Ch. 25 & 26 Dna and Protein Synthesis

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D. DNA

Name the four bases in DNA and describe the structure of DNA using the following terms: The four bases of DNA are adenine, thymine, guanine, and cytosine.

nucleotide (sugar, phosphate, base)
Sugar: pentose deoxyribose; phosphate: phosporic acid, nitrogen base (A, T, G, C)

complementary base pairing
A-T; G-C joined by hydrogen bonds. Purines (with double ring) always bond with a pyrimidine (single ring).

double helix
Double spiral; three dimensional

hydrogen bonding
Hydrogen bonding between bases

Describe DNA replication with reference to three basic steps: unzipping
The hydrogen bonds between the paired bases break. The enzyme helicase causes the molecule to unwind (to lose its helix shape).

complementary base pairing
Free complementary nucleotides in nucleus move into place by complementary base pairing.

joining of adjacent nucleotides
The complementary nucleotides join to form new strands carried out by the DNA polymerase enzyme (puts many –poly DNA together).

Define recombinant DNA
Definition: DNA that contains genes from more than one source.

Describe three uses for recombinant DNA
Drugs
Hormones
Vaccines
Nucleic acids for research
Compare and contrast the general structural composition of DNA and RNA DNA RNA

Sugar (pentose)Deoxyribose Ribose

Bases AGTC AGUC

Strands Double stranded with base single stranded

pairing

Helix Yes No

Similarities:

Nucleotides are basic structural unit
Complementary base pairing by hydrogen bonds
Both have a pentose sugar and phosphoric acid
E. Protein Synthesis

Demonstrate a knowledge of the basic steps of protein synthesis, identifying the roles of DNA, mRNA, and ribosomes in the process of transcription and translation Transcription
RNA molecule makes complementary copy of DNA
RNA goes into cytoplasm
Translation
Initiation: mRNA brings copy of DNA to ribosomal subunit, where when attached, becomes ribosome Elongation: tRNA brings amino acids...
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