† SO YOU’RE A MUTANT ¢

You’re not alone! Mutations are far more common than you think. But what does this

mean? Where do you go from here? See inside for more information on mutations, where they

come from, and what results when they appear in the human and animal genome.

MUTATIONSAND YOU

The Effects of Mutations

The effects of mutations can range from severe to invisible. Humans have lots of DNA that doesn’t code for proteins. If there are mutations in these sections, they are not expressed in our outward appearance or body function. Consequences occur when mutations occur in sections of our DNA known as “genes” that determine how proteins are built in our bodies.

When consequences of mutations do occur, they are most often not deadly or disease-causing, despite popular misconceptions. Many common traits in human beings are the result of mutations, from blue eyes to red hair. When a trait is present in over 1% of the population, it becomes known as a polymorphism, and is no longer considered to be as unlikely as a mutation.

Mutations create genetic variation, without which evolution could not occur! Sometimes, mutations can lead to survival advantages, which then cause the mutation to be passed on with increasing frequency in a population.

Occasionally, severe consequences result from genetic mutations. Mutations in the genes that regulate against unlimited cellular division can ultimately lead to cancer. Other diseases that can result from mutations are sickle-cell anemia, phenylketonuria, cystic fibrosis, and many others; each of these diseases results from a mutation in just one gene.

Resources

Find out more about the information presented in this brochure at the following resources:

http://learn.genetics.utah.edu/content/variation/mutation/

http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/genemutation

http://evolution.berkeley.edu/evolibrary/article/evo_18

http://learn.genetics.utah.edu/content/variation/outcomes/

http://www.philly.com/philly/blogs/evolution/The-Genetics-of-Venus-the-Famous-Cat.html

BY MS. KIMBERLY SCHOCH

KSCHOCH@GPSBULLDOGS.ORG

MARCH 2015

Cats are mutants too! All About MutationsWhat is a mutation?

Mutations are natural alterations that change the amount or sequence of DNA, the genetic material of living things. DNA replication is very accurate and rarely results in problems, but around one mistake is made in each chunk of 100,000 nucleotides. This means around 120,000 small mistakes each time one of our cells divides. Normally, these mistakes are corrected by the enzymes of DNA replication, but occasionally they are not- an uncorrected mistake is a mutation.

Sometimes, environmental factors increase mutations in DNA. Some of these are ultraviolet rays, dangerous chemicals, and radiation- these are known as mutagens. Sometimes, the mutations that they cause are repaired- other times they are not, and they can cause problems in our cells.

DNA Mutations

Changes in DNA• Point Mutation- A change in a single nucleotide in a DNA sequence• Insertion/Deletion- An insertion or deletion of one or several nucleotides in a DNA sequenceThese changes can result insilent mutations, nonsense mutations, and frameshiftmutations. Silent mutations do not change theamino acids present in thefinal polypeptide, missensemutations cause a change in the affectedamino acid, nonsensemutations result in apremature stop, and frameshiftmutations change the “readingframe” of the polypeptide chain; since DNA is read in3 nucleotide fragments, adding or removing one canchange the way that the codeis read.

Chromosome Mutations• Deletion- The loss of a piece of a chromosome

• Duplication- A piece of DNA from a homologous chromosome remains attached to another when they separate.

• Inversion- A piece of a chromosome is removed and becomes reattached to its original chromosome in the reverse direction.

• Translocation- A portion of chromosome from a completely different chromosome becomes attached.

• Gene Rearrangement- An entire gene is relocated on a chromosome

The cat to the left has a condition known as polydactyly, which means that extra digits are present on the cat’s paws. Normally, cats have 18 toes total on their front and back paws, but polydactyl cats can have up to 27! This mutation causes an alteration in the SHH, or “Sonic Hedgehog” protein- this alteration is caused by a single base change. Cats with this condition typically enjoy normal, happy lives, and may even have increased dexterity!_______________________________________A deletionin its DNA results in the smallerlimbs seenin this “Munchkincat” to theright. Manypeople think these cats, whose limb bones fail to grow properly, are extra cute- however, their condition can result in painful osteoarthritis and kittens with the condition sometimes die before birth._______________________________________Below is Venus, a cat famous for her unusual coloration. Her condition is believed to be because of mutations on her X chromosomes. As she is a female cat, she has one X chromosome from both her father and her mother. One of her X chromosomes contains the mutation for orange color and the other contains one for “agouti” coloring.