(5-7) Macromolecules: Weak Bonds, Nucleic Acids, Chromatin

Macromolecules are - _ (units?) in size

1,000-1,000,000 daltons

bonds are generally used to link small organic molecules into macromolecules

covalent

bonds are primarily structural whereas bonds usually determine the action of a molecule

covalent; weak

Different types of weaks bonds

ionic, hydrogen, van der waal interactions, and hydrophobic interactions

Ionic bond

interaction between a fully or partially charged group. Ex. sodium chloride has a interaction between Na+ and Cl-

Hydrogen bonds

created by an interaction in which a hydrogen atom is shared between two electronegative atoms (like O). one of the most common weak bonds.

Van der waal force

transient interaction based on random chance. For a brief period of time an electron in one atom has an attraction to the protons of a second atom. Weakest bond.

Hydrophobic interactions

not caused by an attraction between hydrophobic molecules, rather it is caused by a repulsion between those molecules and water which causes them to group closely together.

Nucleic acids

DNA or RNA. consists of linked nucleotides.

DNA represents about ___% of total matter in a cell and RNA takes up __-__%

1; 3-5

DNA is found in and RNA is found in __

nucleus; anywhere in the cell

Draw simple double stranded DNA nucleic acid with 2 nucleotides on each strand with all of the base pairs found in DNA

Phosphodiester linkage

bond between the 3’ carbon, a phosphate group and the 5’ carbon and that same phosphate group. Links nucleotides together in nucleic acids

Adjacent nucleotides describe

nucleotides next to one another on the same strand (not complimentary

t/f doubles stranded RNA is rare

false, it is actually one of the primary forms of RNA

Is it possible for a RNA strand and DNA strand to associate into a double stranded form?

yes

DNA is incredibly (stable or unstable)

stable

Chromatin

DNA which wrapped and organized by associated proteins

Histones

positively charged proteins that interact together to form a basis of a structure to stabilize DNA

Nucleosome (what does it consist of?)

globular histone octamer consisting of 2 of each-H2A, H2B, H3, H4. protects DNA from being degraded by nucleases

How many times does DNA turn around a nucleosome? How many bp is this?

1.7; 146

Beads on a string

conformation of DNA associated with nucleosomes which protects the DNA from nucleases and makes the DNA stable

H1

non-nucleosomal histone protein. Wraps itself around the DNA found between nucleosomes.

Forms of chromatin from tightest conformation to loosest

chromosome, heterochromatin, euchromatin

Diameter across the a chromatid of a chromosome

1400 nm

Heterochromatin is found where in the nucleus?

it is organized along the innermost membrane of the nucleus (around the edge of the nucleus)

What form of chromatin is usually transcribed?

euchromatin