Cell Transport Mechanisms

Membrane

- Membrane controls what gets in/out of the cell

- Some things pass through easier than others

Brownian motion

Innate random movement of molecules

Natural movement

Transport: Passive

- No energy required for these transport materials

- The Moving through materials WITH concentration gradient (HIGH TO LOW)

Transport: Active

- Requires use of energy to transport

- Moving materials AGAINST concentration gradient (LOW TO HIGH)

Passive Transport: Diffusion (Simple)

- Movemen of parcels down a concentration gradient (HIGH TO LOW)

- Particles naturally spread out

- Diffusion continues until dynamic equilibrium is reached

Passive Transport: Facilitated Diffusion

Diffusion through protein channels

Passive Transport - Osmosis (Water)

- Diffusion of water across a membrane.

- Is influenced by solutes (dissolved particles) in the water.

- (HIGH TO LOW concentration of water)

Hypotonic

- solution with less solute (more water) compared to another solution

Isotonic

- equal solute (equal water) compared to another solution

Membranes are/are NOT selectively permeable?

ARE

Hypertonic

- solution with more solute compared to another solution

HYPERtonic

more

HYPOtonic

less

ISOtonic

equal

Hypotonic Environment

Creates the problem of water moving into the cell

Hypotonic Environment: No cell wall

Animal cells will swell and possibly lyse(pop)

Hypotonic Environment: Has cell wall

- Some protists have contractile vacuoles

- Plant cells become turgid(swollen)

Hypertonic Environment

Creates the problem of water loss

Hypertonic Environment: No cell wall

Animal cells shrivel = crenate (shriveling up) = could die

Hypertonic Environment: Has cell wall

- Plant cells will plasmolyze

- More likely to recover

Isotonic Environment

No difference in concentration of water between cell & environment

Isotonic Environment: No cell wall

Animal cells - no problem: cell is stable

Isotonic Environment: Has cell wall

Plant cells - cells are flaccid - lower pressure inside

Active Transport: Protein Pumps

- Cells may need to move molecules AGAINST the concentration gradient

- "Costs" energy = ATP

- shape change transports solute from one side of the membrane to the other

- Moves sodium and potassium ions in/out of the cell

Active Transport: Protein Pumps - How many sodium ions and potassium ions gets moved in and out of the cell?

3 sodium ions OUT of the cell and 2 potassium ions INTO the cell

Endocytosis

is how the cell brings in large particles

Aquaporins

protein channels found in cell membranes that allow water molecules to pass through

Active Transport: Endocytosis: Phagocytosis

Brings in large solid particles

Phagocytosis means

cell eating

Pinocytosis means

cell drinking

Active Transport: Endocytosis: Pinocytosis

Brings in liquids

Active Transport: Endocytosis:

Receptor-mediated endocytosis

- They bond to specific particles on the outside of the membrane

- triggering the cell membrane to fold inward and engulf these bound molecules into a new vesicle, thereby bringing them into the cell

Active Transport: Exocytosis

- Gets rid of large particles or large amounts of particles in the cell

- Could be waste, something that the cell makes intentionally (hormones, proteins)

Receptor-mediated endocytosis means

bonding specfic

Definition of metabolism

- sum or all cheminal reactions in a cell/organizam

- involves energy transformations and transformations of matter

Potential Energy means

stored energy or location of material

Potential Energy examples

- Chemical

- Nuclear

- Gravitational

- Elastic

Kinetic Energy means

energy of motion

Kinetic Energy examples

- Mechanical

- Thermal (heat)

- Sound

- Electrical

- Radiant (light)

Anabolic Pathways consist of

- Build complicated molecules from simpler ones

- Endergonic Reaction: Consume energy

- Also called up-hill and non-spontaneous reactions

Anabolic Pathways defintion

use energy to build complex molecules from simpler precursors

Catabolic Pathways consist of

- Break down complex molecules into simpler compounds

- Exergonic Reactions: Release energy

- Also called down-hill and spontaneous reactions

Catabolic Pathways definition

break down complex molecules into simpler ones, releasing energy

What does not affect membrane permeability?

The polarity of membrane phospholipids

How can a lipid be distinguished from a sugar?

Lipids are mostly nonpolar.

True or false? Osmosis is a type of diffusion.

True

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?

Amphipathic nature

Which of the following particles could diffuse easily through a cell membrane?

Oxygen

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.

True

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?

Hypotonic

What name is given to the process by which water crosses a selectively permeable membrane?

osmosis

If a solution surrounding a cell is hypertonic relative to the inside of the cell, how will water move?

