DNA Mutations

Chromosomes and DNA

Each chromosome contains a long strand of DNABody cells contain 23 pairs of chromosomesChromosomes and DNADNA carries the code that controls what cells are made of and what they do

The rungs of the DNA ladder are made from pairs of bases

There are four basesThese bases always pair together in the same way

How do you think the four bases pair up?

A always pairs with TC always pairs with G

DNA and Protein Synthesis DNA contains the genetic information to make amino acids

Amino acids combine to make proteins

These proteins determine the physical traits of an organism and control cellular functions.

Proteins do everything, and DNA gets all the credit!

Think of them as tiny minions who do all the work

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DNA and Protein Synthesis Codon: three bases code for a specific protein:ex: AAA = Lysine

The codons code for 20 amino acids

Just like the alphabet has 26 letters to make all the words we know, the 20 amino acids make all the different proteins found in living organisms

The codons are the template for protein synthesis, which takes place on the ribosomes (rRNA) in the cytoplasm

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DNA and Protein Synthesis - TranscriptionTranscription:

1)DNA unzips

2)mRNA (messenger ribonucleic acid) copies info from DNA using base pairings

RNA is different from DNA Single stranded, not double stranded Instead of deoxyribose, it has ribose instead of Thymine, it uses Uracil

3)Carries the genetic code from the nucleus to the ribosome in the cytoplasm

9The amino acids join together to form a proteinWe need proteins to make and repair cellsProteins are made in the cytoplasm

DNA and Protein Synthesis Amino acids are linked together in the same order as the codons , creating a protein chain

Just like linking letters to make words, linking amino acids makes proteinsmRNACUA AUG UGC Amino AcidAmino AcidAmino Acid11Leucine methionineDNA MutationsWhat is a mutation?

Change in the DNA of a gene.

2) When a cell puts its genetic code into action it is making precisely the proteins it needs for its structure and function.

3) If something changes a genes code words, the resulting protein may change.

4) If the protein is central to the cells architecture then a mutation could result in an abnormal cell.

DNA and MutationsMutations are any changes that take place in DNA:

Can be spontaneous or caused by mutagens ex: Chemicals, high temperatures, UV light, radiation

Can change the genetic code, and be replicated when forming new body cells.

In sex cells, can be passed on to offspring.

Mutations can be neutral, beneficial, or harmful ex: Blue eyes a mutation that occurred 6-10,000 years ago, can be traced back to one ancestor what kind of mutation is that?

13Types of Gene Mutations1) Substitution- can be a simple substitution in one base of the gene sequence.For example: Original: CAC GCC ATT GCG ATGMutation: CAC GCC ATG GCG ATG

One amino acid will replace another in this type of mutation thereby altering the resulting protein.

DNA and Mutations Lets looks at different mutationsTHE DOG BIT THE CAT

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DNA and Mutations - SubstitutionTHE DOG BIT THE CAT

Substitution - Replace just one letter:THE DOG BIT THE CAR

16Types of Gene Mutations1) A Substitution is a Point Mutation

Because it occurs at only one base in the DNA Strand.

Types of Gene MutationsRemember that DNA sequences are read in groups of three (codons) so we can use a simple sentence to demonstrate a substitution.

Original The Fat Cat Ate The Wee RatSubstitution The Fat Hat Ate The Wee RatWhere did the substitution occur?The letter C in Cat was changed to an H

Gene Mutations Substitutions: Sickle Cell AnemiaSickle Cell Anemia is a disease of red blood cells.

Codon for glutamic acid has been changed to code for valine because of a substitution in one codon in the gene for the protein hemoglobin.

Four hemoglobin proteins carry oxygen inside red blood cells.

The change in the amino acid causes the hemoglobin to fold abnormally causing a sickle shaped red blood cell.

Sickle Cell AnemiaThe mutation affects the folding and stability of the hemoglobin protein

Frameshift Mutations-Insertions and DeletionsInsertions and Deletions can be point mutations

One or several base pairs are inserted into a gene or deleted from it.

This results in a shift in the reading frame or frameshift.

Therefore insertions and deletions are called frameshift mutations

DNA and Mutations - DeletionTHE DOG BIT THE CAT

Deletion: Delete just one letter (T):THE DOG BIT HEC AT

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DNA and Mutations-InsertionsTHE DOG BIT THE CAT

Insertion - Add just one letter (E):THE DOE GBI TTH ECA T

Cells have proof reading proteins that constantly check the DNA and fix errors, so most are corrected

23Frameshift MutationsFrame- Shift Mutation in DNA can be demonstrated with a simple sentence.

Original The Fat Cat Ate The Wee RatFrame Shift The Fat CaA teT heW eeR at.Which letter (base) was deleted?The letter t in CAT.DeletionsSome times whole sections of genes are deleted.

Original The Fat Cat Ate The Wee RatDeletion The Fat Ate The Wee RatWhere did the deletion occur?The word Cat was deleted.

Insertions (Duplications and Tandem Repeats)Sometimes whole sections of genes are inserted.Original The Fat Cat Ate The Wee RatInsertion The Fat Cat Cat Ate The Wee Rata duplication or.

Original The Fat Cat Ate The Wee RatInsertion The Fat Cat Cat Cat Ate The Wee Rat.a tandem repeat (duplication continues through several generations)How do Mutations Occur?Can occur spontaneously when copying errors occur (replication is fast and there are lots of free nucleotides around during replication.)

2) Exposure to mutagens mutation causing agents in the environmentTypes of MutagensUltraviolet radiation in sunlight Skin cancer may result!!!

Types of Mutagens2) X-rays

Types of Mutagens3) Environmental Agents

Natural or manmade chemicals in the environment

Many carcinogens or cancer-causing agents disrupt DNA.

How are mutations fixed?Proofreading- cells have built in mechanisms that catch and repair most of the changes that occur in DNA.Mutations in eukaryotic cells are rare.In somatic cells any good or bad consequences will not be passed on to offspring.If a mutation occurs in a gamete it may be passed to the next generation.

Mutation and EvolutionA mutation and the protein made from the mutated gene that is passed from generation to generation (inherited) can have a beneficial, harmful, or neutral effect on an organisms ability to survive in its prevailing environment.

Therefore, gene mutations provide the foundation for change in a population of organisms mutations provide the foundation for evolution by natural selection.

Mutation Practice

Original DNA: TAC CTC GTA AAC CCT TAA GGG ACT

Mutation 1: TAC CTC GTA CAC CCT TAA GGG ACT

Circle all that apply: Deletion, Addition, Substitution, Inversion, Duplication