Cellular Foundations Exam 2

Plasma Membrane

helps maintain the unique life-giving internal chemistry of the cell

Selectively permeable (plasma membrane)

ensures that the cell interior is chemically different from the extracellular environment

Phospholipid bilayer with embedded proteins

What is the plasma membrane composed of?

Passive Transport

the spontaneous movement of a substance, can take place without an input of energy

Active Transport

the movement of a substance in response to an input of energy

Diffusion

the passive transport of a substance from a region of higher concentration to a region of lower concentration

Equilibrium

this is reached when concentration gradients disappear and therefore diffusion ceases (substances continue to move, but net movement ceases).

Osmosis

the diffusion of water molecules (from an area of lower solute to an area of higher solute) across a selectively permeable membrane

Hypotonic solution

has a lower solute concentration than the cytosol of a cell, which causes water to flow into the cell and make it swell.

Hypertonic solution

has a higher solute concentration than the cytosol of a cell, which causes water to flow out of the cell and make it shrink.

Isotonic solution

has an equal concentration of solute inside and outside the cell

Simple Diffusion

very small molecules (oxygen and carbon dioxide) can cross cell membranes without assistance

Facilitated Diffusion

the passive transmembrane movement of a substance WITH the assistance of membrane transport proteins (Channel proteins and Carrier proteins)

Channel Proteins

move substances down a concentration gradient, without an energy input, selecting cargo (ions) based on size, shape, and chemical characteristics.

Carrier Proteins

transport specific molecules across the plasma membrane based on the shape of the molecule (passive or active)

Passive Carrier Proteins

assist in the diffusion of molecules and ions from an area of lower concentration

the protein called GLUT which help maintain blood glucose levels through facilitated diffusio

What is the passive carrier of glucose?

Active Carrier Proteins

Use ATP to pump ions or molecules across the membrane against a concentration gradient

Exocytosis

substances to be exported from a cell are packaged into transport vesicles that fuse with the plasma membrane and expel the contents

Endocytosis

brings substances into the cell by wrapping them in a section of the plasma membrane that eventually breaks free inside the cell

Pinocytosis

a nonspecific type of endocytosis that brings in all the material in an immediate area

Phagocytosis

used to ingest large particles, such as a bacteria or virus

tight junctions, anchoring junctions, and gap junctions

What are the three types of junctions?

Tight junctions

formed by belts of proteins that create leak-proof sheets of cells, which can be found in the skin and lining of body cavities

Anchoring junctions

form patches of proteins that extend through the plasma membrane and link cells that typically undergo heavy structural stress

Gap junctions

direct cytoplasmic connections between two cells formed by protein-lined tunnels that span the intercellular space between adjacent cells

Plasmodesmata

tunnels through the cell wall that connect the plasma membranes and cytoplasm of adjacent cells

Receptor protein

What do target cells receive a signal from?

the higher the rate of diffusion

The greater the difference in concentration between two points…

Metabolic Rate

a measure of the speed with which your body uses energy, dependent on genetics

Energy

the capacity of any object to do work

Work

defined as the capacity to bring about a change in a defined system

Potential Energy

The energy stored in any system as a consequence of its position

Kinetic Energy

The energy a system possesses as a consequence of its state of motion

Chemical Energy

the potential energy stored in atoms because of their bonding and position in relation to other atoms

Mechanical, electrical, light, and heat are all examples of…

kinetic energy

1st Law of Thermodynamics

energy can be neither created nor destroyed; it can be converted from one form to another

2nd Law of Thermodynamics

the natural tendency of the universe is to become less organized over time; an input is required to maintain order

Photosynthesis

the process by which producers (autotrophs) obtain energy from their non-living environment; production of glucose

Photosynthesis Equation

6 CO2 + 6 H2O + light energy > C6H12O6 + 6O2

Aerobic Respiration Equation

C6H12O6 + 6O2 > 6CO2 + 6H2O + energy(ATP)

Catabolism

releases chemical energy in the process of breaking down complex biomolecules.

Anabolism

creating complex biomolecules that require energy.

Cellular respiration

uses the chemical energy in food to turn ADP into ATP

Oxidation

is the loss of a molecule, atom, or ion

Reduction

the gain of electrons by a molecule, atom, or ion

Enzymes

speed up chemical activity, lowering activation energy, reusable, substrate specific, highly regulated, often have co-vitamins

What are potential reasons enzymes are denatured?

Heat and Acidity

What inhibits enzymes?

a molecule bonding to enzymes when it’s not supposed to

Substrates

bind to the active site of an enzyme based on the site’s size, shape, and chemistry

the 3-dimensional shapes of both

What does the binding of an enzyme and its substrate depend on?

If the products are at a lower energy state than the reactants.

When can chemical reactions occur spontaneously?

Glycolysis, Citric Acid (Krebs) Cycle, Oxidative phosphorylation

What are the three steps of Aerobic Respiration?

Cytoplasm

Where does glycolysis take place?

Matrix mitochondria

Where does the Citric Acid Cycle take place?

Cristae mitochondria

Where does oxidative phosphorylation take place?

Glycolysis

Glucose > 2 NADH + 2 ATP + 2 Pyruvate

Fermentation

the recycling process where 2 NADH become 2 NAD+

Aerobic processes

The 2nd and 3rd stages of cellular respiration are strictly what?

Citric Acid Cycle

2 Acetyl-COA > 6 NADH + 2 FADH2 + 2 ATP + 4 CO2

Oxidation Phosphorylation

10 NADH + 2 FADH2 + O2 > 32 ATP + H2O

32 ATP

How many ATP per glucose?

light dependent reactions and light independent (Calvin cycle)

What are the two stages of photosynthesis?

Light Dependent Reactions

light + H2O > ATP + NADPH

Light Independent Reactions (Calvin Cycle)

ATP + NADPH + CO2 > Glucose

Substrates

bind to the active site of an enzyme based on the site’s size, shape, and chemistry

If the products are at a lower energy state than the reactants

When do chemical reactions occur spontaneously?

Stoma

openings that allow for gas exchange

Chloroplasts

suited to carry out photosynthesis

Stomata (plural)

pores on the lower side of the leaf that regulate entry of CO2 and close at night

Chlorophyll

absorbs light energy; drives synthesis of energy carriers

Photo system II

light + H2O > ATP

Photo system I

light > NADPH

Thylakoid membrane

Where do light dependent reactions occur?

Light independent reactions (Calvin cycle)

CO2 + ATP + NADPH > Glucose

6 turns

How many turns in the Calvin cycle to produce glucose?

C3 plants

fix CO2 through the Calvin cycle alone; they are called C3 plants because

the first stable product of carbon fixation is a 3-carbon molecule

C3 photosynthesis

can be inefficient because these plants lose fixed carbon due

to photorespiration, which is worst under bright light and hot and dry conditions

C4 and CAM plants

have evolved variant forms of photosynthesis in which the first

stable product of carbon fixation is a 4-carbon molecule; photosynthesis is more

efficient in these plants under hot, dry, sunny conditions because photorespiration

is minimized