biology - carnes ap bio · the cell from the external environment. ... – isotonic solution:...

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

PowerPoint® Lecture Presentations for

Biology

Eighth Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp

BIG IDEA II Biological systems utilize free energy and molecular building blocks

to grow, to reproduce and to maintain dynamic homeostasis.

Enduring Understanding 2.B

Growth, reproduction and dynamic homeostasis

require that cells create and maintain internal environments

that are different from their external environments.

Essential Knowledge 2.B.1

Cell membranes are selectively permeable due to their structure.


Essential Knowledge 2.B.1: Cell membranes are selectively permeable due to their structure.

• Learning Objectives:

– (2.10) The student is able to use representations and

models to pose scientific questions about the

properties of cell membranes and selective

permeability based on molecular structure.

– (2.11) The student is able to construct models that

connect the movement of molecules across

membranes with membrane structure and function.


Cell membranes separate the internal environment of the cell from the external environment.

• The cell or plasma membrane is selectively permeable; that is, it allows

some substances to cross it more easily than others.

• The structure of the cell membrane results in its selectively permeable

properties.


Selective permeability is a direct consequence of membrane structure, as described by the fluid mosaic model.

Fig. 7-2

Hydrophilic head

WATER

Hydrophobic tail

WATER

Fig. 7-3

Phospholipid

bilayer

Hydrophobic regions of protein

Hydrophilic regions of protein

Fig. 7-9

(a) Transport

ATP

(b) Enzymatic activity

Enzymes

(c) Signal transduction

Signal transduction

Signaling molecule

Receptor

(d) Cell-cell recognition

Glyco-

protein

(e) Intercellular joining (f) Attachment to

the cytoskeleton

and extracellular

matrix (ECM)


Selective Permeability of the Cell Membrane


Selective Permeability of the Cell Membrane

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=HEs46fr84VY-CM&tbnid=RIUN2-Diy2Fj3M:&ved=0CAUQjRw&url=http%3A%2F%2Faecbio11.wikia.com%2Fwiki%2FFile%3APhospholipid_structure.jpg&ei=DrhaUqGpHpH49gSr_oAg&bvm=bv.53899372,d.eWU&psig=AFQjCNHa4T9b7HrrsXUILbWivW0Cs2Ncuw&ust=1381763465199291


Types of Transport Proteins

• Transport proteins allow passage of hydrophilic

substances across the membrane:

1. Some transport proteins, called channel proteins, have a

hydrophilic channel that certain molecules or ions can use

as a tunnel.

2. Channel proteins called aquaporins facilitate the passage of

water.

3. Other transport proteins, called carrier proteins, bind to

molecules and change shape to shuttle them across the

membrane.

• A transport protein is specific for the substance it moves –

i.e. FORM FITS FUNCTION!!!



Cell walls provide a structural boundary, as well as a permeability barrier for some substances to the internal environment.

• The cell wall is the tough, usually flexible but sometimes fairly

rigid layer that surrounds some types of cells. Cell walls provide

a structural boundary, as well as a permeability barrier for some

substances to the internal environments.

– It is located outside the cell membrane and provides these cells

with structural support and protection, in addition to acting as a

filtering mechanism.

– A major function of the cell wall is to act as a pressure vessel,

preventing over-expansion when water enters the cell.

– Cell walls are found in plants, bacteria, fungi, algae, and some

archaea. Animals and protozoa do not have cell walls.

– The material in the cell wall varies between species, and can also

differ depending on cell type and developmental stage.


Plant Cell Walls


Fungi Cell Walls


Bacterial Cell Walls



Biology

Eighth Edition





Enduring Understanding 2.B Growth, reproduction and dynamic homeostasis require that cells create and

maintain internal environments that are different from their external environments.

Essential Knowledge 2.B.2 Growth and dynamic homeostasis are maintained by the

constant movement of molecules across membranes.


Essential Knowledge 2.B.2: Growth and dynamic homeostasis

are maintained by the constant movement of molecules across membranes.



models to analyze situations or solve problems

qualitatively and quantitatively to investigate

whether dynamic homeostasis is maintained by the

active movement of molecules across membranes.


Passive transport does not require the input of metabolic energy; the net movement of molecules is from high concentration to low concentration.

