Investigating Cell Structure and Function

1. Cell Theory

2. Microscopy-

a. History

b. Types

3. Studying cell organelles

a.Cell homogenization

b. Cell Fractionation

4. Prokaryotic vs. Eukaryotic cells

5. Animal cell structures/functions

6. Plant cell structures/functions

Review-A solution of pH 5 has how many times (X) the number of protons (H+) than a solution of pH

7?

1. 2

2. ½

3. 100

4. 1/100

What do these organisms have in common?

Where did these cells come from?

What insight about cells can you get from these pictures?

What if you could gain the powers of the organisms that you eat?

• Eat a fish-breathe under water

• Eat a bird-fly

• Eat a chameleon-blend in with your environment

• Eat an algae-photosynthesize

The Emerald Sea Slug

The Emerald Sea Slug is capable of stealing both the genes and cell organelles that are responsible

for photosynthesis from the algae

• allows the slug to temporarily give up its life as an animal and instead "live like a plant,“

• first known example of horizontal gene transfer in multicellular organisms.

• remarkably, the sea slug can pass some of the ability it gains to the next generation

What does the acquired algae gene do ?

• After they are eaten, an algal gene is incorporated into the slug chromosome

• The acquired algal gene is needed to repair damage to chloroplasts, and keep them functioning.

• Therefore, the sea slug does not need to continually consume algae to retain its powers. It is capable of maintaining photosynthesis for as long as nine months.

LE 6-2

Measurements1 centimeter (cm) = 10–2 meter (m) = 0.4 inch1 millimeter (mm) = 10–3 m1 micrometer (µm) = 10–3 mm = 10–6 m1 nanometer (nm) = 10–3 µm = 10–9 m

10 m

1 mHuman height

Length of somenerve andmuscle cells

Chicken egg

0.1 m

1 cm

Frog egg1 mm

100 µm

Most plant andanimal cells

10 µmNucleus

1 µm

Most bacteria

Mitochondrion

Smallest bacteria

Viruses100 nm

10 nmRibosomes

Proteins

Lipids

1 nmSmall molecules

Atoms0.1 nmU

na

ide

d e

ye

Lig

ht

mic

rosc

op

e

Ele

ctr

on

mic

ros

co

pe

Anton Van Leeuwenhoek-mid 1600’s)

Robert Hooke-Cells (mid-1600’s)

Table 7.1 Different Types of Light Microscopy: A Comparison

LE 6-3a

Brightfield (unstained specimen)

50 µmBrightfield (stained specimen)

Phase-contrast

LE 6-3b

50 µm

50 µm

Confocal

Differential-interference-contrast (Nomarski)

Fluorescence

LE 6-41 µm

1 µm

Scanning electronmicroscopy (SEM) Cilia

Longitudinalsection ofcilium

Transmission electronmicroscopy (TEM)

Cross sectionof cilium

LE 6-4a

1 µm

Scanning electronmicroscopy (SEM)

Cilia

LE 6-4b

1 µm

Longitudinalsection ofcilium

Transmission electronmicroscopy (TEM)

Cross sectionof cilium

LE 6-9a

Flagellum

Centrosome

CYTOSKELETON

Microfilaments

Intermediate filaments

Microtubules

Peroxisome

Microvilli

ENDOPLASMIC RETICULUM (ER

Rough ER Smooth ER

MitochondrionLysosome

Golgi apparatus

Ribosomes:

Plasma membrane

Nuclear envelope

NUCLEUS

In animal cells but not plant cells: LysosomesCentriolesFlagella (in some plant sperm)

Nucleolus

Chromatin

Inner Life of A Cell

• http://www.studiodaily.com/main/searchlist/6850.html

LE 6-5a

Homogenization

HomogenateTissuecells

Differential centrifugation

LE 6-5b

Pellet rich innuclei andcellular debris

Pellet rich inmitochondria (and chloro-plasts if cellsare from a plant)

Pellet rich in“microsomes”(pieces of plasmamembranes andcells’ internalmembranes) Pellet rich in

ribosomes

150,000 g3 hr

80,000 g60 min

20,000 g20 min

1000 g(1000 times theforce of gravity)

