Notes - DNA, Genes, and Chromosomes

Cells and DNA All organisms are made of one or more cells With few exceptions, all cells contain DNA All organisms have DNA

What is the relationship between DNA, genes, and chromosomes? DNA is found in all living things and carries the instructions to make proteins – A single DNA strand holds the information to build many different proteins

What is the relationship between DNA, genes, and chromosomes? Chromosomes are strands of DNA that are coiled up – A chromosome holds the information to build many different proteins

Why does DNA exist in two forms? The DNA instructions can only be “read” and copied when the strand is unwound During cell division, the copied DNA must be sorted and separated into two new cells - In order to prevent the strands from getting tangled and damaged during cell division, they are wound into chromosomes

What is the relationship between DNA, genes, and chromosomes? Genes are pieces of DNA that hold the information to build 1 type of protein – A chromosome has many genes

What is the relationship between DNA, genes, and chromosomes?

Analogy Chromosomes are like phone books because chromosomes have many genes just like phone books have many phone numbers

Analogy 385-4230 calls Stratford High School Genes are like phone numbers because genes hold the information to build 1 specific protein just like phone numbers hold the information to call 1 specific place 385-4230 calls Stratford High School

How does the code work? DNA is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).

Who Discovered DNA? Watson and Crick and Franklin discovered how these six subunits were arranged to make the structure of DNA. The model is called a double helix because two long strands twist around each other like a twisted ladder.

How are the base pairs held together? The rails of the ladder are made of alternating sugar and phosphate molecules. The steps of the ladder are made of two bases joined together with either two or three weak hydrogen bonds

Genetic Mutations A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people.