A powerpoint presentation for Mrs. Tabor's 7th grade science students. I have a FITB note sheet to accompany this presentation and would be happy to email it to you. Contact stabor@belgradeschools.com

1. What we already know:
• The nucleus contains DNA
• Eukaryotes have linear DNA
• Prokaryotes have circular DNA
• DNA is copied during Interphase of
the Cell Cycle

2. What we already know:
• Traits are distinguishing
features or
characteristics
• Traits are passed from
parent to offspring
• Traits are passed on
through genes
• Genes are specific
sections of DNA
• In sexual reproduction,
offspring get half of
their genes from each
parent

3. DNA is
INFORMATION
• DNA= deoxyribose
nucleic acid
• A molecule that
stores information
• Contains the
instructions for
making proteins
• Like a cookbook
contains the
instructions for
making a cake

4. Proteins and
Amino Acids
• Proteins are large
molecules made up of
chains of amino acids
• There are 20 different
amino acids that
combine into thousands
of different proteins
• Folding of the string of
amino acids is critical for
protein function

5. 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

6. Check for Understanding:
• What is the relationship between
proteins and amino acids?
• What is a trait?
• When is DNA copied?
• What is a gene?

7. Check for Understanding:
• What is the relationship between proteins and
amino acids?
• 20 amino acids come together in
various combinations to make proteins
• What is a trait?
• Distinguishing features or
characteristics
• When is DNA copied?
• During Interphase of the Cell Cycle
• What is a gene?
• A specific section of DNA that contains
the code for a protein

8. DNA & The Genetic Code
• DNA molecule is shaped like
a twisted ladder
• The molecule is formed from
nucleotide subunits that
consist of:
• Phosphate
• Sugar (Deoxyribose)
• Nitrogen Base

9. DNA & The Genetic Code
• The side rails of the
ladder are formed by the
sugar-phophates
• The rungs of the ladder
are formed by two bases
coming together
• There are four different
bases in DNA
• Adenine
• Thymine
• Cytosine
• Guanine
All Tigers Can Growl

10. Some comic relief…

11. DNA Structure Video

12. DNA & The Genetic Code
• The sequence (order) of
bases in a strand of DNA
makes the code for building
proteins
• The genetic code is a
“triplet” code meaning that
every three bases codes
for one amino acid
• A gene is the entire
sequence of bases that
codes for a specific protein
• Like a recipe for a
specific dish

13. Replication of the DNA
• Replication is the
copying of DNA
1. Two strands
separate
2. Free-floating
nucleotides match
up with the
nucleotides on each
strand
3. Two identical
molecules of DNA
are made

14. Watch Replication in Action
• This movie shows a computer animation of how DNA is replicated
Another video on YouTube

15. 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?

16. Check for Understanding
• What three components make up the nucleotide
subunit?
• Phosphate, Sugar, Nitrogen Base
• What are the four bases and what is the rule
about how they pair together?
• Adenine pairs with Thymine
• Cytosine pairs with Guanine
• Describe what is meant by a “triplet code.”
• Three bases code for one amino acid
• What are the steps of DNA replication?
1. Strands separate
2. Nucleotides pair up
3. Two identical strands are made

17. RNA is needed to make proteins:
• RNA is ribonucleic acid and
is very similar to DNA
except:
1. RNA has ribose sugar
instead of deoxyribose
sugar
2. RNA has Uracil instead
of Thymine
3. RNA is a single strand

18. RNA is needed to make proteins:
• EUKARYOTES: RNA copies the information from the
DNA inside the nucleus then travels outside to the
cytoplasm
• PROKARYOTES: RNA and proteins are made in the
cytoplasm

19. 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)
• mRNA carries the message or code
outside the nucleus
• rRNA makes up part of the ribosome
• tRNA brings the correct amino acids
to the ribosome for protein
construction

20. Check for Understanding
• How is RNA different from
DNA?
• What are the three types of
RNA involved in making
proteins?

21. Check for Understanding
• How is RNA different from DNA?
1. RNA has ribose sugar instead of
deoxyribose sugar
2. RNA has Uracil instead of Thymine
3. RNA is a single strand
• What are the three types of RNA involved in
making proteins?
1. messanger RNA (mRNA)
2. ribosomal RNA (rRNA)
3. transfer RNA (tRNA)

22. • Transcription produces a
Transcription 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

23. • Transcription is different than
Transcription 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
• Transcription on YouTube

24. Check for understanding
• What are the steps of transcription?
• How is transcription different than
replication?

25. Check for understanding
• What are the steps of transcription?
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
• How is transcription 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

26. 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!

27. Translation • 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

29. Brain Break!
• Link to Translation
Video
• Another video that
reviews Translation
and Transcription

30. 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

31. The Central Dogma
• The process of making
proteins is the same in all
cells
• This is the foundation of
molecular biology,
biochemistry, and genetics
Transcription Translation
DNA RNA Protein
Another YouTube video!

32. 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?

33. Check for understanding
• Where does translation occur?
• In the cytoplasm
• Which RNA makes up the ribosome?
• rRNA
• Which RNA is the “recipe?”
• mRNA
• Which RNA does the actual translation of bases
into amino acids?
• tRNA
• What is the “central dogma” of molecular biology?
Transcription Translation
DNA RNA Protein

34. 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)

35. The Universal Genetic Code

36. The Universal Genetic Code

37. Check your answers:
• Replication:
• T-A-C-T-G-C
• Transcription
• A-U-G-A-C-G
• Translation
• Met (Methionine) and Thr (Threonine)

38. A HISTORY OF DNA
•(1928) Frederick Griffith
•Discovers that a “transforming factor”
changes harmless bacteria into deadly
bacteria
•(1952) Rosalind Franklin
•Takes x-ray photographs of DNA
•(1953) James Watson and Francis Crick
•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