Presentation on theme: "DNA What is it? DNA A chemical molecule that has all the information to run and build a living organism. Contains instructions for genes (inherited traits)"— Presentation transcript:
DNA What is it?
DNA A chemical molecule that has all the information to run and build a living organism. Contains instructions for genes (inherited traits) and for proteins (structures and functions – like enzymes)
Types of proteins
DNA MODEL (deoxyribonucleic acid) Double stranded molecule with 2 sides called a helix Looks like a twisted ladder structure Rungs (steps) are called bases or nucleotides. (abbreviated as A, C, T, G) Sides are made of sugar & phosphate molecules alternating The sugar is deoxyribose Found in every living cell in structures called chromosomes, inside the nucleus.
Base pairs are: A with T C with G always
Phosphate molecules Deoxyribose (sugar) molecules Nitrogen bases Hydrogen bonds Sugar phosphate (backbone) Notice base pairings: A with T & C with G
DNA replication (copying itself) Required during growth or repair of cells. The weak hydrogen bonds are unzipped by an enzyme called DNA helicase. Free floating nucleotides from in the nucleus attach themselves to the exposed DNA strands. DNA the new bases are “glued” or fused together with DNA polymerase and the 2 new molecules of DNA are formed.
DNA replication (copying itself) ACGATGCAC _________ GTA CGT ___ CAT GCA UNZIPPED BY HELICASE 2 NEW DNA STRANDS COPIES OF EACH OTHER! TGC TAC GTG Glued BY polymerase CAT GCA GTA CGT
who contributed to the discovery of the DNA model Timeline in text pg
DNA is also responsible in making RNA in a process called transcription. RNA will function as a template to help make proteins for the body. Remember that proteins can be structural (muscles, hair, fingernails, etc) but can also be functional in the body systems like enzymes or hormones. RNA differs from DNA in 4 main ways: Single stranded Ribose sugar Uracil base instead of thymine Moves out of nucleus to be functional. bases pairings Sugar phosphate backbones RNADNA Ribonucleic aciddeoxyribonucleic acid 8 9 Add As 11B
3 forms of RNA mRNA messenger- comes out of nucleus to be the carrier of the code to make proteins. The code is read 3 bases at a time called the codon. tRNA transfer – transfers the amino acids to the growing protein or peptide chain- attaches to the mRNA with an anticodon base pairing with the codon. rRNA ribosomal- helps the ribosomes read the code on the mRNA, so the correct amino acids are delivered in the correct order. 11
DNA MAKES RNA IN A PROCESS CALLED TRANSCRIPTION. An enzyme, RNA polymerase, separates the strands of DNA. The free floating bases in the nucleus are attracted to the bases on the DNA strand. They assemble the same as in replication except URACIL bonds with ADENINE. ACGATGCAC _________ GTACGT______ TGCTACGTG CATGCA THE NEW FORMING mRNA strand CAU GCA
A protein is made by a process called translation. Text pages Know parts and how to read the circle (mRNA & inside out) For what amino acids are part of new protein.