Biology Journal 10/14/2013
What do the letters in the
acronym DNA stand for?
Deoxyribonucleic Acid
What are the 4 most commonly
occurring elements in living things?
Carbon, Hydrogen, Oxygen, Nitrogen
What 5 elements are found in DNA?
Carbon, Hydrogen, Oxygen, Nitrogen,
Phosphorous
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3.3 DNA Structure
Assessment statement
3.3.1 Outline DNA nucleotide structure in terms of sugar
(deoxyribose), base and phosphate.
3.3.2 State the names of the four bases in DNA.
3.3.3 Outline how DNA nucleotides are linked together by covalent
bonds into a single strand.
3.3.4 Explain how a DNA double helix is formed using
complementary base pairing and hydrogen bonds.
3.3.5 Draw and label a simple diagram of the molecular structure of
DNA. An extension of the diagram in 3.3.3 is sufficient to show
the complementary base pairs of A–T and G–C, held together
by hydrogen bonds and the sugar–phosphate backbones.
DNAyeeeeeee
What do you call these types of carbohydrates?
A
Disaccharide
B Monosaccharide
C
Disaccharide
D Polysaccharide
What is the name of these carbohydrates?
A
Lactose
B Ribose
C
Sucrose
D Starch
+
→
+
H2O
What are the reactants of this reaction?
2 glucose molecules.
What are the products of this reaction?
Lactose and water.
What kind of reaction is this?
It is a condensation synthesis (it’s called
condensation because water is made from the OH
and H groups of the reactants)
The Parts of DNA
Deoxyribose: a monosaccharide,
or “sugar.” C5H10O4.
What is the difference between ribose
and deoxyribose?
Ribose
C5H10O5
Deoxyribose
C5H10O4
The Parts of DNA
Phosphate: PO4
The Parts of DNA
Deoxyribose and phosphate alternate to
make up the “sugar-phosophate
backbone.”
The Parts of DNA
The bases (aka nitrogenous bases, aka
nucleic acids, aka nucleotides)
• Adenine, cytosine, thymine, guanine
What is a hydrogen bond?
Hydrogen bonds are attractions between
positive and negative sides of
molecules.
A always pairs with T
C always pairs with G
A and G are larger, 2-ringed bases.
T and C are smaller, 1-ringed bases.
Thus, every base pair consists of a 1ringed base and a 2-ringed base.
How might this help find and correct errors
(mutations) in DNA?
A and T are joined by 2 hydrogen bonds.
G and C are joined by 3 hydrogen bonds.
How might this help find and correct errors
(mutations) in DNA?
DNA Can be represented in many ways…
Which of the following are not
found in pairs?
Adenine and
Thymine
Dookies
Twins
Aces
Thymine and
Cytosine
Deoxyribose
Phosphate
A
T
G
C
Hydrogen bonds
Where’s the
base pairs?
Where’s the
backbone?
The double helix is a twisted ladder
shape that helps the DNA take up
less space.
Histones are a
protein that the DNA
wraps around to take
up less space
The way that DNA wraps
around histones is called the
“pearl necklace” shape.
Histones are like little stones
that the DNA wraps around.
How long
would this
ball of yarn
be if it
wasn’t
wrapped
around
something?
Histones are a
protein.
What is another
word for a
protein?
What are
proteins made
out of?
3.3 DNA Structure
Assessment statement
3.3.1 Outline DNA nucleotide structure in terms of sugar
(deoxyribose), base and phosphate.
3.3.2 State the names of the four bases in DNA.
3.3.3 Outline how DNA nucleotides are linked together by covalent
bonds into a single strand.
3.3.4 Explain how a DNA double helix is formed using
complementary base pairing and hydrogen bonds.
3.3.5 Draw and label a simple diagram of the molecular structure of
DNA. An extension of the diagram in 3.3.3 is sufficient to show
the complementary base pairs of A–T and G–C, held together
by hydrogen bonds and the sugar–phosphate backbones.
Biology Journal 10/15/2013
DNA is a huge molecule! There are 2
ways in which DNA compacts itself to
take up less space. What are they?
Biology Journal 10/15/2013
Standard 3.3.5 is “Draw and label a simple
diagram of the molecular structure of
DNA.” Can you do it?
3.3 DNA Replication
Assessment statement
3.4.1 Explain DNA replication in terms of unwinding the
double helix and separation of the strands by
helicase, followed by formation of the new
complementary strands by DNA polymerase.
