Aim: What is DNA and Genetic Information Notepack 31 Aim: What is DNA and Genetic Information DO NOW: Write down 2 things you know about DNA.

What is DNA? DNA is a special molecule found in the cells which make up a chromosome. Chromosomes are found in the nucleus of a cell. (Therefore DNA is in the nucleus) There are 23 pairs of chromosomes (46) in the human cell. DNA is an instruction manual for all the processes that the organism does. DNA has all the information needed to make an entire individual. Everyone's DNA is unique

The History of the Structure of DNA Watson and Crick were the first to propose the Double Helix Model as “shape of DNA.”

What is the structure of the DNA molecule? DNA is a HUGE long molecule. DNA is made up of 2 sides connected together by paired nucleic bases. (looks like a ladder) The molecule is also twisted forming a double helix

Where Does Everything Fit? Unwound, the DNA in a single cell would measure the length of about 3 meters or just over 3 yards. But because of its tight coil over coil wrapping, DNA can fit nicely in the nucleus of a cell.

Human Chromosomes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Y X

The Basic Structure of DNA Backbone - two “strands” wrapping around one another create the “double helix shape.” Each strand is composed (made up of) a combination of four different bases. Each base is paired with its corresponding base and held together by a hydrogen bond. DON’T COPY

Backbone - two “strands” wrapping around one another create the “double helix shape.” Each strand is composed (made up of) a combination of four different bases. There are only four types of nucleic bases: Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Base pairing – bases on one strand pair can only pair with specific base on the opposite strand A and T pair C and G pair

Base Pairing Adenine T A Thymine G C Cytosine Guanine

A T C G C T T A G A

Why are these base pairing important? DNA carries hereditary information (traits from parents). Hereditary information is found in genes. Genes are a sequence of bases found on a section or part of DNA. Specific genes are found on specific parts of a chromosome. The order of these bases found on genes makes the instruction or “code” for specific proteins

Gene for making insulin Gene for making sperm Gene for making insulin Gene for lips size Gene for eye color Gene for hair color

How does DNA control activities in the cell? Because DNA is a huge molecule, it cannot leave the nucleus (the nuclear membrane). DNA make a smaller molecule called RNA which can leave the nucleus and bring DNA’s message to the ribosome.

RNA is a molecule that is made by DNA. RNA is much smaller than DNA. What is RNA? RNA is a molecule that is made by DNA. RNA is much smaller than DNA. RNA is only made up of one strand. RNA is also made up of 4 nucleic bases: Adenine (A) Cytosine (C) Guanine (G) Uracil (U)

How is RNA made? When it is time for DNA to instruct the cell to make something, the DNA will unzip. Free floating Nucleic bases will pair up on the exposed DNA bases. C with G G with C T with A A with U Once completed, the RNA molecule will detach from the DNA and the DNA will rezip.