DNA- The Genetic Material
Why should I care about DNA?
•DNA stores the information that
tells cells which _______ to make
•Your proteins give you your
_________________________
•Your DNA is _____________from
everyone else’s DNA on earth
Does DNA have anything to do with
why I am so special?
•_______, it’s the
variability of DNA
that makes us all
different!
Who Discovered the Structure
of DNA?
___________________________ discovered the
structure of DNA after observing an X-ray picture of
it taken by ___________________________
The Structure of DNA
DNA is composed of __ connected
________________________
________________ backbone, with
_____________ in the middle
4 Bases
Adenine Guanine
Cytosine Thymine
Bases complement one another
___ bonds to ___, ___bonds to ___
(bases bond together by ___________ bonds)
The two strands are _____________ together
Structure of DNA
Additional DNA Facts
•Shape of DNA is a ____________ (a Twisted Ladder)
•Sugar in DNA = _________________
•1 base + 1 phosphate + 1 sugar = _______________
Nucleotide
Deoxyribose
DNA Replication
Why does DNA replicate?
•Cells get ___________, new cells must be ________
•New cells must make _____________ of themselves
•Copies of replicated genes can be passed on to
________________
How is DNA Replicated?
1. _______________ breaks hydrogen bonds in the
middle of the strand, creating a ______________
2. Unpaired bases form new bonds with free
_______________ in the cell
3. New strand is rewound together by_________
_____________, creating 2 identical DNA molecules
Sometimes replication errors make a __________ (A
bonds to a G); DNA polymerase usually proofreads
the strand
There are ______________ bases in the average cell
DNA Replication
DNA Replication
Transcription
DNA is the material used to make ______________
DNA is located in the _____________ of the cell
Proteins are made in structures called
_________________, in the cytoplasm of the cell
DNA _________________ leave the nucleus of the
cell because it is double stranded
Transcription
Mr. DelPrato I am afraid for the DNA, it
can’t get to the ribosome! What I am to
do?
Relax, _______ is the key!
What is RNA?
•A nucleic acid that is _________________
•_______________ is the sugar
•Instead of thymine, _________________
•_________________ stranded
Steps of Transcription
1. DNA strand ___________________________
2. Free nucleotides bond to bases, except ____ in
RNA bonds to _______ from DNA
3. _______________________________ joins
single stranded RNA together
4.________________________ moves to the
ribosome in the cytoplasm (or on the Rough ER)
Transcription
2 Models of Transcription
Transcription
Animation of Transcription!
http://www.johnkyrk.com/DNAtranscription.html
Translation (Protein Synthesis)
What is protein synthesis?
The Conversion of RNA to
____________, which make up
proteins
Why is it called translation?
The genetic code (ATCG) is
_______________________
Globular Protein found in Human Blood
(serum albumin)
Where does it occur?
At the ____________________________
How Does it Happen?
1. Initiation
A. Ribosome _______________ to mRNA
B. tRNA brings _____________ and AA to ribosome
2. Elongation
A. More tRNA’s bring more ____________________
B. AA’s connected together to make ____________
3. Termination
A. Ribosome reaches a _______________________
B. Polypeptide (_____________) is broken off and becomes
part of the ______________________
C. Golgi apparatus ______________ completed protein; ER
________________ it in/out of cell
Translation- The Movie
Translation Animation Part 2!
Translation Animation
The processes of transcription
and translation are the same in
all living organisms!
Blue Whale
Tarantula
Gene Mutations
Definition - a _________________________of bases
within a gene
Causes –
• Mutations can be spontaneous or caused by
environmental influences called _____________.
• Mutagens include radiation (X-rays, UV radiation),
and organic chemicals (in cigarette smoke and
pesticides).
Types of Mutations
Frameshift mutations –
•one or more bases are ________________from
a sequence of DNA
•can result in nonfunctional proteins
•can result in no protein at all – stop codon where
there shouldn’t be one
Point mutations (3 Types) –
•One base is __________________ for another
•May result in change of amino acid sequence
•May not affect protein at all
Types of point mutations
1. Silent mutation - the change in the codon results in the
____________________________
Ex: UAU  UAC both code for tyrosine
2. Nonsense mutation - a codon is changed to a ________
_______________; resulting protein may be too short to
function
Ex: UAC  UAG (a stop codon)
3. Missense mutation - involves the substitution of a
______________________, the result may be a protein
that cannot reach its final shape
Ex: Hbs which causes sickle-cell disease
Repair of Mutations
DNA polymerase ______________________against
the old strand and detects mismatched pairs,
reducing mistakes to one in a billion nucleotide pairs
replicated.
If errors occur in sex cells – mutation may be passed
onto offspring
If errors occur in body cells - cancer may result