AP Biology Test Return/Lab return/Study guide return Chapter 13-15 Next test December 6  Study guide Corrections too

Chapter 13- Meiosis Heredity- or inheritance transmission of traits from one generation to the next Genes- coded information with traits, segments of DNA Gametes- reproductive cells (sperm and egg)

Somatic cells- cells other than reproductive cells Locus- a specific location on a chromosome Asexual reproduction vs Sexual reproduction Life cycle- generation to generation sequence of stages in reproductive history

Chromosomes 46 human chromosomes (somatic) 2n (2 sets) Karyotype Autosomes vs sex chromosomes Haploid (n) – cells with a single chromosome set

Fertilization- union of gametes (sperm and egg) zygote is formed Zygote- fertilized egg, diploid because it contains 2 haploid sets from each parent Meiosis- process to form gametes, reducing chromosome number by half

Meiosis Interphase Meiosis I Meiosis II Separates homologous chromosomes Meiosis II Separates sister chromatids

Meiosis I Prophase I Metaphase I Anaphase I Telophase I, Cytokinesis Crossing over occurs Metaphase I Homologous chromosome PAIRS line up at middle Anaphase I Duplicated homologous chromosomes separate Telophase I, Cytokinesis 2 cells result

Meiosis II Prophase II Metaphase II Anaphase II Homologous chromosomes (sister chromatids) line up at center Anaphase II Sister chromatids separate Telophase II, Cytokinesis

Mendel and Gene Idea Chapter 14 Blending hypothesis- genetic material mixes in a manner which blends traits Mendel- peas Traits- characteristic inherited True-breeding – plants self-pollinate to have same traits as parents Hybridize- cross (or cross-pollinate)

P generation – parent F1 = Offspring of P F2 = offspring of F1

Genotype – Phenotype – Alleles- alternative forms of traits Dominant- Recessive-

AP Biology

Mendel’s laws Law of segregation- Law of independent assortment- 2 alleles for a heritable character separate during gamete production (end up in different gametes) Law of independent assortment- Each pair of alleles segregates independently during gamete formation.

Problem: Homozygous black rabbit mates with a homozygous white rabbit Phenotypic ratio: Genotypic ratio:

Problem: Carry out a cross for the F1 generation: Phenotypic ratio: Genotypic ratio:

Problem: A brown tall rabbit is mated with a white short rabbit. Brown and tall are dominant. Construct a punnett square

Problem: Use F1 to determine the F2 generation

Laws of probability govern Mendelian inheritance Probability of tossing heads with normal coin: Probability of rolling a 3 with a 6 sided die:

Law of multiplication Used to determine probability of two or more independent events. Probability that 2 girls are born in a row to a family: Probability that 6 girls are born in a row to a family:

Law of addition: The probability of an event that can occur in two or more mutually exclusive ways The probability of producing an F2 heterozygote:

Mendel genetics = simple genetics Incomplete dominance – intermediate offspring Codominance – both traits are shown

Many genes exist in populations in more than two allelic forms: ABO blood groups: IA, IB, i

Pleiotrophic- when genes affect more than one phenotypic characteristic Polygenic inheritance- additive effects of two or more genes on a single phenotypic character.

Pedigrees

AP BIO Finish Chapter 15 Lab Tuesday Test Thursday

AP Biology Thomas Morgan Worked with Drosophila (fruit flies) Discovered wild type – characteristic found in nature Mutants were alternatives to the wild type Fruit flies- carry eye color on X chromosome White eyes – w Red eyes – w+

Not All organisms are XX and XY

SRY gene on Y SRY (sex-determining region of Y) gene was discovered in 1990. Individuals with the SRY gene embryonic gonads develop into testes Individuals without the SRY gene develop ovaries

Genes located on Sex Chromosomes Sex-linked genes On Y = Y-linked genes On X = X-linked genes Color blindness Hemophilia Duchenne muscular dystrophy

Problem: Mother heterozygous for color blindness Father is not colorblind Results:

Barr body Females inherit 2 X chromosomes, only 1 X chromosome is active. Barr body- during development 1 X chromosome per cell condenses into a compact Barr body. Barr bodies are not expressed.

Linked genes Linked genes – genes located near each other on the same chromosome and tend to be inherited together.

Crossing over Accounts for recombination of linked genes Occurs in prophase I meiosis I New combinations result in varied offspring

Alterations of chromosome number Nondisjunction – members of a pair of homologous chromosomes do not separate properly during meiosis I Or sister chromatids fail to separate during meiosis II. Trisomic, monosomic cells Polyploid – organisms with more than two complete sets of chromosomes

Breakage of chromosome structure Deletion – when a chromosomal fragment is lost Duplication- occurs when a fragent becomes attached as an extra segment to a sister chromatid. Inversion – When chromosome fragment reattaches to the original chromosome in the reverse direction Translocation- fragment joins a non homologous chromosome