dna replication mr. mah living environment dna (de-oxy-ribo-nucleic acid) a nucleic acid that stores...
TRANSCRIPT
DNA Replication
Mr. Mah
Living Environment
DNA(de-oxy-ribo-nucleic acid)a nucleic acid that stores and transmits the genetic
information from one generation to the next
Where in the cell is DNA found?
People knew that DNA was made up of:
•Adenine (A)•Guanine (G)•Cytosine (C)•Thymine (T)
Your Challenge: Figure out the shape of DNA
Erwin Chargaff• Discovered that in any
sample of DNA, the amount of A equals the amount of T and the amount of C equals the amount of G.
• This suggested that A binds with T and that C binds with G.
Rosalind Franklin’sX-Ray Crystallography
• Took x-ray photographs of crystallized DNA
• Discovered that the shape of DNA must be a helix, because of the x-ray pattern
• Died of cancer
(too many x-rays?)
An example of X-Ray Crystallography
Watson and Crick• Credited for
discovering the structure of DNA in 1953
• Used Chargaff and Franklin’s discoveries along with toy models to discover the structure
A 3-D Model of DNA
NUCLEOTIDESMade up of:• A phosphate group• 5 carbon sugar• Nitrogenous Base
(nitrogen containing)
PURINES•Adenine (A)
•Guanine (G)
PYRIMIDINES
•Cytosine (C)
•Thymine (T)
Base Pairing in DNA
A-T
C-G
Write the complementary DNA strand for each of these DNA
strands:DNA
• GAATTACA• CCAATTAG• ATAGACAG• CCAGTACA
DNA• CTTAATGT• GGTTAATC• TATCTGTC• GGTCATGT
Each of the 96 columns represents one DNA sequence. A different colored dye attached to each
of the four nucleotides.
ReplicationThe act of making an exact copy of
DNA
Semi-Conservative Replication
Each strand of the original molecule acts as a template for the synthesis of a new
complementary DNA molecule
With semi-conservative
replication, each new strand is ½ new and ½
old
Examples of DNA Replication
RNA(ribo-nucleic acid)
a nucleic acid that is a messenger between DNA
and the ribosomes
Differences between DNA and RNA
1. Different sugars (DNA=deoxyribose)(RNA=ribose)
2. RNA is single stranded (1 side)DNA is double stranded (2sides)
3. RNA has “U” (uracil)DNA has “T” (thymine)
Always remember…
RNAloves
U
Write the RNA strand for each of these DNA strands:
½ Strand of DNA
• GAATTACA• CCAATTAG• ATAGACAG• CCAGTACA
RNA
• CUUAAUGU• GGUUAAUC• UAUCUGUC• GGUCAUGU
TranscriptionThe process by which DNA is
copied into mRNA
mRNAMessenger RNA, is the copy of the DNA that goes from the nucleus
to the ribosome
FACTProteins are made up of amino acids
tRNATransfer RNA,
matches up with mRNA and has an
amino acid on its top
CODONEach combination of 3
nucleotides on a strand of mRNA
ANTICODONEach combination of 3 nucleotides on
a tRNA
TranslationThe decoding of a
mRNA message into proteins
rRNARibosomal RNA, glues
together all of the amino acids into a polypeptide chain
Table of Codons