Chromosomes - important tings Flashcards
Tell me about the Necleolus Organiser regions
- what are they associated with
- what do they made up of.
- associated with the nucleolus.
- consist of tandem repeats of rDNA, and segements of chromosomes that contains genes for rRNA.
what processes can chromatin undergo and what can it not undergo
can’t undergo translation, but undergoes everything else (transcrption, replication, repair, gene recombination and cell division.
when do chromatids form
during the s phase when DNA is replicated
what is an allele
variation of a gene
what terminology (and how much of each) is used to describe genetic material during the following processes -
1. before rpelication
2. after replication
3. during prophase
4. after anaphase
- 1 chromosome and 1 chromatid
- 1 chromasome and 2 sister chromatids
- 1 chromosome and 2 sister chromatids
- 2 chromosomes and 1 chromatid each
what is an locus
location of gene on a chromosome
How many autosomal and sex chromosomes do cells have
we have 44 autosomes autosomal chromosomes.
And 2 sex chromosomes
46 in total.
In what stage of cell divsion, aloows for karyotypes to be made of chromosomes. and what microscope is used.
Metaphase. using a light microscope.
what are duplicated, condensed chromosomes called?
dyads.
which classification of chromosomes can also be called sat-chromosomes and why.
Which species can they be found in.
Accrocentric Chromosomes, they have satellites and a secondary constriction - marking the site of NORs on their chromosomes.
found in rare species.
what are satellites, and what can they be used for.
Tandem repeats - multiple repeats of a sequence of nucleotides.
the length of the sequence differs between individuals, but those that are closely related have more similar satellites. so can be used for DNA profiling.
what are kinetchores, and how many base pairs are they made up of.
attachment site for the spindle fibres which help pull apart the sister chromatids at the centromere in anaphase.
- a complex made of about 80 different base pairs.
the interphase chromosomes are in what structural state
a single strand of DNA wound around histones. - chromatin
During mitosis, all synthetic processes stop. true or false
true, cos all other processes like transcription and some replication happens during the interphase of the cell cycle.
what plays a majour role in chromosome condensation during mitosis
methylation, increases the hydrophic nature of the histones, making DNA tightly wound to them - forming heterchromatin again.
what information can be read from a karyotype
- chromosomes morphological size
- number of chromosome
- chromosomes size
How many copies of each chromosome are in the interphase nucleus
2 copies, a result of replication during synthesis or the interphase.
what are cetromeres
the primary constriction on chromosomes, seperating the p and q arms
what are centrosomes, describe their function
they are a component of the cells, replicate during the G1 or S ohase of cell division.
they are needed in mitosis, in the prometaphse phase, where they move to opposite poles and are the origin of the mitotic spindle.
describe the structure of centrosomes and centrioles
Centrosome cosiest if centrioles at 90 degrees to each other.
Where in the cell cycle does transcription occur
In the G2 phase
