Biology (9700): Chapter 5, The mitotic cell cycle

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Chpt 5: The Mitotic Cell Cycle
(Cell cycle and nuclear division)
Chromosomes
Describe the structure of a chromosome




Structures:



Chpt 5: The Mitotic Cell Cycle (Cell cycle and nuclear division) 1

, 1. Telomeres: A region of repetitive nucleotide sequences at each end of a
chromatid, which:

a. Allows chromosome to replicate properly during cell division: during
replication, chromosome is shortened (DNA is lost) - prevents loss of
entire genes

b. Help organise chromosomes in cells

c. Prevents the chromosomes from unravelling and sticking to other
chromosomes, by acting as a cap/aglet

2. Chromatids: Identical strands of DNA, bound by centromere (1 chromatid = 1
DNA molecule)

a. Sister chromatids: genetically identical chromatids that make up the stx
of the chromosome

3. Kinetochore: the protein structure on chromatids, next to centromere,
containing a binding site, site for the attachment of spindle fiber

4. Genes: small sections of DNA that code for a particular protein and give
rise to a specific feature

DNA structure is maintained by histone proteins

5. Centromere: a narrow region containing no DNA which binds the 2 sister
chromatids together


Cell cycle
Outline the stages of the mitotic cell cycle

1. Interphase: cell growth

Longest phase in the cell cycle

Longest phase: G1

Where cell grows to normal size after division and carries out normal
functions - making proteins

All genetic material is in the form of chromatins




Chpt 5: The Mitotic Cell Cycle (Cell cycle and nuclear division) 2