AP BIO Unit 2 Review

cell theory?

1. all living things are composed of cells

2. the cell is the basic unit of life

3. all cells come from preexisting cells

cell types?

prokaryotes & eukaryotes

prokaryotes characteristics?

• plasma membrane

• cytosol

• ribosomes

• circular chromosomes of DNA in a nucleoid

• also contain plasmids

• 1-10 micrometer diameter

eukaryotes characteristics?

• plasma membrane

• cytosol

• ribosomes

• chromosomes of DNA in a nucleus

• typically don’t contain plasmids

• membrane bound organelles

• 10-100 micrometer diameter

what happens to cell size as a cell gets bigger?

SA:V decreases

what happens when SA:V decreases?

there is less SA to bring in needed materials for the greater volume; waste cannot get out fast enough to prevent the cell from dying

what is the endomembrane system composed of?

1. nuclear envelope

2. endoplasmic reticulum (smooth and rough)

3. golgi apparatus

4. vesicles

5. lysosomes

6. plasma membrane

what does the endomembrane system do?

• it optimizes reactions by minimizing competitive reactions and localizing needed molecules and conditions

• can increase SA in organelles where reactions occur

• creates a transport system for materials exiting or entering the cell

rough endoplasmic reticulum characteristics?

• rough bc of ribosomes attached to the outside surface

• proteins made here are released from the cell

smooth endoplasmic reticulum characteristics?

• doesn’t have any attached ribosomes; also has a different shape

• it makes lipids

golgi apparatus characteristics?

• modifies, sorts, and packages up proteins before sending them out

vesicle characteristics?

• can form in various locations in the cell

• RER, SER, golgi, lysosomes, cell membrane

• they store or transport things

lysosome characteristics?

• contain digestive enzymes that break down macromolecules

• can also be used to digest food in single-celled organisms

mitochondria characteristics?

• organelle w/ double membrane

• the inner membrane has folds into the interior called cristae

• this is the site of cellular respiration which generates energy for the cell

chloroplasts characteristics?

• organelle with the least 2 membranes

• this is the site of photosynthesis where carbon dioxide and water are used to create glucose

• found only in plants

water vacuole characteristics?

• stores water and nutrients for later use

• generates turgor pressure for the plant

• found only in plants

nucleus characteristics?

• stores genetic information in DNA (chromatin)

• made of the nuclear membrane, DNA and the nucleus

nuclear membrane characteristics?

• separates the inside of the nucleus from the outside

• made of the same kind of membrane as the cell membrane

nucleolus characteristics?

• makes ribosomes

• usually 1 or 2 found in eukaryotic cells

ribosomes characteristics?

• read copies of genes which gives them instructions to make proteins

• non membrane-bound

cytoskeleton characteristicsmicrotubules ?

• involved in structure of the cell and movement of things inside the cell

microtubules characteristics?

• hollow tubes made of repeating dual protein complexes

• structural support inside the cell

• serve as highway system for chromosomes and vesicles

microfilaments characteristics?

• composed of 2 twinning acting protein filaments

• involved in changing cell shape

• along with motor proteins and myosin filaments, they can cause movement such as cell contraction during mitosis

intermediate filaments characteristics?

• made of twisted, string protein filaments

• involved in stabilizing cell shape

centrioles characteristics?

• made of microtubules

• used during mitosis when a cell reproduces itself

• not found in plant cells

cilia and flagella characteristics

• made of microtubules

• involved in movement of materials near a cell

what does the cell membrane look like?

• made of a phosphoipid bilayer

• contains protein molecules

• carbohydrates attached to protein molecules called glycoproteins

• carbohydrates attached to lipids called glycoplipids

• cholesterol

• inside layered with cytoskeleton

• outside layered with extracellular matrix

phsopholipid billayer characteristics?

• double layer of phospholipid molecules

• interspersed with cholesterol molecules and proteins

• it is a selectively permeable membrane

what happens with selective permiability?

• what gets through the phospholipid bilayer depends on 3 things:

• size: larger molecules can’t get through

• charge: charged molecules can’t get through

• solubility: water soluble molecules can’t get through

membrane proteins characteristics?

• proteins can be integral or peripheral

• can play active roles in cell functioning or play a structural role

characteristics of glycolipids and glycoproteins?

• consists of a carbohydrate chain attached to a membrane proteins or a phospholipid

• involved in recognition by other cells and other chemical messengers

functions of the cell membrane?

• regulates what enters and leaves the cell

• provides protection and support

structure/function of cell walls?

• provide support and protection

• barrier to some substances

• protection from osmotic lysis (explosion due to overfilling w/ water

• cell walls of plants, fungi and bacteria are made of different substances.

what do all cells exist in to survive?

liquids; meaning there’s water inside and outside of the cell

how do cells cross the membrane?

particles come in and out of cell changing the concentration both inside and outside the cell; particles moving though the phospholipid bilayer do this by simple diffusion

what is diffusion?

