Download DNA & MODERN GENETICS

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 CG. (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.