Term
|
Definition
Uncondensed regions of chromatin, during interphase.
They contain most of the active genes.
They stain very lightly. |
|
|
Term
|
Definition
Condensed regions of the chromosomes.
They contain very few genes.
They stain heavily. |
|
|
Term
| Facultative Heterochromatin |
|
Definition
Some regions of the chromosome that are euchromatin in some cells but heterochromatin in other cells.
Example: The X chromosomes in female mammals (Barr body). |
|
|
Term
|
Definition
The fisrt level of DNA packaging.
A core of 8 histone proteins with about 1.7 turns of DNA wrapped around it. |
|
|
Term
|
Definition
DNA between nucleosomes with variable lengths.
Can be digested by DNase 1. |
|
|
Term
| The 30 nm Chromatin Fiber |
|
Definition
The fifth histone protein, H1, that binds to the DNA where it enters and exits the nucleosome.
This is the form most euchromatins take in the interphase because it can easily revert to the beads-on-a-string structure when necessary for transcription. |
|
|
Term
| Chromatin-Remodeling Complexes |
|
Definition
| Multi-subunit enzymes, that use ATP to rearrange the nucleosomes, make the DNA more or less accessible to other proteins. |
|
|
Term
|
Definition
A protein that methylates the DNA.
Example: cytosine to 5-methyl cytosine.
Bacteria have 6-methyl adenine as well, and the main function is to protect against invading DNA. |
|
|
Term
|
Definition
A case when both copies of a chromosomes come from the same parent.
Examples: Prader-Willi syndrome, and Angelman syndrome. |
|
|
Term
|
Definition
| Joins the Okazaki Fragments. |
|
|
Term
|
Definition
| The second enzamatic activity of the DNA polymerase, which removes the RNA primer from the previous Okazaki Fragment as it moves down the template strand. |
|
|
Term
|
Definition
Cuts one strand and allows the other to relax, then re-ligates the cut strand.
Another form cuts both strands to allow one DNA double helix to pass through another, then re-ligates both cut strands. |
|
|
Term
| Single Strand Binding Protein (SSB) |
|
Definition
| Binds to single stranded DNA and prevents it from base pairing. |
|
|
Term
|
Definition
| An enzyme that synthesizes RNA primers. |
|
|
Term
|
Definition
| The enzyme that catalyzes the synthesis of the second strand of DNA molecule. |
|
|
Term
|
Definition
Any permenant change in the DNA molecule nucleotide sequence.
Mutations in the genes can alter or destroy the function of the gene's product. |
|
|
Term
|
Definition
Mutations that occur in the cells that become sperm or eggs.
These mutations are heritable. |
|
|
Term
|
Definition
Mutations that occur in the body cells.
It can only affect the individual, not his/her descendants.
Example: cancer. |
|
|
Term
| Pre-adaptive Mutation, or Exaptation |
|
Definition
| Having a mutation which has no, or a slightly bad effect on an organosm. Then a change in the environment makes that mutation valuable. |
|
|