• Passive Transport is the diffusion of a substance across a

semi-permeable membrane from an area of high

concentration to an area of low concentration WITHOUT

the use of energy.

• Passive transport plays a primary role in the import of

resources and the export of wastes.

– Diffusion is the tendency for molecules to spread out evenly into

the available space.

– Although each molecule moves randomly, diffusion of a

population of molecules may exhibit a net movement in one

direction.

– At dynamic equilibrium, as many molecules cross one way as

cross in the other direction.


Fig. 7-11 Molecules of dye Membrane (cross section)

WATER

Net diffusion Net diffusion Equilibrium

(a) Diffusion of one solute

Net diffusion

Net diffusion

Net diffusion

Net diffusion

Equilibrium

Equilibrium

(b) Diffusion of two solutes


• Substances diffuse down their concentration

gradient, the difference in concentration of a

substance from one area to another.

• No work must be done to move substances down

the concentration gradient.

• The diffusion of a substance across a biological

membrane is passive transport because it

requires no energy from the cell to make it

happen.


Passive Transport & Concentration Gradients


DIFFUSION EXISTS IN TWO FORMS: Dialysis and Osmosis

• Dialysis: the PASSIVE movement of particles across a semi-permeable membrane from an area of high concentration to an area of low concentration (no energy).

• Osmosis: the PASSIVE movement of water molecules across a semi-permeable membrane from an area of high concentration to an area of low concentration (no energy).


Effects of Osmosis on Water Balance

• Osmosis is the diffusion of water across a

selectively permeable membrane.

• Water diffuses across a membrane from the

region of lower solute concentration to the region

of higher solute concentration.

• THIS MEANS THAT WATER ALWAYS

ATTEMPTS TO DILUTE!!!!


Lower

concentration of solute (sugar)

Fig. 7-12

H2O

Higher

concentration of sugar

Selectively permeable

membrane

Same concentration

of sugar

Osmosis


Water Balance of Cells Without Walls

• Tonicity is the ability of a solution to cause a cell

to gain or lose water:

– Isotonic solution: Solute concentration is the

same as that inside the cell; no net water

movement across the plasma membrane

– Hypertonic solution: Solute concentration is

greater than that inside the cell; cell loses

water

– Hypotonic solution: Solute concentration is

less than that inside the cell; cell gains water


Fig. 7-13

Hypotonic solution

(a) Animal

cell

(b) Plant

cell

H2O

Lysed

H2O

Turgid (normal)

H2O

H2O

H2O

H2O

Normal

Isotonic solution

Flaccid

H2O

H2O

Shriveled

Plasmolyzed

Hypertonic solution


• Hypertonic or hypotonic environments create

osmotic problems for organisms.

• Osmoregulation, the control of water balance, is

a necessary adaptation for life in such

environments.

• The protist Paramecium, which is hypertonic to its

pond water environment, has a contractile vacuole

that acts as a pump to regulate its water balance.


Osmoregulation

Fig. 7-14

Filling vacuole 50 µm

(a) A contractile vacuole fills with fluid that enters from a system of canals radiating throughout the cytoplasm.

Contracting vacuole

(b) When full, the vacuole and canals contract, expelling

fluid from the cell.


Water Balance of Cells with Walls

• Cell walls help maintain water balance.

• A plant cell in a hypotonic solution swells until the

wall opposes uptake; the cell is now turgid (firm).

• If a plant cell and its surroundings are isotonic,

there is no net movement of water into the cell; the

cell becomes flaccid (limp), and the plant may

wilt.



• In a hypertonic environment, plant cells lose

water; eventually, the membrane pulls away from

the wall, a usually lethal effect called plasmolysis.


Water Balance of Cells with Walls


Understanding Water Potential

• Water potential (Ψ) is a measure of the potential energy of water.

• It relies on the combined effects of two factors, solute concentration

and pressure potential, which are incorporated into a single

measurement called water potential (Ψ).

• This measurement allows us to understand in which direction water will

flow due to osmosis, gravity, and pressure, even surface tension.

• It allows us to predict whether or not water will flow into a cell.

• Water potential is measure as:


Understanding Water Potential

• The standard for measuring

water potential is pure water.

• Pure water has a water potential

of ZERO bars.

• Water potential is measured on

either side of a membrane.

