Download powerpoint notes

Nucleic Acids
• Large polymers
• Made of linked nucleotides
• Components of a nucleotide?
• A nucleotide consists of a 5-carbon
sugar, phosphate group, nitrogenous
base
2 types
DNA / RNA structure
DNA
Sugar
Nitrogenous
bases
Shape
RNA
• DNA is
anti-parallel
One strand is
“flipped” in
relation to
the other
Fig. 8-5
CELL CYCLE IN EUKARYOTIC
CELLS
INTERPHASE
G1
First gap phase
-growth
-normal cell activities
S
(DNA synthesis)
-DNA copies (replicates)
itself
G2
Second gap phase
-growth
-cell prepares for mitosis
Mitosis = division of the nucleus
Cytokinesis = division of the cytoplasm
Two strands
separate
Nucleotides come
and pair with their
complementary
base
DNA replication
Semi-conservative
replication
The new strand
consists of one
old DNA and one
new DNA strand
DNA replication starts at an origin of
replication (many in eukaryotes)
forming replication bubbles
Enzymes involved in replication
• Helicase  unwinds the double helix
• DNA polymerase  builds the new DNA
strand
• DNA ligase “glues” DNA fragments
together
DNA Polymerase
• Adds nucleotides to a growing
nucleic acid chain
• Can ONLY add to the 3’ end of
the chain
–Result:
–The two sides of the DNA molecule
are copied differently
Function of DNA?????
But where is eukaryotic DNA found?
Where are proteins built?
Central idea of
genetics
Flow of genetic
information in
organisms
Trait
template
Where would
this occur?
Where would
this occur?
Structure of a
chromosome
made up of DNA
and Protein
many genes on
single chromosome
Structure of a gene
3 types of RNA
all coded for by the
DNA in the nucleus
tRNA
•Transfer RNA
mRNA
• Messenger RNA
rRNA
• Ribosomal RNA
Process of Transcription
Step 1 Initiation
•The promoter is sequence of DNA recognized by
RNA polymerase
•Determines which of the two strands will act as the
template
Step 2: Elongation
RNA polymerase moves down the DNA elongating the mRNA
strand based on the sequence in DNA
RNA will use
Uracil to base pair
with Adenine
Step 3: Termination
When RNA polymerase reaches the terminator region on the
DNA it will stop and release the mRNA
template
Codon:
3 nucleotide
sequence
that specifies
one amino
acid or
signals
translation to
stop
Who are the players
in translation??
mRNA
tRNA
Ribosomes (made of
protein and rRNA)
mRNA
tRNA
Ribosome
Made of rRNA and Protein
Large subunit
Initiation of Translation
Elongation of the polypeptide chain
Termination
Met - Gln - Arg - Cys
RNA processing in Eukaryotic cells
Prokaryotic cell
•No RNA processing
•Transcription and translation may occur
simultaneously
AIDS research
Malaria
Recently, scientists engineered
several rhesus macaques to
express GFP, along with a protein
that pre-disposes the animals to
Huntington's disease, a
neurodegenerative disorder. The
researchers used GFP to confirm
that the monkeys had received the
disease-causing gene
Prokaryote
• transcription and translation can occur simultaneously
• no nucleus
Prokaryotic cell
•Transcription and translation may occur
simultaneously
•No RNA processing
Two strands
separate
Nucleotides come
and pair with their
complementary
base
DNA replication
Semi-conservative
replication
The new strand
consists of one
old DNA and one
new DNA strand
Enzymes involved in replication
• Helicase  unwinds the double helix
• DNA polymerase  builds the new DNA
strand
• DNA ligase “glues” DNA fragments
together
DNA Polymerase
• Adds nucleotides to a growing
nucleic acid chain
• Can ONLY add to the 3’ end of
the chain
–Result:
–The two sides of the DNA molecule
are copied differently