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DNA Replication

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Title: DNA Replication


1
DNA Replication Protein Synthesis Designed
by Mr. Gaccione
2
BioTech DNA Review
3
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.
4
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.

5
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.

6
DNA is a long molecule made up of repeating
units called nucleotides. Each nucleotide is
made up of three parts 1. phosphate group 2.
carbon sugar (deoxyribose) 3. nitrogen base
The Structure of DNA
7
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.

8
(No Transcript)
9
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

10
Chargaffs Rules
  • Chargaff discovered how the nitrogenous bases
    bond together.
  • Adenine always bonds with Thymine Cytosine always
    bonds with Guanine

11
DNA
12
Hydrogen bonding
13
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.

14
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.

15
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.

16
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.

17
Point Mutation
C
18
Thymine mutation
  • Caused by exposure to UV light.
  • 2 adjacent thymine residues become covalently
    linked.

19
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)

20
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.

21
DNA Replication
C
T
A
C
C
G
G
G
A
T
G
G
C
C
T
A
T
22
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.

23
RNA differs from DNA
  • Ribose is the
  • sugar rather than
  • deoxyribose.
  • Uracil instead of
  • Thymine
  • Adenine, Guanine
  • Cytosine stay the same.
  • 3. Single stranded

24
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

25
Protein Synthesis -2 Steps Transcription
translation
  • Transcription
  • First step in protein synthesis
  • mRNA transcribes a message (code) from DNA
  • Occurs in the nucleus

26
Protein Synthesis Transcription
27
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.

28
Protein Synthesis-Transcription
29
Protein Synthesis Transcription
30
Protein Synthesis -Transcription ?aking mR?? from
D?? template
C
U
A
C
C
G
G
A
U
A
31
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
32
Protein Synthesis - Translation Draw and label
the boxes, tRNA, mRNA rRNA
tRNA
rRNA
mRNA
33
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???
34
Protein Synthesis -Translation Review
?
?
tRNA
?
rRNA
rRNA
?
?
mRNA
mRNA
?
?
rRNA
Amino acid
?
mRNA
?
?
?
mRNA
tRNA
tRNA
35
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.

36
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
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