3.4.2 Explain the significance of complementary base
pairing in the conservation of the base sequence of
DNA.
3.4.3 State that DNA replication is semi-conservative.
The two strands of DNA can be
separated, called unzipping.
•
Remember, the 2 strands are connected by hydrogen
bonds, which are much weaker than covalent bonds.
DNA Helicase is the enzyme that does
the unzipping. DNA Helicase un-does
the double helix.
In college, all the cool kids wear
ironic, pun-driven science t-shirts
DNA Helicase
Simplified
model
DNA Helicase
Space-filling
model
DNA Helicase
Model showing
-helixes and
-sheets.
DNA unzips during
replication (when
DNA copies itself)
When do you think your cells would
replicate their DNA?
Your cells replicate their DNA before they divide to make new
cells. They do this…
For routine replacement of cells (such as skin cells, blood
cells, stomach cells, etc)
When you grow or gain weight
When you are injured and need to replace dead cells
If one strand of DNA has these
base pairs, then what are the base
pairs on the complementary strand?
CTAATCGTATATAGTCC
GATTAGCATATATCAGG
In replication…
DNA helicase unzips DNA.
DNA polymerase adds in the
complementary (matching)
bases to each single strand,
creating 2 identical strands.
When DNA
replicates, the
new DNA
molecules both
consist of one
new strand and
one original
strand. This is
called semiconservative
replication.
It took scientists a while to figure out that DNA
replication was semi-conservative, as opposed
to some other pattern.
Your assignment:
•
•
•
•
Show DNA replication using the pieces provided.
Show at least 3 base pairs in the “starting DNA”
Show at least 2 base pairs in each “new strand of DNA”
Label:
–
–
–
–
–
Parent strand of DNA and New strands
DNA helicase
DNA polymerase
Hydrogen bonds
Each of the molecules in DNA (deoxyribose, phosphate, cytosine,
adenine, guanine, thymine)
• Define the job of:
– DNA helicase
– DNA polymerase
Biology Journal 10/15/2013
What are the names of the two most
important enzymes in DNA replication?
What does each one do?
DNA helicase: unzips DNA, making 2
single-strands.
DNA Polymerase: adds in new
complementary bases (and backbone) to
each single strand, making 2 complete
copies of DNA.
Biology Journal 10/17/2013
In DNA replication, what do you start
with?
DNA
What do you end with?
2 sets of the original DNA (through semiconservative replication)
What is the purpose of replication?
When cells divide, each new cells needs
a full set of DNA.
DNA Replication
• DNA helicase unzips the DNA
• DNA polymerase connects
together matching bases to
make 2 new strands.
Making
a copy
3.3 Transcription and Translation
Assessment statement
Compare the structure of RNA and DNA.
 names of sugars
 bases
 the number of strands
Compare the structure of RNA and DNA.
 names of sugars
 bases
 the number of strands
Outline DNA transcription in terms of the Outline DNA transcription in terms of the formation of an RNA strand
formation of an RNA strand complementary complementary to the DNA strand by RNA polymerase.
to the DNA strand by RNA polymerase.
Describe the genetic code in terms of
codons composed of triplets of bases.
Describe the genetic code in terms of codons composed of triplets of
bases.
Explain the process of translation, leading
to polypeptide formation.
 roles of messenger RNA (mRNA) and
transfer RNA (tRNA)
 codons and anticodons
 ribosomes and amino acids
Explain the process of translation, leading to polypeptide formation.
 roles of messenger RNA (mRNA) and transfer RNA (tRNA)
 codons and anticodons
 ribosomes and amino acids
Discuss the relationship between 1 gene
Discuss the relationship between 1 gene and 1 polypeptide. Originally, it
and 1 polypeptide. Originally, it was
was assumed that 1 gene would invariably code for one polypeptide,
assumed that 1 gene would invariably code many exceptions have been discovered.
for one polypeptide, many exceptions have
been discovered.
Transcription and
Translation
DNA has the “recipe” to make proteins.
A gene is a segment
of DNA that has the
instructions to make
a particular protein.
“Hmmm… how many teaspoons of
cytosine was I supposed to add?”
The base pairs on DNA
determine the amino
acids, and thus the
specific shape, that the
protein will have.
For example… we all have genes for hair color.
The base pairs on this DNA determines what
proteins are in our hair, and thus, what our hair
looks like.
Of course, you can
always change it later…
What does it mean
to be a translator?
What does it
mean to
transcribe
something?
