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EXERCISE 10: THE GENETIC MATERIAL
BIOL 11 (GENERAL BIOLOGY)
DNA AND RNA
• Two types of nucleic acids• Long molecules made up of units
called nucleotides• Each nucleotide is made up of three
parts: • a 5-carbon sugar (pentose)
• a phosphate group
• a nitrogenous base
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OO=P-O
O
N
CH2
O
C1C4
C3 C2
5
Nitrogenous Bases
1. Adenine (A)
2. Guanine (G)
1. Thymine (T)
2. Cytosine (C)
3. Uracil (U)T or C
A or G
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• DNA stores genetic information in most living organisms.
• In simple terms, DNAcontains the instructions for making proteins within the cell.
• DNA is organized into chromosomes, w/c are found within the nuclei of cells.
• Genes are segments in the chromosomes.
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STRUCTURE OF A DNA
• DNA is a very long polymer.
• The basic shape is like a twisted ladder or zipper.
• This is called a double helix (2 strands twisted together).
ONE STRAND OF DNA
• The backbone of the molecule is alternating phosphate and deoxyribose, a sugar, parts.
• The teeth are nitrogenousbases.
phosphate
deoxyribose
bases
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• DNA has four different bases:
• Cytosine C
• Thymine T
• Adenine A
• Guanine G
CHARGAFF’S RULE
• Adenine must pair with Thymine
• Guanine must pair with Cytosine
• Their amounts in a given DNA molecule will be about the same.
G CT A
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DNA STRUCTURE
Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.
G
G
A
T
T
A
A
C
T
G
C
A
T
C
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RNA (RIBONUCLEIC ACID)
• RNA forms the genetic material in viruses.
• Serves as genetic messenger, passing information from the DNA to other parts of the cell.
STRUCTURE OF RNA
• Single-stranded molecule composed of nucleotides.
• Pentose sugar is ribose.
• Nitrogenous bases are:
• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Uracil (U)
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TYPES OF RNA
Three main types
• Messenger RNA (mRNA) – transfers DNA code to ribosomes for translation.
• Transfer RNA (tRNA) – brings amino acids to ribosomes for protein synthesis.
• Ribosomal RNA (rRNA) – Ribosomes are made of rRNA and protein.
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DNA Structure vs. RNA Structure
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