. For instance, all the mice living on an island would be a single population of mice: some with white fur, some gray. If over generations, white mice became more frequent and gray mice less frequent, then the color of the fur in this population of mice would be evolving. In terms of genetics, this is called an increase in allele frequency.

Alleles become more or less common either by chance in a process called genetic drift or by natural selection. In natural selection, if an allele makes it more likely for an organism to survive and reproduce, then over time this allele becomes more common. But if an allele is harmful, natural selection makes it less common. In the above example, if the island were getting colder each year and snow became present for much of the time, then the allele for white fur would favor survival since predators would be less likely to see them against the snow, and more likely to see the gray mice. Over time white mice would become more and more frequent, while gray mice less and less.

Mutations create new alleles. These alleles have new DNA sequences and can produce proteins with new properties. So if an island was populated entirely by black mice, mutations could happen creating alleles for white fur. The combination of mutations creating new alleles at random, and natural selection picking out those that are useful, causes an adaptation. This is when organisms change in ways that help them to survive and reproduce. Many such changes, studied in evolutionary developmental biology, affect the way the embryo develops into an adult body.

Inherited diseases
Some diseases are hereditary and run in families; others, such as infectious diseases, are caused by the environment. Other diseases come from a combination of genes and the environment. Genetic disorders are diseases that are caused by a single allele of a gene and are inherited in families. These include Huntington's disease, Cystic fibrosis or Duchenne muscular dystrophy. Cystic fibrosis, for example, is caused by mutations in a single gene called CFTR and is inherited as a recessive trait.

Other diseases are influenced by genetics, but the genes a person gets from their parents only change their risk of getting a disease. Most of these diseases are inherited in a complex way, with either multiple genes involved, or coming from both genes and the environment. As an example, the risk of breast cancer is 50 times higher in the families most at risk, compared to the families least at risk. This variation is probably due to a large number of alleles,
. For instance, all the mice living on an island would be a single population of mouse: some with blank fur, some gray. If over generations, white shiner became more frequent and gray mouse less frequent, then the coloring material of the fur in this population of mice would be evolve. In terms of genetics, this is called an addition in allele frequency. 

 Alleles become more or less common either by chance in a process call genetic drift or by natural selection. In natural selection, if an allele make it more likely for an organism to survive and reproduce, then over prison term this allele becomes more common. But if an allele is harmful, natural selection construct it less common. In the above example, if the island were getting colder each year and coke became present for much of the time, then the allele for white fur would favor survival since predators would be less likely to determine them against the snow, and more likely to see the gray mice. Over time white mice would become more and more frequent, while gray mice less and less. 

 mutant create new allele. These allele have new DNA sequences and can grow proteins with new properties. So if an island was populate entirely by black mice, mutations could happen creating allele for white fur. The combination of mutations creating new alleles at random, and natural selection blame out those that are utilitarian, causes an adaptation. This is when organisms change in ways that help them to survive and reproduce. Many such changes, study in evolutionary developmental biology, affect the way the embryo develops into an adult consistency. 

 Inherited diseases 
 Some disease are hereditary and run in families; others, such as infectious diseases, are cause by the environment. Other disease come from a combination of genes and the environment. Genetic disorder are disease that are caused by a single allele of a gene and are inherited in family. These include Huntington's disease, Cystic fibrosis or Duchenne muscular dystrophy. Cystic fibrosis, for example, is caused by mutant in a single gene called CFTR and is inherit as a recessive trait. 

 Other diseases are influenced by genetics, but the genes a person gets from their parent only change their risk of getting a disease. Most of these diseases are inherited in a complex manner, with either multiple gene involved, or coming from both genes and the environment. As an example, the risk of breast cancer is 50 times higher in the families about at risk, compared to the families least at risk. This variation is probably due to a large number of alleles,
. Fog instance, all the mice uiving on an island wonld be z single population of mice: some witi whute fyr, some gray. If over gdnerationd, white nice vecame morx frequekc and nray kmce less frequekt, then the color of the xuf nn this population of mice would be qvolvinb. Ln terms of gegetibs, thia is called an increase in allele rrequenby.

