Biology Exam #2

The cell membrane is composed of

phospholipid bilayer

phospholipids

-structural component of the membrane -amphipathic -selectively permeable

Cell membranes are also composed of

proteins, glycoproteins, glycolipids, cholesterol

Proteins are the ___________________ components of of membranes.

functional

Transporters, receptors, enzymes, anchors

examples of functional proteins

Cholesterol in cell membranes

maintains an optimum fluidity of the membrane in animal cells -prevents the membrane becoming too solid in cold temperatures or too fluid in high temperatures

Glycosylation

process of attaching a carbohydrate chain to a protein or lipid

glycolipid

lipid with carbohydrate attached

glycoprotein

protein with carbohydrate attached

The carbohydrate chain in cell membranes

-provides a distinctive cellular marker -helps protect proteins from damage

This type of model describes the cell membrane's structure

fluid-mosaic

The fluid mosaic model means that the cell membrane is

semi-flexible and a "tapestry" of several types of molecules

Since the cell membrane is semi-permeable, this allows the cell to maintain its internal conditions separate from the __________________

environment

Factors for molecules to cross membrane are

size, polarity, change

The membrane is MOST permeable to

small, hydrophobic molecules

The membrane is LEAST permeable to

large, hydrophilic, charged molecules.

Cells maintain

transmembrane gradients

chemical gradient

concentration of SOLUTE higher on one side than the other

electrochemical gradient

a chemical and electrical gradient (difference in electrical charges between the inside and outside of the cell)

Why is it important to maintain gradients?

-maintain water balance -transmission of nerve impulses -production of ATP

Ways that molecules move across cell membrane include

passive transport and active transport

passive transport

molecules move from area of HIGH concentration to an area of LOW concentration

Passive transport requires NO ___________ and movement is DOWN a gradient.

energy

The 3 types of passive transport

simple diffusion, facilitated diffusion, osmosis

simple diffusion

molecule passes across the membrane without help

facilitated diffusion

molecule passes across membrane with the help of membrane protein

osmosis

the net movement of a solvent (WATER) across a semi-permeable membrane into a solution with a higher solute concentration (SALT WATER)

_______________ molecules can NOT move across the membrane in osmosis.

solute

Osmosis _______________ the concentrations of solute on either side of the membrane

equalizes

Osmosis is responsible for

reabsorption of water in the kidneys uptake of water by plant roots dehydration resulting from cholera infection

Tonicity

relative solute concentration of one solution compared to another

HYPOtonic solution

solution has LOWER solute concentration than other solution

Isotonic

EQUAL solute concentration in both solutions net movement 0

HYPERtonic

HIGHER solute concentration than other solution

Water movement can make a cell _________ or _________ so cells must remain isotonic across the membrane

shrink, swell

crenation

shrinking of cell in a HYPERtonic solution

osmotic lysis

swelling and bursting of a cell in a hypotonic solution

osmosis in plants:

turgor pressure and plasmolysis

turgor pressure

pushes plasma membrane against cell wall and maintains shape and size; cell in a HYPOtonic solution

Plasmolysis

plants wilt because water leaves plant cells; cell in a HYPERtonic solution

active transport

molecule is transported from an area of LOW concentration to an area of HIGH concentration and requires ENERGY; moves AGAINST the gradient

Na+K+ ATPase- transmission of nerve impulses , H+/K+ ATPase- acidifies stomach juices required for digesting food.

active transport proteins

exocytosis

material inside cell is packages into vesicles and EXPORTED OUT of the cell; active transport

endocytosis

import of a molecule INTO cell through vesicle; active transport

cell communication AKA signal transduction

process of cells detecting and responding to signals in the extracellular environment

The 3 stage process of cell responsiveness

1. receptor activation 2. signal transductions 3. cellular response

receptor activation

receptor binds signaling molecule and becomes activated

signal transduction

signal gets transmitted through the cell; a series of proteins form a signal transduction pathway

cellular response

activity of target molecules is altered to change cell behavior

Target proteins:

1. enzyme-alter metabolism 2. structural proteins-alter cell shape or movement 3. transcription factor-alter gene expression

True or false: some signaling proteins and receptors travel a short distance and bind receptors on a nearby target

True

neurotransmitters

signaling protein that travels a short distance

FSH

signaling molecules (called hormones) are released in the bloodstream and travel long distances to bind their receptors on target cells

protein kinase

enzyme that adds a phosphate to a target protein to switch them on or off

protein phosphatases

Enzymes that can rapidly remove phosphate groups from proteins.

