Lesson 3 - Properties of Genetic Material Flashcards
genetic material should be FAIRS
F - flexible / respond to external signals
A - altered / generate genetic diversity
I - information
R - replicated and transmitted accurately
S - stable (very)
genetic material should be flexible or …?
respond to external signals
genetic material should be altered or …?
generate genetic diversity
two sections of the chromosome
- p arm
- q arm
p in p arm meaning
petit
short arm of the chromosome
p arm
long arm of the chromosome
q arm
- appears as a constricted region of a chromosome
- plays a key role in helping the cell divide up its DNA during division
- the region where the cell’s spindle fibers attach.
centromere
- region of repetitive DNA sequences at the end of a chromosome
- protect the ends of chromosomes from becoming frayed or tangled
- Each time a cell divides, they become slightly shorter
telomere
composed of DNA and associated proteins
chromatin
two types of proteins in chromatin
- histone
- non-histone chromosomal proteins
small, well-defined, basic proteins
histone
include diverse structural, enzymatic and regulatory proteins
non-histone chromosomal proteins
example of non-histone chromosomal proteins
- transcription factors
- replisomes
two types of chromatin
- heterochromatin
- euchromatin
typically highly condensed, gene-poor, and transcriptionally silent
Heterochromatin
less condensed, gene-rich, and more accessible to transcription.
euchromatin
epigenetic mark
methyl
- flexible regions that flank both ends of the histone fold
- responsible for the formation of stable H2A–H2B and H3–H4 dimers, and the histone octamer is composed of two H2A–H2B dimers and two H3–H4 dimers
Histone tails
repeating units of chromatin composed of DNA and histones
nucleosome
Classes of histones
- H1
- H2A
- H2B
- H3
- H4
other term of H1
linker histone
- bind to linker DNA and are involved in the higher-order condensation of the chromatin
- control the accessibility of linker DNA between two neighbor nucleosomes to DNA-binding proteins and regulate chromatin folding
Linker H1 histones
complex together and act as a spool which the DNA wraps around
H2A, H2B, H3, and H4
octamer
2 copies of each histone (H2A, H2B, H3, H4)
Why is DNA of histone highly conserved
if there are changes, it leads to cell death
around 147 bp supercoiled DNA wrapped twice around a __
histone
how many base pairs of DNA are supercoiled in the histone
147 bp
histone H1 are referred to as __ __
linker DNA
histone H1 associates with
linker DNA
how many bp are there in linker DNA
38-53 base pairs
purpose of linker DNA
connects one nucleosome to the next
histone H1 runs down the center of the coil acting as __
stabilizer
nucleosomes are also described as
“beads on a string”
thickness of chromatin
30nm
two models of chromatin arrangement
- solenoid model
- zig-zag model
- characterized by interactions between consecutive nucleosomes
- helical loop
solenoid model
implies interactions between alternate nucleosomes
zigzag model
represents the basic structural unit of eukaryotic chromatin associated with DNA replication, gene expression and higher order packaging
loop domain
Summary: Levels of Chromatin Packing
- DNA double helix
- DNA wrapped around histone
- nucleosomes coiled into a chromatin fiber
- further condensation of chromatin
- duplicated chromosome
