Bio 1115 Exam 3

Cell membrane

what defines the barrier of a eukaryotic cell and it's contents

Cystic Fibrosis Transmembrane conductance Regulator (CFTR)

pumps chloride ions out of epithelial cells; water follows these ions

Cystic Fibrosis (CF)

CFTR molecules are mutant, which causes chloride transport to be defective; not enough water leaves epithelial tissue and mucus builds up

phospholipids, cholesterol, membrane proteins, and glycocalyx

Components of cell membrane

Phospholipids

molecule that forms the bilayer of cell membranes

Phospholipid head

hydrophilic (polar); contains a phosphate group

Phospholipid tails

hydrophobic (nonpolar); made of two fatty acids

Semi-permeable

quality of lipid bilayer; allows the membrane to let some molecules and ions through, and others cannot

nonpolar substances

What has an easier time crossing the bilayer?

Cholesterol

main sterol in animal membranes; important for maintaining membrane stability and fluidity (keeping the membrane fluid, but not too fluid)

contains an OH (hydrophilic) molecule to keep it attached to phospholipid heads; body and tail are hydrophobic

Polarity of cholesterol molecules

Dropping temperatures

What causes the phospholipid bilayer to become too packed?

Increasing temperatures

What causes the phospholipid bilayer to become too fluid?

Transport proteins

channels that allow selected polar molecules and ions to pass across a membrane (if they can't pass the bilayer); hydrophilic on the inside

True

T or F transport proteins span across the entire membrane?

Recognition proteins

contain carbohydrates attached to cell surface proteins, which serve as "name tags" that help the immune system recognize its own cells

Receptor proteins

recognize and bind molecules from other cells that act as chemical signals, such as hormones

Cell adhesion proteins

perform cell to cell attachments by recognizing and binding receptors or chemical groups on other cells

Integral proteins

penetrate the hydrophobic interior of the lipid bilayer

Peripheral proteins

bound to the surface of the membrane

Integral

What type of proteins are transport proteins?

Integral

What type of proteins are recognition proteins?

Peripheral

What type of proteins are receptor proteins?

Integral

What type of proteins are cell adhesion proteins?

Glycolipids

carbohydrate groups attached to lipid molecules

Glycoproteins

carbohydrate groups attached to recognition proteins

Glycocalyx

a surface coat on the cell that the carbohydrate groups of glycolipids and glycoproteins form; acts as additional protection for cell

Fluid Mosaic model

proposes that the cell membrane consists of a fluid phospholipid bilayer in which proteins are imbedded and flow freely

Transport

controlled movement of molecules and ions across a membrane by proteins

Passive and Active

two categories of transport across a membrane

Passive transport

requires NO energy, movement of molecules from high to low concentration (WITH the concentration gradient)

Active transport

DOES require energy, movement of molecules from low to high concentration (AGAINST the concentration gradient)

ATP

What does active transport require?

Concentration gradient

difference in the concentration of a substance from the outside of the cell to the inside

it's going where there are less molecules like itself

When the movement of a molecule goes WITH the concentration gradient...

it's going where there are more molecules like itself

When the movement of a molecule goes AGAINST the concentration gradient...

Diffusion

a type of passive transport; involves a net movement of molecules or ions

Net movement

number of molecules moving with the direction of the force - number of molecules moving against the direction of the force

yes

Are nonpolar gases able to pass through the membrane?

They are small enough to slip between hydrocarbon tails

Why are individual water molecules able to pass through the membrane, even though they are polar?

polar molecules and charged molecules / atoms (blocked by the hydrophobic core)

What type of molecules / atoms have a hard time passing through the lipid bilayer?

Hydrophobic core of membrane

another name for the lipid bilayer

Facilitated diffusion

movement of SPECIFIC molecules across cell membranes through protein channels

Aquaporin

channel for water molecules (in bulk)

K+ Voltage gated channels

passage for potassium ions; voltage from buildup of K+ opens channels and they close again once the channels run out of charge

Carrier proteins

bind to a specific molecule to facilitate its passage across the membrane

Osmosis

diffusion of water that relies on aquaporins

Tonicity

the ability of a surrounding solution to cause a cell to gain or lose water

Hypotonic solution

when the solute concentration is less than that inside the cell; cell gains water

Hypertonic solution

when the solute concentration is greater than that inside the cell; cell loses water

Isotonic solution

when the solute concentration is equal on the outside and inside of the cell

wherever there are the most solutes

What does water always follow?