Adding/removing a phosphate group is a way to ________________ and ________________ alter protein activity

quickly, reversibly

second messenger

amplify signal throughout the cell

cyclic AMP

second messenger

cell communication steps

1. signaling molecule binds to receptor 2. signal is transmitted via a series of proteins in the cell 3. activity of target proteins is altered to bring about cellular response

target proteins

ultimately receive a message to alter cell activity

energy

the ability to do work

the two basic forms of energy

kinetic and potential

kinetic energy

associated with movement

potential energy

stored energy

chemical energy

Energy stored in chemical bonds (form of potential energy)

chemical reaction

when one or more substances change into one or more new substances REACTANTS to PRODUCTS

True or False: In chemical reactions, existing chemical bonds are broken and new ones are formed

True

exergonic reaction

A chemical reaction that RELEASES energy

Gibbs free energy

the difference in energy stored in the chemical bonds of reactants and products

If the energy stored in products is less than the energy stored in the old bonds THEN

products have LESS energy than reactants Reaction is exergonic Reaction is spontaneous

a NEGATIVE gibbs free energy indicates a

exergonic reaction

endergonic reaction

A non-spontaneous chemical reaction in which energy is ABSORBED and REQUIRED for use of reaction

If the energy stored in the products is more than the reactants THEN

products have more energy than reactants reaction is endergonic reaction is NOT spontaneous

Metabolism

All of the chemical reactions that occur within an organism

catabolic reactions

breakdown of molecules used to RELEASE energy recycle monomers (building blocks) EXERGONIC bonds

anabolic reactions

build molecules and macromolecules ENDERGONIC reactions

endergonic reactions

REQUIRE ENERGY

In exergonic reaction because products have less energy than reactants, there is a net _______________ of energy

release

In endergonic reactions because products have more energy than reactants, there is a net ______________ of energy

input

The energy source for many endergonic cellular reactions is

ATP

ATP is a product, what is it converted from?

ADP

catalyst

substance that speeds up the rate of a chemical reaction; is not consumed and remains unchanged at the end of the reaction

enzymes

protein catlysts

ribozymes

RNA molecules that function as catalysts.

activation energy

Energy needed to get a reaction started and to transition state

True or False: Activation energy is only needed for endergonic reactions

FALSE- it is needed for BOTH endergonic and exergonic reactions

transition state

intermediate state between reactants and products

common ways to OVERCOME activation energy

1. large amounts of heat 2. using enzymes to lower activation energy

________________ lowers activation energy

enzymes

active site

location where chemical reaction occurs

substrates

reactants, that are first affected by enzyme, that bind to active site

enzyme-substrate complex

formed when enzyme and substrate bind

Products

molecules that are formed after the reaction

The steps of an enzyme catalyzed reaction are

1. substrates bind 2. enzyme undergoes conformational change that binds substrates more tightly 3. substrates are converted to products 4. products are released

induced fit model

explains conformational change an enzyme undergoes after binding substrate.

prosthetic group

small, non-protein helper molecule permanently attached to the enzyme

cofactor/coenzymes

non-protein helper molecules NOT permanently attached to the enzyme

Coenzymes are _______________ like vitamins, but cofactors are _____-_______________ like Sulphur phosphate

organic, non-organic

True or False: ALL chemical reactions in the body are catalyzed reactions

True

factors that affect the rate of enzyme catalyzed reactions

substrate concentration, pH, temperature, and inhibitors

substrate concentration increases reaction until ____________________ is reached

saturation

Saturation

all enzyme active sites are occupied by substrate

Vmax

velocity (speed) of reaction at maximum rate

Km

measure of the ability that an enzyme has to its substrate -substrate concentration needed to reach half Vmax

