Chromosomes Flashcards
What is the average length of the naked DNA in a human diploid cell?
2 metres
What are nucleosomes made from?
DNA and chromosomal
What are the two models for coiling of the chromatin loops?
Supercoiling Nucleosome Model
Radical-loop scaffold model
Describe the Supercoiling nucleosome model
how many nucleosomes per turn
10nm Nucleosome supercoil to form 30nm superhelix.
6 nucleosome per turn
Describe the radial-loop scaffold model
Non histone proteins bind at regular intervals to form loops tethering the 30nm superhelices
What are the 2 forms of chromosomes and what are the differences?
Acrocentric- centromere is not in the centre
Metacentric- centromere is in the centre of the chromosomes
Define Karyotyping
Process of pairing and ordering the chromosomes of an organism
What is the name of the short and long arms on a chromosome?
Short Arm=p
Long arm = q
Define Genome
Total of all the genetic information in an organism
Describe the prokaryotic genome
Single circular genome (haploid)
Sometimes carry episomes (aka plasmids; separate from main genome)
Small (bps) and compact
Describe the eukaryotic genome
Multiple copies of (linear, diploid but can be more) chromosomes within the nucleus
Circular mitochondrial and plastid DNA
Large(r) genomes (both bps and compactness)
Where are the chromosomes located?
In the nucleolus, in chromosome territories
How are chromosomes distributed?
Nonrandom radical distribution of chromosomes
How are CT positions correlated with gene content?
Gene poor= further outside near the membrane
Gene Dense = near the centre
These contain co regulated clusters
What are the two types of interphase chromatin ?
Do these are distinct CTs and TADs?
Heterochromatin/ Closed
Euchromatin / open
Yes
Describe the shape of Heterochromatin and if its transcribed
compact and not typically transcribed
Describe the shape of the Euchromatin
relaxed and typically transcribed
What is TAD?
Topologically-associated domains help seperate heterochromatic regions from euchromatic regions
In a view of the chromosome territories
What is LAD?
What is NAD?
What is component A?
What is component B?
LAD= Lamina associated domain NAD= Nuclear Associated Domain
A= Active compartment B= repressed compartment
Histones determine chromatin states- how?
Histones are very basic eg Lysine and Arginine
Control the opening and compression of chromatin
Name 2 histone modifying enzymes and what they have that is corresponding
HATs= Histone Acetyltransferases HMTs= Histone methyltransferase
They have corresponding De-enzymes
Define telomeres
The ends of the chromosomes
Define centromeres
The specialised DNA linking sister chromatids
Define promoter/enhancers
sequences that activates expression of nearby genes
Define silencers
sequences that repress expression of nearby genes
Define insulation
sequences that prevent more distal elements from affecting the expression of nearby genes
Define gene
smallest unit of hereditary coding for a gene product
How many of the human genome codes for proteins?
1.5%
Why do muscles differ?
name 3 things
Different chromatin site
coding gene expression
non coding gene expression
What is the central dogma?
And what does this mean for the causes of genetic diseases?
The ‘Central Dogma’ is the process by which the instructions in DNA are converted into a functional product.
Hence protein defects are a cause of genetic diseases
BUT that hasn’t been found and maybe due to NON-coding regions.
Which are known as pathogenic
What is ENCODED?
List of functional elements of the human genome