• in a solution, particles move from areas with more particles (high conc) to areas with less particles (low conc)

• this occurs with no added energy to make molecules move

• passive diffusion

how does diffusion in liquids work?

• particles will appear to continue to move until there is an equal concentration of them everywhere

• this is equilibrium

• particles will still continue to move but equally in all direction

how does simple diffusion work?

• allows molecules to pass straight through the phospholipid bilayer

• these molecules can’t break any of the 3 rules of selective permeability

• these molecules will move from the side with a high concentration of that molecule to the side with a low concentration

• no energy Is used to make it move

how does facilitated diffusion work?

• molecules will randomly move through the pores in Channel Proteins

• these molecules break 1 or more rules of simple diffusion

• similar to simple diffusion, movement occurs down the concentration gradient with no added energy

• channel proteins allow free movement and acts like a tunnel (ex. aquaporin)

• special ion channels move specific ions

• carrier proteins change the shape and the shape changes causes the solute to move

what is osmosis?

diffusion of water molecules through a selectively permeable membranes

types of osmosis?

1. isotonic

2. hypotonic

3. hypertonic

isotonic solution characteristics?

• “same strength”

• the concentration of solutes is the same inside and outside the cell

• water moves into and out of the cell in equal amounts

• healthy animal cell/ok plant cell

hypertonic solution characteristics?

• “above strength”

• solution outside has a higher solute concentration than the inside of the cell

• more water move out of the ell than in

• dehydrated animal or plant cell

hypotonic solution characteristics?

• “below strength”
  solution outside cell has a lower solute concentration than inside the cell

• more water enters the cell than out

• animal cell experiences lysis (cell destruction)/ healthy plant cell

how does water move in plants?

water potential

what goes on in roots?

• active transport moves nutrients from solid to roots

• root hairs create a large SA to uptake water because of the water potential

• water travels into the vascular tissue of the root by 1 of the 3 different types of movement

characteristics of root hairs?

• the epidermis of root tips is more permeable to water than other cells

• root hairs greatly increases the SA of the root tip

• root hairs can then pass water and nutrients on to other cells

cell compartments?

• travel routes depend on several compartments of plant cells

• the apoplast consists of all the interconnected cell walls

• the symplast consists of all the cytoplasm, connected by plasmodesmata

routes of transport in plants?

• the transmembrane route

• the symplastic route

• the apoplastic route

what happens in the symplastic route?

involves crossing 1 plasma membrane and then remaining within the symplast

what happens in the apoplastic route?

it does not cross a plasma membrane and remains within the apoplast

what happens in the transmembrane route?

it involves repeated moves across plasma membranes

how does transport from epidermis to vascular tissue work?

1. water and nutrients soak into the cell walls of the root hairs; the solution can then travel via the apoplastic route

2. some of the solution crosses the plasma membrane and travels via the symplastic route

3. the solution may switch from apoplastic to symplastic along the way

4. the endodermis cell walls contain a waxy material called the Casparian strip; all materials must cross the plasma membrane into endodermal cells to cross the strip

5. endodermal cells release water into their cell walls which is taken up by the xylem cells

xylem characteristics?

• dead hollow cells used to transport water

• made of tracheids which are connected by pits

• some plants have vessel elements which are shorter, fatter and have perforations rather than pits

stomata characteristics?

the rate of transpiration is controlled by stomata as the surrounding guard cel

role of potassium pumps?

• when it is pumped into guard cells, water flows in. Why? - this bows the shape of the guard cells

• when potassium is pumped out, the water flow is reversed and the guard cells flatten

phloem characteristics

• live cells called sieve tube members

• connected by sieve plate

• lack of a nucleus, ribosomes, and vacuole

• work with companion cells that provide materials to the sieve tube member

what is movement from sugar?

from source to sink

what is a source?

a location that makes sugar or stores sugar as starch

what is a sink?

a location that uses sugar

what is short distance movement similar to?

water movement

how does sugar in a solution move?

from cell to cell via the symplastic or apoplastic route

why Is cotransport needed?

it is required to move sugar across a plasma membrane

what is cotransport?

a type of active transport where a cell membrane proteins simultaneously moves 2 substances across the membrane

what happens in vertical transport?

1. active transport moves sugar from a source into the phloem this reduces water potential

2. osmosis causes water to enter the phloem which increases the pressure and causes movement towards lower pressure areas

3. active transport causes sugar to move into sink cells which owners the pressure

4. this causes water to return to xylem cells

5. since sink cells are always using or storing sugar, concentration there is always lower than the surrounding cells