biol 1001 test 2 hrincevich lsu

receptor proteins

trigger cellular responses upon binding of specific molecules (hormones) of other cells

recognition proteins

glycoproteins that serve as identification tags on the surface of a cell (i.e. "nametag")

enzymatic proteins

promote chemical reactions that synthesize or break apart biological molecules

attachment proteins

anchor the cell membrane to the inner cytoskeleton, to proteins outside the cell, and to other cells

transport proteins

regulate the movement of hydrophilic molecules through the plasma membrane

channel proteins

form channels to allow specific ions or water molecules to pass through the membrane

carrier proteins

have binding sites that can temporarily attach to specific molecules on one side of the membrane and then move them through the membrane to the other side

fluid

a substance whose molecules can flow past one another (have no defined shape)

solute

a substance that can be dissolved (atoms, ions, or molecules) in a solvent

solvent

a fluid capable of dissolving a solute

concentration

defines the amount of solute in a given amount of solvent

gradient

a physical difference in temperature, pressure, charge, or concentration between two adjoining regions of space

within the fluid mosaic of a plasma membrane, what is the role of transport and channel proteins?

they permit salts and sugars to move through the plasma membrane

passive transport

movement of substances across cell membranes down concentration gradients, no energy required

facilitated diffusion; passive or energy-requiring?

passive

simple diffusion; passive or energy-requiring?

passive

osmosis; passive or energy-requiring?

passive

active transport; passive or energy-requiring?

energy-requiring

endocytosis; passive or energy-requiring?

energy-requiring

exocytosis; passive or energy-requiring?

energy-requiring

simple diffusion

substances move down their concentration gradients across a membrane

facilitated diffusion

substances move down their concentration gradients with the help of channel and carrier transport proteins

osmosis

diffusion of water across selectively permeable membranes, from high concentration to low concentration

energy-requiring transport

movement of substances into or out of a cell using cellular energy, usually supplied by ATP

active transport

proteins use energy to move substances across plasma membranes, against their concentration graidents

endocytosis

cells engulf particles and transport them using vesicles

exocytosis

moves material out of the cell, uses energy and vesicles to dispose of waste products

isotonic solution

equal concentrations of water and dissolved substances / no net water movement occurs across the membrane

hypertonic solution

greater solute concentration / water moves across a membrane toward the hypertonic solution

hypotonic solution

lower solute concentration / water moves across a membrane away from the hypotonic solution

shrink

when cells are placed into a hypertonic solution, they

swell

when cells are placed into a hypotonic solution, they

unaffected

cells in isotonic solutions

red blood cell shape

biconcave disc

if red blood cells are taken from the body and placed in a hypertonic solution, what happens to the cell?

the cells shrivel up because water leaves them

if red blood cells are taken from the body and placed in a hypotonic solution, what happens to the cell?

the cells swell up

osmosis moves water from a region of what to what?

low concentration of dissolved material to a region of high concentration

plasma membranes are best described as what?

double layer of phospholipids with hydrophobic tails oriented toward one another

suppose that plasma membranes were single layers of phospholipids with heads facing the external environment. the interior of this hypothetical cell would have to be what?

hydrophobic and nonpolar

the cytoplasm of a certain cell, such as a neuron, already has a high concentration of potassium ions. how can potassium ions continue to enter the cell?

active transport

pinocytosis

"cell drinking" moves liquids into the cell

phagocytosis

"cell eating" moves large particles into the cell

the blood plasma of a man who drinks saltwater will become ____ to his red blood cells, whereas the red blood cells will be ____ to the blood plasma

hypertonic; hypotonic

type of membrane protein responsible for conveying external messages such as those sent by a hormone signal

receptor protein

the hydrophobic tails of a phospholipid bilayer are oriented toward the what

interior of the plasma membrane (i.e. toward one another)

the optimum reaction rate of a particular enzyme occurs at pH 7.3 at 37 degrees C. this reaction would probably proceed faster by doing what?

increasing the temperature to 38 degrees C and keeping the pH at 7.3

similar to a car, a human body is approximately how efficient in converting chemical energy to movement?

