DNA: genes on chromosomes

1
DNA genes on chromosomes
2
DNA is composed of nucleotides
A Nucleotide has - Deoxyribose Sugar -
Phosphate - Nitrogen Base Adenine Thymine Guanine
Cytosine A - T and G - C
3
DNA is a helix molecule
Hydrogen bonds are in between the bases. Note
the nucleotidespairing.
4
DNA self replicates before cell division
5
5 3
The DNA strand opens and will add nucleotides. A
to T and G to C.
C
A
G
T
One strand grows continuously, the other grows
discontinuously.
Enzymes join the strands.
5
3
6
(No Transcript)
7
DNA produces proteins in two steps
Transcription mRNA production Translation
protein production
8
Transcription is when the mRNA produced. mRNA
from DNA as expected.. GGG CCC TTT AAA
CCC GGG AAA UUU
The bases of the DNA are matched up with the RNA
bases A-U, T-A, G-C, C-G AAA TTT GGG CCC GGG CCC
TAA
UUU AAACCC GGG CCC GGG AUU
9
Synthesis starts at the beginning of a gene
10
Transcription moves in a 5 to 3 direction
11
(No Transcript)
12
Transcription finishes as mRNA is released
13
The DNA triplets help code for amino acids during
translation because DNA is in control of the
triplets of mRNA (the codon). The anti-codon of
the tRNA matches this codon on the ribosome and
brings with it an amino acid.
UUU AAACCC GGG CCC GGG AUU
GGG Pro
CCC Gly
AAA Phe
UUU Lys
GGG Pro
CCC Gly
UAA Ile
Bonds form between amino acids
14
When the chain is complete, a new protein has
been formed. Video of Protein Synthesis.
15
(No Transcript)
16
On the ribosome mRNA codons match tRNA anticodons
linking amino acids
17
Steps to Protein Synthesis

• Transcription Production of mRNA by DNA in
  nucleus. Base pairs match up A to U and G to C
  (RNA has no Thymine).

• Translation In the cytoplasm, on the ribosome,
  the mRNA codon matches tRNA anticodon to bring
  the proper amino acid in for bonding. Once the
  whole mRNA is read by the ribosome, the stop
  codon ends the production of the peptide chain
  the protein is complete!

18
How is RNA different than DNA?

• Ribose Sugar
• Uracil for Thymine
• Single strand
• not self replicating
• found all over the cell

19

• Nucleolus - Site of ribosome production
• Nucleus - location of DNA, cell organizer
• Chromosomes - coiled chromatin
• Chromatin - DNA and proteins not coiled
• DNA - helix shaped molecule with base sequences
  that make up the genetic code
• RNA - made by DNA, assists DNA to make proteins
  as a messenger (mRNA), transfer molecule (tRNA)
  and ribosomal RNA (rRNA).

20
END!