Chapter 3: Cell Structure and Function

Question 1

Common features of living organisms

Answer 1

• grow
• reproduce
• DNA genomes
• metabolism
• adaptable-homeostasis

Question 2

Phospholipid by layer is ___________ (polar and nonpolar)

Answer 2

Amphipathic

Question 3

The two layers in the phospholipid bilayer

Answer 3

Leaflets

Question 4

What helps maintain the fluidity of membranes?

Answer 4

Hopanoids- Stiffening agents (bacteria)

Sterols- in eukaryotes, (esterol for fungi and cholesterol for animal cells)

Question 5

Function of membrane proteins

Answer 5

• support
• signaling and communication
• export
• transport
• establish concentration gradients

Question 6

Passive diffusion….
Facilitated diffusion…
Active transport…
Endocytosis and exocytosis…

Answer 6

• passive diffusion- gases like oxygen and carbon dioxide, lipids also dissolve in lipid bilayer
• facilitated diffusion- osmosis
• Active transport- cotransport (sodium potassium pump for ions)
• Exocytosis and Endocytosis-plasma membrane pinches to form a vesicle

Question 7

How do you small uncharged molecules like O2 and CO2 get through the membrane?

Answer 7

By passive diffusion

Question 8

Movement is not ATP dependent, high concentration to low concentration
* uses membrane bound carrier proteins

Answer 8

Facilitated diffusion

Question 9

Channel that that the membrane can use to move water into the cell

Answer 9

Aquaporin

Question 10

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

Answer 10

Tonicity

Question 11

When talking about plant cells, what is it called when the cell is in a hypertonic solution and a hypotonic solution?

Answer 11

Hyper- plasmalysis (lyse)

Hypo- turgid

Question 12

Move substances against their concentration gradient also utilizes a carrier proteins
Helps to maintain ion gradients
Requires energy like ATP

Answer 12

Active transport

Question 13

Uses ion gradients to cotransport more than one substance

uses an electrochemical gradient – generated by active transport – as an energy source to move molecules against their gradient, and thus does not directly require a chemical source of energy such as ATP.

Answer 13

Secondary active transport

Symporter- moves to substances in the same direction
Antiporter- moves to substances in opposite directions
Uniporter-moves one substance

Question 14

Energy dependent transporter that chemically modifies the molecule as it is brought into the cell.

Ex: glucose can be phosphorylated

Answer 14

Group translocation

Question 15

-can diffuse across the membrane and increase or decrease the hydrogen concentration within the cell

Answer 15

Membrane-permanent weak acids and bases

A- or BH+ is soluble in the bloodstream, uncharged HA or A is hydrophobic and can penetrate the cell membrane

Question 16

How do prokaryotes protect the cell membrane?

Answer 16

Most common structural support is the cell wall

Question 17

What are the functions of the cell wall?

Answer 17

• shape (protoplast)
• protection
• attachment (biofilms)
• pathogenicity (LPS, endotoxin in cell wall)

Question 18

Bacterial cell envelopes…

Answer 18

Gram +, thick cell wall multiple layers of peptidoglycan (purple)

Gram -, thin layer of peptidoglycan in cell wall, with additional outer membrane (pink)

Mycobacterium, complex multilayer cell wall

Question 19

Teichoic acid is unique to what kind of bacteria?

Answer 19

Gram-positive

*50%, negatively charged, helps pathogens attach to cells, key roles in antibiotic resistance, regulation of cell division

Question 20

Describe the structure of the gram-positive cell wall

Answer 20

• composed primarily of peptidoglycan

• lipoteichoic acid links to plasma membrane
• wall teichoic acid links to peptidoglycan

*** very small periplasm

Question 21

Propionibacteria acnes is what type of bacteria?

Answer 21

Gram-positive

Part of the normal flora in sebaceous glands

Question 22

Describe the structure of Graham negative cell walls

Answer 22

-thin layer of peptidoglycan 10-20%
-larger periplasmic space (between plasma membrane and outer membrane, 20-40% of cell volume)
(many enzymes present like hydrolytic enzymes and transport proteins)
-much higher lipid content, much lower peptidoglycan content. Crystal violet can escape from the cell wall. Saffron stays (pink)

Question 23

Where is the outer membrane found?

How is it attached to peptidoglycan?

Answer 23

Bilayer membrane found only in gram negative. External to cell wall. (Lipid proteins)

Attached by Braun’s lipoproteins

Question 24

LPS is an endotoxin that makes what type of bacteria much more pathogenic?

Answer 24

Gram negative

Question 25

What are porins? And what type of bacteria has them?

Answer 25

Span the outer membrane. Allow small molecules to penetrate the outer membrane, structure, defense against some antibiotics Gram negative

Question 26

What is the clinical significance of LPS (Lipopolysaccharide)?

Answer 26

- stability of outer membrane - negative charge - attachment - permeability (porins) - protection - endotoxin (lipid A)

Question 27

Bacterium that has a thick capsule, endotoxin LPS, and exotoxins Secreted by upper respiratory tract secretions Localized in trachea, bronchi -toxin a inflammation (sticky exudate) -three states (catarrhal, spasmodic, convalescent) -DTaP vaccine -Can cause secondary infections like pneumonia

Answer 27

Bordetella Pertussis or “whooping cough”

Question 28

The three stages of pertussis disease

Answer 28

* catarrhal- kind of like the common cold * spasmodic (paroxysmal)- severe cough, choking and gagging, fractured ribs * convalescent- Cough subsides, but Lasting cough for months

Question 29

Who developed the Gram stain?

