The Cell Cycle Flashcards
What is the most basic function of the cell?
Duplicates DNA and creates 2 daughter cells
What takes longer Interphase or M phase?
Interphase is longer- 10/12 hours
M phase- 1 hour
Define G1
The cell-cycle gap phase between M and S phase
Define G2
The cell-cycle gap between S and M phase
Define interphase
Period after the End of one M phase and the beginning of the next
Define M phase
The cell-cycle phase during which the duplicated chromosomes are segregated and packaged into daughter nuclei ( mitosis) and distributed into daughter cells( cytokinesis)
Define S phase
The cell-cycle phase during which DNA replication and chromosome duplication
How is the DNA packaged in eukaryotic cells?
DNA is packed in chromatin
How is the DNA packaged in eukaryotic cells?
DNA is packed in chromatin: the complex of histones, non-histone proteins and nuclear DNA
Describe the shape of the histone
Histone octamer with dimers H3-H4 and H2A-H2B, 2 copies
What are the three minimal DNA sequence elements required for replication and why?
1) DNA replicator origin sequence
2) Centromere where kinetochore protein complex is formed allowing for separation
3) Telomere are repeated DNA sequences that allow the end of the chromosomes to be replicated
What are nucleosomes?
What are they composed of?
How many histones in the core?
Nucleosome are basic structural units of chromatin
Composed of DNA and histones
4 histones
What is the shape of the nucleosome?
4 histones make up the core of the Nucleosomes and share the histone fold formed from 3 alpha helices connected by two loops
What is the shape of the nucleosome?
4 histones make up the core of the Nucleosomes and share the histone fold formed from 3 alpha helices connected by two loops
In interphase nuclei chromatin is arranged how?
What proteins are involved in this formation?
Chromatin is arranged in loops
Architectural Proteins, cohesin complex and CTCF
Chromatin loops form / are grouped in what in interphase?
They form Topologically Associating Domain (TADS)
TAD are grouped into compartments, these may be transcriptionally-active (type A) or inactive (type B)
compartments belong to individual Chromosomal Territories, which are occupied by single chromosomes decondensed after mitosis
How can chromosomal territories can be visualised?
Chromosomal territories can be visualised using fluorescent staining A technique to paint chromosomes using multi-colour FISH (spectral karyotyping) helps to visualise entire chromosomes, both in mitosis and during interphase
Loop becomes more extended when gene is being expressed in the loop
What is the function of chromatin loop?
Function in chromosomal compaction and in the regulation of gene expression
In a metaphase, an individual chromatid contains how many DNA molecules?
One
What is the most important protein in establishing loops?
Condensin
Cohesin plays an important role in what?
Interphase
Condensin has an important role in what?
Mitosis
Cell control is similar in all eukaryotic organism? Yes or no
Yes
How many cell cycle check points are there and how do they work?
Cell cycle checkpoints may arrest the cycle at three different transitions, if something goes wrong. They work like binary switches that launch events in a complete, irreversible fashion