• Water flows from an area of high

water potential to an area of

lower water potential.


Understanding Solute Potential

• Solute potential is also called osmotic

potential because solutes affect the

direction of osmosis.

• Solute potential DECREASES with

increasing solute CONCENTRATION; and

this decrease causes a DECREASE IN

WATER POTENTIAL.

• This is because solutes bind to water

molecules reducing the number of free

water molecules to move and therefore

perform work.

• This means that INCREASING solute

concentration DECREASES water

potential!


Effect of Solute on Water Potential


Calculating Solute Potential (ΨS)

• Once you know a solute concentration, you can calculate solute potential

using the following formula: (ΨS ) = – iCRT

• Pure water has a solute potential (Ψs) of zero. Solute potential can never be positive.

• Adding solute to pure water is a negative experience; thus the solute potential becomes negative.

– i = The ionization constant (two what degree will the substance produce ions in water):

• for NaCl this would be 2;

• for sucrose or glucose, this number is 1

– C = Molar concentration (experimentally determined)

• Iso-osmolar molarity: would allow you to place a potato in the solution and get no movement of water.

• Point at which the line crosses 0 on the graph.

– R = Pressure constant = 0.0831 liter bar/mole K

– T = Temperature in degrees Kelvin = 273 + °C of solution


Pressure Potential (ΨP)

• Pressure potential is the sum of all pressure on water. It is measured in units

of MPa or Bars.

– Turgor pressure is the force caused by the cell membrane pushing against

the cell wall. Wall pressure is an equal and opposite force exerted by the

cell wall. It counteracts the movement of water due to osmosis.

– Pressure potential can be NEGATIVE as in water tension (transpiration in

the xylem of a plant).

– Pressure potential can be POSITIVE as in turgor pressure (water in living

cells under positive pressure).

– Pure water in an open container has a water potential of zero at one

atmospheric pressure.

– If physical pressure is applied to a solution, then its water potential (the

potential for the water to move and do work) will be affected. How it is

affected depends upon the direction of the pressure.

– Increased pressure raises water potential!


Effect of Positive Pressure on Water Potential


Effect of Negative Pressure on Water Potential


Water Potential in Plant Cells - Turgid


Water Potential in Plant Cells - Plasmolysis


Key Points to Remember

• Water always moves from [hi] to [low] concentration, or from [hi]

to [low] potential. This means that water always moves from

hypotonic to hypertonic.

• [Solute] is related to osmotic potential (the potential for water

to move across a semi-permeable membrane from high to low

concentration).

– Increased solutes decreases water potential.

• [Pressure] is related to pressure potential.

– Increased pressure raises water potential.

• Always use ZERO for pressure potential in animal cells and

open containers.

– 1 bar of pressure = 1 atmosphere.


Facilitated Diffusion

• In facilitated diffusion, transport proteins speed

the passive movement of molecules across the

plasma membrane.

• Channel proteins provide corridors that allow a

specific molecule or ion to cross the membrane -

facilitated diffusion is still passive because the

solute moves down its concentration gradient.

• Channel proteins include:

– Aquaporins, for facilitated diffusion of water

– Ion channels that open or close in response to a

stimulus (gated channels)


Fig. 7-15

EXTRACELLULAR FLUID

Channel protein

(a) A channel protein

Solute CYTOPLASM

Solute Carrier protein

(b) A carrier protein


Active transport requires free energy to move molecules from regions of low concentration to regions of high concentration.

• Active Transport uses free energy to move

molecules AGAINST their concentration gradients

via proteins imbedded in the cell membrane.

– Active transport is a process where free energy (often

provided by ATP) is used by proteins embedded in the

membrane to “move” molecules and/or ions across the

membrane and to establish and maintain concentration

gradients.

– Membrane proteins are NECESSARY for active

transport.

– Active transport allows cells to maintain concentration

gradients that DIFFER from their surroundings.


Fig. 7-17 Passive transport

Diffusion Facilitated diffusion

Active transport

ATP


Figure 8.15 The sodium-potassium pump: a specific case of active transport


How Ion Pumps Maintain Membrane Potential

• Membrane potential is the voltage difference

across a membrane:

– Voltage is created by differences in the distribution

of positive and negative ions.

