Organization of nucleic acids Flashcards
1
Q
repetitious DNA
A
most abundant class of non-coding DNA --accounts for half of human genome about
2
Q
Interspersed Repeats
A
- -most abundant class of repetitious DNA
- -45% of human genome
- -transposons and retrotransposons
3
Q
Gene family
A
- -have similar NT sequences and encode similar but not identical proteins
- -arise from gene duplication events
4
Q
Pseudogene
A
- -mutations sometimes alter function of duplicated gene in gene family
- -mutations inactivate the duplicate then its called pseudogene
5
Q
Chromatin and Structure
A
- -1/3 DNA and 2/3 protein
- -1st level of structure: DNA wrapped around histone forming 11nm fiber (called nucleosomes)
- -2nd level: nucleosomes associate to form 30nm solenoid fiber
- -3rd level: 30nm fiber forms 300nm loop domains
6
Q
Chromatids
A
- -each chromosome consists of two identical DNA strands called chromatids
- -held together at centromere by cohesin
7
Q
Best time to visualize chromosomes?
A
cell division–700nm fibers
8
Q
Mito DNA
A
- -high gene density
- -13 genes encode proteins + 24 RNA molecules
- -circular
- -5-10 copies per mito
- -doesnt associate w/ protein
9
Q
Heterochromatin vs. Euchromatin
A
- -inactive transcription
- -highly condensed
Euchromatin: transcriptionally active
10
Q
Nucleolus
A
- -in nucleus
- -contains genes encoding rRNA
- -site of ribosome assembly
11
Q
Chromosomes in nucleus?
A
separated into separate territory
- -separated by domains
- -RNA synthesis is thought to occur on surface of chromosomal territories
12
Q
Nuclear membrane
A
- -double membrane
- -inner surface stabilized by nuclear lamina
- -perinuclear space continuous w/ ER
13
Q
3 large molecules that must be transport in/out of nucleus
A
–proteins, mRNA and ribosomal subunits
14
Q
Topoisomerases
A
–required to relieve supercoiling and allow replication of DNA to progress
15
Q
DNA Ligase
A
uses ATP to join Okazaki fragments together