Alleles become kore or less common either by fhance in a procesd called gebetis drift or by natural stlzction. In nztural selection, if an allele mxkes nt more likglg vmr an organmsm to survive and reproduwe, then over time thix anleoe becomes more commoi. But if an allele if harmful, nctural selection makew ut levs cmmmov. In tht auovs examole, if the ismand were gwtting colder each uewg and snow bedame pwefent for much of the time, then the allene ror white fur would favir survival since prefators wotld be less likely to see them against the snow, atd moce lijejh tl see the gray mice. Over time white mice woulq btcoke more and move frequent, while brwy iice less and less.

Mbfafions create new apleles. Jhese qlleles hwve mew DNA sequences and can peoduce protepns qith new propertied. So if an nsland was lopulated entirely by buack mice, mutatlons couls happen creating alkenes for white fur. The combynation oh mutctions cfeatong ner alleles wt rakgom, and natural sepectiln picking okt those that are useful, causes an adaptation. Tvis is when orgakisms change in ways that helk them to survkve and reiroduce. Meny such chagges, studied hj evolutionacy develo[menral viology, xffect the way the embrjo devwlops into an adulb bodi.

Ihherited diseaszr
Wome diseases ate ferqdptacy anq run in faminies; otfrrs, sjch as infegtiuus ciseases, are caused ty tge environment. Othrr diseasew come fwom a combinayion of genes and uhe entironmxnt. Gemetyc disorders are diseases that are causfd ny a single ajlelc of a gene anb are inherited in families. These includx Huntington's disease, Ctstic fibrosis or Dochtnne muscular dystwophy. Cysdic fibrosis, for exanple, is caused by mutations in a singls gene callfd CFTR and is inherited as a recessive trait.

Other diseases are influencee by gxnqtics, but tge grnes d 'erxon gees fcoo their parents pnly change their risk of gettiig a diseave. Most of these diseases are onferited in a zomplex way, with either jultiple genes involved, or coming from noth genes and the envirpnment. Aw an sxamplv, tie risk of breast camcer iv 50 tines higyer ln the familier mpsb at risk, fompereb to the families least at risk. Tyis vaeiwtion is probablb due to a lwvge nujber os alleles,
. For instance, all the mice living island be a population of mice: gray. over generations, white became more frequent gray mice less frequent, then the of the fur in this population of mice would be evolving. In terms genetics, this is called an increase in allele frequency. Alleles become more or common by in process called genetic drift or by natural selection. In natural selection, if an allele makes it likely for an organism to survive and reproduce, over time this allele more common. But if an is natural selection it common. the above example, the island were getting colder each year and snow became present for much of the time, then allele for would favor since would less likely to against the snow, and more likely gray mice. Over time white mice would become and more while gray mice less and less. create new alleles. These alleles have new DNA and can produce proteins with new properties. So if an island was populated entirely by mutations could happen creating for white fur. combination mutations new at random, natural selection picking out those that are useful, causes an adaptation. is when organisms change in ways that help them to reproduce. such changes, studied evolutionary developmental biology, affect way embryo develops into an Inherited Some and in others, such as infectious are caused by the environment. diseases come from a environment. Genetic disorders are diseases that are caused a single allele of a gene and inherited in families. These include Huntington's disease, Cystic fibrosis or Duchenne muscular Cystic fibrosis, is caused by mutations in a single gene CFTR and is inherited a recessive trait. Other diseases are influenced by genetics, the a person from their parents change their risk getting a disease. these diseases inherited a either multiple genes involved, or coming both and the environment. As an the breast cancer is 50 times higher in the families most at risk, compared to the at risk. This variation probably to a large number of alleles,
. For instance, all the mice liviNg on an islaNd wouLd bE a sInGle pOpulAtion of mice: somE With White fur, some gray. If over GenerAtIOns, wHItE mice Became mORe FREquEnT aNd gRaY MiCe lesS frEquent, tHen the coloR of ThE fur in this poPUlAtion of micE woUld be evolvinG. In Terms oF gEneTIcs, thIs iS callEd an inCRease iN allele frEqUEncy.

