Lecture 19: cell cycle and mitosis Flashcards
requirements for cell division
- receipt of a signal to direct the cell to divide
- DNA replication
- DNA distribution (mitosis)
- cytokinesis
Which of the following are differences between cell division and mitosis?
cell division includes cytokinesis but mitosis only includes nuclear division
identical chromatids
can be found in one chromosome
Interphase has three distinct phases
- G1: cell growth and differentiation
- S: synthesis and replication of chromosomes
- G2: synthesis of molecules, other than DNA, needed for cell division
- G0: cells that never divide such as nerve cells
mitosis
equal distribution of DNA into daughter cells
5 phases of mitosis
- prophase
- prometaphase
- metaphase
- anaphase
- telophase
Early Prophase
- chromosomes condense
- mitotic spindle grows out of the centrosomes
- kinetochore appears at the centromeres
- centrosomes migrate towards the poles
prometaphase
- nuclear envelope disintegrates
- kinetochore appears at the centromere of each chromatid
- spindle fibers attach to the kinetochore
metaphase
the centromere-kinetochore complexes align in the equator of the cell
anaphase
- chromatid disjunction
- DNA molecules move toward opposite poles
telophase
- nuclear envelope reforms
- spindle disappears
- DNA reverts to chromatin
- nucleolus reforms
3 types of microtubules
- kinetochore: attach to each chromatid
- polar or non-kinetochore: overlap with each other
- astral: attach the centrosome to the cell pole
Cytokinesis is different in animal and plant cells
- animal cells develop cleavage
- plant cells have a cell plate
in a cell that is ready to divide, a homologous pair of chromosomes consists of
two chromosomes and four chromatids
which of the following is true of. species that has a chromosome number of 2n=16
there are 8 homologous pairs
what happens when cell cycle is out of control
-cancer grows from one original cancer cell
cancer
arises from one cell that progresses too quickly through the cell cycle
cyclins
family of. proteins that activate a specific kinase
cyclin dependent kinase
activated by cyclin
what is thee name of the process by which cancer cells break off tumors and spread to other parts of the body?
metastasis
traits of cancer cells
- released from the telomere shortening and apoptosis
- undergo metastasis
- accumulation of mutations
telomerase
enzyme that catalyzes addition of telomere DNA sequences
-found in germ line cells, unicellular eukaryotes, and cancer cells
metastasis
migration of cancer cells from primary tour to grow secondary tumors at distant locations in the body
oncogene
codes for a protein that stimulates cell division
tumor supressor gene
loss of function of protein removes inhibition of cell division
viral oncogene
infection with a virus that has the oncogene can lead to loss of cell cycle control
the incidence of cancer increases with age because
the longer we live, the more mutations accumulate
