structure and function of dna
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Structure and Function of DNA. Structure of DNA(deoxyribonucleic acid). Discovered by Watson & Crick in 1953 DNA is a nucleic acid DNA is made up of small subunits called nucleotides. The nucleotides are made up of: deoxyribose(sugar) phosphate group - PowerPoint PPT PresentationTRANSCRIPT
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Structure and Function of DNA
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Structure of DNA(deoxyribonucleic acid)
• Discovered by Watson & Crick in 1953
• DNA is a nucleic acid
• DNA is made up of small subunits called nucleotides
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The nucleotides are made up of:
•deoxyribose(sugar)
•phosphate group
• nitrogen bases-4 types1. Adenine- A2. Guanine-G3. Cytosine- C4. Thymine-T
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DNA is actually 2 long chains of nucleotides that are joined together in the form of a ladder. The ladder is twisted in the form of a double helix or spiral
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Hydrogen bonds
Nucleotide
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Structure of DNA
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The sides of the ladder are composed if alternating deoxyribose(sugar) and phosphate. The rungs of the ladder are composed of pairs of nitrogen bases.
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The nitrogen bases always pair up in a specific pattern.
•Adenine(A) pairs up with Thymine(T)
•Guanine(G) pairs up with Cytosine(C)
Example
A G C T A C G C A one side T C G A T G C G T other side
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All organisms have the same type of nucleotides. The nucleotide arrangement provides for all the different types
Ex- A mouse and a rosebush have the same nucleotides. However, they are different because their nucleotides are in different orders.
*This sequence of nucleotides forms the genetic information(code) of an organism.
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Replication of DNA
Before meiosis and mitosis (during Interphase) a copy of DNA must be made so that when the new cells are formed, they each get an exact copy of the genetic information.
This DNA copy is made through a process known as replication.
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Steps of Replication
During replication, each strand serves as a pattern or TEMPLATE to make new DNA molecule.• First step: DNA (H bonds are broken)
unzips into 2 strands
• Second step: free nucleotides join onto “unzipped” strands to form 2 new strands of DNA
• 2 complete strands will result, these will be exactly alike
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Figure 12–11 DNA ReplicationSection 12-2
Go to Section:
Growth
Growth
Replication fork
DNA polymerase
New strand
Original strand DNA
polymerase
Nitrogenous bases
Replication fork
Original strand
New strand
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Warmup- Transcribe the DNA and translate the codon sequence into a protein.
DNA mRNA tRNA Amino acid
GCC CGG GCC
AAA UUU AAA
CGC GCG CGC
GCG CGC GCG
TTT AAA UUU
ATT UAA AUU