Answer 29

Hans Christan Gram

Question 30

Members of genus ___________ have very complex cell envelopes. Why are they difficult to stain?

Answer 30

Mycobacterium. Difficult to stay in because of waxy coating but if they do stain, it will stain as gram-positive (membrane lipids- mycolic acid) * waxy coating helps to prevent phagocytosis and engulfing, excludes many antibiotics, can escape host defenses* -slow growing Ex. Mycobacterium sap., Norcrdia, Legionella

Question 31

Do mycobacterium have a cell wall?

Answer 31

No

Question 32

How acid fast positive and negative cells stain? Acid fast staining is used in what type of bacteria?

Answer 32

Acid fast positive- Hot pink Acid fast negative- Blue or green Used on mycobacteria

Question 33

Mycobacterium tuberculosis

Answer 33

``` Transmitted through droplets Disease attacks lungs -latent and active TB Can cause severe cough maybe blood, chest pain can affect other parts of the body * granulomas à cessation ```

Question 34

How is tuberculosis tested for?

Answer 34

Skin test: PPD injection | >15mm it is positive

Question 35

Regular structured layers of proteins or glycoprotein that self assembles external to the cell, associated directly with peptidoglycan surface in gram positive, in gram negative it adheres to other membrane -crystalline layer

Answer 35

S layer * National protective layer commonly found in free living bacteria and in archaea

Question 36

What are the functions of the S layer?

Answer 36

- protection (osmotic stress) pH stress - maintain shape - adhesion - protects from host defenses

Question 37

Do you all bacteria cells have a saw wall?

Answer 37

No Mollicutes are bacteria without a true cell wall. Have sterile like lipids in the membrane to help stabilize * mycoplasma and chlamydia lack cell walls

Question 38

Smallest known free living bacteria With penicillin work against bacteria?

Answer 38

Mycoplasma M. Pneunomiae causes walking pneumonia, atypical pneumonia No, it does not have a cell wall

Question 39

Caused by bacteria without a cell wall Transmitted by direct sexual contact Most common STD in U.S. Most are asymptomatic Can cause pelvic inflammatory disease Can cause ocular disease trachoma during childbirth

Answer 39

Chlamydia/ chlamydia trachomatis

Question 40

How does the archaeal cell wall differ from bacterial cell wall?

Answer 40

- S layer is external to plasma membrane | - pseudomurein

Question 41

What are two layers external to the cell wall in bacteria?

Answer 41

* capsules-polysaccharides, well organized firmly attached structure, not easily removed from the cell. Can evade phagocytosis, why not be recognized by the house, prevents dying * slime layers-smaller, thinner, less organize and easy to remove. May help motility. Helps prevent dehydration.* aids an attachment (biofilms)

Question 42

Describe the bacterial Cytoskeleton

Answer 42

- (FtsZ (Tubulin) - MreB /MBl (actin) shape - CreS (intermediate filaments) forms polymer along crescent shaped bacteria, curved

Question 43

Polyhedral bodies that are packed with the enzyme RuBisCO, which is needed for CO2 fixation

Answer 43

Carboxysomes

Question 44

Proteins and gas field, increases buoyancy

Answer 44

Gas vesicles

Question 45

What are inclusion bodies used for?

Answer 45

Storage that can later be used by the cell Ex. Glycogen, carbon, etc. Can vary in size, number, and content

Question 46

Short, thin, hair like protein appendages, used for attachment motility and DNA uptake Made of pilin protein

Answer 46

Fimbriae

Question 47

Longer, thicker, hollow, less numerous extension of cells

Answer 47

Pili

Question 48

Membrane embedded extensions in the cytoplasm | Tips to create adhesion factors called holdfasts

Answer 48

Stalks

Question 49

Thread like, locomotive appendage that extends from the plasma membrane in cell wall Helical propellers made of flagellin proteins Different species have varying numbers and arrangement of these

Answer 49

Flagella

Question 50

Very number and arrangement of flagella... ``` Atrichous- Monotrichous- Amphitrichous- Lophotrichous- Petririchous- ```

Answer 50

Atrichous-none Monotrichous- one Amphitrichous- One or more from each pole Lophotrichous- more than one extending from the same pole Petririchous- flagella covered on all edges

Question 51

Flagella and cilia are constructed of __________

Answer 51

Microtubules Flagella-100-200 microns in length, move in Undulating fashion Cilia-5-20 microns in length, more numerous, both have a core of microtubules that is sheath by plasma membrane

Question 52

Membraneous sac that contains hydrolytic enzymes. Most eukaryotic cells have these. To digest macromolecules lysosome enzymes are made by the rough ER. Then transferred to Golgi for processing, combined with food vacuoles to help digest “autophagy”

Answer 52

Lysosome

Question 53

Metabolic compartment bound by single membrane, enzymes for oxidation of fatty acids may produce hydrogen peroxide. Abundant in liver cells helps with degradation of fat

Answer 53

Peroxisome

Question 54

What supports the Endo symbiotic hypothesis

Answer 54

Mitochondria and chloroplasts similarities with bacteria - same size - double membrane - free ribosomes - Circular DNA - can make their own proteins - lack histone proteins - can grow and reproduce independently via binary fission

Question 55

Energy conservation organelle in some anaerobic protist Has double membrane but does not have sister name, generally lacks DNA, ATP is generated by a fermentation process, not cellular respiration, products include CO2 hydrogen and acetate Descended from common mitochondrial ancestor

Answer 55

Hydrogenosome