LESSON 2: THE CELL CYCLE Flashcards
- sequence of growth and division of a cell
- name we give the process through which cells replicate and 2 new cells
- has different stages: G1, S, G2, and M
cell cycle
- process that enables cells to change and acquire specific structures and functions
- importance:
- development
- maintenance
- tissue repair
cell modification
- has 3 types:
- differentiation
- specialization
- adaption
- less specialized cell to a more specialized cell
e.g, embryonic development (stem cell > nerve cell)
tissue regeneration (cells in tissue like skin can differentiate to replace damaged cells)
stem cell > muscle/fat/bone/blood/nervous/epithelial/immune/sex cell
differentiation
- cell develops specific structures and functions tailored to perform particular tasks
e.g, RBC ( O transport due to presence of hemogoblin)
neurons ( transmits nerve impulses)
specialization
- modifications in a cell
- undergoes in response to environmental changes
e.g, muscle cells (mitochondria increases, physical activity increases)
adaption
cell modification according to location
top: apical
mid: lateral
bot: basal
- found on apical surface of the cell
apical modification
- locomotion
- formed from microtubules
cilia & flagella
move cell / engulf prey
pseudopods
- found in intestines (bowel movement)
villi & microvilli
- compound secreted by the cell on its apical surface
- glycoprotein = main ingredient
extracellular matrix (ecm)
- desmosomes/hemidesmosomes
- like an anchor on basal surface of the cell
- connects ecm
basal modification
found on basal surface of the cell
lateral modification
lateral modification:
- prevent leakage of ecf (extracellular fluid)
- regulate movement of water and solutes between epithelial layers
tight junction
lateral modification:
- fasten cells like stapler
adhering junction
communicating junctions
e.g,: plants: xylem, phloem: H2O and nutrients transport
guard cell: regulates gas exchange and H2O loss
animals: bone cells (osteocytes): maintain bone structure
skin cells (keratinocytes): form protective barrier
gap junctions
implications of cell modification
development processes: formation of tissues & organs
diseases & disorders
tissue engineering
- cells grow, organelles double prior to the actual
- 95% of the cells’ life is spent here
- has 3 parts
- Growth 1 (G1)
- Synthesis (S)
- Growth 2 (G2)
- lasts 3-15 hours
interphase
-organelles double
-each cell needs a complete set of organelles
g1
-dna is replicated
-each cell needs a complete and identical set of DNA
s
-proteins needed for mitosis are produced
g2
- doubles and separates during mitosis
- chromatin is packed here
- dna is tangled to a substance of chromatin
- structures of tightly packed dna
chromosomes
- process by which the cell nucleus divides into 2 identical nuclei
- “identical twins”
- only lasts 7hrs
- occurs in steps:
- prophase
- metaphase
- anaphase
- telophase
- cytokineses
mitosis
- shortest phase, 2 events only
1. chromosomes line up across middle of the cell
2. spindle fibers connect
metaphase
- chromosomes condense and are more visible
- the nuclear membrane disappears
- centrioles have separated and taken positions on the opposite poles of the cell
- spindle fibers form and radiate toward cell’s center
prophase
- 3 events
1. centromeres that join sister chromatids split
2. sister chromatids separate, becoming individual chromosomes
3. separated chromatids move to opposite poles of the cell
anaphase
- last mitosis phase
1. chromosomes uncoil
2. a nuclear envelope forms around the chromosomes at each pole of the cell
3. spindle fibers breakdown and dissolves
4. cytokinesis begins
telophase
- division of cytoplasm to 2 individual cells
cytokinesis
- sperm and egg cell combine
- how humans are formed
- “extra”
- makes egg in ovaries and sperm
meiosis
combination of egg and cell
zygote is formed (46 chromosomes)
cell with 2 of each kind of chromosomes (1 from each parent)
diploid (2n)
gametes (either sperm or egg cells)
haploid
organism-gamete
fruit fly
dog
pea
human
(fdph)
(frst)
4
39
7
23
- paired chromosomes w/genes for the same trait arranged in same order
- may have different alleles
homologous chromosomes
- chromosomes replicate
- each chromosome has 2 identical sister chromatids
interphase 1
- exchange of gene material by non-sister chromatids during late prophase 1 of meiosis
- results of new combination of alleles
crossing over
- each pair of homologous chromosomes come together to form a tetrad
prophase 1
- homologous chromosome lines up together in pair
metaphase 1
- spindle fibers attach to centromeres of each pair
- homologous chromosomes separate and move to opposite ends of cell
anaphase 1
- spindle fiber breaks down
- chromosomes uncoil
- cytoplasm divides
- another cell division is needed because number of chromosome hasn’t been reduced
telophase 1
- just like mitosis, but remember the chromosomes didn’t duplicate in interphase 2
meiosis 2
- chromosomes line up
- spindle fibers begin to form
prophase 2
chromosomes line up on metaphase plate
metaphase 2
- centromeres split
- sister chromatids separate and move to cell’s opposite side
anaphase 2
- nuclei reform
- spindle fibers disappear
- cytoplasm divides to two
- # chromosomes in each daughter cell have been reduced by half
telophase 2
has 2 types:
- passive transport
- active transport
cellular transport
amount of solute
concentration
mixture of 2+ substances
solution
dissolved substance
solute
diffusion of water
osmosis
bacteria and plants - turgor pressure
protists - contractive vacuole
salty water fish - specialized gills
rbc - kidneys
osmotic pressure
- movement of larger molecules e.g, glucose, ions, protein channels - transported through: ?
facilitated diffusion
high concentration of solute
hypertonic solution
low solute concentration
hypotonic solute
low > high
balance
high > low
hypo (swell = bursts = cytolysis)
iso (dynamic equilibrium)
hyper (shrink = plasmolysis)
low to high concentration movement
active transport
proteins that work as pumps e.g, exhalation
active transport
types of active transport:
- movement of large materials inside cell
- food moved in
- types: specific/nonspecific
forms: phagocytosis(cell-eating)/pinocytosis(cell-drinking)
endocytosis
types of active transport:
- movement of material outside the cell
- reverse of endocytosis
- vesicle moves to cell surface
- membrane of vesicle fuses
exocytosis
- chemical reaction occurring continuously in living things
- photosynthesis/food breakdown
- ends w/ase
- belongs to proteins
functions:
- catalysts (lower activation energy of reaction taking less energy for reaction to take place
enzymes
factors affecting enzyme
- temperature
- pH (7-normal, 2-acid, 8-base)
- hormones
- inhibitor
