Download PP Notes DNA continued

DNA Continued
(Deoxyribonucleic Acid)
Genetic material of cells…
• GENES – units of genetic material that
CODES FOR A SPECIFIC TRAIT
• Like for eye color or hair color.
• Genes located on chromosomes
• DNA is made up of repeating molecules
called NUCLEOTIDES
Genetic Diversity…
• Different arrangements of NUCLEOTIDES
in a nucleic acid (DNA) provides the key
to DIVERSITY among living organisms.
The Code of Life…
• The “code” of the chromosome is the
SPECIFIC ORDER that bases in the
nucleotides occur.
A T C G T A T G C G G…
See p. 332
DNA is wrapped tightly around
histones and coiled tightly to form
chromosomes
DNA Replication
• During Interphase
• DNA must be copied
• The DNA molecule produces
2 IDENTICAL new
complementary strands
following the rules of base
pairing:
A-T, G-C
DNA Replication
• Each strand of the
original DNA serves
as a template for the
new strand
• See page 334
DNA Replication
The two strands of the
parental molecule
separate, and each
functions as a template
for the making of a new
complementary strand.
.
DNA Template
Parental DNA
New DNA
Steps in Replication
1. An enzyme called DNA Helicase unwinds
and unzips the DNA molecule
Steps in Replication
2. An enzyme called DNA Polymerase attaches to
the parent DNA molecule in several different
spots. It inserts the complementary bases,
making two copies of the DNA molecule
Speed of Replication
Prokaryotes have a single
circular strand of DNA to
replicate. This takes about 40
minutes.
Speed of Replication
Eukaryotes if their DNA was done by
one polymerase molecule per
chromosome would take about a month
for the DNA to replicate.
Multiple polymerase latch on the
replicating DNA simultaneously and as
a result replication in humans takes
about an hour.
Replication Quiz
A---?
G---?
C---?
2. When does replication occur?
T---?
3. Describe how replication works. A---?
G---?
A---?
4. Use the complementary rule to
G---?
create the complementary
C---?
strand:
A---?
G---?
T---?
1. Why is replication necessary?
Replication Quiz
A---T
1. Why is replication necessary?
G---C
So both new cells will have the correct
C---G
DNA
T---A
A---T
2. When does replication occur?
G---C
During interphase (S phase).
A---T
G---C
3. Describe how replication works.
C---G
Enzymes unzip DNA and complementary
A---T
nucleotides join each original strand.
G---C
4. Use the complementary rule to
T---A
create the complementary strand:
What is the purpose of DNA?
• DNA controls cell function by serving as a
template (blueprint) for PROTEIN
structure. (Remember Proteins made of
amino acids.)
What do proteins do?
• Proteins are found everywhere .... every
nook and corner in the cell .. most things
are made from proteins as well
The processes to make proteins
We need RNA
• Single stranded nucleic acid
• Sugar in the nucleotide is
RIBOSE not deoxyribose
• Uracil replaces Thymine in the
base pairs.
Types of RNA
Messenger RNA
mRNA
Carries code from DNA to ribosomes to
make proteins
Ribosomal RNA
Makes up the ribosome
rRNA
Transfer RNA
“grabs” the amino acids from the
cytoplasm to make proteins
tRNA
Transcription
• DNA can “unzip”
itself and RNA
nucleotides
match up to the
DNA strand.
mRNA is produced by a
process known as :
Transcription
Making proteins
Anticodon: three
complementary
nucleotides on tRNA
Codon: (Three
nucleotides on
mRNA)
How are Proteins made?
• By reading the codon (3 nucleotides in a row) on
the mRNA by the ribosome RNA.
• Then matching the codon with the anticondon (3
opposite nucleotides) on the tRNA
• The tRNA is carrying an amino acid which then
links together with other amino acids.
• Called Translation
Translation
• The cell uses
information from
“messenger”
RNA to produce
proteins
1.
2.
3.
4.
5.
6.
Transcription/Translation Quiz
Why is transcription necessary?
Describe transcription.
Why is translation necessary?
Describe translation.
What are the main differences
between DNA and RNA.
Using the chart on page 338,
identify the amino acids coded for by
these codons: UGGCAGUGC
1. Why is transcription necessary?
Transcription makes messenger RNA (MRNA)
to carry the code for proteins out of the
nucleus to the ribosomes in the cytoplasm.
2. Describe transcription.
RNA polymerase binds to DNA, separates the
strands, then uses one strand as a template to
assemble MRNA.
3. Why is translation necessary?
Translation assures that the right amino acids
are joined together by peptides to form the
correct protein.
4. Describe translation.
The cell uses information from MRNA to
produce proteins.
5. What are the main differences between
DNA and RNA.
DNA has deoxyribose, RNA has ribose;
DNA has 2 strands, RNA has one strand;
DNA has thymine, RNA has uracil.
6. Using the chart on page 303, identify the
amino acids coded for by these codons:
UGGCAGUGC
tryptophan-glutamine-cysteine
AMAZING DNA FACTS…
• DNA from a single human
cell extends in a single
thread for almost 2 meters
long!!!
• It contains information
equal to some 600,000
printed pages of 500 words
each!!!
(a library of about 1,000
books)