Cell cycle and cell division Flashcards
what are the three stages of cell cycle?
interphase
nuclear division
cell division
what is interphase?
the period between divisions
what are the stages of interphase?
G1 phase; cells increase in mass
S phase; DNA replicates
G2 phase; cell prepares for division, synthesises and stores ATP and new organelles
what is cytokinesis?
cytoplasm divides
can all cells go under cell cycle?
no, specialised cells do not undergo cell division
Example; RBCs can not divide to produce more cells, they must be produced by bone marrow cells.
what is a gene?
a section of DNA which codes for one specific amino polypeptide
what are intergenic regions?
sequence of DNA bases between genes
what is a chromosome
a chromosome is an independent DNA molecule which has been supercoiled into a condensed form
what is a centromere
identical copies of DNA molecule are attached at a central point called centromere
what ae chromatids?
genetically identical copies of DNA molecule made during semi conservative DNA replication
what are histones?
proteins that help DNA molecules supercoil
what are homologous chromosomes?
chromosomes that have the same genes in the same loci but different alleles of the gene
what is mitosis used for?
-growth of organism
-repairing damage cells/tissues
-replacement of worn out cells
what is cytokinesis?
in-pinching of the cell membrane to create two genetically identical daughter cells
what happens in prophase?
- nuclear membrane starts to break down
- centrioles move to opposite poles and form spindle fibres
- chromosomes supercoil and become visible
what must take place first before mitosis?
semi-conservative DNA replication
telophase
- nuclear membrane starts to reform around each set of separated chromosomes
- chromosomes uncoil and become invisible
What is an allele?
Different version of the same gene
metaphase
- chromosomes attach to spindle fibres by their centromeres
- chromosomes align along the equator of the cell
2n=____ in humans/diploid organisms
46
what is the difference between mitosis and meosis?
MITOSIS: gentically identical daughter cells produced
2 diploid daughter cells produced
no crossing over and independent segregation
somatic cells(body cells)
MEIOSIS: genetically different daughter cells produced
4 hapoiud cells produced
cossing over and independent segregation occurs
sex cells(gametes)
