Biology FINAL MATERIAL – Flashcards

1.) chemical carcinogens- chemical in cigarettes, chemicals in plastics, preservatives in foods, pesticides 2.) radiation exposure- UV radiation from sun (assoc. with skin cancer), radon exposure (radioactive gas created naturally by radioactive decay of uranium in certain rocks- if house is built on top of this sediment, radon can escape rock into basement- mostly a problem in very well insulated homes during winter months due to air inside house not exchanging with outside air- radon is 2nd leading cause of lung cancer after smoking), frequent x-ray exposure (primarily technicians), radiation release from nuclear power plants, nuclear weapons 3.) viruses- can be assoc. with several diff. cancers (HPV assoc. with cervical cancer, throat cancer, anal cancer, penile cancer, vaginal cancer- there is a vaccine for this!), Hepatitis can cause liver cancer, also some viruses assoc. with leukemias and lymphomas, ALL viruses must insert their own DNA or RNA into nucleic acids of cells they infect in order to replicate (host cell follows those instructions to make viral proteins and other components- a few viruses also have ability to affect genes controlling cell division in the host cell- THESE ARE THE VIRUSES ASSOC. WITH CANCER) 4.) genetics- no one can inherit cancer, but we can pass on MUTATIONS in genes that put offspring at a higher risk- only 1-5% of all cancers are thought to be related to genetics but where there is a relationship it is strong- if you inherit gene assoc. with breast cancer, chance of developing it is over 80% (12.5% for average woman) 5.) immune deficiencies- immune system can recognize and kill some cancer cells when it is working BUT immune system can be suppressed due to a variety of diseases (ex: AIDS), immunosuppressive drugs (taken deliberately to suppress immune system) to avoid transplant rejection OR to treat autoimmune diseases- these diseases involve immune system attacking your own tissues/organs, also- aging gradually suppresses immune system which is why more elderly ppl are diagnosed with cancer compared to younger generation 6.) diet- high saturated fat, low fiber (assoc. with breast, colon, rectal, and prostate cancer) 7.) alcohol- heavy consumption assoc. with liver, breast, mouth, and throat cancers 8.) hormones- estrogen/testosterone... assoc. with breast, prostate, ovarian, uterine cancers- low risk assoc. with birth control pills, also risk with hormone replacement therapy 9.) sedentary lifestyle- no exercise, assoc. with breast, prostate, lung, colon, endometrial cancers

1.) surgery- usually occurs first, surgical removal of cancerous tumors, surround tissue (to see if cancer cells are leaving tumor), and nearest lymph nodes (EXCEPTIONS: tumors in difficult to reach locations such as brain, or patients already severely immune compromised- in these cases, doctors will try to shrink tumors first w/ chemo and/or radiation) 2.) chemotherapy- there are drugs designed to kill cells in process of cell division (ex: some drugs interfere with synthesize of thymine during DNA replication before cell division- not replicated properly= can't divide properly) (ex: other drugs work to stop formation of spindle apparatus during mitosis) chemo is designed to be systematic (pass thru all systems of the body thru blood stream) so, it catches obvious cancer cells near tumor as well as cells far from tumor of origin- PROBLEM: chemo is not able to tell the difference between cancer cells and healthy cells in process of cell division. so, healthy cells are killed as well... systems containing cells that divide frequently will be impacted most... these include hair follicles, digestive system (chemo often assoc. with vomiting, lack of appetite, weight loss), bone marrow (white blood cells drop... immune system crash, and red blood cells drop... exhaustion/cold, and platelets drop... excessive bleeding), reproductive system 3.) radiation therapy- also designed to kill dividing cells, HIGH dose radiation directed over a very limited area of body (region of tumor and nearest lymph nodes), rest of body is protected as much as possible (this radiation would kill patients within a few days from acute radiation poisoning if directed over whole body), kills cells because it causes so many DNA mutations so fast that proof reading enzyme cant keep up during DNA replication, so cells die... common side effects are burns... radiation also causes fatigue and may cause minor damage to organs very close to site of original tumors (ex: breast cancer radiation can cause minor damage to lungs/heart) 4.) immunotherapy- still fairly new therapy, becoming part of conventional treatments, involves stimulating immune system to attack cancer cells beyond normal response

