DNA+and+Genes

DNA and Genes What You’ll Learn You will relate the structure of DNA to its function. You will explain the role of DNA in protein production. You will distinguish among different types of mutations. = Section 1 = Vocabulary Review Vocabulary: Nucleotide- subunit of a nucleic acid formed from a simple sugar, a phosphate group and a nitrogenous base New Vocabulary: Nitrogenous base__-__ carbon ring structure found in the DNA or RNA that contains one or more atoms of nitrogen includes adenine, guanine, cytosine, thymine, and uracil. __ Double helix- __ Shape of a DNA molecule formed when two twisted DNA strands are coiled into a springlike structure and held together by hydrogen bonds between the bases. __ DNA replication- __ Process in which chromosomal DNA is copied before mitosis and meiosis. // P.S. all vocabulary for sections given by Biology- The Dynamics of Life // DNA ultimately determines an organisms trait by the genetic information that is held in the molecule. DNA gets control by determining the structure of your proteins. Proteins are found in all living things. //DNA is the genetic material// Alfred Hershey and Martha Chase performed experiments using radioactivity labeled viruses that infect bacteria in 1952. Before this experiment scientists believed that proteins were the genetic material. Hershey and Chase made two different types of viruses. One virus contained a radioactive DNA and the other had a radioactive protein. Only the DNA penetrated the bacteria walls and produced new viruses. This was the evidence for DNA being the genetic material. //The structure of nucleotides// DNA is able to hold much information because it is a very long molecule. DNA is a polymer made of repeating subunits called nucleotides. Nucleotides are made up of three parts: a simple sugar, a phosphate, and a nitrogenous base. The simple sugar that is found in DNA is called deoxribose. This gives DNA its name, deoxyribonucleic acid. There are four nitrogenous bases possible, adenine (A), guanine (G), cytosine (C), and thymine (T). [] // The structure of DNA // James Watson and Francis Crick published a letter in a journal in 1953, it was only about one page in length, and however it was very important. They proposed that two chains of nucleotides held together by nitrogenous bases were how DNA was made. They said that the nucleotides were held by weak hydrogen bonds. The base pairs were also complementary to other base pairs. Adenine is complementary with Thymine and Guanine matches with Cytosine. DNA is composed of two strands that are twisted. This shape is called a double helix. // The importance of nucleotide sequences // Different organisms are composed of different proteins; however the DNA that the organism contains is made up of the same four nucleotides. The sequence makes the difference. The sequence: A-T-T-G-A-C contains different information than the sequence T-C-C-C-A-A-A. The close the DNA sequence he more closely related the organisms are. This is why many scientists say that humans are more closely related to chimpanzee’s than those of a gorilla. // How DNA replicates // Replication begins when an enzyme breaks the weak hydrogen bonds between the bases that hold the two strands together. Another enzyme comes and “zips” back up the DNA strand with the same nucleotides. The new strand gains the same complementary nucleotides as the original DNA strand. // Copying DNA // DNA is copied during interphase prior to mitosis and meiosis.
 * What is DNA? **
 * Replication of DNA **

= Section 2 = Vocabulary Review Vocabulary: __Polymer__ a large molecule formed from smaller subunits that are bonded together. New Vocabulary: __ Messenger RNA- __ RNA that transports information from DNA in the nucleus to the cell’s cytoplasm. __ Ribosomal RNA __ - RNA that makes up the ribosome’s; clamps onto mRNA and uses its information to assemble amino acids in the correct order.

