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

RNADNA

RNApolymerase

TranscriptionSection 12-3

Adenine (DNA and RNA)Cystosine (DNA and RNA)Guanine(DNA and RNA)Thymine (DNA only)Uracil (RNA only)

Transcription (Steps)

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

DNA RNA

A U

T A

C G

C G

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

U A

C G

G C

Codon = 3 mRNA nucleotides (bases)

Anti-codon = 3 tRNA nucleotides (bases)

3 bases code for 1 specific amino acid

from to to make up

Concept MapSection 12-3

also called which functions to also called also called which functions towhich functions to

can be

RNA

Messenger RNA Ribosomal RNA Transfer RNA

mRNA Carry instructions

rRNACombine

with proteins tRNABring

amino acids toribosome

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

Messenger RNA

Messenger RNA is transcribed in the nucleus.

mRNA Start codon

Ribosome

Methionine

Phenylalanine

tRNA

Lysine

Nucleus

TranslationSection 12-3

mRNA

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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

Deletion

Insertion/

Duplication

Inversion

Translocation

Chromosomal MutationsSection 12-4

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