Chapter 5-Mitotic Cell Cycle Flashcards
name of process through which a cell makes exact copies of itself
mitosis
name the parts of chromosomes (4 parts)
chromatids
kinetochore
telomeres
centromeres
how many DNA molecules are in one chromosome?
2 molecules, one DNA molecule in each chromatid
how do chromosomes divide equally?
one chromatid goes into one daughter cell and the other goes into the other daughter cell
DNA+protein=?
and name the protein
chromatin
and the protein is histone
what is a nucleosome and describe its structure
- cylindrical structure made of up of 8 histone molecules
2. DNA is wrapped around the outside of the cylinder.
when are chromosomes the most coiled?
interphase
describe mitosis
a process by which genetically identical cells are made
how can uncontrolled cell division result in cancer?
mutations
chromatin exists in what 2 forms
euchromatin and hetrochromatin
during interphase, which type of chromatin is the majority of chromatin found as?
euchromatin
when is chromatin most condensed or coiled (darker)?
during metaphase
which is the first stage of a cell cycle?
interphase
what does a cell do during interphase?
carries out normal functions until it gets a signal to divide again
what happens after the signal for cell division has been recieved?
DNA replicates itself (so that each chromatid will have one DNA molecule)
what is the name of the phase when DNA replicates?
S phase (synthesis of DNA phase)
name parts of a cell cycle (3 parts)
- interphase (consists of G1, S, G2)
- mitosis
- cytokinesis
what are the 4 stages of mitosis? (in order)
- prophase
- anaphase
- metaphase
- telophase
what does the cell look like during early prophase?
- nuclear envelope is present
- nucleolus is present
- centrosomes (things that make spindles) replicate just before prophase
- chromosomes start to appear as they become shorter and thicker
what does a cell look like during late prophase?
- nuclear envelope disappears
- nucleolus disappears
- chromosomes now consist as 2 identical chromatids
- centrosomes start to move at the end of poles
what does a cell look like during metaphase?
- centroSOMES reach poles
- spindles are formed and attached to centroMERES
- chromosomes line up across the equator of the cell
what does a cell look like during anaphase?
- sister chromatids are pulled apart by spindles
- chromatids separate at the centroMERES
(2 points)
what happens during telophase?
- nucleolus re-forms
- nuclear envelope re-forming
- remains of the spindles breakdown
- chromatids reach the pole
- cytokinesis takes place
(5 points)
what is the role of the centromere?
- needed for separation of chromatids
2. spindles attach to the centromere to pull the chromatid to the pole
describe what are kinetochores
- made of proteins molecules which bind to the the DNA in centromere and microtubules
- bundles of microtubules extend from the kinetochores to the poles during mitosis
describe centrosomes
- found in animal cells that act as a microtubule organizing centre (for the construction of spindle)
- each centrosome = pair of centrioles = large no. of proteins
these proteins control the production of microtubules and not the centrioles
4 significances of mitosis
- growth
- replacement of damaged cells and tissues
- asexual reproduction
- immune response
what are telomeres?
they are structures found at the end of chromosomes with extra DNA bases (with no useful information). they prevent important DNA bases from being lost.
what are stem cells?
cells that are not specialized and can change themselves to any type of cell i.e. tissue cell, muscle cell, etc.
types of stem cells
- totipotent: stem cells that can change into any type of cell
- embryonic stem cells are pluripotent because they have to become different types of cells.
- adult stem cells are multipotent because even though they can specialize to become different cells, they are restricted.
what results in cancer?
uncontrolled mitosis
what is a tumour and how is it formed?
a tumour is a mass of cells formed bh cancerous cells dividing uncontrollably
what type of change in the body causes cancer?
mutation in the gene that controls cell division to become an oncogene
(oncogene is a mutated gene)
what is a cancer causing agent?
carcinogen
not all tumours are cancerous. so what are the cancerous tumours called and why are they cancerous ?
malignant tumours
they are cancerous because they interfere with the normal functioning of the body
