• 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...

Introduction

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.

Middle

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.

Conclusion

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)

    A simple improvement that can be made is to use the eyepiece pointer to 'scan' along the rows of cells when observing the number of cells in each mitotic phase. A more complex, yet more effective method would be to connect a photographic eyepiece; obtaining and printing copies of the

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

    in species that reproduce asexually the chromosome number is the same in all the cells of the organism; among sexually reproducing organisms, each cell except the sex cell contains a pair of each chromosome For many years, scientists believed that Neanderthals were the direct ancestors of modern humans.

  2. What is the relationship between genotype and phenotype?

    can act on the outward appearance of an individual, the genotype must first be manifested into protein molecules via protein synthesis. This begins in the nucleus when a RNA helicase enzyme locates the end of the DNA section to be transcribed and causes part of the helix to unwind.

  1. 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

  2. patterns of growth and development

    They use the whole hand to hole something. By 9 months the baby can hold things with their fingers and thumb. They learn that the can control when they want to open their hands and therefore drop the object. They will poke to things with the index finger and hold things with the tip of the index finger and the thumb.

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

    can deposit while substrate that are too small are carried away by the water. The stony beds of the river are suited for adult shrimps as their legs allow them to cling on to rocks; this would be less possible for muddy substrate.

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

    Measuring tape 3 * Measuring distance from sea to shore. * Laying out each of the three zones to a set distance. Provided a simple and accurate means of measuring relatively large linear distances. Stopwatch 1 To keep the length of time spent per quadrat constant.

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