Deoxy WHAT Unwinding the mystery of DNA Standard

Deoxyribonucleic Acid § What exactly is DNA? – Long molecule of nucleotides – Carries

What are nucleic acids? § Nucleic Acids are organic molecules that serve as the

Nucleotides § Each nucleotide is made up of three parts: – – – A

Discovery of ‘Double Helix’ § Prior to discovery of shape of DNA, scientists thought

DNA-The Double Helix § Two single strands of nucleotides wound around each other that

RNA: § -A single chain of nucleotides with nitrogenous bases exposed along the side

Base Pairing Rule § Chargraff’s Rules: § DNA: RNA: – A=T A=U – G=C

RNA versus DNA § 3 Main Differences: -Single Strand versus double strand -Sugar is

Types of RNA § 3 Main types of RNA – Messenger RNA = m.

RNA’s Job § RNA’s Main job is protein synthesis – Messenger RNA carries the

Relationship of Chromosomes, DNA, and genes Chromosomes are structures in the nucleus of a

Continued: § A Gene is a specific location on a chromosome, consisting of a

DNA as the ‘code of life’ § Considered the code of life or blueprint

Continued: § Number of chromosomes varies with type of organism. Example- humans = 23

Slides: 16

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Deoxy- WHAT? ? ? Unwinding the mystery of DNA Standard B 4. 1 -4. 3 - The student will compare DNA and RNA in terms of structure, nucleotides and base pairs; they will be able to summarize the relationship amond DNA, Genes and chromosomes; and explain how DNA functions as the code of life.

Deoxyribonucleic Acid § What exactly is DNA? – Long molecule of nucleotides – Carries genetic information from one generation to the next – Puts information to work by determining heritable traits – Is easily copied

What are nucleic acids? § Nucleic Acids are organic molecules that serve as the blue print for proteins. § Through the action of proteins- nucleic acids are the basis of all cellular activity § 2 types of nucleic acids: – DNA- deoxyribonucleic acid – RNA- ribonucleic acid – Both are composed of small units called nucleotides.

Nucleotides § Each nucleotide is made up of three parts: – – – A simple 5 - Carbon sugar= deoxyribose A Phosphate group A nitrogenous base: Cytosine (C), Guanine (G) Adenine (A), Thymine (T)(DNA only) Uracil (U) (RNA only) 4 different possible bases and 2 groups – Purines and Pyrimidines – Purines = adenine and guanine – Pyrimidines = cytosine and thymine

Discovery of ‘Double Helix’ § Prior to discovery of shape of DNA, scientists thought DNA was merely a ‘string of nucleotides’. § The work of many different scientists led to the discovery by Watson and Crick. – Avery – Franklin – Hershey and Chase – Griffith

DNA-The Double Helix § Two single strands of nucleotides wound around each other that are chemically bonded through the axis of the helix § Resembles a twisted ladder or spiral staircase. § Held together by hydrogen bonds that ONLY form between certain base pairs. – Guanine and Cytosine – Adenine and Thymine

RNA: § -A single chain of nucleotides with nitrogenous bases exposed along the side § -When RNA bonds to a strand of DNA- each RNA base can only bond with one type of DNA. § -This is called complementary base pairing § -Guanine-Cytosine § -Uracil- Adenine

Base Pairing Rule § Chargraff’s Rules: § DNA: RNA: – A=T A=U – G=C Bacteria and Humans both obey this ruledespite structural differences.

RNA versus DNA § 3 Main Differences: -Single Strand versus double strand -Sugar is Ribose versus Deoxyribose -Contains Uracil in place of Thymine

Types of RNA § 3 Main types of RNA – Messenger RNA = m. RNA – Ribosomal RNA = r. RNA – Transfer RNA = t. RNA

RNA’s Job § RNA’s Main job is protein synthesis – Messenger RNA carries the instructions from DNA to the rest of the cell. – Proteins are assembled on the ribosomes. Ribosomal RNA – Transfer RNA transfers each amino acid to the ribosome by its specified m. RNA codon.

Relationship of Chromosomes, DNA, and genes Chromosomes are structures in the nucleus of a cell consisting essentially of one long thread of DNA that is tightly coiled. DNA- composed of nucleotides- is the blueprint for the synthesis of proteins by the arrangement of nitrogenous bases. ** the code for a particular amino acid is determined by the sequence of 3 base pairs on the DNA

Continued: § A Gene is a specific location on a chromosome, consisting of a segment of DNA, that codes for a particular protein – The particular proteins coded by the DNA on the genes determine the characteristics of an organism – Each chromosome consists of hundreds of genes determining the many proteins for an individual organism

DNA as the ‘code of life’ § Considered the code of life or blueprint because it contains the code for each protein that the organism needs. § The specific protein is determined by the order of nitrogenous bases § Each cell in an organisms body contains a complete set of chromosomes

Continued: § Number of chromosomes varies with type of organism. Example- humans = 23 pairs, dogs = 39 pairs, potatoes = 24 pairs § 23 rd pair determines sex (sex chromosomes), other 22 pairs= autosomal § Every cell contains one pair of the autosomal chromosomes (one from Mom and one from dad) § Each chromosome consists of thousands of genes § The closer you are related, the more similar your genes.

To be continued…. . § The end