25%

catalysts

increase the reaction rate, not permanently altered during reaction, can be used over and over again, biological catalysts are specific enzymes, do not increase activation energy requirements

in cells, endergonic reactions are often coupled with enzymatic reactions that store energy, true or false?

false

when a high-energy bond of ATP is broken, primarily what happens to the energy?

it drives endergonic reactions in the cell

desmosomes

attach cells together, are found where cells need to adhere tightly together under the stresses of movement (i.e. small intestine)

tight junctions

make cell attachments leakproof, found where tubes and sacs must hold contents without leaking (i.e. urinary bladder)

gap junctions

animals; allow for direct communication between cells

plasmodesmata

plants; allow for direct communication between cells

imagine you are conducting an experiment on a yeast enzyme known as sucrase. this enzyme is used by yeast cells to break down sucrose into glucose and fructose. what type of reaction is this?

exergonic

entropy is a measure of an increase in what?

randomness

in the liver, the polysaccharide glycogen is broken down into glucose monomers. the glucose molecules are then released into the blood when blood sugar levels need to be raised. this process is an example of what type of reaction?

exergonic

energy

the capacity to do work

work

a force acting on an object that causes that object to move

chemical energy

the energy that is contained in molecules and released by chemical reactions

the energy of the movement of electrons down a concentration gradient via electron transport within chloroplasts and mitochondria is used to generate molecules of

ATP

potential energy

stored energy, i.e. chemical energy in bonds, electrical charge in a battery, rock at top of a hill

kinetic energy

energy of movement, i.e. light, heat, electricity, and the movement of objects

where is glucose synthesized during photosynthesis?

cytoplasm

albino corn has no chlorophyll. you would expect albino corn seedlings to

fail to thrive because they cannot capture light energy

hydrogen ions cross the thylakoid membranes from the stroma by

active transport

first law of thermodynamics

energy can neither be created nor destroyed, but can change form

the second law of thermodynamics

the amount of useful energy decreases when energy is converted from one form to another

entropy

a measure of disorder or more precisely unpredictability

which process of photosynthesis is linked to the production of ATP

photosystem II

c3 plants are adapted to ____ environmental conditions, whereas c4 plants are adapted to ____ conditions

dry; wet

during the process of photosynthesis, solar energy is converted to

chemical energy

which of the following provides oxygen as an end product

light reaction

the primary function of the light reactions of photosynthesis is to

produce energy-rich ATP and NADPH

the energy source in photosynthesis is

visible light

if no oxygen is available to a cell, then the net ATP production resulting from the metabolism of a single glucose molecule is what?

two ATP molecules

chemiosmosis links a hydrogen ion gradient to the production of ATP. true or false

true

the term "chemiosmosis" is associated with which process

the electron transport chain

when oxygen is present, what happens?

most animal cells utilize aerobic cellular respiration

during glycolysis, "glucose activation" refers to what?

use of two ATP molecules to make one fructose bisphosphate molecule

the step in aerobic respiration that produces the most ATP per molecule of glucose is what

chemiosmosis

at the end of glycolysis, the original carbons of the glucose molecule form what

two molecules of pyruvate

which of the following processes occurs in a membrane?

a. glycolysis

b. the krebs cycle

c. the electron transport chain

the electron transport chain

carbon dioxide is considered a waste product of cellular respiration, true or false

true

chemical reaction

a process that forms or breaks chemical bonds holding atoms together

exergonic

releases energy

endergonic

input of energy

metabolism

the sum of all the chemical reactions inside a cell

competitive inhibition

substance that is not the enzyme's normal substrate binds to the active site of the enzyme, competing with the substrate for the active site

noncompetitive inhibition

a molecule binds to a site on the enzyme different from the active site

feedback inhibition

negative feedback type of allosteric inhibition that causes a metabolic pathway to stop producing its product when quantities reach an optimum level

arsenic poisoning

blotch marks on soles of feet and palms of hands

(napoleon)

low temperatures ____ molecular movement

slow

high temperatures cause enzyme shape to ____

be altered, destroying function

both the upper and lower surfaces of a leaf consist of a layer of transparent cells called ____

the epidermis

transparent, waxy, and waterproof covering that reduces the evaporation of water from leaves

cuticle

leaves obtain co2 for photosynthesis from the air through pores in the epidermis called ___

stomata

mesophyll

layers of cells where photosynthesis occurs

bundle sheath cells

surround vascular bundles and supply water and minerals to the mesophyll

chloroplasts are organelles with a ____ ____ enclosing a fluid called the ____

double membrane; stroma