DNA & MODERN GENETICS

DNA IS A SET OF INSTRUCTIONS FOR MAKING CELL PARTS

DNA IS A SET OF INSTRUCTIONS FOR

MAKING CELL PARTS• DNA & RNA ARE REQUIRED TO

MAKE PROTEINS

• CHANGES IN DNA CAN PRODUCE VARIATION

• MODERN GENETICS USES DNA TECHNOLOGY

DNA & RNA ARE NEEDED TO MAKE PROTEINS

• DNA IS THE INFORMATION MOLECULE: it stores information- that’s it.

• RNA IS NEEDED TO MAKE PROTEIN:• RNA carries data from DNA to a ribosome, where

amino acids are brought together to make protein.• 3 types of RNA are involved in this: messenger RNA

(mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA).

• In eukaryotic cells RNA copies DNA data in nucleus and takes it to cytoplasm for protein synthesis.

DNA: Information Molecule• Proteins are large molecules made up of amino acids.

23 different types join in different orders to make up thousands of different proteins found in body.

• DNA stores information on how to link the right amino acids in the right order to get the right protein.

• DNA molecule is a double stranded spiral, or twisted ladder made up of nucleotide subunits.

• The sides of the ladder are made of sugars & phosphates (of the nucleotide). The rung is made of 2 nitrogen bases bonding together (from 2 nucleotides)

DNA: continued

• There are 4 different nucleotides in DNA, identified by their bases: adenine (A), thymine (T), cytosine (C), and guanine (G).

• Bases fit together like puzzle pieces: A-T, and C-G. (All-Tigers Can-Growl)

• The order of bases determines the “code” for making protein. 3 nucleotide bases code for 1 amino acid (TCT codes for the amino acid arginine) some amino acids have 2- 4 different codes, all for the same amino acid.

• GENE: the entire sequence of bases that codes for all the amino acids in a protein.

DNA continued

• Each gene is made up a a sequence of bases at a certain spot on DNA

• REPLICATION: DNA being copied before a cell divides.

• First, the 2 strands separate by the nitrogen bases “unbonding”.

• Next, nucleotides in the area match up, base by base to the open DNA strand (A-T, C-G)

• Two identical DNA molecules are formed.• During replication, DNA strand is used as a template

(pattern that makes a matching product)

RNA NEEDED TO MAKE PROTEINS

• TRANSCRIPTION: process of transferring information from DNA to RNA.

• RNA is made up of 4 types of nucleotides also, but 1 is different. Instead of Thymine (T), RNA uses Uracil (U). Others are the same (A,C,G).

• During transcription, DNA is used as a template again, but to make a single strand of RNA. As DNA unzips, RNA bases match up to DNA (A-U and C-G), then RNA strand is released & moves into cytoplasm, while DNA zips back up.

• Many copies of RNA can be made from the same gene in a short period of time

RNA continued• To make proteins, cells must translate the language

of nucleotide bases into the language of amino acids.• 3 specific bases = one amino acid• TRANSLATION: the assembly of amino acids in

their proper sequence. Takes place in cytoplasm & involves 3 types of RNA.

• Proteins are made on RIBOSOMES (made of ribosomal RNA and proteins).

• DNA is like cookbook, mRNA like a recipe copy, ribosome = kitchen, tRNA gathers ingredients.

RNA continued• A tRNA molecule has 1 end that attaches to amino acid and

other end has a triplet of bases to match up to triplet on mRNA.

• Translation starts with ribosome attaching to beginning of mRNA strand; tRNA carrying an amino acid matches up to mRNA triplet of bases.

• The ribosome attaches one amino acid to another as it moves along mRNA molecule; tRNA releases from mRNA after their amino acid attaches to chain of amino acids.

• Ribosome completes translation when it reaches end of mRNA strand; newly made protein molecule (chain of amino acids) now releases.