The Study of Inherited Characteristics Ch 10.1 and Ch12 Genetics The Study of Inherited Characteristics Ch 10.1 and Ch12

Important Vocab. Meiosis: a type of division that produces sex cells

Meiosis in the Gonads makes gametes: Sperm Meiotic cell division Egg

X Y

Gene section of DNA on a chromosome that controls a specific trait.

Alleles RR Rr TT Tt Alleles are variations of a gene Code for a trait One from each parent

Alleles Dominant Allele: Recessive Allele: R r Upper case letter of the alphabet Codes for dominant traits Recessive Allele: Lower case letter of the alphabet Codes for recessive traits R r

Dominant Trait Bb BB or Bb “Dominates” Shows in the outward appearance Even when recessive allele is present Bb BB or Bb

Bb Recessive Trait bb “hidden” May be masked by a dominant allele Albinism “hidden” May be masked by a dominant allele Bb bb

Genotype Bb Genotype: The allele combination of the organism (i.e. TT, Tt or tt)

Phenotype Phenotype – the way an organism looks and behaves as a result of its genotype (e.g. The rabbit looks brown (even though it might be Bb in its genotype)

Homozygous: Pure condition 2 same case alleles BB= dominant bb= recessive Heterozygous: Hybrid condition 2 different case alleles Bb

How to Solve Genetics problems READ and Make a Key ex. B= black fur, b= white fur Parent genotypes (Write them down) ex. BB x Bb Gametes (Figure out what the gametes would be) Fill in Punnett square to get offspring Phenotypes/Genotypes of offspring (Write them out)– Best if written as a reduced fraction!

B BB Bb Monohybrid Cross Punnett Square Cross for one characteristic Example: Hair color

b B Generations Bb P generation = the original parents. Genetic Cross= Mating F1= Children 1st “filial” generation Parents b B Bb

2nd Generation- F2 B b BB Bb bb Children of the cross between the children of an F1 The grandchildren of the original P generation parents B b BB Bb bb

Incomplete dominance Hybrid is a blend of traits Example: RR=red Rr=pink rr=white Pink Carnation

Codominance Codominance—showing both alleles at the same time e.g. Checkered chicken (Black and white at same time) B= Black W= White BB= Black, WW =white BW = black and white (checkered). Another example is Blood Type! A, B, AB or O

Multiple Alleles More than two types of alleles for a gene. TYPES: Example: Blood Type TYPES: A IAIA, IAi B IBIB , IBi AB IAIB O ii

Polygenic traits Polygenic trait = a trait that is influenced by more than one gene. e.g. Eye color, skin color, hair color, height, etc… What do all of these characteristics have in common that can help you to recognize that the trait is polygenic?

X-Linked Traits Sex-linked Trait in on the sex chromosome XX= Female XY Male e.g. red & white eyes Female= XX Add eye trait= XRXR or XRXr XrXr Male= XY XRY or XrY “Y” is empty

Color Vision

Mendel’s Laws Law of Segregation Law of Independent Assortment when gametes are made, allele pairs segregate (separate) and randomly recombine at fertilization (with the allele of the other parent). Law of Independent Assortment genes for different traits (ex. Height and seed color) are inherited independently of each other. (i.e. how tall you are will NOT affect what color your seeds are)

Chromosome Number Homologous Chromosomes are the sets of each pair Different # for different species Full set = 2N=Diploid N= # pairs 1 pair from mother 1 pair from father Humans= 23 pairs or 46 total

Autosomes & Sex Chromosomes Autosomes = # 1-22 for all traits except sex Sex chromosomes= Pair # 23 XX(female) or XY(male)

Trisomy: an additional chromosome e.g. Down Syndrome (3 of #21)

Klinefelter’s = XXY

Pedigree Charts Male = Female= Sexual Union= Offspring=

Pedigree Chart -Cystic Fibrosis

Mutation A to A G C A X T G C Change in DNA code Caused by: Chemical damage Errors in Replication X-ray damage UV damage A T G C X

Mutation Changes in the DNA = Changes in the final proteins made =Changes in the organism

Questions?