VCU Exam 1

Question 1

plasma membrane

Answer 1

the outermost membrane of the cell, mostly made up of phospholipids, proteins, and carbohydrates (glycolipids & glycoproteins)

Question 2

phospholipids

Answer 2

polar hydrophillic head and non-polar hydrophobic tail

Question 3

phospholipid tail

Answer 3

made out of 2 fatty acid chains.
Kinked chain- unsaturated (in hydrogen), more fluidity
Straight chain- saturated fatty acid, less fluidity

Question 4

phospholipid bilayer

Answer 4

self-organizing and repairing, form a liposome (sphere) with heads pointing outward

Question 5

amphipathic

Answer 5

molecules with both hydrophillic and hydrophobic regions

Question 6

Van der Waals interactions/forces

Answer 6

very weak bonds between phospholipid tails that can easily form or break allowing the tails to be fluid

Question 7

fluid mosaic model

Answer 7

a longer chain of fatty acid tails has more Van der Waals interactions= stronger bond, less fluidity
the lipid bilayer is a fluid structure that allows molecules to move laterally within the membrane, and is a mosaic (a mixture) of two types of molecules, lipids and proteins.

Question 8

cholesterol

Answer 8

30% of animal (only) cell membranes, in between the spaces of the tails, less fluidity under normal cell temp, in cold temp it helps retain some fluidity because it won’t let the tails get rigid

Question 9

peripheral membrane proteins

Answer 9

proteins temporarily attached to the surface of the membrane through weak non-covalent interactions

Question 10

integral membrane proteins

Answer 10

proteins extend part way into the hydrophobic (tails) region of the membrane, permanently associated with the cell membrane and cannot be separated

Question 11

transmembrane proteins

Answer 11

extend all the way across the lipid bilayer, also technically considered integral proteins

Question 12

transporter proteins

Answer 12

have to be transmembrane, transport molecules through a channel going in either directions, can be gated

Question 13

carrier protein

Answer 13

changes shapes, specific as to what can pass through, can transport more than 1 molecule

Question 14

receptor proteins

Answer 14

have to be transmembrane, relay a message from one side of the membrane to the other, protein changes shape when a molecule binds to it creating a signal

Question 15

enzymes

Answer 15

can be integral, peripheral, or transmembrane, speeds up a reaction

Question 16

ATP synthase

Answer 16

synthesizes ATP = ADP + inorganic phosphate. H+ ions will attach and spin causing ATP synthase to rotate, acting as a transporter

Question 17

anchors

Answer 17

can be integral or transmembrane, hold another protein in place, hold onto the cytoskeleton fibers, holding onto another protein helping it stay in place

Question 18

selective barrier

Answer 18

the plasma membrane regulate what molecules can pass through in and out of the cell to maintain homeostasis

Question 19

diffusion

Answer 19

passive transport (require no energy) molecules move down a conc. gradient (from high to low) through the bilayer

Question 20

facilitated diffusion

Answer 20

passive transport. large or hydrophillic molecules pass through protein channels or carriers in the plasma membrane

Question 21

aquaporins

Answer 21

specific protein channel, allow water to flow through the plasma membrane more readily by facilitated diffusion.

Question 22

osmosis

Answer 22

diffusion of water, water moves from regions of high water conc. to low water conc.

Question 23

primary active transport

Answer 23

NaK pump moves 3 Na ions out and 2 K+ ions in by using ATP. Na conc. is high on the outside of the cell and K+ conc. is high on the inside of the cell

Question 24

secondary active transport

Answer 24

transmembrane pump uses ATP to move protons from the inside to the outside creating an electrochemical gradient.

Question 25

electrochemical gradient

Answer 25

concentration and charge difference between the inside and outside of the cell (outside= positive)

Question 26

hypotonic

Answer 26

low solute, water moves from the outside in, cell swells or burst. plants prefer to be hypotonic to retain more water (cell wall prevents bursting)

Question 27

hypertonic

Answer 27

high solute, water moves from the inside out, cell shrinks

Question 28

isotonic

Answer 28

solute and water concentrations are equal, water will move in both directions but no net movement. animals prefer to be isotonic

Question 29

contractile vacuoles

Answer 29

present in some single celled organisms to prevent bursting. compartments that take excess water from inside the cell and release it into the outside environment by contraction

Question 30

antiporter

Answer 30

transport more than one molecule in opposite directions

Question 31

symporter

Answer 31

transport more than one molecule in the same direction

Question 32

prokaryotes

Answer 32

bacteria and archaea. single celled, no nucleus or membrane bound organelles, store DNA in nucleoid

Question 33

eukaryotes

Answer 33

eukarya: plants, animals, fungi, protists. multicellular, has a nucleus that store DNA, enzymes, nucleolus, and membrane bound organelles

Question 34

endoplasmic reticulum

Answer 34

smooth ER- lipid production, calcium storage, detoxification rough ER- contain ribosomes (protein production) transitional ER- products from smooth and rough ER can be stored or transported other places in the cell by budding vesicle

Question 35

Golgi apparatus

Answer 35

sorts proteins and lipids to other organelles, the plasma membrane, or the cell exterior, produce macromolecules, forming protein complexes, transport protein complexes by vesicles, modify molecules

