• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Gene mutations

Extracts from this document...


Gene mutations What is a gene mutation? Sudden and spontaneous changes in phenotype, for which there are no conventional genetic explanations or any microscopic evidence of chromosomal mutation, can only be explained in terms of changes in gene structure. A gene mutation or point mutation (since it applies to a particular gene locus) is the result of a change in the nucleotide sequence of the DNA molecule in a particular region of the chromosome. Such a change in the base sequence of the gene is transmitted to mRNA during transcription and may result in a change in the amino acid sequence of the polypeptide chain produced from it during translation at the ribosomes. ...read more.


Somatic mutations are probably very common and go unnoticed, hut in some cases they niay produce cells with an increased rate of growth and division. These cells may give rise to a tumour which may be benign and not affect other tissues, or malignant, which live parasitically on healthy cells, a condition known as cancer. The effects of gene mutation are extremely variable. Most minor gene mutations pass unnoticed in the phenotype since they are recessive, but there arc several cases where a change in a single base in the genetic code can have a profound effect on the phenotype. Sickle cell anaemia in humans is an example of base substitution mutation affecting a base in one of the genes involved in the production of hacmoglobin. ...read more.


Gene reshuffling as a result of crossing-over, independent assortment, random fertilisation and mutations, may increase the amount of continuous variation but the evolutionary implications of this are often short-lived since the changes produced may be rapidly diluted. Certain gene mutations, on the other hand, increase discontinuous variation and this has the more profound effect on changes in the population. Most gene mutations are recessive to the 'normal' allele which has come to form genetic equilibrium with the rest of the genotype and the environment as a result of successfully withstanding selection over many generations. Being recessive the mutant alleles may remain in the population for many generations until they come together in the homozygous condition and are expressed phenotypically. Occasionally a dominant mutant allele may arise in which case it will appear imniediately in the phenotype. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Genetics, Evolution & Biodiversity 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 AS and A Level Genetics, Evolution & Biodiversity essays

  1. Marked by a teacher

    An Investigation into the Mitotic Nuclear Division of Allium Sativum Root Tip Cells, and ...

    5 star(s)

    Appendix: Background Knowledge/Research The Cell Cycle & Mitotic Nuclear Division: Abstract Mitosis is the process of cell division in which eukaryotic cells undergo nuclear division, producing two genetically identical daughter cells. Biologically, mitosis has great significance as a means for the process of nuclear division to occur during cellular growth, repair and asexual reproduction.

  2. Recombinant DNA, genetically engineered DNA prepared in vitro by cutting up DNA molecules and ...

    But lack of knowledge of why faulty versions of these genes impart a tendency toward breast cancer had hampered further progress in helping such women. When the genes were first discovered, their normal function was not known. This is common upon the discovery of a gene whose altered version confers a high risk for developing a specific disease.

  1. patterns of growth and development

    They often listen to stories then play them out later, they also know more songs and rhymes and loves to sing them. They know about 2,000 words. As they head towards 7 or 8 they perfect their syntax (word arrangement)

  2. Investigating the effect of trampling on salt marsh

    Adaption of the plan during the experiment- As the experiment went on I realised that I needed help when measuring the distance and slope angle between the ranging poles because the wind was quite strong that day. I asked for help from my colleague to hold up the poles and

  1. An Investigation into the effect of flow rate on the size of Gammarus pulex

    Water temperature. - Digital meter. - Mercury thermometer. Digital temperature meter Same Greater accuracy obtained if thermometer is always left in the water when the temperature reading is taken. The level of the stream was low, making the accuracy of the temperature very difficult.

  2. Mutation and its Consequences - Gene mutations occur when there is change in the ...

    > Deletion o Deletion involves the loss of a base, which causes a frame shift in the other direction as all the bases move along to replace the one that has been lost.

  1. What is the relationship between genotype and phenotype?

    Note that the genotype can not always be deciphered from the phenotype of the organism, as in the case of the alleles for plant height in a Salvia, both the genotypes Tt (heterozygote) and TT (homozygote) both give rise to tall plants. Thus, the genotype is often determined through crosses.

  2. Investigating the colour variation of Littorina littoralis and their abundance across the upper, middle ...

    It was therefore established the areas in which it were possible to walk, and areas to avoid. Working on the rocky shore meant that it was possible, to become out of sight of those supervising the activity. The supervisors therefore, made regular checks on those carrying out investigations This investigation

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