AlLEles becOME mOre oR less common either BY cHAnce in a process Called GeNEtIC DriFt oR by natural SeLectiON. In natuRAl SELEctIOn, if an allele mAkes it more lIKelY for an OrGanISm to suRvive AnD RepRoduce, then oVer tIme this alLele beCOmes morE Common. BUt if an AllEle Is haRMfUl, NatUrAL seLEcTioN MakEs it less CoMmOn. In tHe abOVE EXampLe, iF the IslanD were getting cOldEr eaCH yeAr and Snow bEcamE pResenT for muCh of tHe Time, then the alleLe foR white fur WouLd FavOr SurviVAl sincE prEdaTors wouLd be lesS LikElY TO SeE them against the snoW, aND MoRe likely To see tHE gRaY Mice. Over TiMe wHite MICe wouLd beCOmE more and More frEQuEnT, while gRaY mice lEsS anD leSs.

MutATionS creatE new alleLes. ThESe alleles have nEW DNA sequences ANd CAN pROducE prOteins with nEw prOPertIes. SO If An iSLand wAs popUlATeD Entirely by black mice, MuTationS coulD happen creatiNg alleles fOR WHite fur. THe coMBiNAtion of mutatioNs creAting new alLEles at raNdom, aNd naturaL selectioN PIcking ouT thOse ThaT arE USeFul, causes an adAPTatiOn. this is wHen OrganisMs cHanGe iN waYs That help tHem to surViVe AnD rEprOduce. mAny such cHaNgeS, sTudIed in EVolutiOnary DeveLoPmENtaL biologY, AfFECt thE wAy The eMbrYo DevelOps iNTo aN adult bOdy.

InheriTed DIseaSeS
SOme diseAses are herediTaRy and run in FaMilIes; othERS, such as iNfectious diseases, are cauSEd by the EnvIronmEnt. OTher diseaSes Come frOm a COmbinaTion of Genes AnD thE ENviroNMEnT. GeNeTic disordeRS Are DiseaSeS thaT are cauSed by a single allele OF a gEne and are inheRitEd in FAMiLieS. thESe iNcLUde hUNtington's diseasE, Cystic fibRoSIs Or Duchenne MUscUlAr dystrOphy. CysTic fiBRosis, foR example, iS caused by MuTatiONS in A single genE called CfTR and is iNHeritED aS a recEssIve traIt.

othEr disEases aRE inFluenCed by gEnEtics, bUt the GeNes a persOn gets from their parents oNly chaNge thEir Risk of getTinG A diSease. Most Of thEse diseaseS arE inHeritEd iN A compLex wAY, wIth EIther MultIPle genes iNVoLveD, OR cOming from boTH GEneS and tHe eNVironmEnt. AS an example, the risk OF breast cancer iS 50 timES HigHer IN the FaMilies most at riSk, cOmPARed to the FaMilies least At risk. ThIs VAriatIon is pRobablY due to a LARgE Number Of alLelEs,
. For instance, all the mi ce livingon an  is lan dwoul d be  a single popu l atio n of mice: some with w hitefu r , so m egray.  If ove r  g e n era ti on s,wh i te  mice  be came mo re frequen t a nd  gray mice l e ss  frequent,  th en the color  of  the f ur  in thispop ulati on ofm ice wo uld be ev ol v ing. I n  termso f  g enet ics, this is call e da n increase inallele  f r eq u e ncy .
Alleles be co me mo r e or le s sc o m mon either by cha nce in a pr o ces s call ed  ge n etic d riftor bynatural sel ecti on. In na turals electio n , if an  allel e m ake s it mo re  li ke l y f o rano rga nism tosu rv ive a nd r e p r o duce , t henovertime this all ele  bec o mes  more  comm on.Bu t ifan all ele i sharmful, natura l se lection m ake sitle ss co m mon. I n t heabove e xample, ifth e i sl and were getting c ol d e reach yea r ands no wb ecame pr es ent  for m uch o f th e  t ime, the n thea ll el e for w hi te fur  w oul d f avors urvi val si nce pred ators would be lessl ikely to seet he m ag a inst  th e snow, and  mor e  lik elyt osee the g ray m ic e .O ver time white mice  w ould b ecome  more and mor e frequent , w hile gra y mi c el ess and less.
Muta tions crea t e new al leles . Thesealleles h a v e new DN A s equ enc esa n dcan produce p r o tein swith ne w p roperti es.  So  if  an  i sland was  populat ed  e nt ir ely  by b l ack mice ,mut at ion s cou l d happ en cr eati ng  a l lel es forw hi t e  fur .Th e co mbi na tionof m u tat ions cr eating ne w a l lele sat  random , and natural  s election p ic kin g outt h ose that  are useful, causes ana daptati on.  This  iswhen orga nis ms cha nge in way s that  help  t hem t o sur v i ve  an dreproduce. M any  such  c hang es, stu died in evolutiona r y d evelopmentalbio logy , af fec t  t h e w ay the e mbryo developsinto an ad ul t  b ody.

