DNA Replication

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DNA Replication Protein Synthesis Designed
by Mr. Gaccione
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BioTech DNA Review
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The Size of DNA...
DNA is located in the nucleus in the form of
chromosomes.If the DNA of one cell is
stretched out, it makes a 7 ft. long
string.There are 5 trillion cells in the
human body.If you connected all the DNA
together, it would be long enough that it would
take light over 10 hours to travel its length.
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The Size of DNA...

• Chromosomes contain a single, long piece of DNA
• A chromosome is about 0.004 mm long
• The DNA is about 4 cm long
• This is 10,000x longer than the chromosome
• Thus DNA must be wrapped tightly to fit into
  cells
• Imagine fitting 900 yards (300m) of rope into a
  backpack.

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The Size of DNA...

• The DNA molecule looks like a ladder that has
  been twisted.
• The DNA molecule is
• made from two strands,
• twisted together in a
• double helix.
• Watson Crick
• created the double
• helix model for DNA.

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DNA is a long molecule made up of repeating
units called nucleotides.Each nucleotide is
made up of three parts 1. phosphate group2.
carbon sugar (deoxyribose)3. nitrogen base
The Structure of DNA
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Repeating Nucleotides

• The sides of the DNA ladder(backbone) is formed
  by phosphate and sugar groups.
• The nitrogenous bases are
• the rungs of the DNA ladder.
• DNA is 250 million nitrogen
• bases long.

• RNA is 3000 nitrogen bases long.

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(No Transcript)
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Nitrogenous Bases

• There are four kinds of nitrogenous bases.
• They are divided into two classes
• purines and pyrmidines
• Purines (bigger)
• Adenine and Guanine
• Pyrmidines (smaller)
• Cytosine and Thymine

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Chargaffs Rules

• Chargaff discovered how the nitrogenous bases
  bond together.
• Adenine always bonds with Thymine Cytosine always
  bonds with Guanine

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DNA
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Hydrogen bonding
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DNA Sequence

• The particular order of the nitrogen bases is
  called the DNA sequence.
• This sequence makes each individual unique.
• An elm tree, eel an elephant has the same DNA,
  but what makes them different is the order of the
  bases.

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DNA Genes

• Each chromosome carries 2,000 genes.
• 23 chromosomes 30,000 to 40,000 genes
• This is known as The Human Genome
• Genes are locations on chromosomes that give us
  our traits.
• Many of these are common to all human beings.
• So, 99.9 of your DNA is identical to everyone
  else's.

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DNA Genes

• The remaining 0.01 influences the differences
  between us.
• height, hair color and
• susceptibility to a particular disease
• Environmental factors, such as lifestyle (smoking
  and nutrition) also influence the way we look and
  our susceptibility to disease.

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Mutations

• Mutations are caused by mutatgens.
• Examples of mutagens
• UV rays, smoking radiation
• Mutations are mistakes in the nitrogen bases or
  in the DNA sequence.

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Point Mutation
C
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Thymine mutation

• Caused by exposure to UV light.
• 2 adjacent thymine residues become covalently
  linked.

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Mutations

• RNA polymerase adds ribonucleotides not
  deoxynucleotides
• RNA polymerase does not have the ability to
  proofread what they transcribe
• RNA will have an error 1 in every 10,000
  nucleotides
• DNA will have an error 1 in ten million
  nucleotides)

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DNA Replication DNA replication makes an exact
copy of the strand, complete with 1 old and 1 new
strand.

• Step 1
• DNA unwinds unzips with the help of DNA
  polymerase
• Step 2
• Each strand of the parent DNA is used as a
• template to make the new daughter strand.
• Step 3
• Free floating nucleotides are added by DNA
  polymerase.

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DNA Replication
C
T
A
C
C
G
G
G
A
T
G
G
C
C
T
A
T
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DNA to mRNA to Protein

• ?DNA acts as a manager in the process of making
  proteins.
• ?DNA is the template or starting sequence that is
  copied into RNA that is then used to make a
  protein.

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RNA differs from DNA

• Ribose is the
• sugar rather than
• deoxyribose.
• Uracil instead of
• Thymine
• Adenine, Guanine
• Cytosine stay the same.
• 3. Single stranded

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Three Different RNAs

• messenger RNA (mRNA) takes a message or 3
  letter code(codon) from DNA
• GUA---UUC---GUU---AGU---UGA
• ribosomal RNA (rRNA)
• meeting place for three RNAs
• 3. transfer RNA (tRNA) brings
• anti-codon amino acid

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Protein Synthesis -2 StepsTranscription
translation

• Transcription
• First step in protein synthesis
• mRNA transcribes a message (code) from DNA
• Occurs in the nucleus

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Protein Synthesis Transcription
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Protein Synthesis -Transcription

• Step 1
• DNA unwinds unzips with the help of RNA
  polymerase
• Step 2
• Only one strand of the parent DNA is used as a
• template to make mRNA.
• Step 3
• Free floating nucleotides are added by RNA
  polymerase, making mRNA.

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Protein Synthesis-Transcription
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Protein Synthesis Transcription
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Protein Synthesis -Transcription?aking mR?? from
D?? template
C
U
A
C
C
G
G
A
U
A
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Protein Synthesis -Translation
Amino acid

• Translation
• Goal to make a protein
• Second step in protein synthesis
• All three RNAs meet
• (mRNA, rRNA tRNA)
• Occurs in the cytoplasm

UAC
--UUC--GUU--AUG--
Amino acid
--AUG--
tRNA brings anti-codon amino acid
Anti-codon
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Protein Synthesis - TranslationDraw and label
the boxes, tRNA, mRNA rRNA
tRNA
rRNA
mRNA
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Translation
Amino Acid?
Amino Acid?
Amino Acid?
Amino Acid?
Amino Acid?
Met
Phe
Val
Ser
Stop!
ANTI- CODON?
ANTI- CODON?
UAC
ANTI- CODON?

• ANTI-
• CODON?

AAG
CAA
UCA
ACU
ANTI- CODON?
rRNA mRNA are in the cytoplasm. Where is
tRNA???
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Protein Synthesis -Translation Review
?
?
tRNA
?
rRNA
rRNA
?
?
mRNA
mRNA
?
?
rRNA
Amino acid
?
mRNA
?
?
?
mRNA
tRNA
tRNA
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Protein Synthesis -Translation Review

• Translation is the meeting of all three RNAs
  (mRNA, rRNA tRNA).
• It takes place in the cytoplasm.
• The goal is to string together amino acids to
  form a protein.
• Proteins make up our skin, blood, muscles, heart,
  enzymes, stomach lining intestinal linings.

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Protein Synthesis - Key Words
Transcription DNA Double Helix 3-5 strand
5-3 strand Phosphate Group Deoxyribose
Sugars Ribose sugars Hydrogen Bonds
RNA polymerase Nucleus Nuclear
pore ER Complementary base pairs rRNA mRN
A tRNA