All cells come from existing cells. This is observed by ____________ and __________ reproduction.
sexual and asexual
Why aren't all organisms made of just 1 cell?
because we're too complex
Why do cells divide instead of growing larger?
-too much demand for DNA
- harder for a cell to move nutrients around
The point of being in homeostasis is to be _______.
stable
Cells cycle between ____________ and ________.
stability, change
What are some situations in which an organism's cells would need to divide?
- if a tissue is in need of repair
- if the organism is growing
Birth, growth, development, reproduction and death are all involved with the ______________ of organisms like us.
life cycles
the regular pattern of growth, DNA duplication, and cell division that occurs in eukaryotic cells (or cells w/ nuclei)
Cell Cycle
Cell Cycles:
- divided into _______
- names are based on naming practices when ____________ was limited
- scientist didn't observe cells actively ________
- separated cells into 2 phases
stages
technology
dividing
resting phase is
interphase
dividing phase is
mitosis
Mitosis also includes the final stage called ___________.
cytokinesis
Which phase of the cell cycle do cells spend the most time in?
G1
Once _____________ developed, our idea of the cell cycle changed.
technology
What stage was added?
Synthesis Stage
G1 and G2 are called "gaps" because....
-they weren't able to observe everything
- eventually realized this is where growth and regular celluar functions occur
In the G1 phase, cells duplicate their _________ and carry out normal functions.
organelles
In the S phase, cells duplicate their _____, which ensures that each new cell recieves a _____ set of DNA as compared to the original cell.
DNA, full
In the G2 phase, additional growth occurs, until the cell is ready to ________ in the M phase.
divide
Cell cycle has _________ preventing the cells from moving on before certain conditions are met.
checkpoints
What happens in the G1 checkpoint?
-the DNA is checked to make sure it is not damaged and that it can be properly replicated
-sends signals to other cells when more cell division is needed
What happens in the G2 checkpoint?
The cell checks to make sure any DNA errors that formed during the S phase have been repaired.
What could happen if the internal factors that control the G2 checkpoint are not blocked in response to a failure of the checkpoint?
The cell will keep dividing even though the DNA has errors.
List the order of highest rate of division to lowest rate.
1 Embryos
2 Children
3 Adults
What stage are cells in when they don't need to divide reguarly? When they're in this stage, what occurs?
G0 (g-zero); everyday functions
What is the size of a cell?
10-20 micrometers
surface area is...
length x width x number of sides
volume is...
length x width x height
As the cell gets larger, the surface area -to- volume ratio ___________.
decreases
_________ and ________ factors regulate cell division.
internal and external
_______________ is programmed cellular division. Interal/external signals activate the _______, which produce self destructive enzymes.
Apoptosis, genes
__________ is uncontrolled cellular division. Clumps of these cells are __________.
Cancer, tumors
Apoptosis occurs:
- when cells are no longer needed
-damaged _____
- ___________ development
-____________________ time/ certain # of cell divisions
DNA
embryonic
predetermined
Evidence that cells may have turned cancerous:
- _______ ________ form crowding existing cells
- cells ________ more frequently than normal
cell clumps
divide
________ _______ was the first person to view cells under a microscope.
Robert Hooke
What was Robert limited by?
technology
3 main principles of cell theory:
- all organisms are made up of ________
- all existing cells are ________________ by other living cells
- the cell is the most basic unit of ______
cells
produced
life
Cell Theory changed over time as new discoveries came to light. What does this say about a scientific theory?
- A theory is based on the work of many scientists and leads to accurate predictions.
- New evidence that has been confirmed through observation and experiment may result in the modification of a theory.