Genetics and Evolution

these genes separate and recombine independently of one another, with every combo of alleles having the same likelihood of occurring division of genes during meiosis is random and therefore no 2 gametes will have same combo of genetic info, all combos have equal chance

genes separate into distinct alleles during gamete formation

purpose is to isolate and study traits monohybrid: P generation is selected based on one particular trait, one parent has dominant trait and other has recessive dihybrid: P generation is selected for 2 traits that differ bw parents

diagram of familial genetic history and traces inherited traits from one generation to next circles-females squares-males homozygous dominant- filled in heterozygous dominant- partially filled in

genes close together on chromosome are more likely to be inherited together not found close- not inherited together

traits that differ bw males and females located on sex chromosome genes on Y chromosomes only expressed in males Y chr is smaller and has fewer genes X chromosome larger and found in males and females • -males have one allele for every X gene so this is the trait that will be expressed regardless if dominant or recessive • -females have 2 X chromosomes so the dominant allele will express itself for X linked traits

• -many genes have multiple alleles • -multiple alleles means higher genetic diversity, more complex rules of dominance, and more combos of phenotypes • codominance: appearance of 2 dominant alleles, both dominant genes are expressed • incomplete dominance: one allele is not completely dominant over the other

polygenic: traits determined by multiple genes, observed in continuous variation epistasis: one gene suppresses the expressed phenotype of another gene - -these are not alleles for the same trait - -phenotype expressed by one gene dependent on modifier gene that masks the trait pleiotropy: one gene can have multiple effects, one gene influences many traits

within mitochondria or chloroplasts passed from parent to offspring primary type of organelle inheritance from extranuclear organelles is called uniparental inheritance bc comes from mother • • most common in eukaryotic animals that undergo sexual reproduction • -most important is mitochondrial inheritance • —-major energy producers • —-genetic material within this replicates independently of the material within the nucleus • —at fertilization the egg provides a copy of the mothers mitochondrial DNA and this is passed on to offspring

euploidy: equal # of chromosomes that is exact multiple of the haploid number monoploid: half the normal number of chromosomes - -monoploid in adult state - -plants and fungi, insects - -sterile non reproducing polyploid: more than 2 pairs of chromosomes - -flowering plants: exist and reproduce at increasingly higher ploidy levels - -humans with this, rare and lethal nondisjunction: results in chromosome abnormalities, which is the failure of one or more chromosomes to fully separate monosomy: nondisjunction results in loss of single chromosome trisomy: chromosome is added Turner syndrome: monosomy that does not result in death or miscarriage, when females are missing X chromosome Down syndrome: excess genetic material on chromosome 21

deletion: section of chromosome is lost during cell division duplication: sections are duplicated, occurs when homologous chromosomes exchange unequal amounts of info during recombination or DNA is copied onto incorrect strand (Huntington’s) translocation: nonhomologous chromosomes exchange info within a cell, normal set of traits but can be infertile inversion: section of chromosome breaks off, becomes inverted, and reattaches to same chromosome - -not usually genetic abnormalities unless accompanied with duplication or deletion

cystic fibrosis- autosomal recessive, deletion of protein producing material on CFTR gene –inherited by having 2 parents as carriers of mutated gene huntingtons: degenerative disease, breaks down nerve cells in brain, presents later in life - -duplication of genetic material causing large amts of huntingtons protein - -autosomal dominant - -parents have 50% chance of passing it on sickle cell anemia: autosomal recessive • -beta globin substituted • -red blood cells sickle shape • -cells break easily, low blood counts as result muscular dystrophy: degeneration of skeletal muscle tissue • -mutation in gene that prevents proper production of dystrophin–builds and repairs muscle • -gene defect on X chromosome therefore X linked recessive PKU: gene defect leads to increased phenylalanine levels which is amino acid in proteins • -autosomal recessive • -mutation in PAH gene which prevents amino acid from breaking down Tay-Sachs: degenerative nerve disease, destroys brain and spinal cord cells • -autosomal recessive • -mutation in HEXA gene which makes enzymes that break down and remove toxins Albinism: lacks proper amt of melanin • -autosomal recessive • -others passed thru X chromosome • -mutation in TYR gene Polydactyly: extra fingers or toes • -mutation in GL13 gene • -autosomal recessive or dominant Hemophilia: X linked recessive, primarily in males –linked to deleted or defected gene that produces blood clotting protein Red green color blindness: X linked, mutation in genes that produce proteins in the retina to detect certain colors

• -can have no effect or be harmful • -some can cause variation in traits –DNA mutations in gametes are passed on genetic variation is more complex in eukaryotes that undergo sexual reproduction –asexually reproducing organisms make offspring by replicating exact copies of DNA from one parent, this limits genetic variation

also called recombination happens during meiosis source of genetic variation among eukaryotes is during prophase 1

bacteria and archaebacteria (protozoa and algae) exchange genetic info by the 3 methods below: • -which creates variation • -these below allow them to make new DNA sequences transduction: host bacterium is infected by a bacterial virus or phage, that absorbs genetic info from the host to its own genetic code transformation: bacterium takes up DNA from a source oustide the cell, this exogenous DNA is absorbed thru the membrane, must be in a state of competence for this (sufficiently permeable to receive info) conjugation: genetic exchange in bacteria that requires cell to cell contact - -plasmids are exchanged over a connection bw 2 diff bacteria - -plasmids are small extrachromosal DNA from within bacteria - –these plasmids replciate independently from the DNA in a chromosome - –conjugation begins when bacterium produces sex pilus - -portion of DNA is transferred thru pilus - -the genetic info transferred can recombine with the genetic info within that new cell (host)

division of genes during meiosis happens randomly and independently of gene division in other gametes therefore no 2 gametes will contain the exact same combo of genetic info and all combos of genetic info have an equal chance of occurring

genetic drift: changes to allele distribution within pop • -variation in gene frequency, accounts for random nature in which traits are passed on • -affects small pop • -exposed to natural disaster or disease nonrandom mating: probability of 2 members of a pop. will mate is not equal to others in pop. sexual selection (form of nonrandom mating): choose mates based on advantageous characteristics

gene flow: movement of alleles from one pop to another via migration • -can introduce new alleles and gene combos • -increases genetic diversity • -alters frequency of alleles

• pop large in size and no genetic drift • isolated pop., no immigration or emigration • no genetic mutations • mating is random • no natural selection

genotype: p2+2pq+q2=1 - p is dominant allele - q is recessive allele - p2: frequency of homozygous dominant q2: frequency of homozygous recessive 2pq: frequency of heterozygous sum of p and q must equal 1 p+q=1 : allele frequency in a pop. ==totals are divided by the total number of alleles

natural selection: members of a pop. best adapted to environment survive and reproduce (fitness) –favorable traits passed on 4 basic conditions for nat selection to occur: • -inherited variation • -overproduction of offspring • -fitness to environment • -differential reproduction differential reproduction: biologically fit animals alter gene pool of pop. so not all membranes reproduce at same rate Artificial selection: intentionally breed organisms with the same desirable traits thru selective breeding

intersexual reproduction: select mates based on visual cues

does not involve survival of fittest, is random alters alleles and traits in gene pool can happen due to humans, disease, or natural disasters bottleneck effect: survival is random, results in less genetic diversity, descendants of same small population and genetically similar founder effect: small pop. becomes isolated from large pop. thru migration –small pop has led genetic diversity

–evolution of one organism affects that of another –typically happens bw those that have close –interdependent ecological relationship also predator prey likely to evolve together competition drives evolution • -occurs when 2 species share niche (space and role) and compete for same limited resource • -one species will become extinct mutualism: both species benefit