait, where red is dominant Eye color in fruit flies is a sex linked trait, where red is dominant. If a female fruit fly is a carrier and is mated with a white-eyed male, what percent of their offspring would have white eyes? A. 0% B. 25% C. 50% D. 75% C

When roan cattle are mated, 25% of the offspring are red, 50% are roan, and 25% are white. Upon examination, it can be seen that the coat of a roan cow consists of both red and white hairs. What controls this trait? A. Incomplete dominance B. Codominant alleles C. Sex-linked genes D. Polygenic inheritance B

A man heterozygous for blood type A marries a woman heterozygous for blood type B. What is the chance that their first child will have type O blood? A. 0% B. 25% C. 50% D. 75% B

A. Nondisjunction; down syndrome   When homologous chromosomes fail to separate during meiosis, which is known as _____________. This event can lead to a disorder such as ___________. A A. Nondisjunction; down syndrome B. Translocation; diabetes C. Disjunction; Cystic fibrosis D. Crossing over; sickle cell anemia

If a mother develops melanoma, skin cancer, why is she not concerned that her unborn child will have the same condition? A. The mutation has not occurred in the gametes and therefore is not inheritable B. The mutation has not occurred in the somatic cell and therefore is not inheritable C. The DNA of the child only came from the father D. The DNA of the child can be repaired through gene therapy A

Chromosomal Abnormality Pedigree Blood Type Vocabulary Genotype Phenotype Allele Dominant Recessive Incomplete Dominance Codominance Multiple Alleles Sex – linked traits Homozygous Heterozygous Sex chromosomes Karyotype Chromosomal Abnormality Pedigree Blood Type Trisomy 21 (Down’s Syndrome)   Essential Questions Distinguish when recessive traits are expressed in the phenotype.   What are examples of human sex-linked traits? Who is affected most often? Interpret pedigrees and karyotypes in order to identify patterns of inheritance? Generalize autosomal inheritance patterns. Explain the connections between genetics and the environment with regards to general traits as well as human genetic disorders.

Red and blue are 2 popular variations of a particular flower Red and blue are 2 popular variations of a particular flower. A gardener began experiments breeding with this flower. His results are shown in the following 2 ratios: F1: 0 red, 0 blue, 100 purple F2 25% red, 25% blue, 50% purple What type of inheritance is shown by these flowers? In mice, brown hair is dominant to white. Cross a heterozygous female with a heterozygous male. The phenotypic ratio will yield? A unit of heredity, composed of a segment of DNA on a chromosome that contains information required to manufacture a protein and will eventually be expressed as a trait, is called a:

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