• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9
  10. 10
    10
  11. 11
    11
  12. 12
    12
  13. 13
    13
  14. 14
    14
  15. 15
    15
  16. 16
    16

IB Genetic Unit Notes

Extracts from this document...

Introduction

GENETICS BIOLOGY NOTES. Chromosomes, genes, alleles and mutations. 4.1.1: State that eukaryote chromosomes are made of DNA and proteins. Eukaryote chromosomes are made of DNA and proteins. DNA is a huge molecule consisting of two paired strands in the form of a double helix. Supported by protein, about 50% of the chromosomes is built of protein. TN: The names of the proteins (histones) are not required, nor is the structural relationship between DNA and the proteins. 4.1.2: Define gene, allele and genome. Gene - A heritable factor that controls a specific characteristic and consists of a length of DNA occupying a position on a chromosome known as a locus. Allele - one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of the gene. Genome - the whole of the genetic information of an organism. 4.1.3: Define gene mutation. Gene mutation is a change in the base sequence of the gene. 4.1.4: Explain the consequence of a base substitution mutation in relation to the processes of transcription and translation, using the example of sickle-cell anaemia. GAG has mutated to GTG causing glutamic acid to be replaced by valine, and hence sickle-cell anaemia. - Substitution: the replacement of one (or more) base with another. - Because of the redundancy of the genetic code, some substitutions will have no effect on the amino acid sequence coded for by the gene. - Where the substitution does have an effect, it may produce either mis-sense, altering a single amino acid, or nonsense, introducing a new stop codon. - Sick cell anaemia: is substitution in gene for � chain of haemoglobin. Meiosis 4.2.1: State that meiosis is a reduction division of a diploid nucleus to form haploid nuclei In meiosis, four daughter cells are produced - each with half the number of chromosomes of the parent cell. ...read more.

Middle

gene 4.3.11: Predict that the genotypic and phenotypic ratios of offspring of monohybrid crosses involving any of the above patterns of inheritance. --- 4.3.12: Deduce the genotypes and phenotypes of individuals in pedigree charts. * Roman numeral identifies generation number * Arabic numeral identifies individual within a generation, numbering from left to right * square = male; circle = female * shaded = affected by genetic disorder or trait For dominant and recessive alleles, upper-case and lower-case letters, respectively, should be used. Letters representing alleles should be chosen with care to avoid confusion between upper and lower case. For codominance, the main letter should relate to the gene and the suffix to the allele, both uppercase. For example, red and white codominant flowers colours should be represented as CR and Cw respectively. For sickle-cell anaemia, Hb^ is normal and Hb' is sickle cell. Genetic Engineering and Biotechnology 4.4.1: Outline the use of polymerase chain reaction (PCR) to copy and amplify minute quantities of DNA. Polymerase chain reaction (PCR) is used when a research would like to investigate a certain DNA sequence. This sequence is 'photocopied' several times by using enzymes to replicate DNA, thus no living organisms are required. The DNA is heated to break the hydrogen bonds. Primers are added to start the process of DNA replication. Mixture is cooled and the primers bond to the original, but now single stranded DNA. Nucleotides and a thermostable DNA polymerase are added. The nucleotides will bond with the 'exposed' organic bases of the single stranded DNA then the DNA polymerase will then join them into a DNA strand. Through this, each of the original strands form a new complementary strand. These strands are heated and separated and will fnction as a template for more DNA strands to be formed. A large amount of identical copies of the original DNA can therefore be made quickly. 4.4.2: State that, in gel electrophoresis, fragments of DNA move in an electric field and are separated according to their size. ...read more.

