Cellular Biology Flashcards
Facilitated Diffusion
the net movement of dissolved particles down their concentration gradient through special channels - does not require energy
Active Transport
the net movement of dissolved particles against their concentration gradients with the help of transport proteins - requires energy
Symporter
moves two or more ions or molecules in the same direction
Antiporter
exchange one or more ions for another ion or molecule
Pumps
energy-dependent carriers (require ATP)
Endocytosis
a process in which the cell membrane invaginates
Pinocytosis
the ingestion of fluids or small particles
Phagocytosis
the engulfing of large particles
Exocytosis
a vesicle within the cell fuses with the cell membrane & releases a large volume of contents to the outside
brownian movement
kinetic energy spreads small suspended particles throughout the cytoplasm of the cell
cytosis or streaming
the circular motion of cytoplasm around the cell transports
endoplasmic reticulum
the ER forms a network of channels throughout the cytoplasm & provides a direct continuous passage from the plasma membrane to the nuclear membrane
diffusion
sufficient means of transport for food & oxygen from the environment to the cells
circulatory system
includes vessels to transport fluid & a pump to drive the circulation
Cell Division
the process by which a cell doubles its organelles & cytoplasm, replicates its DNA & then divides in two
Interphase (mitosis)
a period of growth & chromosome replication
a cell spends 90% of its life time in interphase
G1 phase
the phase that initiates interphase
the active growth phase & can vary in length
the cell increases in size & synthesizes proteins
the length of the G1 phase determines the length of the entire cycle
S phase
the period of DNA synthesis
G2 phase
the cell prepares to divide
it grows & synthesizes proteins
M phase
the last phase of the cell cycle
this is where mitosis or meiosis occurs
results in 2 or 4 non-identical daughter cells
Mitosis
the division & distribution of the cell’s DNA to its two daughter cells such that each cell receives a complete copy of its original genome
takes place in somatic cells
Prophase (mitosis)
the chromosomes condense & the centriole pairs separate & move toward the opposite poles of the cell
Metaphase (mitosis)
the centriole pairs are now at opposite poles of the cell
the fibers of the spindle apparatus attach to each chromatid & its corresponding kinetochere (protein location)
the spindle fibers align the chromosomes @ the center of the cell, forming the metaphase plate
Anaphase (mitosis)
the centrioles split so that each chromatid has its own distinct centrome, allowing sister chromatids to separate
The sister chromatids are pulled toward the opposite poles of the cell by the shortening spindle fibers
Cytokinesis (mitosis)
division into two daughter cells each with a complete nucleus & its own set of organelles
Meiosis
similar to mitosis, but produces haploid cells (halving the # of chromosomes)
involves two divisions of primary sex cells resulting in four haploid cells called gametes
Interphase (meiosis)
the parent cell’s chromosomes are replicated, resulting in the 2N number of sister chromatid
Prophase I (meiosis)
chromatin condenses into chromosomes, spindle forms, & the nucleoli & nuclear membrane disappears
synapsis
homologous chromosomes come together & intertwince
tetrad
2 sister chromatids - contain 4 chromatids
crossing over
when chromosomes exchange equivalent pieces of DNA (cannot occur with sister chromatids)
chiasmata
the points of contact between homologous chromosomes where crossing over can occur
Metaphase I (meiosis)
homologous pairs align at the equatorial plane & each pair attaches to a separate spindle fiber at the kinetochere
Anaphase I (meiosis)
the homologous pairs separate & are pulled to opposite poles of the cell (disjunction)
mother chromatid forms a daughter chromatid
nondisjunction
occurs when cells do no separate appropriately during meiosis, results in the daughter cells having an incorrect # of chromosomes
Telophase I (meiosis)
a nuclear membrane forms around each new nucleus
second meiotic division
chromosomes align at the equator, separate & move to opposite poles & are surrounded by a re-formed nuclear membrane