• Two combined forces, collectively called the

electrochemical gradient, drive the diffusion of

ions across a membrane:

– A chemical force (the ion’s concentration gradient)

– An electrical force (the effect of the membrane

potential on the ion’s movement)



• An electrogenic pump is a transport protein that generates voltage across a

membrane:

– For example, the sodium-potassium pump is the major electrogenic

pump of animal cells.

• The main electrogenic pump of plants, fungi, and bacteria is a proton pump.


Cellular Pumps


Cotransport

• Cotransport is coupled transport by a membrane protein. It occurs

when the active transport of a solute indirectly drives the transport of

another solute:

– For example, plants commonly use the gradient of hydrogen ions

generated by proton pumps to drive the active transport of

nutrients into the cell.



The processes of endocytosis and exocytosis move large molecules from the external environment to the internal environment and vice versa.

• Bulk transport across the plasma membrane

occurs by exocytosis and endocytosis.

– Small molecules and water enter or leave the

cell through the lipid bilayer or by transport

proteins, but large molecules, such as

polysaccharides and proteins, cross the

membrane in bulk via vesicles.

– Bulk transport requires energy and is therefore

a type of ACTIVE transport.



Exocytosis

• In exocytosis, transport vesicles migrate to the

membrane, fuse with it, and release their contents.

– Many secretory cells use exocytosis to export

their products (proteins).

– In what part of the cell were these proteins

made? The ER or cytoplasm?



Endocytosis

• In endocytosis, the cell takes in macromolecules

by forming vesicles from the plasma membrane.

• Endocytosis is a reversal of exocytosis, involving

different proteins.

• There are three types of endocytosis:

– Phagocytosis (“cellular eating”)

– Pinocytosis (“cellular drinking”)

– Receptor-mediated endocytosis



• In phagocytosis a cell engulfs a particle in a

vacuole. The vacuole fuses with a lysosome to

digest the particle.

• In pinocytosis, molecules are taken up when

extracellular fluid is “gulped” into tiny vesicles.

• In receptor-mediated endocytosis, binding of

ligands to receptors triggers vesicle formation:

– A ligand is any molecule that binds specifically to a

receptor site of another molecule.


Phagocytosis & Pinocytosis

Fig. 7-20 PHAGOCYTOSIS

EXTRACELLULAR

FLUID

CYTOPLASM

Pseudopodium

“Food”or other particle

Food vacuole

PINOCYTOSIS

1 µm

Pseudopodium

of amoeba

Bacterium

Food vacuole

An amoeba engulfing a bacterium

via phagocytosis (TEM)

Plasma membrane

Vesicle

0.5 µm

Pinocytosis vesicles forming (arrows) in a cell lining a small

blood vessel (TEM)

RECEPTOR-MEDIATED ENDOCYTOSIS

Receptor

Coat protein

Coated vesicle

Coated pit

Ligand

Coat protein

Plasma membrane

A coated pit

and a coated vesicle formed during receptor- mediated endocytosis (TEMs)

0.25 µm



Biology

Eighth Edition





Enduring Understanding 2.B

Growth, reproduction and dynamic homeostasis

require that cells create and maintain internal environments

that are different from their external environments.

Essential Knowledge 2.B.3

Eukaryotic cells maintain internal membranes

that partition the cell into specialized regions.


Essential Knowledge 2.B.3: Eukaryotic cells maintain internal

membranes that partition the cell into specialized regions.


– (2.13) The student is able to explain how internal

membranes and organelles contribute to cell functions.


models to describe differences in prokaryotic and

eukaryotic cells.


Overview: The Fundamental Units of Life

• All organisms are made of cells.

• The cell is the simplest collection of matter

that can live.

• Cell structure is correlated to cellular function.

• All cells are related by their descent from earlier

cells.


Types of Cells

• The basic structural and functional unit of every

organism is one of two types of cells: prokaryotic

or eukaryotic.

• Eukaryotic cells have internal membranes that

compartmentalize their functions:

– Protists, fungi, animals, and plants all consist

of eukaryotic cells.

• Only organisms of the domains Bacteria and

Archaea consist of prokaryotic cells.


