Lecture 12 Flashcards
What happens when a cell reaches a certain size?
It either divides or stops growing
What is the range of time it takes for a cell to go through a cell cycle?
8-20 hours
What are the two main phases in the cell cycle?
Interphase and M phase
Interphase?
When the cell is growing and actively metabolising
- G1
- S phase (chromosomes duplicate)
- G2
M phase?
When the cell is actively dividing
- Prophase
- Metaphase
- Anaphase
- Telophase
Two types of chromatin?
Heterochromatin and euchromatin
Heterochromatin?
- Condensed
- DNA is inactive
Euchromatin?
- Unravelled
- Genes are expressible (DNA is active)
What happens to the chromatin in the early stages of mitosis?
They become more and more condensed
Centromere?
- A fix point in the centre of the chromosome that holds the two chromatids together
- Holds the chromosome in its shape
- Controls the movement of the chromosomes
Are the sister chromatids identical?
Yes, bc they each have the same DNA
Kinetochore?
- During late pro-metaphase when the 2 sister chromatids are separated from one another, an extra plate formed of protein is found at the centromere. This is the kinetochore, and is where the microtubules attach when pulling the chromatids apart
- Control assemble and disassembly of spindle fibre microtubules
- One on each chromatid
Where is the telomere located?
At the ends of the chromatids
What is the function of the telomere?
- Protect end of chromosome from deterioration or fusion with neighbouring chromosomes
- Maintain the structural integrity of the DNA
- Ensures complete DNA replication with the enzyme telomerase
- Position chromosomes in the nucleus
Structure of the telomere?
- DNA and protein that cap the ends of the chromosome
- 5 - TTAGGG - 3 repeating DNA sequence (repeated over 1000 times)
Karyotype?
A chart that orders the homologous chromosome pairs by number, size and morphology (biggest to smallest)
Gap 1?
- High levels of RNA transcription and protein synthesis
- Prepares to duplicate DNA
- Continuation of cytokinesis
- Increasing number of organelles such as mitochondria
S phase?
- DNA synthesis and replication
- RNA transcription and protein synthesis is continued