AP Bio Unit 2: Cell Structure and Function

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cell

simplest collection of matter that can be alive

archaea

prokaryotic cells only found in certain locations

prokaryotic cells

no nucleus, dna in unbounded area (nucleoid), no membrane bound organelles, cytoplasma bound by the plasma membrane

basic features of all cells

plasma membrane, cytosol (semifluid), chromosone (carry genes), ribosomes (make proteins)

nucleoid

dna in an unbound region

eukaryotic cells

dna in nucleus with double membrane, membrane bound organelle cytoplasm in between plasma membrane and nucleus

membrane bound organelles

E.R, golgi bodies, mitochondrial, chloroplasts

plasma membrane

selective barrier that seperates the interior cell from the exterior, regulates what enters and exist the cell

cell size increases

surface area to volume ratio decreases

proteins in the plasma membrane

work as enzymes, transporters, receptors, etc

plant cells contain both

cell wall and cell membrane together

nucleus

contains most of cell’s genes

nuclear envelope

surrounds the nucleus, separates from cytoplasm, double membrane of a lipid bilayer

chromosomes

discrete units of dna

chromatin

unraveled chromosomes

chromatin makeup

made up of one DNA + proteins, blue dna wrapped around purple proteins

ribosones

ribosomal RNA and protein make up

ribosome protein synthesis

in cytosol (free ribosomes) or outside (bound ribosones)

endoplasmic reticulum (ER)

smooth er withour ribosones and rough er with ribosone surface

smooth er functions

synthesizes lipids

metabolizes carbs

detoxifies drugs and poisons

makes up most of the liver

rough er functions

bound ribosomes that secret glycoproteins

distributes transport vesicles

membrane factory of the cell

Golgi apparatus consists of

flattened membranous sacs (cisternae)

golgi apparatus functions

modifies products of ER, manufactures some macromolecules, sorts/packages materials for transport

trans and cis golgi apparatus

trans = shipping, cis = recieves

lysosome

bubble sac of enzymes

lysosomes creation then movement

rough er —> golgi apparatus

phagocytosis

cellular eating

lysosome fuses with

food vacuole and digests the molecules

autophagy

lysosome uses enzymes to break down organelles and recycle

vacuoles

storage; large vesicle's from ER and Golgi

formed by phagocytosis

food vacuole

found in freshwater single cell organisms; remove excess water

contractile vacuoles

central vacuoles

mature plant cells, hold organic compounds and water

endomembrane system purpose

make proteins

endomembrane system steps

nucleus: instructions

er: makes proteins at ribosomes

golgi: processing and shipping

lysosomes: enzymes, break and recycle

vacuoles: stores

plasma membrane: controls ins and outs

mitochondria

makes ATP, bacteria in cells

chloroplasts

photosynthetic bacteria, turns light to sugar

endosymbiont theory

mitochondria and chloroplasts similarities (double membrane, free ribosomes, circular DNA molecules, grow/reproduce somewhat independent in cells)

peroxisomes

produce hydrogen peroxide and convert it to water

cytoskeleton

network of fibers, organizes cell structures and activities, three types

three types of cytoskeltons

microtubules: larger

microfilaments: smaller

intermediate filaments: in-between

roles of cytoskeleton

1) support cell and main its shape

2) cell motility; interacts with motor proteins to move (tracks)

example of cytoskeleton movement

vesicles can travel along tracks from the cytoplasm

microtubule roles

1) shaping the cell

2) guiding movement of organelles

3) separating chromosomes during cell division

4) cilia and flagella

flagella and cilia

made up of microtubules, extensions from cells

microfilament roles

1) muscle contraction

2) amoeba movement

3) cytoplasmic steaming

pseudopodia

cellular extensions, allows movement of cells

cytoplasmic streaming

chloroplasts moving on microfilaments

cell wall

extracellular structure; protects cell, maintains its shape, prevents excessive uptake of water

plant cell wall made of

cellulose fibers

plasmodesmata

only in plant cells, moves water and small solutes

tight junctions in animal cells

prevents movement between cells

desmosomes in animal cells

glue for cells

gap junctions in animal cells

movement channels; plasmodesmata to animal cells

selective permeability

some substances cross more easily than others

amphiathic

containing hydrophobic and hydrophilic regions

fluid mosaic model

protein molecules bobbing in a fluid bilayer of phospholipids

membranes are held together by

weak hydrophobic interactions

unsaturated fatty acids membranes

more fluid

fatty acids membranes

less fluid

warm temperatures and cholesterol

cholesterol restrains movement of phospholipids

cool temperatures and cholesterol

cholesterol prevents tight packing to which allows fluidity

peripheral proteins

bound to surface of membrane

integral membranes

penetrate into hydrophobic tails

functions of cell surface membranes

transport and cell to cell recognition

cell to cell recognition

cells recognize each other by binding to other molecules often containing carbohydrates

glycolipids

membrane carbohydrates + lipids

glycoproteins

membrane carbohydrates + proteins

distribution of proteins, lipids, and carbohydrates in plasma membrane is determined

when membrane is build in ER and Golgi

hydrophobic nonpolar molecules

pass though membrane rapidly

hydrophilic molecules

including ions and polar molecules do not pass through membrane easily, utilizes transport proteins

transport proteins

allows passage of hydrophilic substances across the membrane

aquaporins

channel proteins; facilitate transport of water molecules

carrier proteins

bond to molecule and shuttle them across plasma membrane

diffusion

tendency for molecules to spread out evenly into the available space

dynamic equilibrium

equal exchange of 1 to 1 ratio

concentration gradient

region where density of substance increases or decreases

passive transport

diffusion of a substance across a biological membrane; no energy is expended by the cell

osmosis

diffusion of water across selectively permeable membrane

less solutes:

more water concentration

more solutes:

less water concentration

tonicity

ability for a surrounding solution to cause cells to gain or lose water

tonicity depends on

concentration of solutes that cannot cross the membrane

isotonic solution

solute concentration: same as in cell; no net water movement

hypertonic solution

solute concentration is greater than inside cell; water leaves cell

hypotonic solution

solute concentration is less than the cell; cell gains water

osmoregulation

control of solute concentrations and water balance

if a solution is hypotonic then

the cell is hypertonic

animal cells prefer

an isotonic solution

plant cells prefer

a hypotonic solution

bacteria and archaea

live in excessively salty environments —> cellular mechanisms to balance internal/external concentrations

plant cell in hypotonic

cell becomes turgid

facilitated diffusion

movement of molecules through the plasma membrane with a protein; passive transport

ion channels

facilitate the transport of ions

gated channels

ion channels, open or close in respond to a stimulus

carrier proteins undergo

subtle change in shape that can be triggered by the binding and release of the transported molecule

active transport

requires energy, usually through ATP hydrolysis, to move substances against concentration gradients

active transport proteins are always

carrier proteins

active transport

allow cells to maintain concentration gradients that are different from their surroundings

sodium-potassium pump

a transport protein that is energized by transfer of a phosphate group from the hydrolysis of atp