DNA AND PROTEIN SYNTHESIS. 2008. DNA (DEOXYRIBONUCLEIC ACID) Nucleic acid that composes chromosomes and carries genetic information. CHROMOSOME ORGANIZATION 1. A chromosome is an enormous strand of super coiled DNA.
1. A chromosome is an enormous strand of super coiled DNA.
2. Sections of DNA on the chromosome that code for proteins are called genes.
3. Noncoding sections of DNA are called “junk DNA” (regulatory or unknown function)
Composed of nucleotides
1. 5-Carbon Sugar (deoxyribose)
2. Phosphate Group
3. Nitrogen Base (four types, adenine, guanine, thymine and cytosine)
A-T : 2 hydrogen bonds
C-G : 3 hydrogen bonds
Process in which DNA is copied
Gives daughter cells produced by cell division a complete set of genetic information identical to the parent cell.
1. Helicase enzymes unzip the parent strand by separating the nitrogen base pairs.
2. DNA polymerase pairs free DNA nucleotides with the exposed bases on both strands following the base pair rules.
3. Hydrogen bonds reform spontaneously sealing the two strands of each DNA molecule together.
Nucleic acid involved in the synthesis of proteins
Composed of nucleotides, but differs from DNA in three ways.
Three forms of RNA involved in protein synthesis
1. mRNA (messenger): copies instructions in DNA and carries these to the ribosome.
2. tRNA (transfer): carries amino acids to the ribosome.
3. rRNA (ribosomal): composes the ribosome.
Cells build proteins following instructions coded in genes (DNA).
DNA is copied into a complementary strand of mRNA.
1. RNA polymerase untwists and unzips a section of DNA (usually a single gene) from a chromosome.
2. RNA polymerase pairs free RNA nucleotides to the exposed bases of one of the DNA strands following base pair rules.
3. Newly synthesized mRNA separates from template DNA and DNA zips back up.
mRNA strand with instructions for building a protein that leaves the nucleus and goes to the cytoplasm.
TAC CGG ATC CTA GGA TCA
AUG GCC UAG GAU CCU AGU
Structural and functional components of organisms.
The “language” that translates the sequence of nitrogen bases in DNA (mRNA) into the amino acids of a protein.
mRNA AUG GAA CAC GUA CCC UAG
A.A MET G.A HIS VAL PRO STOP
Instructions in mRNA are used to build a protein
ribosome (in the cytoplasm)
1. mRNA binds to the ribosome.
2. Ribosome searches for start codon (AUG)
3. tRNA brings correct amino acid (methionine) to the ribosome.
4. ribosome reads next codon
5. tRNA’s continue lining up amino acids according to codons
6. peptide bonds link amino acids together
7. ribosome reaches STOP codon