DNA Deoxyribonucleic Acid By Diana Bivens

What is DNA? DNA is found in the nucleus contains all genetic information controls protein production Living things are made up of proteins All actions are controlled by proteins called enzymes is made up of nucleotides

DNA Structure Nucleotide Sugar molecule Phosphate group deoxyribose Phosphate group One of 4 Nitrogen bases Adenine (A) Guanine (G) Cytosine (C) Thymine (T)

DNA Structure Phosphates and sugars form backbone of the chain strands are held together by complimentary nitrogen bases with a Hydrogen bond double helix shape Discovered by James Watson and Francis Crick using x-rays made Rosalind Franklin

Complimentary nitrogen bases are joined by a Hydrogen bond and form the rungs of a DNA ladder Adenine (A) always pairs with Thymine (T) Guanine (G) always pairs with Cytosine (C)

Nucleotide Sequences ALL organisms contain the same DNA structures The sequence determines the characteristics of an organism Similar organisms share similar sequences

Replication DNA must be copied before cells divide strands unzip (Hydrogen bonds break) Free floating nucleotides bond to open strands A to T C to G sugars and phosphates from adjacent nucleotides bond together Result: two new DNA molecules, each identical to each other

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/0072943696/student_view0/chapter3/animation__dna_replication__quiz_1_.html

Interesting fact The total length of DNA present in one adult human = nearly 70 trips from the earth to the sun and back.

RNA vs. DNA ribonucleic acid vs. deoxyribonucleic acid Single strand Sugar : ribose Nitrogen bases Adenine Cytosine Guanine Uracil Double stranded Sugar: deoxyribose Nitrogen bases Adenine Cytosine Guanine Thymine

3 types of RNA mRNA: carries the DNA code to the ribosomes rRNA: RNA found within ribosomes tRNA: RNA that transport amino acids for construction of proteins

Transcription Transcription: the making of mRNA from a portion of DNA DNA molecule unzips Free RNA nucleotides pair with nucleotides on DNA strand (Adenine w Uracil/Cytosine w Guanine) Newly made mRNA breaks from DNA DNA “re-zips” mRNA travels from nucleus to ribosomes in cytoplasm

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter3/animation__mrna_synthesis__transcription___quiz_1_.html

Codons Nucleic acids are grouped in 3’s called codons DNA codon: AAA will be transcribed into an mRNA codon: UUU ****UUU codes for the amino acid Phenylalanine

The Genetic Code

The Genetic Code 20 different amino acids 64 possible codons Several different codons can code for one type of amino acid Ex. UUU and UUC : phenylalanine Some codons trigger the beginning and end of protein synthesis (start and stop/terminator codons) Ex. AUG: start codon / UAA: stop codon

Translation Translation: converting mRNA into a protein A ribosome attaches to mRNA tRNA carries amino acids to mRNA anticodons on tRNA pair with mRNA codons ex. UAC (tRNA) – AUG (mRNA) Ribosome slides down mRNA pairing tRNA and attached amino acid to complementary mRNA Adjacent amino acids bond together A protein is assembled

http://www. teachersdomain. org/resource/lsps07. sci. life. stru http://www.teachersdomain.org/resource/lsps07.sci.life.stru.celltrans/

Mutations Mutation: any change in the DNA code that changes the protein it codes for Mutations in sex cells may result in death of embryo A structural or functional problem (rarely) a protein that improves function or structure Mutations in sex cells are passed to offspring

Mutations Mutations in body cells may cause Cells to function improperly Uncontrolled cell division Body cell mutations are NOT passed to offspring

Types of Mutations Point mutation: a change in a single nitrogen base AUG-AAG-UUU-GGC AUG-AAG-GUU-GGC UUU: phenylalanine GUU: valine *a change in an amino acid in a sequence changes the protein it codes for

Types of mutations Frameshift: a single nitrogen base is added or deleted, shifting the reading of the RNA sequence AUG-AAG-UUU-GGC AUG-AAU-GUU-UGG (insertion of U) AUG-AGU-UUG (deletion of A in the second codon)

Chromosomal Mutations Deletion: part of a chromosome is left out Insertion: part of a chromatid breaks off and attaches to its sister chromatid Inversion: part of chromosome breaks off and reinserts backwards Translocation: part of a chromosome breaks off and attaches to another

Causes of Mutations Radiation Medications UV radiation from the sun X-rays Gamma radiation in nuclear reactors Medications Accutaine (acne medication) Thalidomide (anti-nausea)

Causes of Mutations Other chemical agents Asbestos Cyanide Formaldehyde *anything that causes a mutation is called a mutagen