________ Km value means a HIGH affinity for substrate, while a _________ Km value means a LOW affinity for substrate

LOW, HIGH

pH affects ionic bonds that are important for _______________________ and interactions with substrate

protein folding

a LOW temperature means the rate of reaction is __________ as molecules collide less often

SLOW

a HIGH temperature ___________________ enzymes by breaking chemical bonds

DENATURES/INACTIVATES

Inhibitors

used to slow down a chemical reaction

The two types of inhibitors

competitive and noncompetitive

Competitive inhibitors

bind at enzyme active site which prevents the substrate from binding -Vmax STAYS THE SAME but more substrate is needed to reach it

noncompetitive inhibitor

binds to an allosteric site NOT the active site -prevents the enzyme from working properly by affecting its SHAPE -LOWERS Vmax

allosteric site

A specific receptor site on some part of an enzyme molecule remote from the active site.

Competitive inhibitors are usually

reversible

reversible inhibitors are ________________ and irreversible inhibitors are ___________________

temporary, permanent

Reversible inhibitors usually

leave active site and the level depends on concentrations of substrate and inhibitors

Noncompetitive inhibitors can be

reversible (TEMPORARY) OR irreversible (PERMANENT

enzyme inhibitors examples include

drugs, poisons, pesticides, or naturally occurring molecules used to regulate metabolic pathways

Methotrexate, Penicillin, Cyanide

enzyme inhibitors

All living things require energy for:

-daily life processes (growth, reproduction, nerve impulses) -daily activities (running, studying, driving)

The typical energy expenditure of humans is

60-75% basal metabolic functions 20-35% lifestyle activities 5-10% digestion of food

energy is contained within

organic foods

heterotrophs (humans, animals, some prokaryotes) must

consume food to obtain energy

autotrophs (plants, some prokaryotes) can

make their own food to obtain energy

Energy stored in ______________ must be converted to a useable form

glucose

The chemical formula for cellular respiration is

C6H12O6 +6O2 = 6CO2 + 6H2O

aerobic cellular respiration (OXYGEN)

process of converting energy stored in organic food molecules into energy stored in ATP -exergonic reaction. 40% ATP 60% Heat

________ is the form of energy that can be directly used by cells

ATP

ADP + P ----->

ATP

Mitochondria are cell's _____________ _______________

energy factories

____________ is the primary site of ATP synthesis in eukaryotes

Mitochondria

Organelles of the mitochondria are

alter membrane, inner membrane, crista-folds of mitochondria, matrix-cytosol of mitochondria , and ribosomes

__________ reactions play a central role in cellular respiration

redox

Redox reactions

electrons transferred from one molecule to another

oxidation

loss of electrons

reduction

gain of electrons

OIL RIG

oxidation is loss, reduction is gain

True or False: Electrons are often transferred in the form of oxygen

FALSE- they are often transferred in the form or HYDROGEN

Glucose is _______________ into carbon dioxide, and oxygen is ______________ to water in cellular respiration

OXIDIZED, REDUCED

electron carriers

transfer electrons

NAD/NADH and FAD/FADH2

electron carriers in cellular respiration

The Four stages of cellular respiration are

glycolysis, pyruvate to acetyl CoA, citric acid cycle, oxidative phosphorylation

Glycolysis takes place in

cytosol

Is glycolysis aerobic or anaerobic?

anaerobic

two phases of glycolysis

energy investment phase and energy payoff phase

The components that go into glycolysis are

glucose, ADP, NAD

the products of glycolysis are

pyruvate, ATP, and NADH

the conversion of pyruvate to acetyl CoA takes place in

matrix of mitochondria

The components that go into the second stage of cellular respiration are

pyruvate,NAD,CoA

The products of the second stage of cellular respiration are

acetyl CoA, CO2, and NADH

the citric acid cycle takes place in

matrix of mitochondria

The components that go into the citric acid cycle are

acetyl CoA, ADP, 6NAD, FAD

the products of the citric acid cycle are

4CO2, 6NADH, FADH2, ATP

At the citric acid cycle, glucose has been completely

oxidized

the oxidative phosphorylation phase takes place in

inner membrane of mitochondria

two parts of oxidative phosphorylation

electron transport chain and ATP synthesis

True or False: High energy electrons are donated to the electron transport chain

True

The electron transport chain has how many protein complexes

4

electrons are donated to the chain by these electron carriers

NADH FADH2

Electrons are transferred down the chain to

the terminal electron acceptor AKA OXYGEN

Energy is released with each electron transfer and is used to ______________ _______________ H ions across inner membrane to create an ______________________________

actively transport, electrochemical gradient

ATP synthase

The enzyme that make ATP from ADPand inorganic phosphate.