Question 36

mitochondria

Answer 36

ATP production by cellular respiration, has its own DNA , ribosomes, enzymes, and a double membrane (squiggly inner membrane for more surface area to fit more electron transport chains)

Question 37

lysosomes

Answer 37

break down and digest molecules, damaged organelles to be recycled. acidic pH (4.1) where digestive enzymes function best

Question 38

peroxisomes

Answer 38

can aid in cellular respiration, detoxification of damaging molecules (free radicals), make hydrogen peroxide (H2O2) in the process of detoxing, which can be damaging, so it is converted to H2O

Question 39

chloroplasts

Answer 39

only in plant cells, photosynthesis occurs here, contain 3 membranes: outer-> inner-> thylakoid (very important in photosynthesis, contain chlorophyll). Has own DNA, ribosomes, and enzymes

Question 40

vacuole

Answer 40

takes up most of the volume of a plant cell, mostly involved in storage: store pigment molecules to attract pollination, various ions until needed, and toxins as a defense

Question 41

toxins

Answer 41

not toxic when stored in vacuoles but can become toxic if ruptured and mixed with the cytoplasm

Question 42

cytoskeleton

Answer 42

structural protein networks in the cytoplasm

Question 43

microtubules

Answer 43

hollow tube formed from tubulin dimers (alpha and beta), create cilia and flagella and spindle apparatus used in cell division. largest in diameter

Question 44

centrosome

Answer 44

only in animals. microtubules push outward to the cell periphery from a microtubule organizing center

Question 45

intermediate filaments

Answer 45

only in animal cells, medium sized, strong fiber composed of intermediate filament proteins, provides structural support

Question 46

microfilaments

Answer 46

double helix of actin monomers, smallest in diameter, line the inside of the cell helping with structure and integrity of plasma membrane, forms microvilli and contractile ring (pinches off) in cell division

Question 47

nuclear lamina (intermediate filaments)

Answer 47

lines the nuclear envelope like the microfilaments line the plasma membrane (protecting the nucleus)

Question 48

dynamic instability in microtubules and microfilaments

Answer 48

has a plus (+) end and a minus (-) end, the plus end grows faster. dynamic instability is alternating periods of grow rates (in order to find chromosomes in cell division)

Question 49

motor proteins

Answer 49

aid with cellular movements microfilaments- myosin microtubules- kinesin or dynein

Question 50

myosin in microfilaments

Answer 50

walk along actin using ATP. can attach to 2 microfilaments at once pulling it forward as actin pulls back (muscle contraction). will undergo a conformational (structural) change in order to pull or walk.

Question 51

kinesin and dynein in microtubules

Answer 51

walk along microtubules, kinesin will walk towards the plus end and dynein will walk towards the minus end (towards the plasma membrane)

Question 52

cilia (9+2 arrangement)

Answer 52

created by microtubules, nine pairs of microtubules are located around the periphery of these organelles and two microtubules are at the center

Question 53

cell migration

Answer 53

Cells move by extending a lamellipodium at the leading edge and contracting microfilaments at the trailing edge.

Question 54

cellular junctions

Answer 54

areas that allows cells to join to other cells or to the extracellular matrix by cell adhesion molecules

Question 55

adherens juntions

Answer 55

joins 2 different cells together by 1 cadherin from each cell (2 total) form a belt around cells

Question 56

desmosomes

Answer 56

joins 2 cells together by a cluster of cadherins (like buttons on clothes) linked to intermediate filaments inside the cell- making it stronger, more stable and permanent

Question 57

hemidesmosomes

Answer 57

hold cells to the extracellular matrix by integrins linked to intermediate filaments

Question 58

tight junctions

Answer 58

ex: digestive cells, make a seal between cells using various tight junction proteins so molecules have to go through the plasma membrane using a transport mechanism

Question 59

gap junctions

Answer 59

specifically in animals, form a channel using gap junction proteins allowing molecules to move from one cell to the other in either directions

Question 60

plasmodesmata

Answer 60

specifically in plants, passages through the cell wall of adjacent plant cells, continuous plasma membranes

Question 61

extracellular matrix

Answer 61

area to the outside of the cell, mostly composed of a carbohydrate with various polysaccharides and proteins (not as much)

Question 62

extracellular matrix of plants

Answer 62

is the cell wall: 3 parts- middle lamella, primary cell wall and secondary cell wall, provides structural support

Question 63

middle lamella

Answer 63

gel like substance, composed of pectin (polysaccharide) , hold cell together and retain high water content

Question 64

primary cell wall

Answer 64

formed first, composed almost entirely of cellulose and some proteins and pectin, provides some support and structure

Question 65

secondary cell wall

Answer 65

not present in all plant cells, much thicker and stronger (in wood), composed of cellulose and lignin- provides strength and waterproofing, formed in between the primary cell wall and the plasma membrane

Question 66

extracellular matrix of animals

Answer 66

produced by fibroblasts made out of collagen (triple helix) and elastin (elasticity and mobility).

Question 67

fibroblast

Answer 67

mostly extracellular matrix, important for connective tissue: dermis layer of skin, bone, and cartilage

Question 68

epithelial tissues

Answer 68

a lot of the extracellular matrix, epidermis, lining of blood vessels and intestinal tracts

Question 69

basal lamina

Answer 69

specialized extracellular matrix, found in epithelial tissue or connective tissue, provides strength (what hemidesmosomes attach to).