Biology review class 15

What criteria must genetic information meet to fulfill its role in hereditary and development?

stability, able to be expressed, replicate accurately, transmit from parent to offspring

What is the monomer of DNA and RNA?

nucleotide

What is a nucleotide made of?

a phosphate group, five carbon sugar, nitrogenous base

What bonds are present in polymers of a nucleic acids?

phosphodiester link, H bond

Phosphodiester bond

strongest: Links nucleotides together in sugar phosphate backbone

H bond

(weakest) hold the complementary base pairs together, allows strand separation

Helicase

unzips DNA by breaking each bonds

topoisomerase

prevents DNA supercooling

Single strand binding proteins

prevents reformation of H Bonds on a single strand

Primase

ads RNA primers for DNA polymerase

DNA polymerase

Synthesizes new DNA strands

Ligase

seals Okazaki fragment gaps

Telemerase

extends chromosome ends

Nucleosome: 10 nm fiber

DNA wraps around histone proteins, forming bead like structure

30 nm fiber

nucleosome's coil into a compact chromatin fiber

loop domains: 300 nm fiber

chromatin forms loops attached to a protein scaffold

Metaphase chromosome: 700-1400 nm fiber

loops coil further into the highly condensed structure scene during mitosis

Identify the difference between the five carbon sugars in DNA and RNA. Sugar:

DNA uses deoxyribose (lacks 2’ OH), RNA has ribose (has 2’ OH)

Why are the differences important in DNA and RNA?

DNA is more stable for long-term storage and RNA is more flexible for various functions

Van Der Waals Force

moderate: between stacked bases help stabilize the helix

Why is DNA replication completed with a leading strand and a lagging strand?

each new DNA molecule consists of one parental strand in one newly synthesized strand

Leading strand

continuous strand synthesized in the same direction as the replication fork movement.

Lagging stranded

synthesized discontinuously in short fragments called Okazaki fragments because it runs opposite to the replication fork's direction

Semi conservative

each new DNA molecule consists of one parenteral strand and one newly synthesized strand