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63 Cards in this Set
- Front
- Back
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chromosone gene allele gene locus |
alleles differ by one or a few bases |
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types of gene mutation |
silent: gives same protein missense: give diff protein nonsense: gives no protein |
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cause of sickle cell anemia |
base substitution mutation causes missense: you get valine (GUG) instead of glutamic acid (GAG) on 6th codon position in hemoglobin polypeptide makes hemoglobin form insoluble fibrous strands less able to take u oxygen harder for RBC to go through vessels |
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genome def |
The genome is the totality of genetic information of a cell, organism or organelle 46 chromosomes ~3 billion base pairs ~21,000 genes |
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comparing human geen to other |
human= 21k rice = 30k chicken = 17k |
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prokaryotic dna |
genetic material free in cytoplasm in nucleoid region 1 large single chromosone of circular DNA DNA is naked (histone free) most prokaryotes have plasmids- small circular DNA molecules that contain a few genes and are capable of self-replication |
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plasmid conjugation not important |
This exchange of genetic material allows bacteria to evolve new features within a generation |
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autoradiography |
John Cairn measures DNA molecule length E.coli cultured in medium with ribonucleotide thymidine labelled with 3H hydrogen Gently lysed E. coli leaving intact DNA and put on slide Put in photograph emulsion and stored in dark for two months Particles made from heavy thymidine show as dark spots length seen as 1mm |
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eukaryotic DNA |
linear wrapped around 8 histone proteins and a h1 histone making nucleosomes |
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Diferences between chromosomes |
diferent chromosomesthat carry diferent genes differ in where the centro mere is length eukaryotes have at least two (humans have 23) |
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Homologous chromosomes |
Homologous chromosomes carry the same sequence ogenes but not necessarily the same alleles of those genes. |
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Comparison of genome size in T2 phage (virus), Escherichiacoli, Homo sapiens, Drosophila melanogaster (fly), andParis japonica (tree). |
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haploid v diploid nuclei |
A haploid nucleus has one chromosome o each type eg gametes have haploid nuclei 23 chromosomes A diploid nucleus has two chromosomes of each type eg zygote made from fusing gametes has 46 chromosomes |
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# of chromosomes |
characteristic feature of members of a species interbreeding members of species have same # |
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Comparison of diploid chromosome numbers of Parascaris equorum (worm), Oryza sativa(rice), Homo sapiens, Pan troglodytes (chimp),Canis familiaris (dog) |
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sex determination |
Sex is determined by sex chromosomes and others are autosomes X is big with important stuff Y is small with SRY gene to develop boy parts XX = female XY =male all get X from mom egg, sex determined by X or Y of dad sperm |
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karyogram v karyotype |
Karyotype is a property of a cell—the number and type of chromosomes present in the nucleus, not a photograph or diagram of them A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length. |
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using karyograms |
female = XX male = XY down syndrome = 3 copies of chromosome 21 |
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sexual life cycle of eukaryotes |
The halving of the chromosome number during meiosis allows a sexuallife cycle with fusion of gametes (fertilization doubles chromosome number) |
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chromatid v chromosomes |
The two DNA molecules formed by DNA replication prior to cell division are considered to be sister chromatids until the splitting of the centromere at the start of anaphase. After this, they are individual chromosomes. |
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bivalent formation (synapsis) |
occurs in prophase I homologous pairs are held together at chiasmata |
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meiosis I |
1 diploid cell with 46 (2n) chromosomes ie 23 bivalent homologous pair --> 2 haploid cells with 23 (n) chromosomes each with 2 sister chromatid |
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meiosis II |
2 haploid cells with 23 (n) chromosomes each with 2 sister chromatid ----> 4 haploid cells with 23 (n) chromosomes each with 1 chromatid |
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overview of meiosis |
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meiosis and genetic variation |
random Orientation of pairs of homologous chromosomes prior toseparation (in anaphase) crossover: produces new combinations of alleleson the chromosomes of the haploid cells.s decouple linked combinations of alleles and therefore lead to independent assortment |
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reduction division |
meiosis I diploid to haploid |
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Obtaining cells from a fetus |
chorionic villus sampling sampling tool enters vagina and obtains sample from chorion 2% amniocentesis -needle through mom abdomen guided by ultrasound -withdraw sample of amniotic fluid 1% miscarriage |
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Sexualité reproduction and genetic variation |
-Fusion o gametes rom diferent parents promotesgenetic variation. -sexual reproduction> genetic variation> better chance of survival cuz evolution |
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Non-disjunction can cause Down syndrome and other chromosome abnormalities. |
non disjunction = homologous pairs dont separate during anaphase causes one gamete with extra one with less older mom=higher chance eg down syndrome = trisomy 21 Klineelters syndrome=XXY turners syndrom = X |
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chromosome replication |
interphase (s phase) before meiosis each chromosome has 2 chromatids |
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cross over |
the exchange of DNA material betweennon-sister homologous chromatids connections via chiasmata random spot can occur multiple times and between different chromatids within the same homologous pair |
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chiasmata diagram |
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gel electrophoresis |
separates according to size becasue DNA is negatively charged |
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DNA profling |