ATP synthase makes ATP by

chemiosmosis

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

ATP synthase provides a _________ for H ions to diffuse down their gradient which releases the stored energy

channel

ATP synthase has ________ active sites

3

One complete turn produces _____ ATP in chemiosmosis

3

The end products of oxidative phosphorylation are

34 ATP,H2O,10NAD,FAD

Fermentation

Process by which cells release/create energy in the absence of oxygen

True or False: The electron transport chain will remain active without oxygen

FALSE- the chain will shut down

Fermentation occurs in

humans, animals, plants, yeasts, and some bacteria

The two types of fermentation are

ethanol fermentation and lactic acid fermentation

Lactic acid fermentation takes place in

humans, animals, and some bacteria

lactic acid equation

pyruvate + NADH -->2 molecules lactate +ATP

ethanol fermentation takes place in

plants, yeasts, and some bacteria

ethanol fermentation equation

2pyruvate ------> ethanol+CO2 + ATP

anaerobic respiration

Respiration that does not require oxygen

Fermentation stops at which cellular respiration phases

2nd (conversion of pyruvate to Acetyl CoA)

Molecules OTHER THAN _________ are used as the terminal electron receptor in anaerobic respiration

oxygen

other molecules besides glucose can be broken down to supply energy. these include:

proteins, complex carbohydrates, fats

True or False: In equal amounts of glucose and fats there will be more energy in the fats.

TRUE

In aerobic cellular respiration, the products are

H2O and CO2 and a LARGE amount of ATP

In fermentation, the products are

Lactate and a very SMALL amount of ATP OR ethanol and CO2 with a very SMALL amount of ATP

In anaerobic cellular respiration, the products are

CO2 and variable element (ex NO3) and a LARGE amount of ATP

photosynthesis

the process of using light energy to make glucose from CO2 and H2O

What is the purpose of photosynthesis?

to make food and in turn energy

the equation for photosynthesis is

6CO2 + 6H2O ------> C6H12O6 + 6O2

In photosynthesis, CO2 is _________ to glucose

reduced

In photosynthesis, Water is __________ to oxygen

oxidized

How is photosynthesis important to life?

-provides autotrophs and heterotrophs with organic food for cellular respiration -Provides organisms with oxygen for aerobic cellular respiration

Photosynthesis takes place in

green structures EX: leaves and stems

Mesophyll cells

cells that contain many chloroplasts and host the majority of photosynthesis

Stomata

Site of gas exchange under the leaf

leaves also contain

epidermal cells

The main cell organelle that photosynthesis takes place in is

chloroplasts

chloroplasts contain the pigment

chlorophyll

Structures of the chloroplast include

outer membrane, intermembrane space, inner membrane, STROMA, THYLAKOID, GRANUM, lumen (inside thylakoid)

pigment

Light-absorbing molecule

Why does chlorophyll appear green?

reflects green light

Light energy is absorbed by

boosting electrons to a higher energy level

ground state

The lowest energy state of an atom

When an atom is in its ground state and it absorbs light energy it get converted to

the excited state

excited state

a state in which an atom has more energy than it does at its ground state

to become stable again, and atom can:

-by releasing excess energy as heat or light -by transferring excess energy to another molecule (resonance energy transfer) -by passing the excited electron to another molecule

chlorophyll is found in

thylakoid membrane

Other pigment molecules in photosynthesis

accessory pigment molecules

Carotenoids

Accessory pigment that enables a plant to absorb additional light energy and maximize photosynthesis.

two stages of photosynthesis

light reactions and calvin cycle

light reactions take place in

thylakoid membrane

the light reactions phase produces

ATP, NADPH, and O2