Comparing Prokaryotic and Eukaryotic Cells

• Basic features of all cells:

– Plasma membrane

– Semifluid substance called cytosol

– Chromosomes (carry genes)

– Ribosomes (make proteins)


Prokaryotes vs. Eukaryotes

• Prokaryotes:

– Archaea and bacteria generally LACK internal membranes and organelles but have a cell wall!

– NO NUCLEUS, but do have nucleoid region with DNA present

– Small and Simple

– Have cell membranes and cytoplasm

• Ex. Bacteria and Archaea

• Eukaryotes:

– Contain nuclei

– Contains organelles that perform specialized functions

– Unicellular or multicellular

• Ex. Plants, animals, protists, fungi


Fig. 6-6

Fimbriae

Nucleoid

Ribosomes

Plasma membrane

Cell wall

Capsule

Flagella

Bacterial chromosome

(a) A typical rod-shaped bacterium

(b) A thin section through the bacterium Bacillus coagulans (TEM)

0.5 µm


• Eukaryotic cells are characterized by having:

– DNA in a nucleus that is bounded by a

membranous nuclear envelope

– Membrane-bound organelles

– Cytoplasm in the region between the plasma

membrane and nucleus

• Eukaryotic cells are generally much larger than

prokaryotic cells.

Eukaryotic Cells


A View of the Eukaryotic Cell

• A eukaryotic cell has internal membranes that

partition the cell into organelles.

• Plant and animal cells have most of the same

organelles-

– Not in Animal Cells:

• Chloroplasts | central vacuole | tonoplast | cell wall | plasmodesmata

– Not in Plant Cells:

• Lysosomes | centrioles | flagella

Fig. 6-9a

ENDOPLASMIC RETICULUM (ER)

Smooth ER Rough ER Flagellum

Centrosome

CYTOSKELETON:

Microfilaments

Intermediate filaments

Microtubules

Microvilli

Peroxisome

Mitochondrion Lysosome

Golgi apparatus

Ribosomes

Plasma membrane

Nuclear envelope

Nucleolus

Chromatin

NUCLEUS

Fig. 6-9b

NUCLEUS

Nuclear envelope

Nucleolus

Chromatin

Rough endoplasmic reticulum

Smooth endoplasmic reticulum

Ribosomes

Central vacuole

Microfilaments

Intermediate filaments

Microtubules

CYTO- SKELETON

Chloroplast

Plasmodesmata

Wall of adjacent cell

Cell wall

Plasma membrane

Peroxisome

Mitochondrion

Golgi apparatus


Organelles: Emergent Properties

• All biological systems are composed of parts that interact

with each other. These interactions result in

characteristics not found in the individual parts alone. In

other words, “THE WHOLE IS GREATER THAN THE SUM

OF ITS PARTS.”

– This phenomenon is referred to as emergent properties.

• Biological systems from the molecular level to the

ecosystem level exhibit properties of biocomplexity and

diversity.

• Together, these two properties provide robustness to

biological systems, enabling greater resiliency and

flexibility to tolerate and respond to changes in the

environment.


Internal membranes facilitate cellular processes by minimizing competing interactions and by increasing surface area where reactions can occur.


Membranes and membrane-bound organelles in eukaryotic cells localize (compartmentalize) intracellular metabolic processes and specific enzymatic reactions.

• Subcellular Structures that Function in Control:

– Nucleus (plant and animal)

– Centrosome (plant and animal)

• Subcellular Structures that Function in Assembly, Transport, and Storage:

– Endoplasmic reticulum (plant and animal)

– Ribosomes (plant and animal)

– Golgi apparatus (plant and animal)

– Vacuoles (plant -1 large, and animal - many)

– Lysosomes (animal)

– Leucoplasts (plant only)

• Subcellular Structures that Function in Energy Transformations:

– Chloroplasts and Chromoplasts (plant only)

– Mitochondria (plant and animal)


Fig. 6-10 – The Nucleus

Nucleolus

Nucleus

Rough ER

Nuclear lamina (TEM)

Close-up of nuclear envelope

1 µm

1 µm

0.25 µm

Ribosome

Pore complex

Nuclear pore

Outer membrane Inner membrane

Nuclear envelope:

Chromatin

Surface of nuclear envelope

Pore complexes (TEM)


The Endomembrane System

• The endomembrane system regulates protein traffic and

performs metabolic functions in the cell. These membranes

serve to minimize competing interactions and increase the

surface area where reactions can occur.