10 min

Supernatant pouredinto next tube

Figure 6-01

Cell Structure

1. Basic requirements to be a cell• Cytoplasm• DNA• Ribosome• Cell membrane

2. Prokaryotic and eukaryotic cells

3. Limitations to cell sizea. Lower limitsb. Upper limits-SA/volume ratio

Prokaryotic and Eukaryotic Cells

LE 6-6

A typicalrod-shapedbacterium

A thin section through thebacterium Bacilluscoagulans (TEM)

0.5 µm

Pili

Nucleoid

Ribosomes

Plasmamembrane

Cell wall

Capsule

Flagella

Bacterialchromosome

LE 6-7

Total surface area(height x width xnumber of sides xnumber of boxes)

6

125 125

150 750

1

11

5

1.2 66

Total volume(height x width x lengthX number of boxes)

Surface-to-volumeratio(surface area volume)

Surface area increases whileTotal volume remains constant

An overview of animal cell structure

1. Nucleus2. Ribosomes3. Endomembrane Systema. RER & SERb. Vesiclesc. Golgi apparatusd. Vacuolese. Lysosomes4. Mitochondria5. Cytoskeleton

LE 6-9a

Flagellum

Centrosome

CYTOSKELETON

Microfilaments

Intermediate filaments

Microtubules

Peroxisome

Microvilli

ENDOPLASMIC RETICULUM (ER

Rough ER Smooth ER

MitochondrionLysosome

Golgi apparatus

Ribosomes:

Plasma membrane

Nuclear envelope

NUCLEUS

In animal cells but not plant cells: LysosomesCentriolesFlagella (in some plant sperm)

Nucleolus

Chromatin

LE 6-8

Hydrophilicregion

Hydrophobicregion

Carbohydrate side chain

Structure of the plasma membrane

Hydrophilicregion

Phospholipid Proteins

Outside of cell

Inside of cell 0.1 µm

TEM of a plasma membrane

What is contained in the nucleus of a cell?

DNA

Chromoso

mes

Genes

R-rna

All of t

he above

0% 0% 0%0%0%

1. DNA

2. Chromosomes

3. Genes

4. R-rna

5. All of the above

LE 6-10

Close-up of nuclearenvelope

Nucleus

Nucleolus

Chromatin

Nuclear envelope:Inner membraneOuter membrane

Nuclear pore

Porecomplex

Ribosome

Pore complexes (TEM) Nuclear lamina (TEM)

1 µm

Rough ER

Nucleus

1 µm

0.25 µm

Surface of nuclear envelope

What is the function of ribosomes?

Prote

in synth

esis

DNA sy

nthesis

Intra

cellu

lar digesti

on

Transport

of pro

teins o

...

0% 0%0%0%

1. Protein synthesis

2. DNA synthesis

3. Intracellular digestion

4. Transport of proteins outside of the cell

LE 6-11

Ribosomes

0.5 µm

ER Cytosol

Endoplasmicreticulum (ER)

Free ribosomes

Bound ribosomes

Largesubunit

Smallsubunit

Diagram ofa ribosome

TEM showing ERand ribosomes

There is a difference in the make-up of cytoplasmic eukaryotic ribosomes and prokaryotic

ribosomes

True

False

0%0%

1. True

2. False

Proteins that are secreted from a cell are produced by:

Membra

ne-bound rib

o...

Free rib

osomes

0%0%

1. Membrane-bound ribosomes

2. Free ribosomes

Secreted proteins are carried away from the ER by:

The golgi a

pparatu

s

Lyso

somes

Mito

chondria

vesic

les

0% 0%0%0%

1. The golgi apparatus

2. Lysosomes

3. Mitochondria

4. vesicles

LE 6-12

Ribosomes

Smooth ER

Rough ER

ER lumen

Cisternae

Transport vesicle

Smooth ER Rough ER

Transitional ER

200 nm

Nuclearenvelope

If a secreted protein needs to be chemically modified after it leaves the ER in a vesicle, it will go to:

A lyso

some

Mito

chondria

A storage vacu

ole

The Golgi

apparatus

0% 0%0%0%

1. A lysosome

2. Mitochondria

3. A storage vacuole

4. The Golgi apparatus

LE 6-16-3

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi

Plasma membrane

Vesicles from either the ER or the Golgi that contain proteins involved in intracellular digestion fuse to form this

cell organelle

Stora

ge vacuole

Mito

chondria

Lyso

some

0% 0%0%

1. Storage vacuole

2. Mitochondria

3. Lysosome

Lysosomes are involved in destroying “worn out” cell organelles:

True

False

0%0%

1. True

2. False

Up to 5 optional points

• You have 3 minutes to write a short answer to this question:

• Why is it important that the pH of a lysosome is acidic compared to the cytoplasm of the cell?

