Exam 2 Cell Biology FIU Prof Barbieri

What do eukaryotic cells have that bacterial cells lack?
a. plasma membrane
b. internal membrane

b. internal membrane

BOTH HAVE PLASMA MEMBRANES

Membrane Structures include nucleus, endoplasmic reticulum, transport vesicles, mitochondrion, plasma membranes, golgi apparatus, _________, _________, and ___________.
a. lysosomes, endosomes, peroxisomes
b. ribosomes, centrosomes, centrioles

a. lysosomes, endosomes, peroxisomes

Which one is False?
a. Membranes are selective and effectively permeable (plasma and endo-membrane)
b. The specific function of a membrane can involve DNA localization
c. There are active and passive transports for proteins
d. Cell-cell communication happens via gap junctions
e. Signal transduction receptors involve first generation of messengers

e. Signal transduction receptors involve first generation of messengers

*** SECOND GENERATION

Which one is incorrect?
a. Compartmentalization involves membranes forming continuous sheets that enclose intercellular compartments.
b. Scaffold for biochemical activities involve membranes providing a framework that organizes enzymes for effective interaction.

a. Compartmentalization involves membranes forming continuous sheets that enclose intercellular compartments.

**INTRAcellular compartments

Match:
1. Transporting Solutes
2. Responding to External Signals
3. Intracellular interaction
4. Energy transduction
a. Membrane proteins facilitate the movement of substances between compartments
b. membranes transduce photosynthetic energy, converting chemical energy to ATP, and store energy
c. membranes mediate recognition and interaction between adjacent cells
d. membrane receptors transduce signals from outside the cell in response to specific ligands

1. Transporting Solutes:
a. Membrane proteins facilitate the movement of substances between compartments

2. Responding to External Signals:
d. membrane receptors transduce signals from outside the cell in response to specific ligands

3. Intracellular interaction
c. membranes mediate recognition and interaction between adjacent cells

4. Energy transduction:
b. membranes transduce photosynthetic energy, converting chemical energy to ATP, and store energy

Intercellular space can be found _______________________ while intracellular space can be found ___________________.
a. between cells, within cells
b. within cells, between cells

a. between cells, within cells

Membrane Lipids Form Bilayers in __________. The lipid and protein components are bound together by __________. Membranes also contain ____________.
a. alcohol, covalent bonds, ribosomes
b. water, non-covalent bonds, carbohydrates

b. water, non-covalent bonds, carbohydrates

True or False:
1. The Lipid Bilayer is a flexible 2-dimensional fluid.
2. The fluidity of a Lipid Bilayer Depends on Its Composition.
3. Membrane Assembly Begins in the Endoplasmic Reticulum.
4. Certain Phospholipids Are Confined to One Side of the Membrane

All true!

True or False:
In a planar phospholipid bilayer, hydrophobic tails (white tails) are exposed to water along the edges. This shape is conventionally energetically unfavorable.

True

True or False: Formation of a sealed compartment shields hydrophobic tails from water. This involves a sphere shape and is energetically favorable.

True

Does the fluidity of a lipid bilayer depend on its composition?

Yes

The Definition of Diffusion is?

The net movement of molecules and ions from a region of higher concentration to a region of lower concentration.

The free-energy change during the diffusion of non-electrolytes depends on the concentration gradient while The free-energy change during the diffusion of electrolytes depends on the _____________ gradient.
a. electric
b. electrochemical
c. chemical

electrochemical

Why does diffusion differ from osmosis? Describe osmosis

Osmosis is the process by which water or other solvents move through a semipermeable membrane from a region of higher concentration to a region of lower concentration.

Water moves across cell membranes _____ its concentration gradient during osmosis
a. up
b. down

b. down

The cellular process of Active Transport involves: a cellular process that moves substances across a cell membrane from an area of low concentration to an area of high concentration.
This process requires?
Active transport is the opposite of?

Requires ATP

Opposite of passive transport

What does ATP stand for?

adenosine triphosphate

Membrane assembly beings in the
a. smooth endoplasmic reticulum
b. golgi apparatus
c. lysosomes region

a. smooth endoplasmic reticulum

The carbon chain of a lipid bilayer is around ____________ atoms optimal for the thickness of the membrane which is 6-8 nm.
a. 20-32
b. 2000-2200
c. 12-20
d. 1200-3200

c. 12-20

A membrane protein is?

A protein that is attached with a membrane of a cell or organelle.

