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DNA Basics
Deoxyribonucleic Acid
Every living organism has DNA.
Every living thing has
it’s own unique DNA.
But DNA is DNA and…
According to Nat Geo
we share 96% of the
DNA chimps have
and share 50% with
a banana.
Watson and Crick figured out the structure of the
DNA molecule.
But it was Rosalyn Franklin who had the
photograph that made everything make
sense.
Stolen Photo - 51
DNA is found in the nucleus.
DNA is found only in the nucleus, it is so important it
can’t leave the nucleus.
-------ever--------
Your DNA is your blueprint or building instructions.
It is your complete instruction manuel for how to build,
repair and replace you.
(Your DNA codes for building proteins.)
A rose by any other name…
Romeo and Juliet
1. DNA by any other name...
2-3.Chromatin
4. Chromosomes
5. Sister Chromatids
• Deoxyribonucleic Acid
...will still carry your code.
How is DNA structured?
The entire molecule is
twisted into a double
helix.
DNA is a polymer made of
monomers called nucleotides.
• Larry the Cable guy
would just say
something like this...
• It’s som’n perdy big that’s
made from lots of little
bitty things that are perdy
small.
• But it’s all perdy small
really.
• Yor teacher said learn it.
The nucleotides are
composed of 3 things:
• Phosphate group
• Deoxyribose sugar
• Nitrogen base
Nitrogen Bases are :
Adenine, Thymine, Guanine, and Cytosine
A-T
G-C
The DNA backbone is
made of a Sugar and
a phosphate.
The steps of the ladder
are the nitrogen
bases that are held
together by weak
HYDROGEN BONDS
(Hydrogen high-school
heartbreak bonds –
easily broken.)
Replication:
If something needs repair or you
just need more.
• DNA unzips and makes
an exact copy of itself
during interphase of the
cell cycle.
If your body needs to build
something it is called
protein synthesis.
• Synthesis (putting something together)
Why is protein important to me?
All livings need protein
for…everything…
80 % of every cell is
made of protein.
Enzymes speed up
reactions.
Hormones send signals.
DNA needs to make a protein
but DNA doesn't speak the
language that proteins speak.
english
and
You have to have a translator
arabic
1 strand / 2strands
mRNA
1. one strand
2.
AUGC
3. Ribose
DNA
two strands
ATGC
Deoxyribose
There are 2 steps
in protein synthesis
Transcription – a script is a copy.
Translation – late..this is the last part.
Transcription (part 1)
•DNA strand stays in the nucleus
•DNA unzips (enzyme called polymerase)
•mRNA comes into the nucleus and makes a
copy because DNA cannot leave the nucleus.
• MRNA uses a nitrogen base called uracil.
•mRNA takes a copy to a ribosome in the
cytoplasm.
•DNA zips back up and you have the original and
a copy too.
Questions
• What makes a copy of the
DNA?
• Where is the copy made?
• Where is the copy taken?
• What sugar is in DNA?
RNA?
• Why can DNA not leave the nucleus?
• What are the 3 differences between DNA
and RNA?
• DNA strand is…
GTCATACCA
mRNA strand is ?
Translation (part2)
tRNA is the worker. It carries amino acids but it
only reads in 3’s
It translates mRNA into short a 3 letter words.
mRNA has the real code
tRNA has the matching code (or anticode) that matches the
correct amino acid.
rRNA
All of this happens at the ribosome or the
rRNA.
• One by one these tRNA bring amino
acids to link into a protein chain
according to the DNA instructions.
• How amazing is that?
• Should we be clapping now?
Review the steps of Protein Synthesis
1. Transcription (writing the “message”)
􀂾DNA ►mRNA messenger carries code
2. Translation (reading the “message”)
􀂾mRNA ►tRNA►protein (AA chain)
message translated into a protein
messenger carries code
to cytoplasm
to cytoplasm
DNA Replication
DNA unwinds and
makes a copy.
(It’s that simple.)
This creates a replication bubble to copy only what
is needed.
For making big copies the DNA will start copying at
different places at the same time to work faster.
Mutations
are not always bad.
Mutations can be caused by
• Errors in replication
(DNA-DNA)
• Errors in transcription (DNA-RNA)
• Cell Division – (Cancer)
• External Agents – UV radiation, chemicals,
smoking
Mutation Types
1. Point mutation
• The dog bit the cat.
• The dog bit the car.
• Only one letter is changed but the
meaning is very different.
• www.ygyh.org/cf/cause.htm
Mutation Types
2. Frameshift Mutation
• The dog bit the cat.
• The dob itt hec at.
• The “g” is lost but everything is still read in
groups of 3’s.
• Since the language of DNA is in codons
(groups of 3 nucleotides) it can only
translate in 3’s.
• Point Mutations – changes in one or a few
nucleotides
Substitution
THE FAT CAT ATE THE RAT
THE FAT HAT ATE THE RAT
Insertion
THE FAT CAT ATE THE RAT
THE FAT CAT XLW ATE THE RAT
Deletion
THE FAT CAT ATE THE RAT
Glencoe 347
THE FAT ATE THE RAT
sickle cell (ygyh)
338 codon chart
Chromosome Mutations
Changes in number and structure of
entire chromosomes
Original Chromosome ABC * DEF
Deletion
AC * DEF
Duplication
ABBC * DEF
Inversion
AED * CBF
Translocation
ABC * JKL
GHI * DEF
Translocation
Significance of Mutations
•Most are neutral
• Eye color
• Birth marks
•Some are harmful
• Sickle Cell Anemia
• Down Syndrome
•Some are beneficial
• Sickle Cell Anemia to Malaria
• Immunity to HIV
Originally, we all had brown eyes”, said
Professor Eiberg from the Department of
Cellular and Molecular Medicine. “But a
genetic mutation affecting the OCA2 gene
in our chromosomes resulted in the
creation of a “switch”, which literally “turned
off” the ability to produce brown eyes”.
Nature shuffles our genes
The mutation of brown eyes to blue
represents neither a positive nor a
negative mutation. It is one of
several mutations such as hair
colour, baldness, freckles and
beauty spots, which neither
increases nor reduces a human’s chance of
survival.
University of Copenhagen (2008, January
31). Blue-eyed Humans Have A Single,
Common Ancestor. ScienceDaily. Retrieved
February 27,