LE 6-14a

Phagocytosis: lysosome digesting food

1 µm

Plasmamembrane

Food vacuole

Lysosome

Nucleus

Digestiveenzymes

Digestion

Lysosome

Lysosome containsactive hydrolyticenzymes

Food vacuolefuses withlysosome

Hydrolyticenzymes digestfood particles

LE 6-14b

Autophagy: lysosome breaking down damaged organelle

1 µm

Vesicle containingdamaged mitochondrion

Mitochondrionfragment

Lysosome containingtwo damaged organelles

Digestion

Lysosome

Lysosome fuses withvesicle containingdamaged organelle

Peroxisomefragment

Hydrolytic enzymesdigest organellecomponents

Malfunctions within a lysosome can cause diseases.

True

False

0%0%

1. True

2. False

Vacuoles

Can be form

ed by endoc..

.

May s

tore

substa

nces t

h...

Can be fo

rmed by vesic

le...

Can be filled w

ith w

ater

All of t

he above

0% 0% 0%0%0%

1. Can be formed by endocytosis

2. May store substances the cell will need later

3. Can be formed by vesicles joining together

4. Can be filled with water

5. All of the above

LE 7-14

Filling vacuole50 µm

50 µmContracting vacuole

This cell organelle has a structure adapted for making ATP during cellular respiration.

Lyso

some

Nucle

us

Vacuole

Golgi a

pparatu

s

mito

chondria

0% 0% 0%0%0%

1. Lysosome

2. Nucleus

3. Vacuole

4. Golgi apparatus

5. mitochondria

LE 6-17

Mitochondrion

Intermembrane space

Outer membrane

Inner membrane

Cristae

Matrix

100 nmMitochondrialDNA

Freeribosomes in themitochondrialmatrix

The Cytoskeleton

1. Made up of 3 elements

a. Microtubules

b. Microfilaments

c. Intermediate filaments

2. Functions-diverse including maintaining cells shape; motility; contraction; and organelle movement

LE 6-20

Microtubule

Microfilaments0.25 µm

Table 6-1a

LE 6-22

0.25 µm

Microtubule

Centrosome

Centrioles

Longitudinal sectionof one centriole

Microtubules Cross sectionof the other centriole

Cilia and Flagella

• Cell Movement

LE 6-23a

5 µm

Direction of swimming

Motion of flagella

LE 6-23b

15 µm

Direction of organism’s movement

Motion of cilia

Direction ofactive stroke

Direction ofrecovery stroke

This cell organelle contains 2 compartments separated by a membrane, which is necessary for

chemiosmosis to occur

Golgi a

pparatu

...

Mito

chondria RER

Lyso

some

vacu

ole

0% 0% 0%0%0%

1. Golgi apparatus

2. Mitochondria

3. RER

4. Lysosome

5. vacuole

Which of the following statements is/are true?

The cyto

skelet..

.

The cyto

skelet..

.

The cyto

skelet..

.

A and B

B and C

All of t

he abo...

0% 0% 0%0%0%0%

1. The cytoskeleton is composed of protein

2. The cytoskeleton is involved in the segregation of chromosomes during mitosis

3. The cytoskeleton can reorganize by polymerizing/depolymerizing

4. A and B

5. B and C

6. All of the above

LE 6-24a

0.5 µm

Microtubules

PlasmamembraneBasal body

LE 6-24b

Plasmamembrane

Outer microtubuledoublet

0.1 µm

Dynein arms

CentralmicrotubuleCross-linkingproteins insideouter doublets

Radialspoke

0.5 µm

LE 6-25b

Wavelike motion

Cross-linkingproteins insideouter doublets

ATP

Anchoragein cell

Effect of cross-linking proteins

Organelle Movement

• Position of organelles not fixed in the cell

LE 6-21a

Vesicle

Receptor formotor protein

Microtubuleof cytoskeleton

Motor protein(ATP powered)

ATP

LE 6-21b

0.25 µmMicrotubule Vesicles

Table 6-1c

LE 6-26

Microfilaments (actinfilaments)

Microvillus

Plasma membrane

Intermediate filaments

0.25 µm

Table 6-1b

LE 6-27a

Muscle cell

Actin filament

Myosin filamentMyosin arm

Myosin motors in muscle cell contraction

LE 6-27b

Cortex (outer cytoplasm):gel with actin network

Amoeboid movement

Inner cytoplasm: solwith actin subunits

Extendingpseudopodium

LE 6-27c

Nonmovingcytoplasm (gel)

Cytoplasmic streaming in plant cells

Chloroplast

Streamingcytoplasm(sol)

Cell wall

Parallel actinfilaments

Vacuole

Dyneine walking is a key event in this cellular process:

Chemiosmosis

Amoeboid movem...

