Cellular Biology Flashcards
describe cel theory
- all living things are ocmposed of cells
- a cell is the basic functional unit of life
- chemical reactionf of life take place inside the cell
- all cells arise from pre-existing cells
0 cells carry info in form of DNA, genetic info is passed from parent cell to daughter
what are the 6 kingdoms
archaea, protista, fungi, plantae and animalia
function of cell membrane
- plasma mem, selectively permeable
- fluid mosiac model: phospholipid bilayer with embedded proteins (phosphorous containing polar heads face out and hydrocarbon tails in)
- permeable to small hydrophobic mol like oxygen and small polar mol liek water
- others transported w/ carrier proteins
function of the nucleous
- controls cell activites and division
- contains DNA complexed w/ histones to form chromosomes
*histones also involved in gene transcription
- also contains nucleolus where ribosomal synthesis occurs
Function of ribosome
protein synthesis
- free in cytoplasm or bound to ER
function fo ER
- tranport of materials particular those to be secreted
- smooth inolved in metabolism and production of lipids
- rough ER plays role in protien production
function of Golgi apparatus
receives vesicles from smooth ER and modfies tthem and repackages into vesicles
- distributes to cell surface via exocytosis
function of mitochondria
aerobic respiration: energy supplier mainly in fomr of ATP
- has outer and inner phospholipid bilayer
function of cytoplasm
- where most metabolic activity occurs
- transport within occurs via cyckidud (streaming movement within cell)
function of vaculoes/vesicles
membrane bound saces involed in transport and storage that are ingested, secreted, processed or digested by the cell
- vaculoes larger than vesicles
function of centriole
- spindle organization during cell division
- typically pair of centrioles at right angles to each other in centrosome
- only in animal cells
function of lysosomes
- membrane bound vesicles contining hydrolytic enzymes
- involved in intracellular digestion
- rupturing lysosome to release hydrolytic enzymes for autolysis (cell suicide)
function of cytoskeleton
- supprts cell, maintians shape and aids in motility
- comprised of microtubules, microfilaments, and intermediate filaments
Microtubules = hollow rods of polymerized tubulun that radiate throughout the cell providing support and framework for organelle movement in cell
- centrioles comprised of microtubules
- cilia and flagella are specialized arrangements of microtubules
- microfilaments = solid rods of actin impmortant for cel movement and support
simple diffusion
- net movemnt of particles down their concentration gradient, no energy
- ex = Osmosis, diffusion of water from lower solute conc to higher solute conc
hypertonic
- call cytoplasm has lower solute conc then outside, water will flow out and cell will shrivel
- also caled plasmolysis
hypotonic
- extracellular environment less conc then cytoplasm so water flow into cell
- cell wil swell and lyse (burst)
ex: rbc will burst if placed in distilled water
isotonic
extracellular environemnt ahs same conc as inside cell
- water moves back in fourth
facillitated diffusion
- passive transport
- net movement down conc gradient via carrier protein
- still no energy
active transport
- energyrequired to move against conc gradient via transport protein
- general carrier molecules include:
- energy-independent carriers: facilitate movement of compounds along gradient
- symporters: move two or more ions or mol in same direction
- antiport_ exchange of one or more mol or ions for another across membrane
- pumps: energy dependent carriers
endocytosis
- cell membrane invaginates forming vesible that contains extracellular medium
- allows to bring large volumes of extracellular material inside the cell
Pinocytosis: ingetion of fluids or small particles
Phagocytosis: englufing large particles
exocytosis
vesicle in cell fuses with membrane to release a large volume of contants to the outside
ex. occurs wth neurotransmitters
bownian movement
- intracellular circulation
- kinetic energy spreads small suspended particles throughout the cytoplasm of cell
cyclosis or streaming
- ex of intracellular circulation
- circular motion of cytoplasm around the cell transports molecules
Endoplasmid reticulum for intracellular circulation
forms a network of chennels throughout the cytoplasm providing a direct continuous pathway from the plasma membrane to nuclear membrane
examples of extracellular circulation (movement of materials on larger scale thoguh body)
