Transcript DNA Structure and Function

DNA Structure and
Function
What we already know:
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The ____________ contains DNA
Eukaryotes have linear DNA
Prokaryotes have circular DNA
DNA is copied during ___________
of the Cell Cycle
What we already know:
• _________ are distinguishing features or
characteristics
• Traits are passed from _______ to ________
• Traits are passed on through _________
• _______ are specific sections of DNA
• In sexual reproduction, offspring get ______
of their genes from each parent
DNA is INFORMATION
• DNA= _________________
• A molecule that _____________
information
• Contains the instructions for making
___________________
• Like a cookbook contains the
instructions for making a cake
Proteins and
Amino Acids
• _________ are large molecules made up of
chains of amino acids
• There are _____ different amino acids that
combine into thousands of different proteins
• Folding of the string of amino acids is critical for
protein function
Proteins and
Amino Acids
• Proteins can vary in size from
just 20 amino acids, like this
one found in Gila Monster
saliva…
To this protein
nicknamed
“Titan” with
34,350 amino
acids, found in
human muscle
tissue
Check for Understanding: write
answers in your ISN
• What is the relationship between
proteins and amino acids?
• What is a trait?
• When is DNA copied?
• What is a gene?
DNA & The Genetic Code
• DNA molecule is shaped like
a twisted _________
• The molecule is formed from
nucleotide subunits that
consist of:
• _________________
• _________________
• _________________
DNA & The Genetic Code
• The side rails of the
ladder are formed by the
___________________
• The rungs of the ladder
are formed by ________
coming together
• There are four different
bases in DNA
• A____________
• T____________
• C____________
• G____________
DNA & The Genetic Code
• The sequence (order) of
bases in a strand of DNA
makes the code for building
__________________
• The genetic code is a
“triplet” code meaning that
every _________ bases
codes for one amino acid
• A ________ is the entire
sequence of bases that
codes for a specific protein
• Like a recipe for a
specific dish
Replication of the DNA
• Replication is the
copying of DNA
1. Two strands
________________
2. Free-floating
nucleotides match
up with the
nucleotides on each
strand
3. Two ___________
molecules of DNA
are made
Check for Understanding
• What three components make up the
nucleotide subunit?
• What are the four bases and what is the rule
about how they pair together?
• Describe what is meant by a “triplet code.”
• What are the steps of DNA replication?
RNA is needed to make proteins:
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RNA is ribonucleic acid and
is very similar to DNA
except:
1. RNA has _______ sugar
instead of deoxyribose
sugar
2. RNA has _________
instead of Thymine
3. RNA is a __________
strand
RNA is needed to make proteins:
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_____________: RNA copies the information from the
DNA inside the nucleus then travels outside to the
cytoplasm
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______________: RNA and proteins are made in the
cytoplasm
RNA is needed to make proteins:
• Three different types of RNA are
involved in making protein:
• messanger RNA (mRNA)
• ribosomal RNA (rRNA)
• transfer RNA (tRNA)
• _______ carries the message or
code outside the nucleus
• _______ makes up part of the
ribosome
• _______ brings the correct amino
acids to the ribosome for protein
construction
Check for Understanding
• How is RNA different from
DNA?
• What are the three types of
RNA involved in making
proteins?
Transcription
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Transcription produces a
single-stranded molecule of
RNA
One strand of DNA is the
template or pattern
The steps of transcription
are:
1. The DNA molecule
opens up along a gene
2. RNA nucleotides
(A,U,C,G) match up and
join the open DNA
strand
3. The complete RNA
strand is released and
moves to the cytoplasm
Transcription
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Transcription is different than
replication:
1. Only one strand of
DNA is transcribed so
only one strand of
mRNA is produced
2. The mRNA is
released, it does not
stay attached to the
DNA
3. Many copies of mRNA
can be made from a
single gene in a short
period of time
Check for understanding
• What are the steps of transcription?
• How is transcription different than
replication?
Translation
• Translation is how cells
TRANSLATE the language
or code of nucleotide bases
into the language of amino
acids
• Translation occurs in the
cytoplasm at the ribosome
• If DNA is the cookbook, and
mRNA is the recipe, then
the ribosome is the kitchen
and tRNA is the chef!
Translation
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rRNA is part of the
ribosome that attaches to
the mRNA
tRNA has a triplet of bases
on one end and can attach
to a single amino acid on
the other end
tRNA does the translation
of bases to amino acids
when it matches up with
mRNA
Translation
1. Translation begins when a ribosome attaches to the
beginning of an mRNA molecule
2. A tRNA molecule carrying an amino acid matches up to a
complementary triplet on mRNA on the ribosome
3. The ribosome attaches one amino acid to another as it
moves along the mRNA molecule
4. The tRNA molecules are released after the amino acids they
carry are attached to the growing chain of amino acids
5. The ribosome completes the translation when it reaches the
end of the mRNA strand and the newly made protein
molecule is released
The Central Dogma
• The process of making
proteins is the same in all
cells
• This is the foundation of
molecular biology,
biochemistry, and genetics
Translation
Transcription
DNA
RNA
Protein
Check for understanding
• Where does translation occur?
• Which RNA makes up the ribosome?
• Which RNA is the “recipe?”
• Which RNA does the actual translation of
bases into amino acids?
• What is the “central dogma” of molecular
biology?
Replication, Transcription,
Translation Challenge!
• Copy this DNA sequence:
• A-T-G-A-C-G
• Write the base pairs of the complimentary
strand of DNA (replication)
• Write the complimentary mRNA strand to
your new strand (transcription)
• Use the chart to find the correct amino
acids that the tRNA would attach to the
protein (translation)
The Universal Genetic Code
A HISTORY OF DNA
•(1928) __________________________
•Discovers that a “transforming factor”
changes harmless bacteria into deadly
bacteria
•(1952) ________________________
•Takes x-ray photographs of DNA
•(1953) ____________ and ______________
•Use Franklin’s images to describe the
structure of DNA
•(1962) Watson, Crick, and Wilkins win the Nobel
Prize, Franklin has already died from cancer
(1958) so she does not get recognition