Heredity Meiosis and gametogenesis Eukaryotic chromosomes Inheritance patterns
Asexual vs. Sexual Reproduction Asexual reproduction: binary fission, regeneration, vegetative propagation, budding Sexual reproduction: result of gametic fusion, gametes formed from meiosis, promotes genetic recombination (variety) Meiosis: process of gametic nuclear transfer
Sexual life cycles Remember: Asexual life cycles do not require the fusion (fertilization) of sperm and egg.
Meiosis overview Each normal 2N (diploid) cell has 2 sets of chromosomes, one from each gamete. Gametogenesis: specialized cells (spermatocyte, oocyte) undergoing meiosis to produce gametes with some combination of the 2 chromosome sets
Important vocabulary Homologous chromosomes: pair of like chromosomes, having similar length, centromere position, gene loci Linkage group: genes that are linked on the same chromosome (linked loci) Locus (pl. loci): site on chromosome where gene is located on the chromosome
Crossing over Genetic variation in meiosis result of crossing over when chromosomes aligned in tetrad formation Breaks linkage groups (genes found on the same chromosome)
Pine life cycle
Eukaryotic chromosome Allele: alternative form of the same genes Chromosome: condensed double helix (DNA)
Eukaryotic DNA packing Nucleosomes: beads on a string (beads = histones) Chromatin: condensed nucleosomes Looped chromatin on protein scaffolding Chromosomes
Mendels work Law of independent assortment Law of segregation Dominant vs. recessive phenotype Used peas because of fast generations, easily recognizable characteristics, two alleles
Inheritance patterns Mendelian inheritance: AA & Aa = dominant phenotype; aa = recessive phenotype Codominance: Aa = shows both A and a equally
Incomplete dominance Intermediate inheritance AA = dominant Aa = half way between AA and aa aa = recessive phenotype
Inheritance patterns Hybrid: mixed genes between two species Pleiotropy: ability of one gene to affect many different genes
Epistasis Expression of one gene determines the expression of another gene
Polygenic inheritance Many genes affecting a phenotype Leading to many possible phenotypes of a trait
Test cross If Mendelian inheritance, AA and Aa genotypes are indistinguishable. Crossing dominant phenotype with aa. 100% dominant = PP; 1:1 = Pp
Sex-linked Sex-linked: gene loci on sex chromosome (X or Y) Ex: hemophilia, color blindness First discovered in 1910 by Thomas Hunt Morgan Autosomal: gene loci on non-sex chromosome
Sex linkage Look for inheritance patterns that deviate from 3:1 or 1:1. Also look for disorders affecting mostly males.
X-inactivation & Barr bodies
Human pedigrees Square = male Circle = female Colored in = affected
Molecular Genetics – 9% RNA and DNA structure and function Gene regulation Mutation Viral structure and replication Nucleic acid technology and application
DNA structure Nucleotide: nitrogen base, deoxyribose sugar, phosphate group Nitrogen bases: adenine, thymine, cytosine, guanine Joined 5 – 3 (phosphodiester bonds) Sugar-phosphate backbone
RNA structure Nucleotide: nitrogen base, ribose, phosphate group Nitrogen bases: uracil, adenine, guanine, cytosine Single stranded Joined 5-3 In eukaryotes: RNA produced in nucleolus of nucleus. tRNA, rRNA, mRNA
Griffith experiment Avery did a follow-up experiment and coined transformation.
Hershey and Chase
DNA replication models
Meselson and Stahl
Origin of replication
DNA synthesis Leading strand: made continuously Lagging strand: Okazaki fragments
DNA priming Necessary for starting DNA synthesis
Telomeres Necessary to preserve DNA through successive rounds of DNA replication
Controlling gene expression Gene expression = transcription RNA transcript is translated into amino acid polymer. Operons are examples of prokaryotic gene expression control. Methylation is an example of eukaryotic gene expression control.
One enzyme, one protein (controlling gene expression) Beadle and Tatum
RNA processing Removing introns that interrupt the express-able code (exons) Also adding poly-A tail and 5-CAP
tRNA tRNA charged with amino acid assists ribosomes with protein synthesis
Translation - initiation
Translation - elongation
Translation - termination
Point mutation Codon can be mutate due to substitution.
Insertion & deletion Frameshift mutation Mutation: spontaneously occurs; basis of variation in populations
Viral reproduction Lytic vs. lysogenic life cycle Viruses are not cells. Viruses are particles of nucleic material and protein that requires host cells for reproduction. Bacteriophage: viruses that infect bacteria