Ch.3C Protein Synthesis

DNA Replication

• Each nucleotide strand serves as a template for building a new complementary strand

• DNA Polymerase III continues from the primer and covalently adds complementary nucleotides to the template

• DNA Ligase: Splices together the short segments of the discontinuous strand

• “Semiconservative Replication”

Mitosis

NUCLEAR division

Cytokinesis

Division of the cytoplasm

Phases of Mitosis

• Prophase (wind up)

• Metaphase (Line up)

• Anaphase (Split up)

• Telophase (Close up)

Cleavage Furrow

• Formed in late anaphase by contractile ring

• Part of Cytokinesis

• Cytoplasm is pinched into two parts after mitosis ends

Metaphase

Chromosomes cluster at the middle of the cell with their centromeres aligned at the exact center of cell

Metaphase Plate

Arrangement of chromosomes along a plane midway between the poles

Anaphase

• Centromeres of the chromosomes split

• Motor proteins pull chromosomes toward poles

Telophase and Cytokinesis

• New set of chromosomes unwind into chromatin

• New nuclear membrane is formed (Close up!) from the rough ER

• Nucleoli reappear

• Cytokinesis completes cell division

Square Cube Law

• Doubling the diameter of a cell

• increases surface area by factor of 4

• increases volume of cell by factor of 8

• Cells cant get too big or the surface wont be able to be supported by cell

Protein Synthesis

• DNA serves as a master blueprint for protein synthesis

• Triplets of nucleotide bases form the genetic library

Messenger RNA (mRNA)

Carries the genetic information from DNA in the nucleus to the ribosomes in the cytoplasm

Transfer RNA (tRNA)

• Bound to amino acids

• tRNA anticodons base pair with the codons of mRNA at the ribosome to begin the process of synthesis

Ribosomal RNA (rRNA)

A structural component of ribosomes

Transcription

Transfer of information from DNA to RNA

Transcription- RNA Polymerase

• enzyme that oversees synthesis of RNA

• Unwinds DNA template

• Adds complementary ribonucleoside triphosphates on the DNA template

• Joins these RNA nucleotides together

• Encodes a termination signal to stop transcription

Translation

• Start codon attaches to the small subunit of the ribosome

• Methionine: charged initiator tRNA binds to the small subunit

• Large ribosomal unit now binds to this complex, forming a functional ribosome

RNA Codons

• Code for amino acids according to genetic code

• AUG=start and methionine

• ACU= threonine

DNA Triplets

• Transcribed into mRNA Codons by RNA polymerase

• mRNA codons base pair with tRNA anticodons at the rRNA

• Amino Acids are peptide bonded to form proteins