DNA is often called the blueprint of life
DNA is often called the blueprint of life. Deoxyribo. Nucleic DNA contains the instructions for making proteins within the cell. Acid
DNA The Shape of the Molecule is a very long polymer. The basic shape is like a twisted ladder or zipper. This is called a double helix. Two strands twisted together.
One Strand of DNA The backbone of the molecule is alternating phosphate and deoxyribose parts. The teeth are nitrogenous bases. phosphate deoxyribose bases
Nucleotides One deoxyribose together with its phosphate and base make a nucleotide. O O -P O O C C C O Phosphate Nitrogenous base C C O Deoxyribose
Four nitrogenous bases DNA has four different bases: Cytosine C Thymine T Adenine A Guanine G
Two Stranded DNA Remember, DNA has two strands that fit together something like a zipper. The teeth are the nitrogenous bases.
Complementary base pairs Adenine and Thymine always join together A T • Cytosine and Guanine always join together C G •
Hydrogen Bonds bases attract each other because of hydrogen bonds. C N N C C N C Hydrogen O C N bonds are weak but there are millions and millions of them in a single molecule of DNA. N The N C C C N O
DNA codes for proteins The sequence of nucleotides in DNA codes for proteins.
Have your DNA and eat it too! 1 2 Sequence : T A C G T A T G A A A C 3 1. Assemble one side of your DNA molecule. 2. Match the chemical base 4 pairs. 3. Complete your DNA molecule. 4. Twist your model. 5. Label your model. 5
DNA in Your Cells During most of a cell’s life, the cell’s DNA is a form called chromatin Chromatin DNA is loose uncoiled strands of
Before the cell divides; the DNA will wrap itself around proteins to form a chromosome Our genes are on our chromosomes
A chromosome contains two identical parts called chromatids The point at which the two chromatids attach to each other is called the centromere • 2 chromatids = chromosome
Homologous Chromosomes Two similar chromosomes They are the same size, shape, length, and code for the same traits You get one from your mother and one from your father
Types of chromosomes Body cells are called somatic cells Some examples of somatic cells are muscle cells and skin cells In a somatic cell, you have 46 chromosomes; you have 23 pairs of homologous chromosomes Sex sex chromosomes determine your XX – Female XY – Male
DNA Replication DNA has to be copied before a cell divides This happens during the S or synthesis phase of interphase in the cell cycle S phase G 1 interphase Mitosis -prophase -metaphase -anaphase -telophase G 2
Replication is Semiconservative The double stranded DNA is unzipped (breaking the weak hydrogen bonds) to form two single strands, each having the information needed to make a copy of the original.
DNA Extraction Lab
DNA by the numbers Each cell has about 2 m of DNA. The average human has 75 trillion cells. The average human has enough DNA to go from the earth to the sun more than 400 times. The earth is 150 billion m DNA has a diameter of or 93 million miles from only 0. 00002 m. the sun.
Two Kinds of Bases in DNA Pyrimidines are single ring bases. Purines are double ring bases. N C O C N C N N C C C N N C
Thymine and Cytosine are pyrimidines Thymine and cytosine each have one ring of carbon and nitrogen atoms. N O N C C N N O C thymine O C C C N C cytosine
Adenine and Guanine are purines and guanine each have two rings of carbon and nitrogen atoms. Adenine O N N C C N C Adenine N N N C C C N C Guanine C N N C
Hydrogen Bonds, cont. O When N making hydrogen bonds, cytosine always O C pairs up with N guanine, N C And adenine N always pairs up C N with thymine. C (Adenine and C C thymine are shown N N here. ) C C
Chromosomes and DNA Our genes are on our chromosomes. Chromosomes are made up of a chemical called DNA.
DNA in Your Cells sister chromatid
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