• Components of the endomembrane system:

– Nuclear envelope

– Endoplasmic reticulum

– Golgi apparatus

– Lysosomes

– Vacuoles

– Plasma membrane

• These components are either continuous or connected via

transfer by vesicles.

Figure 7.16: relationships among organelles of the endomembrane system


Lysosomes: Digestive Compartments

• A lysosome is a membranous sac of hydrolytic

enzymes that can digest macromolecules.

• Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids.

• Lysosomes use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy.

– Some types of cells can engulf other cells by phagocytosis; this forms a food vacuole.

– When this happens, a lysosome fuses with the food vacuole and digests the molecules.

Figure 7.14 The formation and functions of lysosomes (Layer 1)

Fig. 6-14

Nucleus 1 µm

Lysosome

Digestive

enzymes Lysosome

Plasma

membrane

Food vacuole

(a) Phagocytosis

Digestion

(b) Autophagy

Peroxisome

Vesicle

Lysosome

Mitochondrion

Peroxisome

fragment

Mitochondrion

fragment

Vesicle containing

two damaged organelles 1 µm

Digestion

In phagocytosis, large substances

are taken up by a cell and digested

by lysosome enzymes.

In autophagy, lysosomes also use

enzymes to recycle the cell’s own

organelles and macromolecules.


Apoptosis – Programmed Cell Death

• Programmed destruction of cells (apoptosis) by

their own lysosomal enzymes is important in the

development of many multicellular organisms

(such as tadpoles into frogs).

• This even occurs in the hands of human embryos

(which are webbed until lysosomes digest the

tissue between the fingers).


Lysosomal Disorders

• A variety of inherited disorders called lysosomal

storage diseases affect lysosomal metabolism.

– In Pompe’s disease, the liver is damaged by

an accumulation of glycogen due to the

absence of a lysosomal enzyme needed to

break down that polysaccharide.

– In Tay-sacs disease, a lipid-digesting enzyme

is missing or inactive, and the brain becomes

impaired by an accumulation of lipids in the

cells.


The Golgi Complex

cis face

(“receiving” side of

Golgi apparatus) Cisternae

trans face

(“shipping” side of

Golgi apparatus) TEM of Golgi apparatus

0.1 µm


Fig. 6-11: Ribosomes

Cytosol

Endoplasmic reticulum (ER)

Free ribosomes

Bound ribosomes

Large subunit

Small subunit

Diagram of a ribosome TEM showing ER and ribosomes

0.5 µm

Fig. 6-12

Smooth ER

Rough ER Nuclear envelope

Transitional ER

Rough ER Smooth ER

Transport vesicle

Ribosomes Cisternae

ER lumen

200 nm


Functions of Smooth ER

• The smooth ER

– Synthesizes lipids

– Metabolizes carbohydrates

– Detoxifies poison

– Stores calcium


Functions of Rough ER

• The rough ER

– Functions to compartmentalize the cell, serves as

mechanical support, provides site-specific protein

synthesis with membrane-bound ribosomes.

– Has bound ribosomes, which secrete glycoproteins

(proteins covalently bonded to carbohydrates)

– Distributes transport vesicles, proteins surrounded by

membranes

– Is a membrane factory for the cell


Pathway of Protein-Based Secretions through Cells

ribosome on rough ER vesicle cis Golgi trans Golgi vesicle plasma membrane exocytosis


Mitochondria & Chloroplasts

• Mitochondria and chloroplasts change free energy

from one form to another.

• Mitochondria are the sites of cellular respiration,

a metabolic process that generates ATP.

• Chloroplasts, found in plants and algae, are the

sites of photosynthesis.

• Mitochondria and chloroplasts are NOT part of the

endomembrane system of cells:

– Both have a double membrane, have proteins made by

free ribosomes, and contain their own DNA.


Fig. 6-17

Free ribosomes in the mitochondrial matrix

Intermembrane space

Outer membrane

Inner membrane

Cristae

Matrix

0.1 µm

Fig. 6-18

Ribosomes

Thylakoid

Stroma

Granum

Inner and outer membranes

1 µm


The Cell: A Living Unit is Greater than the Sum of It’s Parts

biology - carnes ap bio · the cell from the external environment. ... – isotonic solution:...

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