IT 3 - Struktur Dan Fungsi DNA - SN
-
Upload
rahmatdarmawantoro -
Category
Documents
-
view
230 -
download
6
description
Transcript of IT 3 - Struktur Dan Fungsi DNA - SN
DNA: Structure and Function
Deoxyribose Nucleic Acid The Architect of Life The Molecule of Heredity The Blueprint of LifeThe First three-dimensional xerox machine
Life Instruction Manual
DNA
Why Study DNA? To truly understand genetics, biologists first had
to discover the chemical structure of the gene This would then help them understand how genes
control the inherited characteristics of living things
Gene expression is what enables cells of the same organism to take on so many different sizes, shapes and functions
(even though just about every cell in an individual contains the same DNA)
1.What organelle is known as the control center of the cell?
2.What structures are found in the nucleus?
3.What are short segments of chromosomes?
4. What are genes/chromosomes composed of?
5. How do genes/chromosomes control the activity of the cell?
Review
nucleus
chromosomes
genes
DNA
produce proteins thatregulate cell functions and become cell structures
ReviewReview
History 1869 - Friedrich Miescher – “discovered” DNA in
nucleus 1928 - Frederick Griffith – Identified DNA as source of
genetic material using bacteria 1930’s - Oswald Avery, Colin MacLeod and Maclyn
McCarty - Confirmed that genes made of DNA 1950 - Alfred Hershey and Martha Chase confirmed
DNA is the biochemical of heredity using radioactive markers bacteriophages
1952- Maurice Wilkins and Rosalind Franklin X-rayed DNA to show repeating nucleotide structure
1953- James Watson and Francis Crick combined data to create a 3-D model of structure called the double helix
Oswald Avery Maclyn McCarty
Martha Chase Alfred HersheyRosalind Franklin
X-ray of double helix
James Watson Francis Crick Frederick Griffith
Watson-Crick Model
• Is a polymer of 1000’s of nucleotide monomers
• Is a double strand of covalently bonded nucleotides in twisted ladder shape • twisted ladder shape = double helix
DNA Structure
Double helix: 2 spirals wound around each other
DNA Shape
But joined in
the middle
• Is a polymer of 1000’s of nucleotide monomers
• Is a double strand of covalently bonded nucleotides in twisted ladder shape twisted ladder shape = double helix
• ‘Rungs’ of ladder = nitrogen bases• ‘Sides’ of ladder = sugar & phosphate groups (also called the DNA backbone)
DNA Structure
SugarPhosphateBackbone
• Nucleotide- Individual unit of DNA.• Made of three parts:• Deoxyribose (5-carbon sugar) • Phosphate group• A nitrogen-containing base
Nucleotide
• Four nitrogen-containing bases• Adenine• Guanine• Cytosine• Thymine
Bases
sugar (deoxyribose)
adenine A
base with a double-ring
structure
guanine (G)
base with a double-ring
structure
cytosine (C)
base with a single-ring structure
thymine (T)
base with a single-ring structure
sugar (deoxyribose)
adenine A
base with a double-ring
structure
guanine (G)
base with a double-ring
structure
cytosine (C)
base with a single-ring structure
thymine (T)
base with a single-ring structure
sugar (deoxyribose)
adenine A
base with a double-ring
structure
guanine (G)
base with a double-ring
structure
cytosine (C)
base with a single-ring structure
thymine (T)
base with a single-ring structure
sugar (deoxyribose)
adenine A
base with a double-ring
structure
guanine (G)
base with a double-ring
structure
cytosine (C)
base with a single-ring structure
thymine (T)
base with a single-ring structure
sugar (deoxyribose)
adenine A
base with a double-ring
structure
guanine (G)
base with a double-ring
structure
cytosine (C)
base with a single-ring structure
thymine (T)
base with a single-ring structure
Adenine double ringed =
Guanine
Thymine single ringed =
Cytosine
Bases
purines
pyrimidines
Deoxyribose (like ribose) is a sugar with 5 carbon atoms in a ringOxygen is one of the ring members In Deoxyribose, one of the OH groups is missing and replaced with hydrogenThus deoxy = - 1 oxygen
Nucleotide
sugar
baseP
OHH
P - the Phosphate groupIs important because it links the sugar on one nucleotide with the phosphate of the next nucleotide to make a polynucleotideNucleotides are connected to each othervia a covalent bond
Nucleotide
sugar
baseP
• Bases are paired together in specific manner
Because of chemical structure and shape• Adenine only pairs with Thymine• Guanine only pairs with Cytosine
Exactly enough room for only one purine and one pyramide base between the two strands of DNA
‘Base Pairing Rule’
• Bases held together in ‘rungs’ by weak hydrogen bonds• 2 hydrogen bonds between A & T• 3 hydrogen bonds between C & G
‘Base Pairing Rule’
DNA
• Scientists wondered how DNA worked. They knew genes do these critical things:• Carry information from one generation to another
• Put information to work to determine an organism’s characteristics
• Can be easily copied• Store and transmit genetic information needed for all cell functions
• In order to do these things it had to be a special molecule!
DNA Function
• Our knowledge of DNA put to use:• Inheritance/ Genetic Counseling• Cell function/protein synthesis• Embryonic development/gene regulation• Evolution/ phylogenetic relationships• Medicine/genetic diseases• Genetic engineering/ recombinant DNA
Understanding DNA
To get an idea of the size of the human genome present in each of our cells, consider the followinganalogy: If the DNA sequence of the human genome were compiled in books, the equivalent of 200 volumes the size of a Manhattan telephonebook (at 1,000 pages each) would be needed tohold it all. It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in one person's genome sequence, calculated on a reading rate of 10 bases per second, equaling 600 bases/minute, 36,000 bases/hour, 864,000 bases/day, 315,360,000 bases/year.
DNA’s Size
Human Genome Project
DNAHow Am I Packaged?
• Nitrogen bases 1. Are like letters in the code 2. Put them in different order make a different gene
A
G
TC
DNAPackage
• Genes 1. Are like words made up of letters 2. A group of nitrogen bases that makes sense 3. Tells the cell to do something
CAT DOGHAT
A
A
T
C
• DNA strand 1. Are like sentences made up of words 2. A long line of genes on each DNA strand
DNAPackage
The cat sat.
One dog ate.The big
hat.
DNAPackage
• Chromosomes 1. Are like books full of sentences 2. DNA strand twists around and around itself
DNAPackage
• Nucleus 1. Is like a bookcase 2. Inside the cell, where all the chromosomes are stored
• So what would a library full of rows and rows of bookcases represent?
many cells together which is a tissue
DNAPackage