Diffusion:
- occurs if cells are in direct or close contact w/ external environment
Circulatory System:
- complex animals whos cells are too far from external environment to transport via diffusion
- requires circulatory system
- includes vessels to transport fluid and a pump to drive circulation
importance of cell division for unicellular vs multicellular organisms
unicellular: means of reproduction
multicellular: means of growth, developemnt and replacemnt of cells
what is interphase
- period of growth and chromosomal replicaiton
- accounts for 90% of lifetime
- after replication chromosome consists of two sister chromatids held together by centromere
*during interphase individual chromosomes are not visible, DNA is celled chromatin
what are the parts of interphase
G1: initiates interphase, described as the active growth phase and can vary in length, cell increases in size and synthesizes proteins
*length of G1 determines lenght of entire cell cycle
S: period of DNA synthesis
G2: cell prepares to divide, it growth and synthesizes proteins
M: mitosis or meiosis
what it mitosis and the 4 phases
division and distribution of cells DNA into two daughter cells
- each cell recieves a complete copy of original genome
- occurs in somatic cells (not gametes)
*nuclear division (karyokinesis) is followed by cel division (cytokinesis)
what is karyokinesis
nuclear division
explain prophase
chromosomes condense and centriole pairs (in animal cells) separate and mvoe towards opposite ends of the poles of cell
- spindle apparatus forms between them and nuclear membrane dissolves allowing spindle fibers to interact with chromosomes
*PMAT
explain metaphase
- centrioles are at opposite poles, fibers of spindle apparatus attach to each chromatid at coresponding kinetochore (a protein location on the centromere)
- the spindle fibers align the chromosomes at the centre of the cell (equator) forming the metaphase plate
explain anaphase
- centromeres split so each chromatid has tis own distinct centromere, allowing sister chromatids to separate
- sister chromatids are pulled twds opp ends of poles y shortening of spindle fibers
*spindle fibers are composed of microtubules
explain telophase
- spindle apparatus disspears
- nuclear memrane forms around each set of newly formed chromosomes
*each nucleus contains the same number (diploid 2N) as the original parent
- chromosomes uncoil
what is cytokinesis
cell division
- near end of telophase cytoplasm divides into 2, each with a complete nucleus and set of organelles
- in animal cells a cleavage furrow forms and cell membrane indents along euator, pinches the cell itno 2
- in plant cells a cell plate forms between the two nuclei, spilling it in half
explain meiosis
- sexual reporduction: requires two parents
- occurs via fusion of teo gametes produced by each parent
- produces haploid 1N cells halving the number of chromosomes
- involves two divisions resulting in 4 gametes
interphase of meiosis
- like mitosis, parent cells chromosomes are replicated resulting in 2N number of sister chromatids
what is the product of the first meiotic division
- two intermediate daughter cells with N chromosomes and sister chromatids
explain prophase 1 meiosis
- chromatin condenses into chromosomes
- spindle apparatus forms and nucleoli and nuclear membrane disappear
- homologous chromosomes come together and intertwine (synapsis)
*each chrom has 2 sister chromatids, each synaptic pair consists of 4 chromatids so called tetrad
*chromosomes can break and cross over to exchange genetic info, the points of contact between homologous chromosomes where crossing over occurs = chiasmata
- sister chromatids no longer identical after crossing over has ocurred
explain metaphase 1 meiosis
- homologous pairs (tetrads) align at equatorial plane and each pair attaches to a separate spindle fiber at the kinetochore
explain anaphase 1 meiosis
- homologous pairs separate and pulled to opp ends of cell (disjunction)
- paternal ones in one and maternal ones in other, get genetic variability due to previous crossing over
explain telophase 1 meiosis
- nuclear membrane forms around each new nucleus
*each chromosome still consists of sister chromatids joined at centromere
what is the product of the second meiotic division
- similar to mitosis but meiosis II is not preceed by chromosomal replication
- get haploid number of chromosomes
*note in woman only one of these daughter cells becomes a functional gamete the other two or three are destroyed by the body