1.) INCOMPLETE DOMINANCE - heterozygous offspring show a phenotype which is intermediate between dominant and recessive phenotype (ex: intermediate between red and white is pink) - BLEND 2.) CODOMINANCE -both alleles are fully expressed- NO BLENDING of the two- both dominant 3.) MULTIPLE ALLELES -more than 2 choices for single- gene trait (ex: 3 alleles- blood types A, B, O- parent with type A and parent with type B can have child with type O 4.) GENE INTERACTIONS -some genes can interfere with or mask expression of other genes (ex: we all have multiple genes coding for skin color, hair color, eye color- but they all depend on one gene which codes for the production of MELANIN or pigment- if this gene is defective, no pigment is produced and offspring is ALBINO) (red eyes= albino) 5.) POLYGENIC TRAITS -these are traits controlled by more than one gene, so there is a greater range in diversity in this trait (ex: skin color- controlled by 3 different genes, homozygous recessive codes for LEAST amount of melanin produced so very fair/pale... homozygous dominant codes for GREATEST amount of melanin production so darkest skin tone... most ppl are a mix) 6.) ENVIRONMENTAL INFLUENCES -these can sometimes "over write" genetic instructions (ex: fair skin will tan with prolonged repeated sun exposure as a protective defense by skin cells- they are responding to UV rays and producing more melanin because it protects against damage from UV rays)

1.) X LINKED DISORDERS -these disorders are caused by recessive genes on x chromosome -FEMALES require recessive allele from BOTH PARENTS to be AFFECTED by the disease ( to have symptoms)... females have true homologous pair (xx)... a heterozygous female would be a healthy carrier -MALES have only one x, and y has different genes (so not true homologous pair)... one recessive allele cannot be "masked" by dominant allele because of y genes... so, JUST ONE recessive allele will cause son to be AFFECTED... NO healthy male carriers... typically, affected males have healthy parents but mom was a healthy carrier **BEWARE OF GENDER WHEN ANSWERING QUESTIONS... ANSWERS WILL ONLY EVER BE 50% OR 0% *** AN AFFECTED DAUGHTER WILL ALWAYS HAVE AN AFFECTED FATHER -EXAMPLES: some forms of color blindness, some forms of muscular dystrophy, some forms of hemophilia 2.) AUTOSOMAL RECESSIVE DISORDERS -autosomes are all chromosomes except x & y so we ALL have homologous pairs and males and females affected equally -to be affected, offspring have to receive recessive allele from BOTH PARENTS -heterozygous offspring will be healthy carriers -most affected offspring will have healthy carrier parents (shock to have an affected child) -EXAMPLES: cystic fibrosis, albinism, some forms of deafness *higher percentages of these in populations w/ low genetic diversity (geographically isolated OR culturally/religiously isolated... ex: Amish) 3.) AUTOSOMAL DOMINANT DISORDERS - disease is due to DOMINANT allele -NO healthy carriers of either gender -both homologous dominant and heterozygous are affected -only one gene is needed to get disease -with these disorders, 2 affected parents can produce healthy offspring (but it is unlikely- 25% chance) -because there are no healthy carriers, these diseases are less common than recessive disorders --> usually they are either FATAL BUT ONLY LATER IN LIFE (after having kids) (ex: huntington's disease, early onset alzheimer's) OR ---> DISEASE ITSELF IS RELATIVELY MILD AND DOES NOT INTERFERE W/REPRODUCTION (ex: dwarfism, polydactyly- extra fingers/toes, achoo syndrome) ***EXCEPTION: progeria... not inherited but is an autosomal dominant disorder... occurs due to random mutation in the gametes in one of the parents... these ppl show rapid aging although they retain small stature... usually die of age related diseases in their teens

during the production of eggs and sperm (gametes), the copies of each gene from homologous chromosomes separate so that each gamete receives one copy... each gamete receives a random assortment of recessive and dominant alleles for each trait (alleles= diff. versions of same gene) (ex: different alleles for eye color- different choices) *DOMINANT allele only requires 1 copy of that allele to be inherited for that trait to be PHYSICALLY EXPRESSED * RECESSIVE allele requires 2 copies (inherited from BOTH parents) in order to be PHYSICALLY EXPRESSED ** if organism receives dominant and recessive allele- ONLY DOMINANT will be physically expressed, but the organism is a carrier for recessive allele and can pass it on to offspring

this is how information passes from DNA to RNA to ribosomes to make proper proteins RECALL: 3 DNA bases correspond to a single amino acid and this code is universal for all species on Earth 2 PARTS: 1.) Transcription 2.) Translation