Does a membrane protein connect cells to each other or to the cell matrix?

BOTH!

MTOC stands for?
a. macrotuberclar center
b. microtubule-organizing centers

b. microtubule-organizing centers

True or False: Microtubules are essential for sperm development and function, however they are not a key part of the sperm tail (flagellum).

False
Microtubules are essential for sperm development and function and they ARE a key part of the sperm tail (flagellum).

Na+/glucose cotransporters are a family of ________ that are responsible for transporting glucose and sodium across cell membranes.
a. lipids
b. carbohydrates
c. proteins

c. proteins

N-linked oligosaccharides processed in the ___________.
a. smooth endoplasmic reticulum
b. golgi

b. golgi

Determination of Membrane Transition Temperature (TM) by Differential Scanning Calorimetry (DSC):
It is a technique used to study what happens to substances when they're heated
It is a thermal transitions (phase transitions) of substances.
It is the lipid bilayer's ________ stage
a. crystallized solid
b. semi-solid (liquid)

b. semi-solid (liquid)

During the semi-solid liquid stage, the graph will look like a
b. a slim bell shape
b. a slim u shape

b. a slim bell shape

A Polypeptide Chain Usually Crosses the Lipid Bilayer as a(n) __________-helix.
a. alpha
b. beta
Membrane Proteins Can Be Solubilized in _________.
c. water
d. detergents
The Underlying Cell ______ reinforces the Plasma Membrane.
e. convex
f. cortex
The Cell Surface Is Coated with __________.
g. carbohydrates
h. proteins

a. alpha

d. detergents

f. cortex

g. carbohydrates

The two carbohydrates that coat the surface layer of cells are?

N-glycosylation and O-glycosylation

Can a cell restrict the movement of its membrane proteins?

Yes

Another word for the basal layer (aka the basement layer where cells attach to) is?

Lamina

True or False: Tight cell junctions are located near the basal/lamina layer?

FALSE!
they are located near the apical surface of the cell (aka the surface which is furthest from the basal/basement layer)

Lipid Bilayers Are Impermeable to ______ and Most Uncharged Polar Molecules.
a. ions
b. proteins
Membrane Transport Proteins Facilitate the Movement of Select Substances _____ Cell Membranes.
a. within
b. across
The Ion Concentrations Inside a Cell Are _________ from Those Outside.
a. identical
b. very different
Differences in the Concentration of Inorganic Ions Across a Cell Membrane Create a ____________.
a. membrane potential
b. action potentials
Solutes Cross Membranes by __________.
a. passive and active transport
b. only pass transport
c. only active transport
Both the Concentration Gradient and Membrane Potential Influence the ______ Transport of Charged Solutes.
a. active
b. passive

a. ions


b. across


b. very different

a. membrane potentials

a. passive and active transport

b. passive

Which one is False?
1. Phospholipid diffusion is restricted within the bilayer
2. phospholipids are confined briefly to certain areas and then hop from one confined area to another.
3. Fences restricting motion are constructed of rows of integral membrane carbohydrates bound to the membrane skeleton by their cytoplasmic domains.

3. Fences restricting motion are constructed of rows of integral membrane carbohydrates bound to the membrane skeleton by their cytoplasmic domains.

*** PROTEINS NOT CARBS

Which one is False?
1. Protein movements are faster than predicted by protein size and membrane viscosity.
2. Interactions with the cytoskeleton, other proteins, and extracellular materials limit protein movements.
3. Techniques that drag tagged proteins within the membrane indicate that some proteins have barriers to lateral diffusion.
4. Genetically modified proteins missing either intracellular or extracellular domains are less restricted.

1. Protein movements are faster than predicted by protein size and membrane viscosity.

**SLOWER NOT FASTER

Net flux is the difference between?

Influx and Efflux

True or False
Flux can occur only by active transport

False
active transport of passive diffusion

What does a plant cell have that an animal cell and a protozoan does not?

Cell wall

What mediates several processes such as signaling, pH balance, volume regulation, and the cell cycle, and in higher organisms, they underlie fertilization, immune responses, secretion, muscle contraction, and all electrical signals in nerves, muscles, and synapses?

Transporters

True or False
Ion channels and ion pumps have completely different behaviors

True

Antiport transporters involve Anion __________ and bicarbonate exchanger.
a. Chloride
b. Calcium
c. Sodium
Symport transports involve _______ and glucose exchangers.
d. Sodium
e. Calcium
f. Chloride

a. Chloride


d. Sodium

Are ion channels always open?
What does a conformational change result in?

