Topic 3 Flashcards

Question

Describe the inheritance of ABO blood groups in humans [5]

Answer 1

- The Ia and Ib alleles are dominant while the i allele is recessive - BT A: IaIa or Iai --> homozygous and heterozygous resp. /BT B: IbIb or Ibi --> homoz. and heteroz. resp. and BT O: only when there is a homoz. recessive phenotype: ii - BT AB: result of co-dominant alleles IaIb -> heteroz. - i, Ia and Ib are alleles - One allele inherited from each parent

Answer 2

- genetic diseases caused by mutations which can abrogate normal cell function -> causing disease phenotype - AR: CF - AD: Huntington's - Co-dom: sickle cell anemia (only one copy of allele needed, but the individual will have milder symptoms if only 1 copy inherited)

Answer 3

- caused by mutation of CFTR gene, chromo. 7 - autosomal recessive disease - excess mucus clogs airways, creating difficulty breathing and pancreatic cysts - if only 1 allele --> carrier

Answer 4

- gene mutation on the Huntingtin (HTT) gene on chromo 4 - autosomal dominant - causes by an excessive number of repeats of the CAG sequence - > 28 repeats is unstable -> sequence amplifies even more. once the number of repeats crosses 40 -> the huntingtin protein misfolds and causes neurodegeneration - symptoms develop in middle age causes uncontrollable spasodic movements + dementia

Answer 5

- X-linked recessive - more common in males (as a result) - coagulation factors for coagulation cascade are on X chromo -> mutation causes defect - fibrin doesn't form properly - clotting impaired

Answer 6

- patients cannot differentiate between red and green hues - mutation on the allele on the X chromo - affects red and green retinal photoreceptor cells

Answer 7

- thyroid defects as high amounts of radioactive iodine - cancer frequency increased - in C particularly, increased amounts of birth defects - organ-specific abnormalities - Reduced t cell counts --> immune defects - some flora fauna variation also occurred - radiation accumulates in the ecosystem through bioaccumulation

Answer 8

- Denaturation: DNA is heated to 95C (1min) to ensure the 2 strands of DNA separate - Annealing: DNA primers attach to the 3' end (55C for 1 min) - Elongation: Taq polymerase (from thermophiles) bind to primer and are used at high temperatures (72C, 2 min) to rapidly replicate the DNA strands

Answer 9

when dna/protein fragments are placed on a block of gel + a current is run through it --> separating them by mass/fragment size - smaller samples less impeded by gel matrix and travel further - diff size -> separate

Answer 10

- DNA cut at specific points using specific restriction endonucleases - negative charge on DNA (bc phosphate group) so fragments separate - frag placed on agarose gel, current run through it -> move negative to positive direction - those frag that travel faster/further -> smaller - compared against industry standards

Answer 11

- proteins come in a variety of sizes and don't have a clear charge - treated which an anionic detergent -> uniform negative charge and linearised - put in polyacrylamide gel and current run through -> compared to industry standards

Answer 12

- HR makes up a larger proportion of the total genome than unique - unique are much shorter sequences than HR - unique are translated into proteins, HR aren't - unique don't vary much between individuals, HR vary highly - unique occur once in a genome, HR occur many times - unique may be genes, HR are not genes - repetitive DNA is used for profiling - satellite DNA is formed from repetitive sequences - prokaryotes usually don't have repetitive sequences

Answer 13

- promote international cooperation - provide evidence for evolutionary relationships - improve ability to SCREEN FOR certain diseases/ find genes causing certain diseases - tailor medication to individual genetic variation - development of new gene therapies - find the functions/structures of certain proteins - all the human genes/their positions mapped - complete human DNA SEQUENCED - find mutations

Answer 14

Methods: - DNA obtained from blood/hair/semen - PCR to amplify the quantity - satellite dna used - Satellite DNA cut into fragments at specific points using restriction endonucleases - different people have different lengths of STRs so the lengths of the fragments will differ - gel electrophoresis of the fragments --> smaller sizes -> move faster so further - number of repeats varies between individuals Aims: - Paternity test - biological father if half of the bands produced are found in the father - forensic investigation - to compare the crime scene dna to suspect's - DNA profile must be complete match of the suspect's

Answer 15

- plasmid isolated from bacteria - plasmid cut open using specific restriction endonucleases - DNA isolated from an organism - gene of interest isolated via cutting with SAME restriction endonucleases - endonucleases create complementary sticky ends (CBP) on the plasmid and the gene of interest -> often 2 diff endo -> ensure the orientation of gene inserting is right and the plasmid doesn't re-anneal - the backbone is spliced together using DNA ligase -> phosphodiester bond formed - recombinant plasmid - plasmid inserted into the host cell (recombinant organism)

Answer 16

- genetic modofocation is when the DNA/genotype of an organism is altered artificially - GM alters some phenotype of the organism - ex - Bt corn (gene from bacillus thuringiensis is inserted into corn --> insecticidal proeprties) Benefits: - Bt reduces need for chemical pesticides -> lower env risk - GMO allows crops to be grown where otherwise it cannot be grown (eg salt tolerant tomatoes) - may increase yield hence economic profit for farmers - reduces need for rainforests to be cleared to grow crops - provides more food - lowered production costs Harmful: - May have impact on non-target organisms -> Bt corn pollen may be toxic to monarch butterfly caterpillars - may impact food chain - people may have reactions to the new food (allergic) - some farmers may not be able to compete (small scale farmers) - risk of cross pollination - risk of long term soil contamination - long term risks unknown

Answer 17

- egg cell isolated from host organism (host cell) - somatic cell isolated from donor organism - haploid nucleus of egg cell is removed - diploid nucleus of the somatic cell is removed and fused with the enucleated egg cell - electric current provided -> stimulate egg to divide into embryo - embryo re-inserted into the uterus of host organism -> clone of donor is created

Answer 18

Through asexual reproduction: - vegetative propagation (plants - as they have meristematic tissue) --> tubers, bulbs, runners) - spores: fungi and some plants - Budding: hydra - binary fission: planaria - fragmentation: starfish - parthenogenesis -> the offspring form from unfertilised ova (some insect/fish species) Through sexual reproduction: - identical twins --> the zygote splits into 2 after fertilisation (monozygotic) - fraternal -> unfertilised egg splits into 2 -> 50% DNA is same (dizygotic)

Answer 19

- SCNT -> traits can be controlled or - separating the cells of an embryo in lab when embryo is in 8-cell stage (morula) - embryo pluripotent --> each cell dev into a new organism - clones of the original embryo formed - though traits cant be controlled as fertilisation still occurs randomly

Answer 20

- all plant stems are divided into nodes -> between nodes are internodes - leaves/roots/aerial roots grow from nodes - cuttings placed in soil with lower nodes covered, and upper exposed - to rapidly propagate plants growth dependent on: - growth hormones - temperature - length of node from cutting (cutting position) - water avail - growth medium - cutting length

Answer 21

- Grew E coli in radioactive thymidine - put contents of the cell on photographic film paper - measured the length of the DNA molecule and photographed it - could show new strands were all labelled with thymidine