2.1 DNA Structure and Cell Division

Learning Target: 5(A) describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication and mitosis, and the importance of the cell cycle to the growth of organisms;

Students should know: Emphasize that interphase (replication of DNA) is not part of mitosis, but part of the cell cycle. Phases of the cell cycle including interphase, mitosis (describe the stages), and cytokinesis Growth is a function of Mitosis

Vocabulary cell cycle DNA Replication Interphase Mitosis Prophase Metaphase Anaphase Telophase daughter cells diploid haploid Cytokinesis Chromosomes Chromatids deoxyribonucleic acid double helix Nucleotide Sequence hydrogen bonds Template Enzyme gene

Types of Nucleic Acids DNA – Deoxyribonucleic Acid; two intertwined strands of genetic information that form a double helix shape. RNA – Ribonucleic Acid; single stranded instructions used to make proteins ATP – Adenosine Triphosphate; high energy molecule ADP – Adenosine Diphosphate; low energy molecule

Thinking Map Create a Tree Map on your green paper classifying the different types of nucleic acids. – 8 minutes

Section 11.1 Summary – pages In 1953, Watson and Crick proposed that DNA is made of two chains of sugar and phosphate held together by nitrogenous bases. Watson and Crick also proposed that DNA is shaped like a long zipper that is twisted into a coil like a spring. DNA STRUCTURE

What are the components of DNA? Deoxyribose Sugar 2 4 nitrogenous bases 3  Two Purines:  Adenine (A)  Guanine (G)  Two Pyrimidines:  Cytosine (C)  Thymine (T) Phosphate group 1 Hydrogen Bonds

Section 11.1 Summary – pages The phosphate groups and sugars of the nucleotides form the backbone of the DNA molecule DNA STURCTURE “Legs of ladder” Phosphate & Sugar Backbone

Section 11.1 Summary – pages The bonds in the backbone between the sugars and phosphates are covalent bonds (strong bonds) DNA STURCTURE

Section 11.1 Summary – pages The nitrogenous bases make up the middle rungs of the DNA molecule. DNA STURCTURENitrogenous Base (A,T,G or C) “Rungs of ladder”

Section 11.1 Summary – pages The bonds between the nitrogenous bases are weak hydrogen bonds (indicated by the dotted line) DNA STURCTURE

Thinking Map Create a Brace Map listing the components of DNA 5 minutes

What is the difference between a purine and pyrimidine? Purines are double-ringed nitrogenous bases. Pyrimidines are single-ringed nitrogenous bases.

How to determine complimentary base pairs, in DNA? In a DNA molecule…  Adenine bonds with Thymine with two hydrogen bonds  Guanine bonds with Cytosine with three hydrogen bonds

1.What is the complementary strand for: ATC GGA TCG

Where is DNA located in a cell? In a prokaryotic cell, DNA is usually arranged in a single circular chromosome that is located in an area called the nucleoid and may be loosely tethered to the cell membrane. In an eukaryotic cell, DNA is contained within the nucleus. During some parts of the cell cycle, DNA is tightly coiled around proteins to form structures called chromosomes that protect the long, delicate strands of DNA – typically rod-shaped.