DNA & RNA

SBI 3U

Two types of Nucleic Acids

• DNA – Deoxyribonucleic Acid (double strand) 4 Bases Adenine, Thymine, Cytosine, Guanine

• RNA - Ribonucleic acid (single strand) 4 Bases Adenine, Uracil (replaces Thymine) Cytosine, Guanine

How DNA works

• The double helix unzips and reveals a section of genetic code.

• http://www.youtube.com/watch?v=hfZ8o9D1tus&feature=related

• http://www.youtube.com/watch?v=z685FFqmrpo&feature=related

Types of RNA• mRNA – messenger RNA Enters the nucleus

through the nuclear pores and “reads” the unzipped portion of the DNA strand.

tRNA – transfer RNA “reads” the mRNA strand in groups of 3 CODONS. Collects correct Amino Acid from the cell cytoplasm and adds this to the developing strand of amino acids.

Abbreviation

Name Function Structure

mRNA messenger RNA

it functions as a blueprint;  it’s a code for

a single protein (or polypeptide chain)

single-stranded, 

tRNA transport RNA

the translator, capable of reading the mRNA language and binding corresponding  amino

acid to a growing peptide chain

 cloverleaf

rRNA ribosomal RNA

the factory, an "enzyme" of sorts

complexed with

proteins

DNA strand unzips.

T A C T T C A A A A A C C G A C C G A T A

mRNA strand

mRNA leaves nucleus returns to Endoplasmic Reticulum . Links to Ribosomes.

tRNA collects amino acids and links them onto the developing protein

Where is DNA found?

• Nucleus of Eukarotic cells• DNA strand in Prokaryotic cells

mRNA

  

    

             

DNA T T C A T A G C C A G

 

A A G U A U C G G U C

mRNA = AAG –UAU- CGC - UC

CODONS

• Genetic Words• Start = AUG (Met) Like the capital letter of a

sentence.• Stop = UGA, UAA, UAG – like the period at the

end of a sentence.

Mutations

• Thesunwashotbuttheoldmandidnotgethishat.• The sun was hot but the old man did not get

his hat.FRAME SHIFT.• T hes unw ash otb utt heo ldm and idn otg

eth ish at.• Th esu nwa sho tbu tth eol dma ndi dno tge

thi sha t.

Genetic Diseases

The sickle cell mutation. One amino acid out of a total 287 differs in sickle cell haemoglobin compared with normal haemoglobin. In the latter, the triplet GAG (guanine, adenine, guanine) codes for the amino acid glutamic acid (left-hand diagram).

Genes

• A gene is a sentence that tells a cell how to make a protein. Any changes to the instructions can alter the gene’s meaning. There are different ways that these changes can occur.

Point Mutation: OriginalThe fat cat ate the wee rat.Point MutationThe fat hat ate the wee rat.Frame-shift mutation:OriginalThe fat cat ate the wee rat.Frame ShiftThe fat caa tet hew eer at.

Deletion: OriginalThe fat cat ate the wee rat.DeletionThe fat ate the wee rat.Insertion: OriginalThe fat cat ate the wee rat.InsertionThe fat cat xlw ate the wee rat.

Inversion:OriginalThe fat cat ate the wee rat.InsertionThe fat tar eew eht eta tac.