*in eukaryotes, this occurs in nucleus and involves both DNA and RNA 1.) those portions of the DNA coding for proteins needed by that SPECIFIC CELL TYPE unzip (bases separate) 2.) RNA "reads" the DNA portion and forms complementary strand w/ the MATCHING base... RNA has 3 of DNA's bases (A, C, G), but not T (Thymine)- instead, RNA has U (Uracil) which pairs w/Adenine 3.) once DNA has been transcribed, it re-seals 4.) RNA is edited, and some "junk" regions are spliced out (our DNA contains a lot of "junk" DNA- most of it we don't know the purpose of, or even it if has one, and some we think is involved w/ gene regulation- which genes are turned on or off) 5.) RNA (once complete) leaves nucleus for cytoplasm

1.) mRNA heads to ribosomes where proteins are assembled 2.) first 3 letters of mRNA is the "start" codon, which cooresponds to an animo acid that starts all proteins. the tRNA molecule with the anticodon (complementary to base pairs to codon) brings first amino acid to start protein EX: anti-codon to AUG is UAC (start amino acid) 3.) after the "start" codon, a variety of different codons will be read (dozens to thousands depending on function of protein). tRNA molecule will continue to assemble protein 4.) protein synthesis continues until a "stop" codon is read... this does not correspond to an amino acid... it indicates the protein is complete and it is sent off to wherever it is needed in the cell

1.) mRNA -messenger RNA -this RNA transcribes the DNA 2.) rRNA -ribosomal RNA -this RNA makes up the structure of the ribosomes (along with protein) 3.) tRNA -transfer RNA -this RNA brings proper amino acid to growing protein

-with exception of "start" amino acid, all other amino acids have more than one codon that will correspond to them (range from 2-6)... this is how a base substitution mutation can correspond to same exact amino acid... this is a silent mutation -silent mutations are often not detrimental to cell, but can be under certain circumstances... amino acids have "preferred" codons (ones most frequently used to code for them)---> there are more tRNA molecules with anti-codon to this available to bring amino acid to growing protein.... THEREFORE, less common codons have fewer tRNAs w/ anti-codon available... this means protein is not assembled as quickly (may not be a problem but could be if protein is needed in a hurry/during an emergency_)

change in the nucleotide sequence of DNA

1.) SOMATIC MUTATIONS -those that occur in somatic (body) cells -during mitosis -not passed on to person's children -CML (leukemia) = example 2.) GERM LINE MUTATIONS -those that occur in the cells of the germ line (the specialized cells that give rise to gametes) -passes mutation on

1.) SILENT MUTATION -does not usually affect protein function -usually result in genetic diversity not expressed as phenotypic differences 2.) LOSS OF FUNCTION MUTATION -affects protein function -almost always recessive inheritance 3.) GAIN OF FUNCTION MUTATION -leads to a protein with an altered function -common in cancer -dominant inheritance 4.) CONDITIONAL MUTATION -affects phenotype only under certain permissive conditions and not detectable under other permissive conditions -many are temp. sensitive -rabbits---> coat color gene, dark fur only in cool environment 5.) REVERSION MUTATION -mutated 2nd time so DNA reverts to original sequence -causes phenotype to go back to wild type

*POINT MUTATION: addition or subtraction of a single nucleotide, or the substitution of one nucleotide base for another 2 KINDS OF BASE SUBSTITUTION 1.) TRANSITION -substitution of one purine for the other purine, or one pyrimidine for the other 2.) TRANSVERSION - substitution of a purine for a pyrimidine, or vice versa

-base substitutions that change the genetic code such that one amino acid substitutes for another -ex: sickle-cell disease -may result in defective protein, but often no effect on protein's function -in some cases, a gain of function missense mutation occurs- TP53 gene (gained cancer causing function)

