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TOPIC 3: Genetics very complete - Coggle Diagram

- - - - changes to the shape of red blood cells cause it to develop a sickle shape, sickle cells may form clots within the capillaries, blocking the blood supply to vital organs.
        sickle cells also destroy themselves at a faster rate than normal red blood cells, leading to a lower immunity and red blood count, leading to anemia.
- - - - Cells were grown for 2 generations in cultures with tritiated thymidine. Cells were then placed onto a dialysis membrane and their cell walls were digested by lysosome.
        
        the cells burst to release their DNA onto the membrane.
        
        a thin film of photographic emulsion was applied to the surface of the membrane and left in the darkness.
        over time, atoms of titrium in dna decayed and emitted high energy electrons, which reacted with the film, and the film was developed under a miscroscope.
        the images showed that chromosome of e.coli was circular long and naked.
        then autoradiography was used to produce photographs of eukaryotic DNA.
- - - - A. two cell divisions / reduction-division / diploid to haploid / meiosis I and meiosis II;
      - B. produce four (haploid) cells;
      - C. for production of sex cells / gametes / spores;
      - D. daughter cells are different from parent cells;
      - E. chromosomes condense / coil / become shorter and fatter during prophase I;
      - F. (homologous) chromosomes pair up in prophase I;
      - G. crossing over / chiasmata formation in prophase I;
      - H. movement of pairs of chromosomes / bivalents to the equator in metaphase I;
      - I. movement of half of the chromosomes to each pole in anaphase I;
      - J. (spindle fibres) pull homologous chromosomes to opposite poles;
      - K. movement of chromatids to opposite poles in anaphase II;
      - L. decondensation / uncoiling in telophase II;
      - M. two haploid cells are formed;
      - N. second division / like mitosis, separates chromatids to opposite poles;
    - - A. in metaphase homologues in centre of cell / spindles attached;
      - B. homologues are separating;
      - C. one pair doesn’t separate / non-disjunction;
      - D. anaphase I / anaphase II;
      - E. in telophase cells divide into two;
      - F. cells have either one more / one less chromosome;
      - G. can occur in second division of meiosis;
      - H. sister chromatids fail to separate;
      - I. two copies of chromosome 21 in gamete;
      - J. fertilization with one gamete / sperm / egg carrying extra chromosome;
      - K. Down’s syndrome is trisomy of chromosome 21;
- - - - gametes are sex cells produced by meosis that fuse together to produce a single cell called a zygote. a zygote is a fertilised egg with a diploid nuclei.
        
        the male gamete is smaller than the egg cell and is able to move with the flagellum, the egg cel cannot.
        in humans, the sperm has a smaller volume than the egg cell.
        parents pass genes onto their offspring in gametes.
        the segregation of alleles in meisosi is indendent, = the speration of homoglous chromsoem pairs leads to the separation of alleles.
      - Fusion of gametes results in diploid zygote with 2 alleles for each gene that may be the same or different alleles. fertilisation forms a diploid nuclei cell with two chromosomes of each type.
        
        if the maternal allele is the same as the paternal allele, the offspring is homozygous for that gene.
        if the maternal allele is different to the paternal allele, the offspring is heterozygous for that gene.
        
        The alleles of each gene separate into different haploid daughter nuclei during meiosis.
        
        The diploid nucleus contians two copies of each gene, but the haploid gamete only contains one.
        the separation of alleles in meiosis is called segregation, allowing each daughter cell to contain one chromosome for each pair and have a haploid nucleus.
      - Dominant alleles mask the effect of recessive alleles but co-dominant alleles have joint effects.
        
        Genotype: The allele combination of an organism.
        Phenotype: The characteristics of an organism (determined by the genotype and the environment).
        DOMINANCE: the dominant allele will mask the effects of the recessive allele, only the dominant allele will be expressed phenotipically
        RECESSIVE: the recessive allele will alwasy be expresed in a homozygous genotype/in the absence of a dominant allele.
        CO-DOMINANCE: occurs when pairs of alleles are both expressed equally in the phenotype of a heterozygous individual.
        
        Inheritance of ABO blood groups
        
        Humans red blood cells can be categorised into different blood groups, based on the structure of a surface glycoprotein.
        the ABO blood groups is controlled by 3 alleles.
        these alleles produce a basic antigen on the surface of RBC's.
        Humans produce antibodies against foreign bodies, so blood trnasufsions arent compatible between all groups.
        
