5.1 Replication and division of nuclei and cells Flashcards
Structure of chromosome (5)
DNA
histone proteins
sister chromatids
centromere
telomere
Telomeres
at the end
Genes
- for different characteristics
in reality each chromosome is typically made up for several thousand genes
Chromatids (4)
two identical chromatids make one chromosome
each chromatid contains one DNA molecule
combination of DNA and proteins (histones)
the protein (histones) is basic - DNA is acidic so interact easily
length of DNA
46 chromosome
centromere
holds the two chromatids together (no genes in this region)
Importance of mitosis (5)
growth of multicellular organisms
replacement of damaged or dead cells
repair of tissue by cell replacement
asexual reproduction
Interphase (3) In order
growth G1
DNA replication S
growth G2
Mitosis (4)
prophase
metaphase
anaphase
telophase
Cytokinesis
cell division
–> two cells are formed
G1
cell grows by producing proteins and cell organelles
–> mitochondria
S (3)
growth of the cell continues as replication of DNA occurs
histones are synthesised and attach to DNA
each chromosome becomes two chromatids
G2 (2)
cell growth continues by protein and cell organelle synthesis
spindle begins to form
–> mitochondria divides
role of telomeres (4)
–> Each time DNA of chromosomes are replicated, ends of the DNA molecules cannot be copied –> sequences can be lost
–> ends are protected by telomeres
–> specail non-coding nucleotide sequences
–> non-coding sequence are lost at each replication of the DNA –> no harm to the genes of the chromosomes
Role of stem cells in cell replacement and tissue repair by mitosis
–> can divide unlimited number of times by mitosis
–> when it divides, each new cell has the potential to remain a stem cell or to develop into a speciallised cell
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