-involves a base substitute that causes a stop codon (for translation) to form somewhere in the mRNA -results in shortened protein -ex: thalassemia mutation -usually proteins don't function

-one or two nucleotides may be inserted into, or deleted from, a sequence of DNA -alter the reading frame in which the 3-base codons are read during translation -usually nonfunctional proteins

1.) DELETION -occurs by the removal of part of the genetic material and can happen if chromosome breaks @ 2 points and rejoins, leaving out DNA between breaks 2.) DUPLICATION -occurs by homologous chromosomes breaking at different positions and then reconnect to the wrong partners- one chromosome gets deleted and other has 2 copies 3.) INVERSION -can also result from breaking and rejoining of a chromosome and can occur if a segment of DNA becomes "flipped," so it runs it opposite direction from original orientation 4.) TRANSLOCATION -when a segment of a chromosome breaks off and becomes attached to a different chromosome

* viruses called retroviruses can insert their genetic material into host cell's genome ---if one happens within a gene, it can cause a loss of function mutation in that gene *another form of DNA- transposon or transposable ---can insert itself into genes and cause mutations ---sequence of genomic DNA is sometimes carried along w/the transposon DNA when it moves, this results in gene DUPLICATION

SPONTANEOUS -permanent changes in the genetic material that occur without any outside influence -ex: movement of transposons ***may occur by several mechanisms: ---the 4 nucelotide bases of DNA can have different structures, leading to mistakes during replication ---bases in DNA may change because of chemical reaction ---DNA polymerase can make errors in replication ---meiosis is not perfect INDUCED -occur when some agent from outside the cell (a mutagen) causes a permanent change in DNA ***certain chemicals & radiation can cause mutations: ---some chemicals can alter nucleotide bases ---some can add groups to the bases ---radiation damages the genetic material

-plants and animals make some -human made mutagens---> nitrates (used to preserve meats) -radiation can also be human made or natural (mutations in survivors of atomic bomb, UV radiation from sun affects Thymine)

-mutation "hot spots" are often located where cytosines have been methylated -thymine as product---> mismatched pair AT= mutation

-provide genetic diversity (advantage if environment changes... BENEFIT) -gene duplication (can lead to gain of function for a gene... BENEFIT) -some can kill in early stages (COST) -some can cause uncontrolled cell division (cancer...COST)

1.) MONTREAL PROTOCOL -international environment agreement -united nations -bans chloroflurocarbons and other substances that cause depletion of ozone layer -decrease skin cancer 2.) BANS ON CIGARETTE SMOKING -cancer causing due to increased exposure of somatic cells in the lungs and throat of carinogens

-birds with different beaks (thick, short, thin, long) -diversity of structure of birds... thought that one species may have been taken and modified for different ends -most explanations for evolutionary change have focused on the effects of gene mutations on the structural proteins that make up organisms -break structure is affected by changes in the timing of protein production as well as he amount of protein made -realization that major evolutionary change can be the result of subtle changes in spatial, temporal, and quantitative distribution of signaling molecules (BMP4 and calmodulin) and changes in the noncoding regions of the DNA that control gene expression

-GENETIC SWITCHES control how the toolkit is used... developmental modules based on a common set of genetic instructions can evolve separately -these switches include gene prompters and the transcription factors that bind to promoters, as well as the enhancers and repressors that can modulate the interactions of transcription factors and promoters -the signals from these determine where, when, and to what extent genes are turned on and off -multiple switches control each gene, creating different expression patterns in different locations... in this way elements of the genetic toolkit can be involved in multiple developmental processes and still allow individual modules to develop and evolve independently -gene switches integrate positional informational in the developing embryo and play key roles in determining the developmental pathways of different modules EX: Drosophila---> members of insect group Diptera, which means "two wings"- that is, they have single pair of wings opposed to 2 pairs of wings---> if ubx is inactivated by mutation, a 2nd pair of wings forms.... thus some major morphological differences among groups of animals can result from relatively small changes in gene expression **segments differentiate under control of genetic swtiches -the binding of a single protein, UBX, determines whether a thoracic segment produces full wings

**because of modularity, transcription factors and other genes of the toolkit can regulate the expression of structural genes in different amounts, at different times, and in different locations