Conclusion

10.2.5: Explain an example of a cross between two linked genes Example looking at the notation TtBb where it was used for non-linked dihybrid cross. To represent that it is linked, the two alleles must be represented as vertical pairs 10.2.6: Identify which of the offspring are recombinants in a dihybrid cross involving linked genes. Recombinants in linked genes are those combinations of genes which the parents DID NOT possess. Polygenic Inheritance 10.3.1: Define polygenic inheritance Polygenic inheritance is the inheritance of phenotypes that are determined by the collective effect of several genes. Discontinuous variation - there is no intermediate form and no overlap between the two phenotypes (i.e. two alleles for tall and dwarf plants.) You either have the characteristic or you don't. For example, blood groups because you can either have one blood group or another, nothing in between. Controlled by alleles of a SINGLE gene or a SMALL number of genes. Environment has little effect. Continuous variation - there is a complete range of measurements from on extreme to the other. It is the combined effect of many genes --> polygenic inheritance, and is often influenced by environmental factors. 10.3.2: Explain that polygenic inheritance can contribute to continuous variation using two examples, one of which must be human skin colour. Polygenic inheritance can contribute to continuous variation. Two examples of this is human skin colour and the seed colour of wheat. Seed colour of grain - this is controlled by 3 genes that interact together to control the phenotype. In this case, for all three of these genes there are only 2 alleles. Despite these limitations, the full range of colours obtained varies from dark red to white, with 5 shades of pink. Human skin colour - ranges from white, shades of brown to black. Colour of skin is due to pigment called melanin. Approx 3+ inherited genes control melanin production. The outcome is an almost continuous distribution from very pale (no alleles coding for melanin production) to very dark brown (all alleles for skin colour code for melanin production). ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Biology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Biology essays

  1. Marked by a teacher

    Neurology and Behaviour. Focus question: Is there an increase in the perception and ...

    5 star(s)

    Graph 2: An Area Distribution of highest disgust responses for each gender The Area Distribution Graph shows how the Female Disgust Response more than often exceeds that f the Male Dsigust Respnse. The results show that Male disgust responses were greater for image numbers five, twelve, fifteen, eighteen and twenty.

  2. What is the effect of different body positions i.e. lying down, sitting and standing ...

    in order to apply error bars to 'figure 1' below Table 7: Average difference between sitting position (control) and lying position and sitting position (control) and standing position for the systolic and diastolic (mmHg) pressure where a positive value means that the pressure in the position was higher than sitting

  1. The Effects of Salinity on Wheat Germination

    for every dish from that day onwards for the next 13 days. 19. At the point at which the seeds sprout (see definition dependant variable: germination - 1.2.1. treatment of variables), make a measurement of their growth on each day onwards until the 14th day of the experiment at which point the experiment will have ended.

  2. biology extended essay - How different diets: vegetarian, vegan and a meat centered diet ...

    173cm 162cm 155cm 175cm 170cm Are you sick now? no no no no no When last did you have a cold? Two weeks ago Last month Three weeks ago Two weeks ago Two weeks ago How often do you have a cold? Twice a year Once a year Twice a year Once a year Once a year How many

  1. Experiment Colours of Light (Wavelength) absorbed by green plant

    The uncertainty of the analog stopwatch is larger than that of digital stopwatch Since digital stopwatch provides less uncertainty than that of analog stopwatch, it is better to use digital stopwatch for the time taken for the test tube inside the centrifuge, the time taken for the test tube to be left in the dark room.

  2. Biology Lab - frequency of cell division in animal and plant cell

    Other organelles in the whitefish blastula cell were too small for the current magnification of the microscope in class. Data Processing: Overview: The raw data which was collected while observing the Onion Root Tip cells and Whitefish Bastula cells for the frequency of division were represented in a table format.

  1. IB Genetic Lab

    of females, and that there is a clear association between the two factors2. This error can be improved in the future by increasing the sample size. This could be done by surveying more females to ensure that a solid conclusion can be drawn from numerous amounts of recorded values, and to increase the reliability of the experiment.

  2. Investigating the Effects of Salt on Seed Germination

    We solved this problem with some other petri dishes by not worrying too much about the spacing but instead placed each seed in the middle of a cotton wool ball so that it didn?t fall off. A minor problem that we experienced was the small sample of seeds initially supposed

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work