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DNA
Jitka Trtílková
Martin Nejezchleb
DNA-deoxyribonucleic acid
• Genetic information is
stored in the molecule of
deoxyribonucleic acid, or
DNA.
• DNA is found in most living
organisms (except viruses).
• DNA resides in the nucleus
of living cells.
store = uložený
Structure of the DNA
In the 1950 four scientists (James Watson,
Francis Crick, Maurice Wilkins and Franklin)
determined the true structure of DNA from
data and X-ray pictures of the molecule. In
1953, Watson and Crick published this
research.
The true structure of the DNA molecule is a
double helix, as shown at right.
Strands of double helix are made from
monomers that are called nucleotides.Each
monomer consists of threecomponents:
a nitrogenous heterocyclic base, a pentose
sugar (2-deoxyriboses), and a phosphate
group. The nitrogenous bases are: adenine,
cytosine,guanine and thymine.
strand = vlákno
double-helix = dvou vláknová šroubovice
consist = skládat se
Nitrogenous bases
The nucleotide bases
of the DNA molecule
form complementary
pairs:
Adenine - Thymine
Guanine - Cytosine
Deoxyribonucleotide
Bonds in molecule of DNA :
Between sugar and phosphate group is ester bond.
Between sugar and nitrogenous base is N-glykosidic
bond.
Two strands in double-helix are bonded by hydrogen
bonds between complementary bases.
DNA - the source of heredity
• The double helix of DNA controls
heredity on the molecular level. The
hereditary information is stored as
the sequence of bases along the
polynucleotide chain. DNA
preserves this information, and uses
it. It does this through two ways:
• DNA molecules can duplicate
themselves, in a process called
replication.
• DNA molecules control the
synthesis of the proteins. Processes
of protein biosynthesis are
transcription and translation.
heredity = dědičnost
chain = řetězec
preserve = uchovávat
DNA replication
Before a cell can divide, it
must duplicate all its DNA.
The Steps of DNA replication:
1) A portion of the double helix is
unwound. Enzyme that catalyze
unwinding of DNA is a DNA
polymerase.
2) A molecule of the DNA polymerase
binds to one strand of the
DNA.This strand is called template
strand. DNA polymerase "read" the
sequence of bases on the template
strand and then "synthesize" the
complementary strand.
3) In the end there are two new
identical molecules of the DNA.
divide = rozdělit se
unwind = rozplést, rozmotat
template = vzor
DNA replication
Transcription
Transcription is the process
through which a DNA
sequence is enzymatically
copied by an RNA polymerase
to produce a complementary
mRNA (messenger RNA).
It is highly analogous to DNA
replication.
Transcription is the beginning
of the process that leads to the
translation of the genetic code
into a functional peptide or
protein.
Transcription = DNA → mRNA
Messenger = posel, kurýr
Translation
Translation is the second process of
protein biosynthesis. The mRNA
carries genetic information
encoded as a ribonucleotide
sequence from the chromosomes
to the ribosomes. The
ribonucleotides are "read" by
translational machinery in a
sequence of nucleotide triplets
called codons. Each of those
triplets codes for a specific amino
acid. The ribosome and tRNA
(transfer RNA) translate this code
to produce proteins.
Translation = mRNA → protein
encoded = zakódovaný
DNA Fingerprinting
Because DNA has unique
structure, it can be used as
a means of identification.
DNA can be extracted from
organic remains (blood,
saliva, etc) left at crime
scenes to identify the
criminal. It can also be used
to determine parentage, the
gender of animals and birds
(where it is difficult to do so
by just looking at them).
This process is called DNA
fingerprinting.
means = prostředek
remains = zbytky
saliva = slina
parentage = původ
gender = pohlaví
Thank you for your attention!