slide 1 of 37 copyright pearson prentice hall nucleic acids and protein synthesis

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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


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)

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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

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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.

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6. DNA follows the “Base Pairing Rule”

Adenine only bonds to ThymineCytosine only bonds to Guanine

Why?

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DNA’s structureWas determined

By James Watson and Francis Crick

In 1953.

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DNA Double Helix

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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.

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Nobel Prize winners in 1962 ~ Crick, Watson and Wilkens

Died in 1958

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Watson: current headof the Human GenomeProject

Crick: died in 2004

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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:


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”.

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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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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.

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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

http://highered.mcgraw-hill.com/sites/0072421975/student_view0/chapter24/animations__english_.html

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