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Transcript of Slide 1 of 37 Copyright Pearson Prentice Hall Nucleic Acids and Protein Synthesis.
Slide 1 of 37
Copyright Pearson Prentice Hall
Nucleic Acids and Protein Synthesis
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Two Types of Nucleic Acids:
1. DNA
2. RNA
Together they have the
code and capability to
make all necessary proteins.
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DNA
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Deoxyribonucleic Acid-our genetic code
-code for making all proteins/enzymes = all our traits and cell reactions
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DNA is:
Located:in the nucleus
of all our cells.
Makes up our:Chromosomes
Number of chromosomes in each of our cells?
46 23 from mom23 from dad
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Chromosomes:-46 linear segments of DNA-Super coil into “bow tie” shaped structures
during cell division.
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Supercoiling of DNA
Approximately 6ft/cell ~ supercoils into mere nanometers
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Human Genome:
- our complete set of genes that makes up a human.
-22,000 genes in our genome.
-99.9% of every humans genes is identical. There is only a .1% sequence variation from person to person
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Genes:segments of DNA that codes for 1 or
more proteins.
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Every cell in your body has an exact copy of all 46 chromosomes but…….
Cells are selective on whatgenes are read and proteins made.
Ex/ skin makes collagen pancreas makes insulin
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-Mapped all of our genes.-Completed in 2003
-Headed by James Watson
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Structure of DNA:1. is a nucleic acid2. made up of nucleotides
Each nucleotide is made up of:1. Pentose sugar (5 sided)
“deoxyribose” 2. Phosphate/phosphoric acid
3. Nitrogen Base (4 types)
12–1 DNA
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The Components and Structure of DNA
Purines: double ring
Pyrimidines: single ring
3. There are four kinds of DNA nitrogen bases:
• Adenine
• Guanine
• Cytosine
• Thymine
12–1 DNA
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5. DNA has a double helix shape (twisted).
4. DNA is made up of a double strand of nucleotides held together with weak hydrogen bonds.
12–1 DNA
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6. DNA follows the “Base Pairing Rule”
Adenine only bonds to ThymineCytosine only bonds to Guanine
Why?
12–1 DNA
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DNA’s structureWas determined
By James Watson and Francis Crick
In 1953.
12–1 DNA
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The Components and Structure of DNA
DNA Double Helix
12–1 DNA
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The Components and Structure of DNA
X-Ray evidence of DNA’s structure was provided by:
Rosalind Franklin and Maurice Wilkens
-took an X-ray of DNA
Rosalind aimed an X-ray beam at concentrated DNA samples and recorded the scattering pattern of the X-rays on film.
12–1 DNA
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Nobel Prize winners in 1962 ~ Crick, Watson and Wilkens
Died in 1958
12–1 DNA
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Watson: current headof the Human GenomeProject
Crick: died in 2004
12–1 DNA
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DNA Replication: -DNA makes an exact copy of itself
-Why?
So cells can divide
and each new cell has an
exact copy of DNA.
-Occurs in all cells
-Some cells lose the ability to divide.Example: nerve, brain, heart
-Some cells divide all the time:Example: skin, bone
12–1 DNA
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-DNA replication requires enzymes.-Each chromosomes is over 20,000 nitrogen bases long so it happens in sections.
Interesting but useless bits of knowledge:
•DNA is an invisibly thin, very long double strand of nucleotides.
•The DNA found in each human cell is almost 2 meters or 6 feet long.•If all the DNA in a human adult were laid end to end the DNA
molecule would stretch 113 billion miles.
•That would equal 610 trips to the sun and back.
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Steps to DNA Replication:
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1. DNA helicase unwinds and unzips DNA by breaking the hydrogen bonds between nitrogen base pairs at several places along each strand.
2. Creating several “replication bubbles”.
12–1 DNA
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12–1 DNA
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3. Two DNA polymerase enzymes, one on each side of the DNA strand add new nucleotides following the base pair rule.
12–1 DNA
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12–1 DNA
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4. This continues until all “replication bubbles” converge to create 2 new DNA molecules.
5. The separate strands of DNA are joined with DNA ligase to create two continuous new strands.
12–1 DNA
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6. Two new strands recoil and two new, identical molecules are formed.
A
T
T
C
G
T
A
A
G
C
T
A
A
G
C
A
T
T
C
G
12–1 DNA
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DNA Replication
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