No.
Ion channels are ion-selective and gated.

A conformational change results in the conducting state.

Equilibrium membrane potential is the membrane potential in _________________ equilibrium.

Electrochemical

Nernst equation and Goldman equation only differ in:
a. goldman is only permeable to several ions
b. goldman is only permeable to 1 ion

a. goldman is only permeable to several ions

Membrane (and Action) Potentials Allow Rapid Long-Distance Communication Along ________

axons

Which is false?
Membrane potential = protein movement
Membrane trafficking = proteins and lipids movement
Signaling Transduction = proteins and lipids signaling

Membrane potential = protein movement

**** ion movement

Speed Is of the Essence: Speed of neural impulse depends on axon diameter and whether axon is ___________.
Resistance to current flow decreases as diameter increases.
Myelin sheaths cause saltatory conduction.

myelinated

Most __________ Alter the Activity of Neurotransmitter Receptors.
The Complexity of Synaptic Signaling Enables Us to Think, Act ,Learn, and Remember.

psychoactive drugs

Mechano-receptors for touch
Thermo-receptors for temperature change
Noci-receptors for pain
Electromagnetic-receptors for light
Chemo-receptors for taste and smell

Which one involves blood chemistry?

Chemo-receptors

Are intermediate filaments weak or strong?
(hint: they're rope-like)

strong

The _________ envelope is supported by a meshwork of intermediate filaments.

nuclear

Microtubules which are hollow, grow from MTOC and display dynamic instability. They also organize?

the cell's interior

Cilia and flagella contain stable microtubules moved by?

Dynein

Microtubules Are Hollow Tubes with Structurally Distinct Ends. They contain:
a. singlet, doublet, and triplet.
b. proximal, middle, and distal

a. singlet, doublet, and triplet.

Microtubule-associated Motor Proteins Drive __________ Transport
a. passive
b. active
c. intercellular
d. intracellular

d. intracellular

Microtubules and Motor Proteins Position Organelles in the
a. cell membrane
b. golgi apparatus
c. cytoplasm

c. cytoplasm

Actin filaments are _______ and flexible. The alpha is ________ while the beta and gamma are __________.
a. thick, muscle, muscle
b. thick, non muscle, muscle
c. thin, non muscle, muscle
d. thin, muscle, non muscle

d. thin, muscle, non muscle

Actin-binding motor proteins are called ___________ and can be divided into 2: conventional type 2 and unconventional.

myosins

True or False: cell crawling depends on cortex rich actin filaments

False
depends on cortical actin

What microfibrils give the plant cell wall its tensile strength?

cellulose

What couples the matrix outside a cell to the cytoskeleton inside it?
a. cellulose
b. collagen
c. integrins
d. polysaccharides

c. integrins

The plant cell wall composition is made up of all except:
a. lignins
b. extensins
c. pectins
d. hemicellulose
e. cellulose
f. centrioles

f. centrioles

What does the term plasmodesmata refer to in a plant cell wall?

Channels

Animal connective tissue consists largely of?

Extracellular matrix

What provides tensile strength in animal connective tissue?

collagen

Laminin separates epithelial cells from ________________. It is found in the ______________. (hint: collagen and proteoglycans)
a. connective tissue, apical surface
b. epithelial tissue, basal lamina
c. connective tissue, basal lamina
d. epithelial tissue, apical surface

c. connective tissue, basal lamina

True or False:
Connective tissue cells can enter the epithelial layer

FALSE
CANNOT ENTER

Which statement is false:
a. Actin remodeling involves regulating cell movement and cell attachment taking into account integrins.
b. They can activate intracellular signaling pathways via Mitogenic Activating Protein Kinase.
c. Cells must be attached to a substrate to grow
d. Apoptosis occurs only in cancer cells

d. Apoptosis occurs only in cancer cells

Apoptosis means cells death.

Fix the sentence: Focal adhesions use common discrete sites via integrin-actin structure of cell attachment.
a. The sites are not discrete, they are open.
b. The sites are not common, they are unique.
c. Its for cell growth, not attachment

b. The sites are not common, they are unique.

