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describe passive process
substances moving down concentration/electrical gradient; no energy req'd
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describe active process
against chemical/electrical gradient or unable to pass bc of permeability factors; reqs energy (ATP0
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what are the 3 passive processes?
diffusion, facilitated diffusion, osmosis
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what r the 2 types of active processes?
active transport and vesicular transport
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what is secondary active transport?
energy from concentration gradient helps 2move substances across; doesn't req ATP
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what is primary active transport?
uses energy to move substance against its concentration/electrical gradient. reqs carrier proteins. uses enzymes (ATPase) to break high energy phosphate bonds of ATP
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what is vesicular transport?
way for larger molecules to get in and out of cell; reqs ATP
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what is endocytosis? and what r the 3 types?
- moving substances into cell via vesicles.
- 3 types: pinocytosis, phagocytosis, and receptor-mediated endocytosis
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what is pinocytosis?
a form of endocytosis; "cell drinking", brings inextracellular liquids and dissolved substances
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what is phagocytosis?
a form of endocytosis; "cell eating"; brings in large particles by forming pseudopodia (evaginations surround larger particles to form phagocytic vesicles)
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what is receptor-mediated endocytosis?
avery selective in what it IMPORTS. membrane contains binding sites for specific substances = protein receptors
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what are the two types of vesicular transport?
endocytosis and exocytosis
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what is exocytosis?
moving substances out of cell. substance is enclosed in vesicle which moves to plasma membrane and dumps contents to outside of cell
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what r some examples of exocytosis?
hormone secretion, neurotransmitter release, mucus secretion
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what r microvilli?
finger-like projections of plasma membrane
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what is cilia?
propels substances along surface of cell. found in respiratory tract
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what is flagellum?
propels entire cell. only cells in body w/flagella r SPERM
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what r the 3 types of membrane junctions btwn cells?
tight junctions, desmosomes, and gap junctions
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what is a tight junction?
keeps cells close together so nothing can pass in btwn. proteins fuse to keep substance from passing. Ex btwn cells lining digestive tract.
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what is a desmosome?
adjacent cells r held together by linking proteins to keep cells from coming apart. found on cells with pull/tension/force. Ex. heart muscle, skin
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what is a gap junction?
cells connected by cylindrical proteins. allows comm btwn cells. Ex. heart muscle 9allows flow of ions btwn cells)
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describe the cytoplasm.
material btwn plasma and nuclear membrane. contains cytosol (intracellular fluid) and organelles
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what r the organelles of the cytoplasm?
cytoskeleton, ribosomes, ER, Golgi apparatus, lysosomes, mitochondria
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what is the cytoskeleton?
network of proteins that provide strength & structural support. composed of filaments
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what r the 3 types of filaments the cytoskeleton is made up of?
microfilaments aka actin filaments, intermediate filaments, and microtubules
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what r ribosome?
- responsible for protein synthesis
- 2 types: free and fixed
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what is the ER?
endoplasmic reticulum - a netwk of intracellular membranes. a site for synthesis of proteins, lipids, and carbs.
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diff btwn smooth and rough ER?
- smooth - no ribosomes; lipid and carb synthesis
- rough - fixed ribosomes on outer surface; protein synthesis
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what is purpose of Golgi Apparatus?
packages & modifies molecules from ER for secretion (exocytosis), incorporation into the plasma membrane, or use w/i the cell (lysosome)
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describe lysosomes
- vesicles containing digestive enzymes
- perform cleanup and recycling function - fuse w/damaged organelles or endocytic vesicles to digest contents and release nutrients
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what is the mitochondria?
responsible for energy (ATP) production. process of energy production = aerobic respiration
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describe the nuclear envelope
double membrane layer. surrounds nucleus. has nuclear pores
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what is the purpose of nuclear pores?
allows communication btwn nucleus and cytoplasm
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what is chromatin?
the uncondensed form of a chromosome, which holds DNA
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what is a chromosome?
the condensed form of a chromatin
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what happens in nucleoli?
ribosome assembly. mature ribosomes move to cytoplasm thru nuclear pores
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what is the purpose of cell division?
req'd for growth of organism and replacement of worn-out cells
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what are the two major steps of cell division?
interphase and mitosis
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Interphase is composed of what smaller phase?
G1, G0, S, and G2
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describe G1 phase
period of cell growth
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describe G0 phase
non-dividing phase. cells may exit cell cycle.
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describe S phase
DNA replication (double helix uncoils, each strand serves as template 4synthesis of complementary strand, each new double helix has 1 old &1 new strand)
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describe G2 phase
growth and final preparation for mitosis and cell division
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what is mitosis?
chromatin condenses into chromosomes; duplicated DNA molecules condense into pair of sister chromatids; nuclear membrane breaks down; spindle fibers form
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describe metaphse
chromosomes align at equator
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describe anaphase
sister chromatids separate and move to opposite poles
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describe telophase
"reversal" of prophase (spindle disappears, nuclear envelope reforms, chromosomes decondense into chromatin)
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describe cytokinesis
cytoplasmic division by contractile ring @ cleavage furrow
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what r the 2 phases of gene expression and protein synthesis
transcription and translation
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what is gene expression and protein synthesis?
process where info in DNA (genes) is use to direct protein synthesis
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what is transcription?
DNA -> mRNA; occurs in nucleus. one strand of DNA (template strand) is used to guide synthesis of mRNA
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pre-mRNA is synthesiszed by which enzyme?
RNA polymerase
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what is RNA processing?
pre-mRNA is processed to form a mature mRNA
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where is mRNA exported from/to in transcription?
from nucleus to cytoplasm
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describe translation
mRNA -> protein; occurs @ribosome (in cytoplasm). 3 stages
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what is a codon?
3 bases in mRNA which specify an amino acid => genetic code
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what r the 3 stages of translation?
initiation, elongation, and termination
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describe stage 1 of translation
initiaion: ribosome assembles on mRNA. tRNA carrying 1st aa binds mRNA/ribsome complex @P-site. binding occurs btwn the codon in the mRNA & the anticodon in the tRNA
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what r the 3 sites of the ribsome?
E, P, and A
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describe 1st part of stage 2 of translation
elongation: tRNA carrying next aa arrives @adjacent binding site in ribosome (A site)aa's @ P & A sites joined by peptide bond thru dehydration synthesis.
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describe 2nd part of stage 2 of translation
tRNA in P site releases its aa. ribosome moves down mRNA by 3 bases (tRNA in Psite moves into Esite, & then exits ribosome; new codon occupies Asite & is ready 2get next tRNA). steps rpt til stop codon in mRNA
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summary of mvmt of tRNAs during stage 2 of translation
elongation: cytoplasm -> Asite -> Psite -> Esite -> cytoplasm
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describe third/final stage of translation?
termination; protein released from last tRNA; ribsome dissociates from mRNA
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