Section 3: What is a gene?

Genes First let’s compare Chromosomes to a towel

Chromosome Chromatin = Long strands of DNA Chromosome : coiled up strand of chromatin The “X” shape is where the chromosome has been copied. ChromatinChromosome

How many chromosomes do we have in our nucleus?

How many chromosomes do we have in our nucleus of each of our cells? a. 23 b. 52 c. 108 d. 46

How many chromosomes do we have in our nucleus of each of our cells?

What is a Gene?  Gene: functional unit that controls inherited trait expression that is passed on from one generation to another generation.

Genes  In other words, Genes are pieces of our DNA that code for our traits.

Proteins from Genes Gene: Part of chromosome that codes for a protein

The Human Genome How many paired nucleotides do we have? (i.e. how many base pairs do we have?)

In 1964, Friedrich Vogel estimated that the total number of genes in the human genome to be ~ 6.7 million

What is a Trait? Trait = Any characteristic Trait

Inherited Trait Inherited trait = a characteristic that you get from your biological parents and…. a trait you are born with. It’s in your DNA! What are some examples? EX: (Write down one of your inherited traits)

Acquired Trait Acquired trait = a characteristic that you develop in your lifetime a trait you learn or pickup after you are born (not inherited from your parents) like you lost an arm, you got a tattoo, you learned a skill like piano What are some examples? EX: (Write down one of your acquired traits)

Section 5: Mutations

Mutations Evr made a mitsake in yourr spelng?

MUTATIONS! A mess up in the DNA sequence

Where do mutations occur? IN THE DNA!! (not the RNA) When do mutations occur? During replication

MUTATIONS! Gene Mutations (2 types): Changes in a single base Chromosomal Mutations (4 types): Changes in whole chromosomes

Gene Mutations, there are two types: Point Mutations Frameshift Mutations

Point Mutation A T G AA T A G C T G G A G G G A T T T T T A C T T A T C G T C C T C C C T A A A A Think about what would happen if the nitrogen bases paired incorrectly. How are proteins made? If you try and make a protein when you have an incorrect nitrogen base you will end up with the protein in the end.

A T G AA T A G C T G G A G G G A T T T T A UG A A U A G C A G G A G G GA U U UU T A C T T A T C G T C C T C C C T A A A A Point Mutation This is showing the bottom DNA strand, with the wrong nitrogen base, being transcribed into an mRNA strand. Because the T was in the DNA strand, we now have an A instead of a U in our mRNA strand. What will that do to the sequence of amino acids?

These happen at only ONE POINT or base Usually one base is replaced by a different base End result: ONE amino acid in the protein chain is wrong A UG A A U A G C A G G A G G GA U U UU Point Mutation METASPSERARG ASP A PHE What amino acid does the AGG codon code for? ? What amino acid does the UGG codon code for?? Are they the same amino acid?

These happen at only ONE POINT or base Usually one base is replaced by a different base End result: ONE amino acid in the protein chain is wrong A UG A A U A G C A G G A G G GA U U UU Point Mutation METASPSERARG ASP A PHE

A A Frameshift mutation will occur when you have a missing nucleotide.

A T G AA T A G C T G G A G G G A T T T T T A C T T A T C G T C C T C C C T A A A A Frameshift

A T G AA T A G C T G G A G G G A T T T T A UG A A U A G C A G G A G G GA U U UU T A C T T A T C G T C C T C C C T A A A A The mRNA will be missing a nucleotide too.

A UG A A U A G GU G G U G G GA U U UU Frameshift

A UG A A U A G G G G U G G G A U U UU Frameshift

A UG A A U A G C U G G A G G GA U U UU METASPSERTRYARGASP A PHE Frameshift

A UG A A U A G GU G G A G G GA U U UU METASPSERTRYARGASP A PHE Frameshift

This causes a SHIFT in the rest of the sequence following the mutation End result: Every amino acid after the mutation is wrong! A UG A A U A G C G G A G G GA U U UU METASPSERGLY ISO

MUTATIONS! Chromosomal Mutations (4) Changes in whole chromosomes

Chromosomal Mutations 1.Deletion: part of the chromosome is lost

Chromosomal Mutations 1.Deletion: part of the chromosome is lost 2.Duplication: part of the chromosome is repeated

Chromosomal Mutations 1.Deletion: part of the chromosome is lost 2.Duplication: part of the chromosome is repeated 3.Inversion: part of the chromosome gets reversed

Chromosomal Mutations 1.Deletion: part of the chromosome is lost 2.Duplication: part of the chromosome is repeated 3.Inversion: part of the chromosome gets reversed 4.Translocation: two chromosomes that are NOT pairs switch information

What you should be able to answer for the quiz: 1.What are the two types of gene mutations? 2.What are the four types of chromosomal mutations? 3.What is the difference between a gene mutation and a chromosomal mutation? 4.Be able to identify examples of the four types of chromosomal mutations? 5.Be able to translate an mRNA strand from DNA and be able to code the amino acid sequence that would result from the mRNA sequence. 6.Know what a codon is and what an anticodon is. 7.What is the difference between Transcription and Translation.

So WHY DNA? To make PROTEIN!!