Chapter 10: Cell Growth & Division Flashcards
Mitosis and cell division produces two ______
identical daughter cells
3 goals of mitosis and cell division:
growth, repair, and development
1st problem: Cell size and material exchange
the larger a cell grows the surface area/volume ratio DECREASES which makes cells less efficient at…
- moving enough nutrients in
- moving waste out
Surface area of the membrane determines
the rate of exchange of materials
Volume of the cell determines
the rate material is used and discarded
As the cell increases, its volume increases faster than its SA, which ____ the ratio of SA:V.
decreases
2nd Problem: DNA Overload
as the cell gets larger, DNA stays the SAME, causing an information shortage.
- DNA demands cannot support the protein needs of large cells
Instead of growing too large, cells _______
divide in half!
- this increases SA/V ratio
- all organisms grow and change: worn-out tissues are replaced by newly produced cells
How does cell division solve the two growth problems?
- SA:V is increases, so efficient exchange of material can occur through the cell membrane
- Each daughter cell gets its own DNA so their is no information shortage.
10.2
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Define The Cell Cycle.
series of events that cells go through as they grow and divide.
Two halves of the cell cycle:
- Interphase
- M Phase
Describe Interphase
the period of the cell cycle between cell divisions
Describe the M phase.
period of time when mitosis and cell division occurs
G_1 phase (Gap 1)
- growing
- synthesizes new proteins and organelles
- longest phase of the cell cycle
S Phase (Synthesis)
- Chromosomes (DNA) are replicated
- key proteins associated with replication are made (centromeres)
G2 Phase (Gap 2)
- shortest of the 3 phases of interphase
- organelles and molecules for cell division are produced (centrioles)
- checkup phase
What stage in the cell cycle would most likely be for a cancer-causing genetic mutation to occur? Why?
S Phase
- this is where DNAs are replicated
At what point in the cell cycle could the cell catch this mutation and either fix it or push the cell into apoptosis (programmed cell death)?
G_2 phase
- G2 phase is the checkup phase before mitosis, and organelles and molecules can be produced to kill the cell.
________ condenses into ________ before mitosis begins.
Chromatin; Chromosomes
Chromatin
a complex of DNA and proteins in the cell nucleus that condenses to form chromosomes
- messy and spread-out
Chromosomes
condensed chromatin
Nucleosome = groups of ______
histone proteins
Centromere
the protein where the chromatids of a chromosome are attached
- the ‘circle in the middle’
In the S phase, how many chromosomes and chromatids are produced?
- 46 chromosomes
- 92 chromatids
Diagram of Mitosis
Describe interphase.
the chromosomes are in an extended form and are seen as chromatin.
- the NUCLEUS is visible.
Describe prophase.
- chromatin condenses into chromosomes
- nucleoli and nuclear envelop break down
- spindle fibers grow from centrioles
- centrioles move to opposite poles of cell
Describe metaphase.
- the chromosomes line up at the equator of the cell.
- spindle fibers from each centriole are attached to the centromeres of the chromosomes.
Describe anaphase.
- the centromeres split
- sister chromatids separate as each is pulled to an opposite pole
Describe telophase.
- chromosomes become longer, thinner, and less distinct.
- new nuclear membranes form.
- the nucleolus reappears.
Describe cytokinesis.
cytoplasmic division
- simultaneous with telophase
Describe cytokinesis in plant cells.
In plant cells, a cell plate forms. The fusion of multiple membrane-bounded vesicles supplies a new plasma membrane for each of the two daughter cells.
- synthesis of a new cell wall between the daughter cells then occurs at the cell plate.
Describe internal regulators.
proteins that respond to events INSIDE the cell.
- Cyclins control the activation of these proteins.
Describe external regulators.
proteins that respond to events OUTSIDE the cell.
- growth factors = most important external regulators
What is contact inhibition?
avoidance behavior by cells to reset cell growth
Describe cyclins.
- proteins that rise and fall in concentration in step to the eukaryotic cell cycle.
- cyclins activate crucial protein kinases called CDK.
A cancer is
uncontrolled cell growth
benign tumor vs malignant tumor
- benign tumors do not invade surrounding tissue or spread around the body.
- malignant tumors may invade its surrounding tissue or spread around the body.
Proto-oncogenes
group of genes that are a normal part of cell divison
Oncogene
group of mutated proto-oncogene cells that have now become cancerous
What is the p53 antioncogene?
p53 is a tumor suppressor gene found mutated in about 1/2 of all human cancers.
- it encodes a gene regulatory protein that is activated by damaged DNA and involved in blocking further progression of the cell cycle
Apoptosis
programmed cell death
What is the difference between cell growth and development?
- Cell growth forms IDENTICAL cells.
- Cell development makes changes occur to form new types of cells.
Describe zygotes and embryos.
Zygotes: Fusion of egg and sperm cell
Embryo: Early development stage
During development, cells _______
differentiate (become SPECIALIZED)
Specialized cells
cells that perform complex functions of the body
- ex: nerve cells, muscle cells, etc.
Totipotent stem cells
can become entire organism
- able to develop into ANY CELL TYPE
Embryonic Stem Cells
Pluripotent - can DIFFERENTIATE into nearly all cells
- 4/5 days into fertilization = embryo becomes a blastocyst (balls of cells with a cluster of cells inside)
Adult Stem Cells
multipotent - a number of cell types
oligopotent - a few cell types
unipotent - one cell type
Induced Pluripotent Stem Cells
created in lab settings. Adult somatic cells are REVERTED back to pluripotent form via treatments
How does 1 cell create all the specialized cell types in the human body?
The first cell is totipotent (able to develop into any cell type)
- only the fertilized egg and cells from first few divisions are totipotent
Embryonic Stem Cells
Embryonic stem cells are pluripotent (can develop into most (not all) cell types),
- unspecialized cells which differentiated cells develop from
Adult Stem Cells
cells that replace cells in the adult body
- Example: Skin and blood cells
- Multipotent
- stem cells in certain tissues may produce cells of that type (ex: blood stem cells producing red/white blood cells)
Asexual Representation v. Sexual Representation
Asexual: reproduction through mitosis or binary fission
Sexual: Reproduction through production of gametes by process of meiosis