What’s the difference between
DNA and RNA?
DNA Structure
•Deoxyribonucleic
acid
•Double stranded
•Uses thymine (T)
•Sugar used is
deoxyribose (C5H10O4)
RNA Structure
•Ribonucleic
acid
•Single stranded
•Uses uracil (U)
•Sugar used is
ribose (C5H10O5)
DNA and RNA comparison
When does your body need to make
different kinds of proteins?
Transcription and
translation is done
every time a cell
makes a protein.
Above: the
structural protein
collagen. This guy
will be making lots
of it soon to repair
his body.
Ancient Egypt was well known for its
scribes that made copies of documents.
Nowadays we
don’t really need
them, we have
copy machines…
Transcription is making a copy of the DNA onto
mRNA (messenger RNA). The enzyme that
makes it is called RNA polymerase.
Some people
transcribe
their homework
all the time.
mRNA is a temporary, disposable copy of DNA.
It’s sent from the nucleus to the ribosome.
DNA is permanent.
You don’t want to
change or mess with it.
RNA is a disposable copy.
If this was a chain of DNA, what
would the mRNA strand be?
CTGACTTAGATA
GACUGAAUCUAU
What does DNA have the
“recipe” to make?
DNA is the recipe to make protein!
What do
ribosomes
do?
Ribosomes make proteins!
What are proteins made out of? Why do
they have the shape that they have?
Proteins are made out of amino acids. The
different chemical properties of the amino
acids cause the chain to fold up in specific
ways.
Translation: mRNA goes to the ribosome,
and it is translated into an amino acid
sequence.
tRNA (transfer
RNA) brings the
correct amino
acid for every 3
base pairs.
The 3 bases on
tRNA is called an
anti-codon.
The 3 bases on mRNA
is called a codon.
How many different kinds of amino
acids are used in the human body?
Every 3 base pairs corresponds
to a different amino acid.
What amino acids does this mRNA code for?
AUG
UUA GAC CUC UGA
A translator puts information from one
language into another.
Translation puts the genetic code (AGTC’s)
into the code of amino acids.
What amino acids does this mRNA code for?
GUA AAA CUU CUA UAG
The translator
(ribosome and tRNA)
The scribe
(RNA polymerase)
Protein
DNA
mRNA
What do we call
this step?
What do we call
this step?
Transcription
Translation
Convert the DNA to mRNA
Then, Convert the mRNA to amino acids.
GCC TAT TCA CTA CTG
CGG AUA AGU GAU GAC
Argenine
Isoleucine
Serine
Aspartic Acid
What do we call this step?
Transcription
What do we call this step?
Translation
Aspartic Acid
Making a Protein
Making a Protein
This is called the central dogma of biology.
(That just means that it is a really
important idea)
Biology Journal 10/18/2013
Transcription
DNA helicase
RNA polymerase
Replication
DNA helicase
DNA polymerase
mRNA
Translation
Ribosome
tRNA
Protein
DNA
Happens in the nucleus
Happens in the cytoplasm /
at the ribosomes
Label each molecule (the pictures).
Label the process that makes each molecule (the purple arrows).
List the name of the enzymes / molecules that carry out each process.
Identify the location where each of these molecules / processes are.
This is called the central dogma of biology.
(That just means that it is a really
important idea)
Convert the DNA to mRNA
Then, Convert the mRNA to amino acids.
GTG TGA CTA GTT ATC
CAC ACU GAU CAA UAG
Histidine
Threonine
Aspartic Acid
Proline
What do we call this step?
Transcription
What do we call this step?
Translation
Stop
Biology Journal 10/21/13
Compare and contrast DNA and RNA in a Venn
diagram.
DNA
Both
RNA
Biology Journal 10/21/13
Compare and contrast DNA and RNA in a Venn
diagram.
DNA
Both
RNA
Has deoxyribose as
its sugar
Has a sugar
phosphate backbone
Has ribose as its sugar
Has the nitrogenous
base T
Has the nitrogenous
bases A, C, and G.
Has the nitrogenous
base U
Double stranded
Contains the genetic
code for proteins
Single stranded
Stays in the nucleus
Can leave the nucleus
Comes in 1 kind
Has several kinds:
mRNA, tRNA, and
rRNA
Cell membrane
Nucleus
Anti-codon
Cytoplasm
Codon
DNA
Transcription
mRNA
Translation
Protein
or
Polypeptide
(this is the end
product!)
