Unit 2 Cells

plasma membrane

Phospholipid bilayer, surrounds cell and transports nutrients and provides support

saturated fatty acid membrane

packed tight; rigid membrane

unsaturated fatty acid membrane

not packed tight; flexible membrane

selectively permeable

allows: small, unchanged, polar molecules; hydrophobic molecules

blocks: large polar molecules; ions

integral proteins

imbedded in bilipid layer

peripheral proteins

attached to membrane surface

channel proteins

passage for hydrophillic substances

aquaporins

channel proteins; increase rate of H20 passage

ion channels

ions; gated channels

gated channels

open and close in response to stimuli

EX: nerve and muscle cells

carrier proteins

specific molecules bind, changing protein shape

transport proteins

use ATP (active transport)

EX: sodium-potassium pump

recognition proteins

unique identification; glycoproteins

EX: blood types

receptor proteins

provide binding sites; activates specific cell response

adhesion proteins

attaches cells to cells; provides anchors for filaments

cholesterol

stability to animal cells

organelles

Structures within cell that help it function

nucleus

contains DNA and nucleoli; site of cell division

chromatin

DNA spread through nucleus like web

chromosomes

DNA becomes rod-shaped as cell begins division; includes 2 long DNA molecules

histones

organize long DNA

nucleosomes

coiling of DNA by histones

nucleoli

concentrations of DNA in process of manufacturing ribosomes

nuclear pores

passageway for proteins and RNA

nuclear envelope

2 bilipid layers; bounded to nucleus, continuous with ER

ribosome

Structure made of proteins and RNA, builds proteins for cell

free ribosomes

Build proteins within the cell

bound ribosomes

attached to ER or nuclear envelope; translates proteins and exports things

smooth ER

Without ribosomes: makes lipids and cleans toxins

rough ER

Covered in ribosomes: makes, folds, and checks proteins

golgi apparatus

Processes, sorts, and packs proteins & lipids

lysosomes

(animal cells only) vesicles from Golgi that break down waste

peroxisomes

animals: breakdown H202, fatty acids, AAs; plants: modify by-products of photosynthesis

mitochondria

carry out cellular respiration; two membranes allow separation of metabolic processes

chloroplasts

(plant cells only) carry out photosynthesis; two membranes

microtubules

Cytoskeleton, helps cell maintain its structure

intermediate filaments

support for cell shape

microfilaments

made of protein actin; found in cells that move by shape change, e.g. muscle cells; cell motility

flagella

long, few, snake-like mvmnt; 9+2 microtubule

EX: sperm

cilia

short, many, back-and-forth mvmnt; 9+2 microtubule

EX: line respiratory tract

centrioles

(animal cells only) organizes cell and guides cell division

transport vesicles

move materials between organelles

food vacuoles

receive nutrients; usually merge with lysosomes

contractile vacuoles

collect and pump water in cell

central vacuoles

(plant cells only) contain most of plant cell interior; exert tugor when full for cell rigidity; functions specialized:

1) store starch, nutrients, waste, etc.

2) lysosome function

3) cell growth by absorbing H20

4) renders large SA-to-V ratio

cell walls

(plant cells only) support

extracellular matrix

(animal cells only) mechanical support, helps bind adjacent cells

cell junctions

anchor cells together for cellular exchange

anchoring junctions

(animals) protein attachments between cells

EX: desmosome

tight junctions

(animals) seal that prevents cellular exchange

communication junctions

allow chemical and electrical signal passage

gap junctions

narrow tunnels; basically channel protein allowing 2 animal cells to communicate

plasmodesmata

(plants) (communication) narrow tunnels; like gap junctions

prokaryotes

plasma membrane, DNA, ribosomes, cytoplasm, cell wall

hypertonic

solute hypertonic to solution=higher [solutes]

hypotonic

Lower concentration of solutes, water flowing into cell causing it to swell

isotonic

Letting in and out equal amount of solute and water

bulk flow

collective movement in response to pressure

passive transport

[higher] to [lower]; increases w/ increase in [x], temp., smaller particle size

diffusion

random mvmnt leads to net mvmnt from [high] to [low]

osmosis

diffusion of water across selectively permeable mmbrn

turgor pressure

osmosis into cell

plasmolysis

osmosis out of cell

cell lysis

swelling of cell b/c excess turgor pressure

facilitated diffusion

diffusion through channel or carrier proteins

active transport

[lower] to [higher]; requires use of E (usually ATP)

electrochemical gradient

combo. of concentration and electrical voltage gradients of ions

cotransport

active transport, move 2 diff substaces across cell membrane at same time

vesicular transport

uses vesicles to move substances across plasma mmbrn

exocytosis

fuse w/ membrane, release contents outside cell

endocytosis

capture substance outside cell, fuse w/ membrane, release contents into cell; 3 types: phagocytosis, pinocytosis, receptor-mediated

phagocytosis

cellular eating; undissolved material enters cell; forms phagocytic vesicle

pinocytosis

cellular drinking; dissolved material enters cell; forms liquid vesicle

receptor-mediated endocytosis

specific molec. (ligands) binds to site, resulting in pinocytosis