DNA
Chromosomes: structures in the nucleus that are made of
DNA and proteins
DNA is located in the Nucleus on Chromosomes
DNA contains all the information a cell
needs to live. It carries the "blueprints"
for making proteins within a cell.
DNA History:
Rosalind Franklin - X-ray photo of
DNA. (1952)
Watson and Crick - described the
DNA molecule from Franklin’s X-ray. (1953)
DNA: Double Helix made of a repeating unit called: Nucleotide
4 Nitrogenous Bases:
Adenine
Guanine
Cytosine
Thymine
DNA: 2 long strands of nucleotides are arranged in a
specific way called:“Complementary Rule”:
(specific pairing between the nitrogen bases)
DNA
1.
2.
3.
ADENINE – THYMINE
CYTOSINE - GUANINE
Replication:
DNA molecule uncoils and unzips.
Each strand of the original DNA serve as a
template for the new strands.
2 new IDENTICAL DNA molecules form.
RNA: Ribonucleic Acid
Single stranded molecule formed by a sequence of nucleotides
Sugar molecule: Ribose.
RNA Bases: Adenine, Cytosine, Guanine, Uracil. (NO THYMINE
IN RNA)
3 types of RNA:
1. messenger RNA (mRNA)
2. Transfer RNA (tRNA)
3. Ribosomal RNA (rRNA)
AIM: What is RNA synthesis?
For a gene to make a protein it must first give the instructions to
mRNA in a process called: DNA Transcription
RNA Synthesis:
DNA “unzip” itself and RNA nucleotides match up to the
DNA strand.
mRNA: copies the message from the DNA in the nucleus and
carry the message to the ribosome.
tRNA-Transfer: RNA brings the correct Amino Acid to the
ribosome from the cytoplasm as it reads the mRNA.
The assembly of
the amino acids
that takes place at
the ribosome
Protein Synthesis
DNA provides the code to make RNA
mRNA attaches to the ribosome
tRNA read the message of mRNA
Amino Acids are added to the growing protein
Mutations: changes in the DNA sequence that affects genetic
information.
Most mutations are harmful, but some can be beneficial to the
organism
Chromosomal mutation: changes in the number or shape of
chromosomes
Gene mutation: random changes in the nucleotides.
Many mutations are harmful to organisms, often causing their death.
Some have no effect and some are beneficial
Genetic Engineering: move sections of DNA (genes) from one
organism to another so that it produces useful biological products.
"Recombinant DNA"
Gene Therapy: The potential of replacing a defective gene in
a human with a normal functioning gene. Ex: cystic fibrosis.