1.) HETEROMETRY ***different measure -Galapagos finches is an example: studies show that beak size and shape in these birds is influenced by the level of expression (i.e. the amount of protein produced) of two regulatory genes -the relative amounts of these proteins determines whether an individual's beak is long, thin, and narrow or short, thick, and deep 2.) HETEROCHRONY ***different time -the evolution of a giraffe's neck is an example (due to bone growth) -bone growth in mammals is the result of the proliferation of cartilage producing cells called chondrocytes -the genetic signal that stops bone growth is delayed in giraffes, so the vertebrae of their necks grows longer.. thus, the evolution of longer necks resulted from CHANGES IN THE TIMING of expression of the genes that control bone formation 3.) HETEROTOPY ***different place -spatial differences in the expression of a developmental gene -different development of feet in ducks and chickens is an example -ducks have webbed feet and chickens do not (a major difference in the adaptation of these species) -webbing is initial present in the chicken embryo but undergoes apoptosis this is stimulated by the protein BMP4 -in ducks, another protein, GREMLIN, binds to BMP4 and inhibits it, preventing apoptosis and resulting in webbed feet

-vertical columns exhibit considerable variation across the groups of vertebrae -most mammals have 7 cervical vartebrae.... some have many more however -these differences result from the spatial patterns of Hox gene expression that govern the transitions from one region to another -over evolutionary time, genetic changes that expanded or contracted the expression domains of the Hox genes resulted in changes in the characteristic numbers of different vertebrae

-sometimes a major developmental change is due to an alteration in the regulatory molecule itself rather than a change in where, when, or how much it is expressed -this is called HETEROTYPY ("different type") -ex: a gene that controls the # of legs in arthropods -ex: gene responsible for kernals of domestic corn (Tga1)---when gene is inserted into kernals there are hard glumes formed over the kernals and therefore less edible kernals

-reptiles---> sex determined by temperature---> temp at which the eggs are incubated -temps can vary among species -red eared slider turtle= high temp makes female, low male -in animals with temperature controlled sex determination... the enzyme aromatase converts testosterone to estrogen... applying estrogen to eggs= female produced -temp can also affect growth rate and adult body size... temp can have affect on reproductive success also

the ability of an organism to modify its development in response to environmental conditions it means that a single genotype has the capacity to produce two or more different phenotypes

-in some species with short life spans, an individual may encounter only one of several distinct but predictable seasonal environments -developmental plasticity allows such individuals to develop the phenotype that enhances their survival in the environment they will encounter as adults -ex: moth, which produces two generations each year... those that hatch in spring eat catkins... those that hatch in summer eat mature leaves... different body resemblances too (camo) -their different larval diets (the different biochemistry of the molecules in oak catkins vs. mature oak leaves) trigger developmental changes that result in two different phenotypes, each of which is camouflage in the respective environments -phenotypic plasticity results in LOWER PREDATION and INCREASED EVOLUTIONARY FITNESS

-one source of environmental information is sunlight, which provides predictive information about seasonal changes -many insects use day length (from sunlight) to enter or exit a period of developmental or reproductive arrest called DIAPAUSE, which enables them to better survive harsh conditions -ex: deer, elk, moose use day length to time development and dropping of antlers -ex: many organisms use day length to optimize the timing of reproductive migration (how many plants initiate flowering also) -light is an environmental signal in plant development... dim light makes plants grow tall and spindly... adaptive to reach a patch of brighter light up higher.... a plant in bright light is compact and bushy because it does not need to grow tall for light, but instead can put more energy into producing leaves

1.) nearly all evolutionary innovations are modifications of previously existing structures 2.) the basic set of regulatory genes that control development is broadly conserved, changing only slowly over the course of evolution

the wings of pterosaurs, birds, and bats are all modified forelimbs and are constructed from the same skeletal components... these components, however, have different forms in different groups, supporting the independent evolution of wings in each group

-the existence of highly conserved developmental genes makes it likely that similar traits will evolve repeatedly, especially among closely related species.. this process is known as PARALLEL EVOLUTION -good example: small fish, the three-spined stickleback... developmental gene Pitx1 encodes for plates and spines... gene is active in these marine fish but mutated and inactive in freshwater populations... supports parallel evolution