DNA to PROTEIN 2 step process of transcription and translation

Protein Synthesis: >Transcription & Translation DNA contains all the information for your traits – in the form of genes These genes are blueprints and need to remain safe – kept inside the nucleus Copies can be made through – a messenger Form proteins (polymers) from the building blocks – amino acids (monomers)

Genotype  Phenotype (genetic) (observable) DNA mRNA tRNA PROTEIN Transcription Translation

Transcription – making mRNA from DNA in the nucleus mRNA – stands for messenger RNA it is the copy of the DNA message for making a protein Occurs in the nucleus only

Transcription Section 12-3 RNA polymerase DNA RNA Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase DNA RNA

Transcription (Steps) DNA RNA A U T C G DNA “unzips” – helicases separate DNA molecule Free-floating RNA w/in the nucleus attach to complementary DNA base pairs Covalent bonds form b/w sugar-phosphate backbone mRNA is released DNA zips back up

mRNA Transcribes DNA message and carries it to ribosomes RNA polymerase is the enzyme that matches up the base pairs No T (thymine) so when it reads the nucleotide A on DNA it matches it with U (Uracil). CLICK ON PICTURE FOR ANIMATION ON TRANSCRIPTION

Translation – using mRNA and tRNA to make proteins Ribosomes are the site of protein synthesis Click here to see mRNA and tRNA work together at that ribosome to build a protein mRNA base codon tRNA base anticodon A U C G

Codon = 3 mRNA nucleotides (bases) Anti-codon = 3 tRNA nucleotides (bases)

3 bases code for 1 specific amino acid

Bring amino acids to ribosome Concept Map Section 12-3 RNA can be Messenger RNA Ribosomal RNA Transfer RNA also called which functions to also called which functions to also called which functions to mRNA Carry instructions rRNA Combine with proteins tRNA Bring amino acids to ribosome from to to make up DNA Ribosome Ribosomes

Review – by now you should know… structure of DNA How DNA replicates Differences b/w DNA & RNA Steps of Transcription & Translation Parts of tRNA 3 types of RNA

Translation Section 12-3 mRNA Go to Section: Nucleus Messenger RNA Messenger RNA is transcribed in the nucleus. mRNA Phenylalanine Lysine Methionine tRNA Ribosome mRNA Start codon Go to Section:

Mutation – permanent change in DNA Important: source of new variation important for evolution. Causes: viruses, high temps, chemicals, radiation Germ-cell Mutations Somatic-cell Mutations Occurs in gametes Occurs in body cells Don’t affect organism, but affects offspring Affects organism itself Ex: skin cancer, leukemia

2 categories of mutations 1) Gene mutations – may involve large segments of DNA or a single nucleotide 2) Chromosome mutations – either changes in the structure of a chromosome or loss or gain of an entire chromosome

Gene Mutations (large segments or a single nucleotide) Point mutations: change in 1 nitrogen base *Can do 1 of 3 things* Change a.a. being coded for the protein Change a.a. to a start and stop codon Not change the a.a. or the protein at all Example: sickle cell anemia http://www.intelihealth.com/i/P/PointMutationGEN.gif

Gene Mutations (large segments or a single nucleotide) Frameshift mutation: addition or deletion of a nitrogen base Changes EVERY triplet & a.a. after the insertion or deletion of a nitrogen base More severe since more a.a. are affected

http://kvhs.nbed.nb.ca/gallant/biology/point_mutations.jpg

http://staff.jccc.net/PDECELL/evolution/mutations/mutypes.gif

Chromosomal Mutations Section 12-4 Deletion Insertion/ Duplication Inversion Translocation

Chromosome mutations – either changes in the structure of a chromosome or loss or gain of an entire chromosome Inversion: chromosome segment breaks off and then reattaches in reverse orientation to the same chr Translocation: chr segment breaks off and attaches to different chr Causes sterility in plants

Chromosome mutations – either changes in the structure of a chromosome or loss or gain of an entire chromosome Deletion: loss of a piece of chr due to chr breakage Nondisjunction: a pair of homologous chr or single chr fails to separate during meiosis 2 kinds of gametes result 1) trisomy (extra chr…3 homologous chr’s ) Down Syndrome (trisomy 21) 2) monosomy (missing a chr…1 homologous chr instead of 2) Ex: Turner’s Syndrome (X monosomy)

Nondisjunction-Chromosome mutation

Nondisjunction – Chr mutation http://www.biology.iupui.edu/biocourses/N100H/images/11nondisjunction.gif