Molecular Information Flow and Protein Processing

Exam 3

what connects the 3’ carbon of one sugar to the 5’ carbon of the adjacent sugar?

Phosphodiester bonds

What is a nucleotide made of?

pentose sugar, nitrogenous base, and a phosphate

What is a nucleoside made of?

pentose sugar and a nitrogenous based (NO phosphate)

DNA and RNA are what kind of nucleotides?

polynucleotides

what supplies the energy for replication

nucleotides

What provides the energy for the reaction?

Hydrolysis of two phosphate groups from ATP molecules

Replication occurs in what direction?

5’ to 3’

What does topoisomerase and DNA gyrase do?

they relax the DNA strands

What does helicase do?

it separates the strands, creating a replication fork

replication is initiated by an

RNA primer

What does DNA polymerase do?

it adds nucleotides to the growing DNA strand and removes the RNA primers

strand that is synthesized continuously

the leading strand

strand that is synthesized discontinuously and created Okazaki fragments

lagging strand

When the RNA primers are removed, the Okazaki fragments join what?

DNA ligase

Why is replication highly accurate?

because of the proofreading capability of DNA polymerase

What is a chromosome?

the main genetic element in prokaryotes

What kind of chromosome do Prokaryotes have?

single circular chromosome

What kind of chromosome do Eukaryotes have?

two or more linear chromosomes

What role does supercoiling play?

it compacts linear DNA to accommodate the genome as it is much longer than the cell

What are mobile genetic elements?

they move from one cell to another or from one chromosome to another

what are plasmids?

self-replicating circular pieces of DNA

what are some functions of plasmids?

• may code for proteins that enhance pathogenicity of a bacterium

• may encode virulence factors in several pathogenic bacteria

• encodes some bacteriocins

• Bioremediation

• is important for conjugation

what are Bacteriocins?

proteins that inhibit or kill closely related species or different strains of the same species; bacteria produced to kill other closely related species

Rhizobia require plasmid-encoded functions in order to?

fix nitrogen

What do resistant (R) factors do?

encode antibiotic resistance

What are the two sets of genes found on R factors?

1. Resistance transfer factor (RTF): group of genes for replication and conjugation

2. R-determinants: resistance genes

What does a conjugative plasmid do?

carry genes for sex pili and helps transfer the plasmids

What do dissimilation plasmids do?

encode enzymes for catabolism of unusual compounds

What are transposons?

segments of DNA that can move from one site to another on the same or different DNA molecule —— are not restricted to only chromosomes

What is transposase?

an enzyme that cuts and reseals DNA

what codes for transposase?

insertion sequences (IS)

What is a gene?

the functional unit of genetic information

What is a genome?

all genetic elements

What is DNA and what does it do?

the “genetic blueprint”; it is able to act as the “molecule of heredity” because it can direct the production of proteins