DNA Aim ◦describe double helix structure of DNA molecule; ◦construct a model of DNA molecule based on the principles of its structure. Terminology English Kazakh Russian backbone complementary complete double helix ladder pairing pentagon rung strand to arrange to encode to transmit негіз комплементарлы толық қос спиральды баспалдақ жұптасу бесбұрыш саты тізбек орналастыру кодтау жеткізу основа комплементарность полный двойная спираль лестница спаривание пятиугольник ступенька цепь располагать кодировать передавать Terminology activity ◦Flapper Triple helix ladder d n a r t s DNA pentagon e r u t c u r t pa s bas e r a g su n e lem g p m o lix c e l b ou backbone he stor e function ns m it A N to a R rra ng e irin y r a t d two tra e e r th run g e t le p m o c to e d o enc Key Terms ◦Double helix - structure formed by two strands of DNA; ◦DNA - a molecule that store and transmit genetic information; ◦Nucleotide - monomer of DNA that consists of sugar, phosphate group, and nitrogenous base. What is DNA? What is DNA? ◦ DNA stands for deoxyribonucleic acid. ◦macromolecule ◦encodes hereditary information ◦stores hereditary information in a cell ◦transmits hereditary information from one generation to the next generation Nucleotide ◦DNA has two strands in opposite directions that form a double helix ◦Each strand has many repeating monomers called nucleotides. ◦Nucleotides have three parts: a phosphate group, a nitrogenous base, and sugar. Bases ◦There are four bases: adenine (A), cytosine (C), guanine (G), and thymine (T). ◦They pair with each other: adenine always pairs with thymine (A - T), while cytosine only with guanine (C - G). ◦It is called complementary base pairing. ◦Pairings of two strands hold DNA together and form a ladder-like structure. Both sides of DNA ladder are the sugar-phosphate backbone, and “rungs” are base pairs. ◦Base pairs can arrange themselves in millions of different sequences. ◦The sequence in which the base pairs line up with one another is like a code. ◦Each section of DNA codes for a different trait—whether it’s your eye color, the size of your ears, or whether you’ll develop a particular disease. REVIEW TIME 1) What do the letters DNA stand for? 2. DNA is a polymer, which means that is made up of many repeating single units (monomers). What are the monomers called? 3. The “backbone” of the DNA molecule is made up of two alternating components, what are these? 4. There are four different variations of these monomers (four different bases), what are the names of those bases? 5)Draw the basic structure of a nucleotide with its three parts. Use the image at the right to complete the follow: ● Circle a nucleotide. ● Label the sugar and phosphate. ● Label the bases that are not already labeled DNA is made up of nitrogenous base pairs. How do nitrogenous bases bond? A) adenine – thymine; cytosine – guanine B) adenine – cytosine; guanine – thymine C) adenine – guanine; cytine – thymine D) adenine – guanine; cytosine – turine E) adenine - guanine; cytosine - uracil DNA looks like a “twisted ladder”. If the “rungs” of the ladder are made up of nitrogenous bases, what are the backbone of the ladder made up of? A) sugars and proteins B) phosphates and salts C) sugars and phosphates D) salts and sugars E) sugars and sulphates Which of the following is not a nitrogenous base found in DNA? A) adenine B) cytosine C) guanine D) uracil E) thymine 4. Where most of DNA is located? A) mitochondrion B) nucleus C) lysosome D) cytoplasm E) plastids Literacy ◦DNA stores information about what? ◦Why is the picture of sugar pentagon shaped? Research Time ◦As you know DNA has two strands which pair with each other. ◦Find explanation why DNA is not a single-stranded and why DNA needs complementary base pairing.