Amino Acid
Or
Ribosome
tRNA
Monopeptide
Transcription
DNA helicase
RNA polymerase
Replication
DNA helicase
DNA polymerase
mRNA
Translation
Ribosome
tRNA
Protein
DNA
Happens in the nucleus
Happens in the cytoplasm /
at the ribosomes
Label each molecule (the pictures).
Label the process that makes each molecule (the purple arrows).
List the name of the enzymes / molecules that carry out each process.
Identify the location where each of these molecules / processes are.
Transcription and translation videos:
Real-time molecules moving with narration (4 min)
https://www.youtube.com/watch?v=41_Ne5mS2ls
Description, live narrator and pictures (12 min)
https://www.youtube.com/watch?v=h3b9ArupXZg
We are going to make a model of all of
these pieces and steps!
•Ribosomes have 2 “subunits” or pieces.
Large Subunit
Small Subunit
•At the start of every gene is a TATA box. It
tells the mRNA polymerase where to start
copying.
TATA box
Actual gene being transcribed
DNA strand:
TCCACGACTATACCGACTACTCTACGGGAATATG
mRNA strand:
GGCUGAUGAGAUGCCCUUAUAC
•mRNA gets a 5’GTP and a poly-A tail to
mark the beginning and end. This helps
identify it and “protect” it.
5’ GTP
Poly-A tail
PPPG
AAAAAAAAA
Just like words,
the base pairs have
to be in a specific
order to make
sense.
Don’t screw up the recipe
“incredible” = some letters that have
meaning.
“iberalideie” = some letters with no
meaning.
“ATTAGCCGCATGATGCTGATGCTAGTCGATGCATGCTAGCTTACGATGCTAGCTAGC
TAGCTGACAAACACACCCCACTGACTGATCGATCGATGCATCGCTTTACGATCGATC
GATCGATCGATCGATCGATGCATCGAAAGATGAGAAAGGGTCGATCGATCGATCGTT
TTATCGATCGATCGATCGATCGATCGATGATCGATCGTTATGCATGCACACACACTAG
CTAGCTAGCTAGTGCTGTTTTGATCATCACAACCACCCAGCATGACTATGTGTGTGT
GAAAAGTGCTACATAAACGTGATGTGTGGGCCCGGCGCGAAAGCGCTGTGTAGCTT
ACGATTTACGATGCTAGCTAGCTAGCTGACAAACTGCTGATGCTAGTCGATAGCTTAC
GATTTACGATGCTAGCTAGCTAGCTGACAAACTGCTGATGCTAGTCGATGCATGCTA
GCTTACGATGCTAGCTAGCTAGCTGACAAACGCTAGTCGATGCATGCTAGCTTACGA
TGCTAGCTAGCTAGCTGACAAACTGCTGATGCTAGTCGATGCATGCTAGCTTACGAT
GCTAGCTAGCTAGCTGACAAACCTAGCTTTGCTGATGCTAGTCGATGCATGCTAGCT
TACGATGCTAGCTAGCTAGCTGACAAACACGATGCTAGCTAGCTAGCTGACAAACAC
ACCCCACTGACTGATCGATCGATGCATCGCTTTACGATCGATCGATCGATCGATCGA
TCGATGCATCGAAAGATGAGAAAGGGTCGATCGATCGATCGTTTTATCGATCGATCG
ATCGATCGATCGATGATCGATCGTTATGCATGCACACACACTAGCTAGCTAGCTAGTG
CTGTTTTGATCATCACAACCACCCAGCATGACTATGTGTGTGTGAAAAGTGCTACATA
AACGTGATGTGTGGGCCCGGCGCGAAAGCGCTGTGTACGTGATGCTGTGATCGAT
GCCTAGCTAGCTAGCTAGCTAGCTAGAATATAATGGGAA”
= hemoglobin. If it were “spelled” a little
differently, hemoglobin would be made with
the wrong amino acids and wouldn’t work!
If a protein is “spelled” a
little differently (called a
mutation), then it would be
made with the wrong amino
acids and it wouldn’t work!
Hemoglobin
With a change to the
DNA, hemoglobin is shaped
differently, clumps
together and causes sickle
cell anemia.
Your skin color is a pigment that is the
result of many proteins. But, if the
DNA is mutated, you could have no
pigment at all!
Evolution you can see: skin color correlates to
intensity of UV-radiation throughout the year.
Wrestling
First Meeting: Today Afterschool
in room 128