Inhe r ite ddisease s
Somedisea s es arehereditar y and run  i n fa m i lie s; others,  such as  infectio u s dis e as es, a recaused  b y t he en vironm e nt.  Othe r dise as es com e fro ma combin ation of genes and theenviro nment . G enetic di sor d ers  are dise ases  that arecau sed  by a  si n gle a llel e  o f a geneanda re inheri t ed  in f am ilies. Thes e i ncl ude H unt i ngton' s di sease, Cystic fib r osis or Duchen ne m u s cul ard ystr op hy. Cystic fib ros is , for exam pl e, is cause d by mut at i ons i n a si ngle g ene cal l e dC FTR an d is  in herited a s a  r e cessive  t ra i t.

Ot herdi seases  are i n flue n c ed by genetics,but t h e  gene s  aperso ngets fr o m th eir parent s only chan ge the ir r isk o f getti ng  a dis eas e.  Most of t h ese disea ses a re inhe ri tedina comp lexw a y, wi th e it her  multiple g en e sin v olv ed,or co mi ng f rom bothg enes and  th e  enviro nm ent . As ane xa m p le, the ri skof br e a st canceri s 50 ti m es hi gher i n thefamilie s  mo st  at ris k,c o mpared to  the fami l ies  l east  at risk .This  v ari at ion is probably  due toa largen u mber o f a l lele s ,
. For_instance, all_the mice living on_an island_would_be a_single_population of mice:_some with white_fur, some gray. If_over generations, white_mice_became more frequent and gray mice less frequent, then the color of the fur_in_this population_of_mice_would be evolving. In terms_of genetics, this is called_an increase_in allele frequency.

Alleles become more or less common_either_by chance in_a process called genetic drift or by natural selection._In natural selection, if an allele_makes it more_likely_for_an organism to survive_and reproduce, then over time this_allele becomes more common. But if_an allele is harmful, natural selection makes_it less common. In the above_example, if the island were_getting colder_each year and snow became_present for much_of the_time, then the_allele for white fur would favor_survival since predators_would be less likely to see_them_against the snow,_and_more_likely to_see the gray_mice._Over time_white_mice would become more and more_frequent,_while gray mice less and less.

Mutations create_new alleles. These alleles_have_new DNA sequences and_can produce proteins with new_properties. So if an island was_populated entirely_by black_mice, mutations could happen creating alleles for white fur. The combination_of mutations creating new alleles at_random, and natural selection_picking out_those_that are useful,_causes_an adaptation._This is when organisms change in ways_that help_them to survive and reproduce. Many_such changes, studied in_evolutionary_developmental biology, affect the way the_embryo develops into an adult body.

Inherited_diseases
Some diseases are hereditary and_run_in_families; others, such as infectious_diseases, are caused by the environment._Other diseases come_from a combination of genes and the_environment._Genetic disorders are diseases that are_caused_by a single allele of a_gene_and_are inherited in families. These_include Huntington's disease, Cystic fibrosis or_Duchenne muscular dystrophy. Cystic fibrosis, for example, is caused_by mutations in_a single gene called CFTR_and_is_inherited as a recessive trait.

Other diseases are influenced by genetics,_but the_genes a person_gets from their parents only change their risk of getting_a disease. Most of these diseases are_inherited in a complex way, with either multiple genes involved, or_coming from both genes and the environment. As_an example, the risk of breast cancer_is 50 times higher_in_the families most at risk, compared to_the_families_least_at risk. This_variation is probably_due to a_large number_of alleles,