        AB: Receive any: Give only to AB
        
        B: Receive O or B: Give to B or AB
        
        A: Receive O or A: Give to A or AB
        
        O: Receive only O: Give any
        
        consequences of incompatible blood tranfusison are agglutination and haemolysis.
  - - - Red-green color blindness
        
        Red-green color blindness is an example of a sex linked recessive condition that is more common in males. it is a genetic disorder whereby an indivuald fails to dsicrinante between red and green colors, occurs due to a mutation in retinal photorcetoro cells, located on an X chromosome.
      - Haemophilia
        
        Haemophilia is a genetic disorder whereby the body fails to control blood clotting. Recessive x-linked. The formation of a blood clot is controlled by coagulation factors located on an x-chromosome, if these factors become defective bleeding cannot be controlled.
  - - - it is not possible to be a carrier for a dominant disorder, as the presence of the allele will be expressed.
- - - - A. DNA is extracted;
      - C. plasmid is a small piece of circular DNA; vector is a DNA molecule that acts as a vehicle to carry the gene of interest to a cell.
      - D. plasmid removed from (host) cell;
      - E. plasmids are cut open with endonucleases (at specific sequences);
      - F. genes / DNA fragments from another organism cleaved by same restriction enzyme;
      - G. gene of interest and plasmid are mixed together;
      - H. addition of “sticky ends” to the DNA copy (so that it will combine with the cut plasmid); restriction enzymes cleave the sugar-phosphate backbone together to generate sticky ends that will join by complemenatry base pairing.
      - I. DNA ligase will seal the plasmid;
      - J. recombinant plasmid is inserted into E. coli/host cell;
      - K. E coli is cultured;
      - L. E coli begins to make protein coded by the gene of interest;
    - - there is a risk of monarch butterflies due to BT Corns.
        BT Corn is a genetically modified crop that has an insecticde producing gene. This insecticde is toxic to monarch butterflies.
      - the spread of Bt corn is impacting the survival rates of monarch butterflies.
        1) pollen from bt corn dusts milkweeds
        2) monarhc butterflies feed on milkweeds that have been dusted with BT corn pollen.
        studies have shown that caterpillars exposed to pollen from bt corn have eaten less and have higher mortality rates.
    - - Many plants species and some animal species have natural methods of cloning; organisms that reproduce asexually will form clones. cloning multicellualr organisms requires the production of stem cells by cell differntiation.
        
        all species can reproduce asexually and hence posses natural methods of cloning.
        
        all bacteria reproduce asexually to produce identical clones
      - Production of clones embryos produced by somatic-cell nuclear transfer
        
        somatic cell nuclear transfer is a method by which cloned embryos can be produced using undifferentiated adult cells.
        
        collect somatic cells (from donor);
        
        isolate nucleus from somatic cell;
        
        collect egg cells from a female;
        
        remove nucleus of egg cell;
        
        to form enucleated egg;
        
        fuse somatic cell / nucleus with enucleated egg;
        
        stimulate fused cell to divide using electric shock / pulses;
        
        culture fused cell in medium to form embryo;
        
        introduce embryo into (uterus of) surrogate mother for implantation;
        
        birth of offspring genetically identical to somatic cell / nucleus donor;
        
        artifical methods of cloning can be used for therapetuici cloning (embryo stimulated to differentiate to create specfici tissue) or reproductive cloning where the embryo is implanted in the tureurs of a surrogate
      - animal cloning methods include: (1) binary fission, the parent organisms splits into 2 indetical daughter cells. (2) budding, cells split off the parental organsim to generate a smaller daughter ogranism. (3) fragmentation, new organisms grow from a separated fragment of the parent organism.
      - plant natural cloning methods: plants have the capacity for vegetative propgation (form of asexual reproduction) whereby small pieces can be induced to grow independently. plants can form runners that grow roots taht develop into clones of the plant.
      - humasn beings are capabkle of creating genetically identical clones through natural means; identical trwins are created when a fertilized egg splits into 2 identical clones = monozygotic twins have the same DNA.
      - Stems can be cut so that roots develop from the cut end of the stem
        This is a way of cloning plants artificially, used by gardeners
        
        STEM CUTTINGS
        
        In most plants, a stem cut below a node is the ideal place to cut
        A node is the position where leaves branch off the stem
        
        The bottom section of the stem is inserted into compost or water Compost must be sterilised beforehand by heating
        Compost should be well watered and aerated
        Hormone rooting powder may assist the process of rooting