Tugror Pressure

results when a water-filled central vacuole pushes plant cell walls from the inside (inflates like a balloon)

Plasmolysis

collapse of a walled cell's cytoplasm due to a lack of water; causes plants to shrivel

1. to take essential nutrients, 2. to remove waste materials, 3. to maintain + ions

3 functions of active transport

Primary active transport

active transport in which ATP is hydrolyzed, yielding the energy required to transport a + ion or molecule against its concentration gradient

H+, Ca2+, Na+, K+

+ Ions pumped in primary active transport

Hydrogen pump

also called proton pump; generates membrane potential and regulates pH in lysosomes and vacuoles

Calcium pump

moves Ca2+ from cytoplasm to cell exterior; also from cytosol to ER

Sodium-Potassium pump

moves 3 Na+ out of cell and 2 K+ into cell

Electrochemical gradient

accumulation of positive or negative charges on 1 side of the membrane; form of potential energy created by S-P pump

-50 to -200 mV

How much membrane potential does the S-P pump create?

Secondary active transport

uses a sodium ion concentration gradient previously made while using ATP in primary active transport

Symport

when the solute moves through the channel in the SAME direction of the driving sodium ion

Antiport

when the solute moves through the channel in the OPPOSITE direction of the driving sodium ion

Exocytosis

Process by which a cell releases large amounts of material

Bulk-Phase Endocytosis

vesicles import water molecules and other substances

Receptor-Mediated Endocytosis

vesicles import molecules specific to the receptors of the cell membrane

Catabolism

breaks down molecules; releases energy; cellular respiration

Anabolism

builds up molecules; stores energy; photosynthesis

6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O

Photosynthesis equation

Photosynthetic cells

contain chloroplasts

Chloroplasts

contain thylakoids

Stroma

fluid portion of chloroplast outside of thylakoids; area of light-independent reactions

Thylakoids

flattened membrane sacs inside the chloroplast (are called granum in stacks), used to convert light energy into chemical energy; contain chlorophyll

Chlorophyll

green pigments in thylakoids that absorb light energy used to carry out photosynthesis

700 nm (red) to 400 nm (violet)

Wavelengths of visible light

Light-dependent reactions

reactions of photosynthesis that use energy from light to produce ATP and NADPH

Photosystems II

the first electron transport chain makes ATP and uses electrons from light

Ground state

the lowest energy state of an atom

Excited state

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

P680

reaction center chlorophyll in the photosystem II

to transfer energy to P680

What are pigments used for in the photosystem?

Fluorescence

when a molecule returns to its ground state by releasing as heat or light

H2O function in Photosystems II

transfers electrons from its hydrogen atoms to P680 to prevent it from becoming P680+

Electron transport chain

a sequence of electron carrier molecules (membrane proteins) that shuttle electrons to P700

Electrons from the PS I electron transport chain being transferred to NADP+

What produces NADPH in light-dependent reactions?

Diffusion of H+ (from water) across the thylakoid lumen into the ATP synthase (photophosphorylation)

What produces ATP in light-dependent reactions?

Light Independent Reactions (Calvin Cycle)

set of reactions in photosynthesis that don't require light; energy from ATP and NADPH is used to build high-energy compounds such as sugar

Carbon fixation

first step of Calvin cycle; rubisco takes CO2 + RuBP and produces 2(3PGA)

Reduction

second step of Calvin cycle; ATP + NADPH + 3PGA = 2(G3P); NADPH gives 2 electrons to 2(3PGA)

Regeneration

third step of Calvin cycle (after 3 cycle turns); 5G3P regenerates RuBP and 1G3P goes towards making glucose

6

How many G3P is needed to make glucose?

True

T or F the overall reactions of photosynthesis and cellular respiration are basically the reverse of each other

Aerobic respiration

Respiration that requires oxygen

Glycolysis

the breakdown of glucose, releasing energy and pyruvic acid. (glucose + 2ATP --> 2 pyriuvate + 4ATP + 2NADH)

2 ATP and 4 NADH

# of ATP and NADH from Glycolysis

Pyruvate Oxidation

pyruvate molecules are oxidized (pyruvate + CoA --> CO2 + NADH + Acetyl - CoA) x 2

2 NADH

# of ATP and NADH from Pyruvate Oxidation

Citric Acid cycle

completes the breakdown of glucose (Acetyl - CoA --> 2CO2 + 3NADH + FADH2 + ATP) x 2