Exam 2 Flashcards
How many base pairs can a typical gene be?
10k bp
How are chromosomes arranged in interphase?
in chromosome territories
What are chromosome territories?
volume of nuclear space that is occupied by a single chromosome
-can vary from cell type and chromosome type
In what states can chromatin be found in a chromosome territory?
euchromatin state and heterochromatin state
Heterochromatin state:
chromatin that shows little or no transcriptional activity
Eurchromatin state:
chromatin that shows significant transcriptional activity
Are there further levels of control of access within territories?
yes, A compartments and B compartments
A compartments:
segments of transcriptionally active DNA
B compartments:
segments of transcriptionally inactive DNA
What are topologically associating domains (TADs)?
stable regulatory units of replication timing
-where TAD is in territory, depends if its gonna be replicated or not
TAD’s (other)
-cohesion: hold chromatin in loops
-promoter: it makes contact “there”
-RNA pol: made of multiproteins
How can molecules interact?
if they have complementary surface structures, then they can bind to each other covalently
-complementary is 2 different things that go well together
What happens when molecules bond to each other?
they change each others shape
-think heme in hemoglobin
Why do we care about change in shape?
change of shape can mean change of function!
inactive confirmation: eagle’s wings-> no flight
active confirmation: eagle’s wings -> flight
Can function of a molecule be altered by covalent modification?
yes
In what 5 ways could a protein structure be modified deliberately?
-phosphorylation
-adenylation
-uridylyation
-ADP-ribosylation
-methylation
case by case, no way to predict
What is the structure of chromatin?
the basic structure of chromatin is the nucleosome
-H2A, H2B, H3, H4
-methylated = condensed (non polar)
-acetylated = uncondensed -> keep repelling each other so they can’t condense
What is the structure of a nucleosome?
8 histones (146 bp)
NCP (nucleosome core particle) and linker DNA (54 bp)
How can nucleosomes be arranged in chromatin?
specific enzymes covalently modify Histones, resulting in a relay series of conformational changing
-active gene (euchromatin)
-silenced gene (heterochromatin)
What is a gene?
a sequence of nucleotides that can be transcribed by proteins to build an RNA molecule
-ALL RNA is transcribed by a gene
What is transcription?
process by which all cells use proteins to make an RNA copy of a DNA sequence
Sense strand:
exact sequence as RNA
Antisense strand:
serves as template strand for transcription