FOR: paternity and forensic investigations -sample obtained -sequnces that vary a lot are amplified using PCR -copid DNA is split into ragments using restriction endonucleases -ragments are separated using gel electrophoresis -pattern of bands = DNA profile |
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Genetic modifcation what pro con |
gene transer between species becasue of universal genetic code eg daffodil gene to make yellow rice grow more, more nutritious, cheaper, in hard conditions, lengthen shelf life adverse health reactions, unknown effects, limit biodiversity, unlzbeled |
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Bt corn (crops) and butterflies |
gen modified to include insecticide gene to kll cor borers killing butterflies when air borne Bt pollen goes in milkweeds sometimes |
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cloning animal plant human |
reproducing asexually makes genetic clones ANIMAL methods: binary fission (split), budidng, fragmentation, parthenogenesis (unferstilized egg makes zygote) PLANT: vegetative propagation (plant the thing and it'll make clones eg cabbage), spores (moss, ferns) HUMAN: identical twins (monozygotic) when zygote splits |
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somatic nuclear transfer |
method by which cloned embryos can be produced using differentiated adult cells
Eg Dolly sheep |
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gene transfer to bacteria |
reverse transcriptase restriction endonuclease at recognition sites of DNA and plasmid DNA ligase introduce back in bacteria (transformation) |
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mendellian genetics |
Law of Segregation: When gametes form, alleles are separated so that each gamete carries only one allele for each gene (cuz of meiosis) Law of Independent Assortment: The segregation of alleles for one gene occurs independently to that of any other gene (except with linked-Thomas Morgan) Principle of Dominance: Recessive alleles will be masked by dominant alleles (codominant is a thing) |
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genetics definitions geno v pheno zygosity dominance: letters carrier Gene loci Allele |
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blood groups geno and pheno |
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constructing punnet grids |
letters represent alleles know genotype and phenotype of parents genotype of parental gametes on grid (mom top, dad side) |
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codominance |
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autosomal genetic diseases |
many- recessive alleles (cystic fibrosis) carriers are heterozygous and dont express some dominant (Huntingtons) or codominant (sicklecell anemia > hetero =milder symptoms)
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huntingtons and cystic fibrosis detail |
Cystic Fibrosis: chromosome 7 recessive allele super thick and sticky mucus in lungs and pancreatic duct Huntingtons chromosome 4 dominant allele gene makes protein named huntingtin which misfolds dementia, spasms |
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sex linked genetic diseases |
only females can be carriers eg Red-green colour blindness and haemophilia write letters as superscripts on X |
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gene mutations chernobyl and hiroshma |
Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer chernobyl: thyroid disease, birth defects hiroshima: more cancer, reduce T cell count> infections |
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pedigree charts autosomal dominant or recessive x linked dominant or recessive |
tien square, aida circle |
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dihybrid cross |
9:3:3:1 ratio linked alleles if F1 with F1 use foil method for combinations of F1 and place at sides of grid |
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linked |
on same chromosome therefore no independent assortment closer together = more likely linked |
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thomas morgan |
discovery of nonmendelian genetics cuz of linked alleles fruit flies: drosophila sex linkage: whit eye male and red eye female normal wings black body linked because close loci on chromosome |
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recombinants |
Recombinants of linked genes are those combinations of genes NOT found in the parents cuz of crossing over in prophase I genes far loci>recombinant frequency high check using est cross with HOMOZYGOUS RECESSIVE |
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phenotype variation |
discrete (one loci) continuous multiple alleles polygenic characteristics like height, hair color normal distribution of middlish affected by environment liek skin color |
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make chi squared |
1Identify hypotheses (null versus alternative) 2Construct a table of frequencies (observed versus expected) 3Apply the chi-squared formula 4Determine the degree of freedom on table (rows-1)(columns-1) 5Identify the p value (significant means > number for 0.05) |
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gene pool |
all the genes and their different alleles, present in an interbreeding population big=diverse will survive small=not diverse will die off |
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Evolution requires that allele frequencies change with time in populations mechanisms |
mutations gene flow: migration sexual reproduction: make new geen combinations natural selection genetic drift: random event (effects small pops more) |
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Comparison of allele frequencies of geographically isolated populations. |
proportion of all the alleles for that gene in a population Allele Frequency Database eg. melaninin in equatorial regions |
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types of natural selection (change in the composition of a gene pool) |
stabilizing (middle size baby) -intermediate favoured, not extremes -env. stable, competition low directional (antibiotic resistance) --one extreme selected for -phenotypic distribution shifts -gradual changes in env. disruptive (bl v wh moths) -both extremes favoured -BIMODAL SPREAD -fluctuating env -may cause speciation |
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types of natural selection diagram |
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Reproductive isolation causes |
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speciation causes |
GRADUAL divergence of isolated populations (beak size) Sympatric Speciation ALLIUM (no geographic barrier) chromosomal error> only breed with peeps with same error Allopatric Speciation (geographic barrier) ABRUPT (insects) Punctuated equilibrium implies long periods without appreciable change and short periods of rapid evolution. |
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Speciation in the genus Allium |
Sympatric Speciation meiotic error causes polyploidy (eg 4n instead of 2n) hybrid vigour: bigger, spoil later induced in ALLIUM: with colchicine chives, garlic, onions |
