Lecture 6 Flashcards
Series of events that cells go through as they grow and divide
The cell cycle
Two halves of the cell cycle
Interphase
M phase
Period of the cell cycle between cell divisions
Interphase
Period of time when mitosis and cell division occurs
M phase
Interphase Steps
Cell grows in size Organelles replicated Replication of DNA Synthesis of proteins (with DNA) Synthesis of proteins (with mitosis)
Parts of Interphase
G1 phase
S phase
G2 phase
Growing
Synthesize proteins
Doing their jobs
Longest phase
G1 phase
Chromosomes replicated
Key proteins are made
S phase
Shortest phase of interphase
Production of molecules for cell division
Check-up phase before mitosis
G2 phase
Conditions that must be satisfies before a cell will grow and divide:
Presence of growth factors
Anchorage to the substratum
Changes in cell contacts
When the preconditions for dividing is not met,
Cell will be delayed in the G1 phase
Phase where the cell spends a variable length of time after M phase
G1 phase
Move through the cell cycle in a regulated way
Normal cells
Used to decide whether to proceed with cell division or not
Information about their internal state
Cuea from the environment
Makes sure that cells don’t divide under unfavorable condition
Regulation
Non-dividing, differentiated state
G0 phase
Most human cells in G0 phase
Liver cells
Nerve cells
Muscle cells
In G0, but can be called back to cell cycle by external cues
Liver cells
Highly specialized
Arrested in G0 and can never divide
Nerve cells
Muscle cells
Cells temporarily or reversible stopped dividing and to have entered in a state of quiescence
G0 phase
Cells that have permanently stopped dividing due toage or accumulated DNA damage are said to be senescent
G0 phase
Failure of cell division control
Unrestrained, uncontrolled cell growth
Cancer
What control is lost?
Lose checkpoint stops
P53
Plays a key role in G1/S restriction point
Gene p53
Halts dell division if it detects damaged DNA
P53 protein
Options of p53 protein:
Stimutes repair enzymes to fix DNA
Forces cell into G0 resting stage
Keeps cell in G1 arrest
Causes apoptosis of damaged cell
Cancer develops only after a cell experiences
~6 key mutations (“hits”)
Development of cancel
Unlimited growth Ignore checkpointa Escape apoptosis Immortality Promotes blood cessel growth Overcome anchor dependence
Turn on growth promoter genes
Unlimited growth
Turn off tumor suppressor genes (p53)
Ignore checkpoints
Turn off suicide genes
Escape apoptosis
Turn on chromosome maintenance genes
Immortality
Turn on blood vessel growth rates
Promote blood vessel growth
Turn off touch-sensor gene
Overcome anchor and density dependence
The chromose are in an extendee form and seen as chromatin in the electron microscope
The nucleus is visible
Mitosis - Interphase
A complex of DNA and proteins in the cell nucleus that condenses to form chromosomesduring cell division
Chromatin
Condensed Chromatin
The same stuff but different form
Chromosomes
Replicated to form an identical copy of itself during the cell cycle (before cell division)
Chromosomes
Two identical copies of a chromosome
Sister chromatids
Area where the chromatids of a chromosome are attached
Centromere
2 major processes of mitotic cell division
Karyokinesis
Cytokinesis
Nuclear division
Preserves diploid number of chromosomes
Karyokinesis
Cytoplasmic division
Cell divide into two daughter cells
Cytokinesis
4 sub-phases of Mitosis
Prophase
Metaphase
Anaphase
Telophase and Cytokinesis
