Chapter 11: Biochemisrty of the Genome

What is passed from cell to cell?

DNA

What must be replicated with accuracy when cells divide?

DNA

What are the two processes to make a protein?

1. transcription

2. translation

Transcription creates what?

RNA

Translation creates what?

Proteins

What are the three phases in each step of making a protein?

1. Initiation

2. Elongation

3. Termination

Function of topoisomerase II (gyrase) in transcription (initiation)

uncoils/unwinds DNA

Function of helicase (initiation)

opens the strands

• replication fork forms

Function of single-stranded binding protein (initiation)

keeps DNA from recoiling

Function of DNA polymerase III (initiation)

begins base-pairing to leading strand toward the replication fork

What does lagging strand need? (initiation)

RNA polymerase to put down a primer

What does other DNA polymerase do? (initiation)

base-pairing from primer away from the replication fork in segments called Okazaki fragments

What does RNA polymerase do as lagging strand synthesis occurs? (elongation)

must place new primer at the fork as it opens

What does DNA polymerase III do in lagging strand synthesis? (elongation)

moves away from the fork-base pairing in the 5’ to 3” direction, forming okazaki fragments

Function of sliding clamp (elongation)

holds each DNA polymerase in place

What happens to primers in lagging strand synthesis? (elongation)

moved and replace by DNA polymerase I

Function of DNA ligase (elongation)

connects the gaps

What happens with chromosomes in termination?

chromosome replication completion

What are chromosomes separated by in termination?

topoisomerase IV

Three types of RNA

1. mRNA

2. tRNA

3. rRNA

What do eukaryotes contain?

exons (codes) and introns (no coding) sequences in DNA

What do prokaryotes not have?

no introns and no RNA processing or modifying

• transcription and translation can occur simultaneously

Function of rRNA

binds to two protein units

Function of mRNA

contains information to build polypeptide chain

Function of tRNA

brings amino acid to ribosome complex

What is a codon?

A 3 base sequence that codes for a gene

What is genotype?

refers to the genetic makeup of an organism and is not visible

What is phenotype

Phenotype refers to gene expression and is physically observable

What are nutrient deficient mutants called?

auxotrophs

What are normal non-mutants called?

prototrophs

What is a silent mutation?

has no effect on the protein sequence

What is a missense mutation?

results in an AA substitution

What is a nonsense mutation?

substitutes a stop codon for an AA

What is a frame shift mutation?

Insertion/deletion of one or more bases

What is an induced mutation?

“forced” or crated by mutagens type of mutation

• smoke

• chemicals

What cause radiation mutations?

X-rays, gamma rays, and ultraviolet

What do X and gamma rays produce?

free radicals which attack other cellular molecules

What is less energetic and in humans affects the skin?

Ultraviolet

How do prokaryotes achieve genetic diversity?

• Transformation

• Transduction

• Conjugation

What is operon theory?

RNA polymerase binds to the promoter site if there is no repressor present. When substrate is present, repressor moves away from the operator site and allows for transcription to occur. The repressor gene codes for the repressor protein. This process allows for the turning on/off of operons dependent on the nutrients present in media.