Biology 181 (Unit 3 Exam)

DNA Polymerase

adds nucleotides to build new DNA strand

Helicase

Unzips DNA (breaks hydrogens bonds)

Primase

Makes RNA Primer

Topoisomerase

Relieves DNA twisting ahead of fork

Ligase

Joins Okazaki fragments

Telomerase

Extends telomeres (protects chromosome ends)

Okazaky Fragments

Short DNA pieces on lagging strands

Telomere

Repeating DNA at chromosome ends (Protect DNA)

Proofreading

DNA polymerase checks & fixes mistakes

Leading Strand

DNA strand made continuously toward replication fork

Lagging strand

DNA strand made in fragments away from fork

Induced mutations

Caused by enviromental factors (chamicals,radiation)

Spontaneous mutations

Occurs naturally during DNA

Insertion

Extra nucleotide ADDED

Substitution

One nucleotide REPLACED with another

Deletion

Nucleotide REMOVED

What is DNA used for by the cell?

Stores genetic information (instructions to make proteins)

What is the purpose of RNA ?

Helps make proteins using DNA instructions

Rosalind Frankllin

Took “PHOTO 51” (X-ray proof DNA is a helix)

Maurice Wilkins

Played an importand role in the discovery of the double helix structure of DNA (Worked with Franklind, shared DNA data with Watson & Crick without her knowledge)

Watson & Crick

Built the 3D double helix model

Central Dogma

DNA→RNA→PROTEIN

DNA (recipe book)

RNA (copy of one recipe)

Protein (final dish)

What happens during INITIATION?

RNA polymerase BINDS to DNA and starts transcription.

What happens during ELONGATION?

RNA polymerase ADDS RNA nucleotides to build RNA strand

What happens during TERMINATION?

RNA polymerase REACHES stop signal and realeases RNA

Promoter

Unique DNA sequence that receuits RNA polymerase to copy/transcript the gene

Where does transcription take place in the cell?

Where DNA is:

Eukariotic→ NUCLEUS

Prokaryotes→ CYTOPLASM

Exon

Part of the transcript is kept and translated (EXPRESSED)

Introns

Noncoding sequence that is not part of the final message (Introns IN THE TRASH)

Which are translated by the ribosomes? (Exons-Introns)

Exons atr translated by ribosomes

Splicing

Intron are cut out and exons are joined together.

5’ cap

Protects mRNA & helps ribosome bind

Poly-A tail

Keep mRNA safe + help in protein production

pre-mRNA vs mRNA

• pre-mRNA→ Raw RNA (has introns & exons, but not processed)

• mRNA→ processed RNA (introns removed, and ready for translation)

Where does translation occur?

Ribosomes in cytoplasm

What role do ribosomes play in the process?

Read mRNA and build proteins. (Protein factory)

Codons

3-nucleotide sequences that code for amino acids

Where are they found? (Codons)

On mRNA

what is the function of START codon?

Signals where the translation begins

what is the function of STOP codon?

Signals where translation ends