__ Transfer RNA __ - RNA that transports amino acids to the ribosomes to be assembled into proteins. Transcription Process in the cell nucleus where enzymes make an RNA copy of a DNA strand. __ Codon- __ Set of three nitrogenous bases that represents an amino acid; order of nitrogenous bases in mRNA determines the type and order of amino acids in a protein. __ Translation- __ Process of converting information in mRNA into a sequence of amino acids in a protein. // P.S. all vocabulary for sections given by Biology- The Dynamics of Life // //Genes and proteins// The information found in the sequence of nucleotides is put to work in a production of proteins. Proteins become key structures and regulates cell functions. Each protein controls something different, for example, filaments in muscle tissue and enzymes that control inner chemical reaction like digesting food or making spinning fibers during mitosis. //RNA// Like DNA, RNA is a nucleic acid. The differences between them are that RNA is single stranded whereas DNA has a double helix. RNA sugar is ribose, in DNA it is deoxyribose. Both have four nitrogenous bases but instead of DNA’s thymine, RNA’s is called uracil. DNA provides instruction for making proteins, and the ‘workers’ build the proteins. RNA molecules are in charge of protein synthesis. There are 3 types of RNA; messenger RNA brings instructions from DNA in the nucleus to the cytoplasm which then the mRNA moves to a ribosome. The ribosome, which is made of, ribosomal RNA, binds to the mRNA and uses the instructions to assemble the amino acids in the correct order. The 3rd type of RNA is transfer RNA and it is the supplier. tRNA delivers amino acids to the ribosome to be assembled into a protein. //Transcription// mRNA carries this information through the nuclear envelope to the ribosome’s for ‘manufacturing’ proteins. In the nucleus, enzymes make an RNA copy of a portion of a DNA strand in a process called transcription. The main difference between transcription and DNA replication is that transcription and DNA replication is the transcription results in the formation of one-single stranded RNA molecule rather than a doubt-strand DNA molecule. //RNA Processing// Genes usually contain many long non-coding nucleotides sequences called introns that are scattered among the coding sequences. Regions that contain information are called extrons. When mRNA is transcribed from DNA, both introns and extrons are copied. //The Genetic Code// The nucleotide sequence transcribed from DNA to a strand of mRNA acts as a genetic message. The unique language uses the 4 different nitrogenous bases as the letters. And to be translated this must happen. Scientists began to discover that a group of 3 nitrogenous bases in mRNA for one amino acid. Each group is known as a codon. 64 combinations are possible when a sequence of 3 is used. Some codons do not code for amino acids but instead they provide info on how to make proteins. All organisms use the same genetic code, for this reason it is said to be universal, and that proves evidence that all life evolved from the same origin. //Translation: From mRNA to Protein// Translation takes place in the ribosome in the cytoplasm. The mRNA is made in the cytoplasm. In the eukaryotic cells RNA is made in the nucleus and then travels to the cytoplasm. //The role of transfer// For proteins to be built about 20 different amino acids dissolve in the cytoplasm must be brought to the ribosome. This is the role of transferring RNA. mRNA joins each codon to the correct tRNA molecule. Base pairing is what makes this happen. The three nucleotides are called anti-codon of the mRNA //Translating the mRNA code// A tRNA molecule brings the first amino acid Vocabulary Review Vocabulary: __ Cancer- __ diseases believed to be caused by changes in the genes that control the cell cycle. New Vocabulary: __Mutation__ Any change or random DNA error in DNA sequence. __ Point mutation- __ Mutation in DNA sequence; occurs from change in a single base pair. __ Frameshift mutation - __ Mutation that occurs when a single base is added or deleted from DNA; cause __ Chromosomal mutation- __ mutation that occurs at the chromosome level resulting in changes in the gene distribution to gametes during meiosis; caused when parts of chromosomes break off or rejoin incorrectly. __ Mutagen- __ any agent that can cause a change in DNA; includes high-energy radiation, chemicals, or high temperatures. // P.S. all vocabulary for sections given by Biology- The Dynamics of Life // Mutations // Mutations in reproductive cells // Mutations affect the reproductive cells of of organism by changing the sequence of the nucleotides inside of the gene of either a sperm or an egg cell. The mutation may produce a new trait or create a protein that does not work correcting. Sometimes, the mutation will cause the embryo to die. This is because of a mutation in a protein that is nonfunctional. Mutations will sometimes have a positive effect. An organism could receive a mutation that makes it faster or stronger. Then the trait would be passed on creating a faster or stronger species. // Mutations in body cells // Damage to a gene may impair the function of that particular cell. Many scientists believe that the buildup of cells with less than optimal functioning is an important cause of aging. Some types of mutations will affect the genes that control cell division. It could speed up the cell division process, which in turn causes cancer. Cancer is the uncontrolled dividing of cells. Cancer is the result of a gene mutation. // The effects of point mutations // A point mutation is a change in a single base pair. Changing one of the base pairs can change an entire meaning of it. Point mutations are less harmful to organisms because they only affect one specific codon. // Frameshift mutations // A Frameshift mutation is a mutation where a single base is added or deleted from the DNA strand. This mutation would cause nearly every amino acid in the protein after deletion to be changed into something new. These can occur in different ways. For example the chromosome could be broken off and lost during either meiosis or mitosis.The structural changes in chromosomes are called chromosomal mutations. These occur in all living organisms, but can be seen most commonly in plants. Very rarely is the chromosomal mutations are passed onto the next generation because the zygote usually dies. [] Some mutations are on accident. Many mutations are caused because of the environment. An agent that causes a change in DNA is called a mutagen. There are many different kinds of mutagens; there are chemical mutagens along with different types of radiation. // Repairing DNA // The cell processes that copy genetic material and pass the information onto future generations is usually very accurate. Mistakes do sometimes occur. Enzymes proofread the DNA and replace the incorrect nucleotides with the correct ones. These “repair” enzymes are very helpful but they are not perfect. If continued exposure happens, there is less of a chance that the mistake will not be fixed.
 * Chromosomal Alterations **
 * Causes of Mutation **

**A quick quiz to see if you understand what you read!** 1. Explain why the structure of a DNA molecule is often described as a zipper. Answer: An enzyme will “unzip” the DNA strand to replace, or copy the DNA that is present. The ability of the strand to do this is considered the ability to unzip and be zipped up by two different types of enzymes 2. What is the complementary sequence to the strand: GGCAGTTCATGC Answer: CCGTCAAGTACG 3. What is the role of tRNA in protein synthesis? Answer: Delivers amino acids to the ribosome’s to be assembled into a protein. 4. What is a mutation? Answer: __ Mutation -__ Any change or random DNA error in DNA sequence. 5. How are mutation and cancer related? Answer: Mutations can cause cell division to speed up. When cells are created faster than when old cells are deleted. The cells will grow at a rapid pace causing the formation of a buildup of cells. The buildup of cells is also called a tumor.


 * DNA and Genes animations**

[|DNA Replication] [|DNA Example] [|Mitosis. Scroll down to see more videos.] [|DNA Sequencing] [|Recombination Between Unlinked Genes] [|Gene Therapy] [|Cloning] [|Adanine, Guanine, Thymine, Cytosine (AGTC)] (Click on "3-D Animation) [|Transcribe and Translate Gene] [|Electrophoresis]