It will move out of the cell via osmosis.

Energy coupling uses

energy released from exergonic reactions to drive essential endergonic reactions (usually the energy in ATP reactions), includes redox reactions

Exergonic

releases energy

Endergonic

absorbs energy

What does Redox Reactions stand for?

reduction-oxidation reactions

What are redox reactions

Chemical reactions that involve the transfer of electrons between atoms/molecules

Reduction meaning in Redox Reactions

Gain of electrons (reduction in valence)

Oxidation meaning in Redox Reactions

Loss of electrons

LEO the lion goes GER stands for

- Lose electrons oxidation

- Gain electron reduction

OIL RIG stands for

Oxidation is LOSS

Reduction is GAIN

Adenosine Triphosphate (ATP)

compound used by cells to store and release energy

Phosphorylation

The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation.

How does ATP work?

Phosphorylation

What is the summary equation for photosynthesis?

6 CO_2 + 6 H_2O + Light energy → C_6H_12O_6 + 6 O_2

What metabolic/energetic categories apply?

- Anabolic

- Endergonic

- Non-spontaneous

- Uphill

What types of organisms conduct photosynthesis?

- Plants

- Algae

- Certain types of protists

- Some prokaryotes

Why is photosynthesis an important process?

- Make own food

- Base of food webs

- Provide glucose + oxygen for respiration

- Key role in carbon cycle

- Remove & store carbon

Organ = Roots

Anchors the plant in the soil, absorbs water and dissolved nutrients/minerals

Organ = Stem

Holds up leaves and transports materials through the plant body

Organ = Leaves

Site of photosynthesis

Structure = Cuticle

- Waxy covering secreted by epidermal cells

- Barrier against pathogens and excess water loss/uptake

Structure = Stoma (or stomata)

- Openings in epidermis surrounded by two guard cells

- Open/close to regulate gas exchange and prevent transpiration (water evaporation)

Tissue = Mesophyll

Cells that perform photosynthesis and store products

Tissue = Vein

(also called Vascular bundle), transports materials

Tissue = Xylem (inside vein)

transports water and dissolved solutes (minerals and salts)

Tissue = Phloem (inside vein)

transports photosynthetic products

Light Definition

a form of electromagnetic energy, which travels in waves and particles called photons

Wavelength Definition

Is the distance between the crests of waves

- Determines the type of electromagnetic energy

The visible light spectrum definition

includes the colors of light we can see

The relationship between wavelength and light energy: Shorter wavelength = __________ energy? (Higher or Lower)

Higher

The relationship between wavelength and light energy: Longer wavelength = __________ energy? (Higher or Lower)

Lower

Pigments Definition

- are molecules that absorb light

- some light is reflected, which are the colors we see

Photosystem

- a group of pigments

- consists of the reaction center and accessory pigments

Reaction Center

Chlorophyll A - main photosynthetic pigment

Has electrons that become excited(gains so much energy) and leave the molecule

What happens when a pigment absorbs light

It goes from a ground state to an excited state, which is unstable

Accessory Pigments

Absorbs different wavelengths of light and pass the energy to the reaction center chlorophyll

Light Reactions

- Occurs in the thylakoid membranes

- Convert solar energy into chemical energy

- Split water, release oxygen, produce ATP, and form NADPH

Calvin Cycle

- Occurs in the stroma

- Forms sugar from carbon dioxide using ATP for energy and NADPH for reducing power

Molecules of _______ _______ (originally found in the air or water) diffuse into the _________ of the chloroplast

carbon dioxide, stroma

The molecule carbon dioxide combines with a molecule of ________ __________

RuBP

This anabolic and endergonic reaction is catalyzed by the enzyme __________.

rubisco

Since the molecule from #3 is an enzyme, CO_2 and RuBP are its:

substrates

The unstable molecule that forms from CO2 coming with RuBP immediately breaks apart into two molecules of __________.

PGA

ATP from the light reactions phosphorylate both of these molecules turning them into _______.

bi-PGA

NADPH from the light reactions provides electrons to reduce these molecules to form two molecules of ______.

G3P

In total, after 6 carbon dioxide molecules go through the Calvin Cycle, how many molecules of G3P are formed?

12

Two molecules of G3P are removed to produce ________.

glucose

The remaining 10 molecules of G3P are phosphorylated by ATP and their atoms rearranged to re-make _______.

RuBP

The 3 stages of the Calvin Cycle are ________ ________, ________, and _________.

carbon fixation, reduction, regeneration