Year 12 Biology - The World of Teaching

Year 12 Biology - The World of Teaching

Year 12 Biology Module 3: The Species Outcomes covered: 3.8, 3.9, 3.10, 3.11

Autosomal Dominant Inheritance Dominant gene located on 1 of the autosomes Letters used are upper case ie BB or Bb Affected individuals have to carry at least 1 dominant gene (heterozygous or homozygous) Passed onto males and females Every person affected must have at least 1

parent with the trait Does not skip generations E.g. Huntingtons disease, Marfan syndrome Autosomal DominantMarfan syndrome Autosomal Recessive Inheritance

The recessive gene is located on 1 of the autosomes Letters used are lower case ie bb Unaffected parents (heterozygous) can produce affected offspring (if they get both recessive genes ie homozygous) Inherited by both males and females Can skip generations If both parents have the trait then all offspring will also

have the trait. The parents are both homozygous. E.g. cystic fibrosis, sickle cell anaemia, thalassemia Autosomal Dominant/ Recessive Problems Cross a pure breeding, black coated guinea pig with a pure breeding, white coated guinea pig. Given that, in

guinea pigs, black coat colour is dominant to white coat colour, determine the genotypes and phenotypes of the first and second generation offspring. Incomplete dominance In a heterozygous organism, neither

gene is dominant, both genes are expressed equally Capital letters used for both alleles Snap dragons- red = RR, white= WW, pink = RW Cows- brown = BB, white= WW, roan=BW Incomplete dominance

Incomplete dominance problems In Andalusian chickens, the black Andalusian character is incompletely dominant to the white-splashed Andalusian character. The heterozygous condition produces blue Andalusian chickens.

Determine the genotypes and phenotypes of the F1 and F2 generations if a pure breeding, black Andalusian is crossed with a pure breeding, white-splashed Andalusian. Co- dominance Occurs when alternative alleles are

present in the genotype and fully observed in the phenotype E.g. ABO blood grouping system, where a single gene locus features multiple alleles- IA, IB, and i. Individuals carrying alleles for both A and B express both in the phenotype AB.

Co- dominance Genotype IA IA or IAi IB IB, or IBi IAIB ii Phenotype

group) A B AB O (blood

Sex linked inheritance Genes are carried on the sex chromosomes (X or Y) Sex-linked notation

XBXB normal female XBXb carrier female XbXb affected female XBY normal male XbY affected male

Sex linked inheritance Dominant Dominant gene on X chromosome Affected males pass to all daughters and none of their sons Genotype= XAY If the mother has an X- linked dominant trait

and is homozygous (XAXA) all children will be affected If Mother heterozygous (XAXa) 50% chance of each child being affected E.g. dwarfism, rickets, brown teeth enamel. Sex linked dominant disorders

Sex linked dominant problems The barred pattern of chicken feathers is inherited by a pair of sex linked genes, B for barred, b for no bars. If a non-barred female is mated to a barred male, a)What will the proportion and appearance of

the offspring? What will be the appearance and proportion of the progeny produced by mating an Fl male with an Fl female? Sex linked Inheritance Recessive Gene located on the X chromosome

More males than females affected (males inherit X from mother) Females can only inherit if the father is affected and mother is a carrier (hetero) or affected (homo) An affected female will pass the trait to all her sons Daughters will be carriers if father is not affected Males cannot be carriers (only have 1 X so either

affected or not) Can skip generations E.g. colour blindness, haemophilia, Duchene muscular dystrophy Sex linked recessive problem Red-green colour blindness in men is caused by

the presence of a sex-linked recessive gene c, whose normal allele is C. a) Can two colour blind parents produce a normal son? b) Can they produce a normal daughter? c) Can two normal parents produce a colourblind son or daughter? d) Can a normal daughter have a colourblind father or

mother? e) Can a colourblind daughter have a normal father or mother? Sex linked Inheritance in Drosophila General Pedigree

refer to NOB2 (new ed) pages 328-332 Autosomal Dominant Pedigree Look for: Trait in every generation

Once leaves the pedigree does not return Every person with the trait must have a parent with the trait Males and females equally affected

Autosomal dominant pedigree Autosomal Recessive Pedigree Look for: Skips in generation

Unaffected parents can have affected children Affected person must be homozygous Males and females affected equally Autosomal recessive

Sex linked Dominant pedigrees Look for: More males being affected Affected males passing onto all daughter (dominant) and none of his sons

Every affected person must have an affected parent Sex linked recessive pedigrees More ales being affected Affected female will pass onto all her sons

Affected male will pass to daughters who will be a carrier (unless mother also affected) Unaffected father and carrier mother can produce affected sons Sex linked recessive

Questions to complete Complete the following: Biochallenge pg 334, ques 2 Review ques pgs 335-338 Ques 6,7,8, 9, 10, 11, 12, 13, 14, This powerpoint was kindly donated to is home to over a thousand powerpoints submitted by teachers. This is a completely free site and requires no registration. Please visit and I hope it will help in your teaching.

Recently Viewed Presentations

  • Abstract a Theological Analysis of The Christ'S Cross Symbol ...

    Abstract a Theological Analysis of The Christ'S Cross Symbol ...

    BACKGROUND. All humans have sinned, but Christ has taken the wages of sin through death on the cross. ... The word of the cross in the original language of the New Testament Bible (Greek) is Stauros and Xulon, when translated...
  • Contemporary Human Geography, 2e Lectures Chapter 4 Folk

    Contemporary Human Geography, 2e Lectures Chapter 4 Folk

    Folk culture traditions are reflected in eighteenth- and nineteenth-century US housing. Popular culture influences are seen in US housing built since 1940. Folk housing
  • Estructuras Pastorales

    Estructuras Pastorales

    Relatividad: las estructuras que un tiempo han sido válidas, en otro tiempo pueden no serlo. ¿Por qué son necesarias las estructuras? Como en toda acción humana en la cual se pretende alcanzar un fin es necesario contar con . estructuras
  • Secondary English Learners

    Secondary English Learners

    Secondary Administrators. July 28, 2014. Secondary English Learners. LIZ: Welcome & Intro. Who is an English Learner? The state defines an EL student as one who has a primary language or "home language" other than English.
  • Martens Schematic View Role related behaviour Social and

    Martens Schematic View Role related behaviour Social and

    Marten's Schematic View Social and environment influences Role related behaviour Typical responses Deep psychological core Social and environment influences External and dynamic - changes according to your perceptions of the situation/environment
  • Vocabulary Words World Literature Week 4 Virulent  Doctors

    Vocabulary Words World Literature Week 4 Virulent Doctors

    Vocabulary Words World Literature Week 4 Virulent Doctors are advising the public to get inoculated against a virulent strain of the bird flu. Virulent Definition: adj.—extremely poisonous, infectious, or damaging to organisms Synonym: infectious, contagious, lethal Antonym: weak Deft The...
  • Announcements New topics: Mesh (loop) method of circuit

    Announcements New topics: Mesh (loop) method of circuit

    Apply KVL to each mesh. Solve for mesh currents. Mesh Analysis: Example #1 Problem: We cannot write KVL for meshes a and b because there is no way to express the voltage drop across the current source in terms of...
  • Introduction to WebEOC® in the Curriculum

    Introduction to WebEOC® in the Curriculum

    Consistent interaction with the IC created a sense of immediacy of both instruction and response. This allows a true appreciation of the responsibility of the IC to manage all divisions yet keep a focus on the objective.