AP Bio~Unit 2 <Cells>

cells

fundamental unit of life

cell structure

correlated to cell function

cell theory

all living things are made of cells, came from pre-existing cells

1540

microscope invented

1665

robert hooke observed cell walls

1674

antoni van leeuwenhoek visualized living cells, “animalcules”

light microscope (LM)

used light to pass through specimens, 1000x, cannot see organelles

electron microscope

1950s, saw 2nm, 100 fold improvement over LM, 2 kinds

scanning electron microscope (SEM)

detailed topography, used electron, saw in 3D

transmission electron microscope (TEM)

internal structure of cell, used electromagnetic lens

magnification

ratio of image size to real size

resolution

measure clarity of image, distance between two points

contrast

visible differences in samples

cytology

study of cell structure, understand the function

cell fractionation

take cells apart, separate major organelles

plasma membrane

selectively permeable, only some things in & out, phospholipid double layer

chromosomes

section of DNA, genetic directions, protein production, replicated accurately during cell divison

ribosomes

units of rRNA & protein, makes proteins, assisted in cell production

eukaryotic cell

DNA in nucleus, double membrane and membrane bound organelles, Domain: eukarya & kingdom of protista, animalia, plantae, fungi

prokaryotic cell

DNA in nucleoid, NOT enclosed region, no membrane bound organelles, Domains: archaea & bacteria

endomembrane system

regulates protein traffic, performs metabolic functions

cytoskeleton

network of fibers, support cell structure, microtubules, microfilaments, & intermediate filaments

cytoskeleton function

mechanical support - balance between opposing forces

maintain shape - in animal cells

anchor cells - dismantle & reassemble cell shape

cell motility - flagella & cilia

microtubules

thickest, guide movement of organelles, separate chromosomes, structure flagella & cilia

microfilaments

thinnest, twisted double chain of actin, resist pulling forces, mobility, contains actin & myosin

intermediate filaments

the middle size, support cell shape

cytoskeleton thickness order (thinnest → thickest)

microfilaments → intermediate filaments → microtubules

centrosome

organizes microtubules, important for cell division, pair of 9 triplets of microtubules in a ring

cilia

a lot of little hairs, moves microbes and debris up and out of airways

flagella

long whip like tail, helps with cell movement

basal body

part of cilia/flagella, anchors to cell, moves by proteins

dynein

motor protein, bending movements of cilia/flagella

dynein walking

movement of flagella

cytoplasmic streaming

circular flow of cytoplasm, speeds distribution of materials

endosymbiont theory

mitochondria & chloroplasts were once in eukaryotic cells that were aerobic bacteria (prokaryote) then got engulfed by anaerobic bacteria (prokaryote)

extracellular matrix

components & connections between cells, coordinate cellular activities, synthesize & secrete materials

cell size

metabolic requirements impose upper limit on size, square micrometer only lets limited amount of substances cross, surface area to volume ratio is critical

cell growth

volume grows more proportional than surface area, small = greater ratio of surface to volume

large cells

larger organisms ≠ larger cells, they have more, cannot get nutrients they need

microvilli

long, thin, projections that increase their surface area, more absorption

specialized cells

has structure that suits its function

differentiation

process that specializes cells

amphipathic

contains hydrophobic & hydrophilic regions

phospholipid bilayer

most abundant lipid, forms double layer

freeze-fraction

studies plasma membrane, splits the middle of phospholipid bilayer

fluidity

phospholipids move within bilayer, drift laterally, rarely flip-flop across membrane, temps cools cause switch form fluid to liquid, solidifying depends on type of lipid, membranes must be liquid to work properly

cholestrol

steroid found in membrane, warm temps → restrains movement, cool temps → maintains fluidity

membrane lipid composition

adaptions specific to environmental conditions, changes due to temp changes

membrane proteins

determines most of membrane specific functions, different in fluid matrix of lipid bilayer

peripheral protein

bound to surface of protein

intergal protein

within the bilayer membrane, penetrate hydrophobic core, one or more nonpolar amino acids

transmembrane

intergal proteins span the membrane

protein function

transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining

carbohydrates

recognize by binding to surface on extracellular surface, bonded to lipid or protein → forms glycolipids or glycoproteins on external side of plasma membrane

sidedness of membrane

inside & outside, asymmetrical of proteins, lipids, & carbs, determined by ER & golgi apparatus

transport protein

hydrophilic molecule across membrane, specific to molecule

channel protein

allows passage

carrier protein

bind then change shape

aquaporin

transport water specifically

passive transport

doesn’t need energy

active transport

needs energy, against concentration gradient, carrier protein

diffusion

tendency to spread out evenly

osmosis

diffusion of water across semipermeable membrane

tonicity

ability of cell to lose or gain water

isotonic

solute concentration same inside & outside

hypotonic

solute concentration greater inside than outside, gains water

hypertonic

solute concentration greater outside than inside, loses water

hydrophobic (non polar)

dissolve in lipid bilayer, ex. hydrocarbons

polar molecules

doesn’t cross membrane easily, ex. sugars

concentration gradient

region where density increases or decreases, substances diffuse down, passive transport

osmoregulation

control of solute concentration & water balance, homeostasis requires

cell walls

maintain water balance

turgid

hypotonic solution, swells until wall opposes uptake, firm

flaccid

no net movement, cells are isotonic, limp

plasmolysis

pulls away from wall, hypertonic, lose water

facilitated diffusion

uses transport & channel proteins, passive moment of molecules or ions to cross

sodium potassium pump

moves sodium & potassium ion in cell membrane, animal cell

membrane potential

voltage difference across a membrane, differences in ions across the membrane

ion pumps

maintains membrane potential

electrochemical gradient

two combined forces drive diffusion of ions

chemical force

ion’s concentration gradient

electrical force

membrane potential on ion movement

electrogenic pump

transport proteins generate voltage

proton pump

store energy, plant cell

cotransport

coupled transport by membrane protein

bulk transport

occurs by exocytosis & endocytosis, molecules & water enter or leave, in bulk via vesicles, requires energy

exocytosis

release contents OUT of the cell

endocytosis

takes IN macromolecules, reversal of exocytosis with different proteins

phagocytosis

“cellular eating”, engulfs particles

pinocytosis

“cellular drinking”, fluid “gulps”

receptor mediated

binding of ligands to receptors

ligand

molecule that binds specifically to receptor

nucleus

stores DNA

nucleolus

produces & assembles ribsomes

chromatin

basic matter of chromosomes, package DNA, strengthens DNA to do cell division, mitosis, & meiosis

lysosomes

digest & break down macromolecules, waste buildup → poisonous & die

golgi apparatus

transports, modifies, & packages proteins & lipids

mitochondria

generates chemical energy to power cell (ATP)

chloroplasts

captures sunlight → converts to energy, plant cells, contains chlorophyll

endoplasmic reticulum

active in membrane synthesis, synthetic & metabolic processes, network of sacks & tubes, animal cells