Cytokenesis

Motility

using..

.

All of t

he abo...

0% 0% 0%0%0%

1. Chemiosmosis

2. Amoeboid movement

3. Cytokenesis

4. Motility using flagella

5. All of the above

Plant Cell Structure

1. All of the same organelles and structures that are in animals plus

a. Cell wall

b. Large central vacuole

c. Chloroplasts

LE 6-9b

Roughendoplasmicreticulum

In plant cells but not animal cells: ChloroplastsCentral vacuole and tonoplastCell wallPlasmodesmata

Smoothendoplasmicreticulum

Ribosomes(small brown dots)

Central vacuole

Microfilaments

IntermediatefilamentsMicrotubules

CYTOSKELETON

Chloroplast

Plasmodesmata

Wall of adjacent cell

Cell wall

Nuclearenvelope

Nucleolus

Chromatin

NUCLEUS

Centrosome

Golgiapparatus

Mitochondrion

Peroxisome

Plasmamembrane

LE 6-28

Centralvacuole of cell

PlasmamembraneSecondarycell wall

Primarycell wall

Middlelamella

1 µm

Centralvacuole of cell

Central vacuoleCytosol

Plasma membrane

Plant cell walls

Plasmodesmata

LE 6-15

5 µm

Central vacuole

Cytosol

Tonoplast

Central vacuole

Nucleus

Cell wall

Chloroplast

LE 6-18

Chloroplast

ChloroplastDNA

RibosomesStroma

Inner and outermembranes

Granum

Thylakoid1 µm

LE 6-19

Chloroplast

Peroxisome

Mitochondrion

1 µm

This cell organelle contains 2 compartments separated by a membrane, which is necessary for

chemiosmosis to occur

Golgi a

pparatu

...

Mito

chondria RER

Chloroplast

2 and 4

0% 0% 0%0%0%

1. Golgi apparatus

2. Mitochondria

3. RER

4. Chloroplast

5. 2 and 4

Because plant cells have a large central

water vacuole, they must also have:

Chloroplasts

Lyso

somes

Mito

chondria

A cell w

all RER

0% 0% 0%0%0%

1. Chloroplasts

2. Lysosomes

3. Mitochondria

4. A cell wall

5. RER

Plays a role in cytoplasmic streaming, amoeboid movement, and muscle contraction:

Micr

ofilaments

Inte

rmediate

f...

Micr

otubules

Dyn

eine walkin...

All of t

he abo...

0% 0% 0%0%0%

1. Microfilaments

2. Intermediate filaments

3. Microtubules

4. Dyneine walking

5. All of the above

These in class clicker questions are helpful

Stro

ngly Agree

Agree

Neutra

l

Disa

gree

Stro

ngly Disa

gree

0% 0% 0%0%0%

1. Strongly Agree

2. Agree

3. Neutral

4. Disagree

5. Strongly Disagree

Cell Surrface Molecules/Connections

1. Cell surface molecules (glycocalyx)

2. Cell Connections-Plants

a. Plasmodesmata

3. Cell connections-Animals

a. Tight junctions

b. Desmosomes

c. Gap junctions

LE 6-29a

EXTRACELLULAR FLUID ProteoglycancomplexCollagen

fiber

Fibronectin

Integrin Micro-filaments

CYTOPLASM

Plasmamembrane

LE 6-30

Interiorof cell

Interiorof cell

0.5 µm Plasmodesmata Plasma membranes

Cell walls

LE 6-31

Tight junctions preventfluid from moving across a layer of cells

Tight junction

0.5 µm

1 µm

0.1 µm

Gap junction

Extracellularmatrix

Spacebetweencells

Plasma membranesof adjacent cells

Intermediatefilaments

Tight junction

Desmosome

Gapjunctions

LE 6-32

5 µ

m