What type of cell junctions are present in the basal site (basement membrane)?
a. tight
b. gap
c. desmosomes
d. hemidesmosomes
e. adhering

d. hemidesmosomes

Epithelial sheets are ________ and rest on a basal lamina.
a. non-polarized
b. polarized

b. polarized

Match the cell junction to the description:
1. Tight Junctions
2. Gap Junctions
a. Allow Cytosolic Inorganic Ions and Small Molecules to Pass from Cell to Cell
b. Make an Epithelium Leakproof and Separate Its Apical and Basolateral Surfaces

1. Tight- a. Allow Cytosolic Inorganic Ions and Small Molecules to Pass from Cell to Cell
2. Gap - Make an Epithelium Leakproof and Separate Its Apical and Basolateral Surfaces

Match the cell junction to the description:
1. Adhesive Junctions
2. Cytoskeleton-linked Junctions
a. keep the Epithelium together and make a belt on the Apical Surfaces
b. Bind Epithelial Cells Robustly to One Another and to the Basal Lamina

1. Adhesive - a. keep the Epithelium together and make a belt on the Apical Surfaces
2. Cytoskeleton-linked - b. Bind Epithelial Cells Robustly to One Another and to the Basal Lamina

Which junction Makes the Epithelium Leakproof and Separate Its Apical and Basolateral Surfaces?
a. gap
b. tight

b. tight

Stem cells are ______________ cells capable of self-renewal and differentiation
a. differentiated
b. undifferentiated

b. undifferentiated

True or False: A Fertilized Egg Gives Rise to Every Cell Type and Tissue in the Body from Stem Cells

True

Which has greater potential for differentiation (pluripotent)?
a. adult stem cells
b. embryonic stem cells

b. embryonic stem cells

Tissues are organized mixtures of many cell types based on 3:

1. cell communication
2. selective cell adhesion
3. cell memory for specialized gene expression

True or False
Different tissues are renewed at the same rate

False
Different rates

What can be used to replace damaged or diseased adult tissue?

Adult somatic stem cells

What is a characteristic feature of peripheral membrane proteins?

A. they penetrate the lipid bilayer completely

B. They are loosely attached to the surface of the membrane

C. They are only found in prokaryotic cells.

D. they cannot interact with lipids at all

B. They are loosely attached to the surface of the membrane

What happened to a cell’s membrane when exposed to low temperatures?

A. The membrane becomes more fluid.

B. The membrane solidifies and becomes less permeable.

C. The membrane remains unchanged.

D. The membrane disintegrates completely.

B. The membrane solidifies and becomes less permeable.

Which carbohydrate component is commonly found on the extracellular surface of cell membranes?

A. Nucleic acids

B. Glycoproteins and glycolipids

C. Phospholipids

D. Steroids

B. Glycoproteins and glycolipids

What type of transport involves the movement of molecules across a membrane against their concentration gradient?

A. Passive transport

B. Facilitated diffusion

C. Active transport

D. Osmosis

C. Active transport

How does saturation level of fatty acids affect membrane properties?

A. Saturated fatty acids increase membrane fluidity

B. Unsaturated fatty acids decrease membrane permeability

C. Saturated fatty acids decrease fluidity, while unsaturated fatty acids increase it.

D. Both saturated and unsaturated fatty acids have no effect on fluidity

C. Saturated fatty acids decrease fluidity, while unsaturated fatty acids increase it

What is the primary function of glycoproteins in the cell membrane?

A. energy storage

B. cell communication and recognition

C. structural integrity

D. transport of molecules

B. cell communication and recognition

Which type of endoplasmic reticulum is involved in protein synthesis and has ribosomes attached to its surface?
A. smooth endoplasmic reticulum

B. rough endoplasmic reticulum

C. golgi apparatus

D. mitochondira

B. rough endoplasmic reticulum

Which lipid component is primarily responsible for forming the bilayer structure of membranes

A. Phospholipids

B. sterols

C. fatty acids

D. glycolipids

A. Phospholipids

What is the main role of cholesterol in the plasma membrane?
A. to provide energy for cellular processes

B. to stabilize membrane fluidity across varying temepratures

C. to act as a receptor for signaling molecules

D. to facilitate active trasnport

B. to stabilize membrane fluidity across varying temperatures

Which of the following best describes the fluid mosaic model of the cell membrane?

A. a rigid structure with fixed components

B. a dynamic arrangement of various proteins floating in or on a fluid lipid bilayer

C. a static layer of phospholipids with no movement

D. a solid layer made entirely of carbohydrates

B. a dynamic arrangement of various proteins floating in or on a fluid lipid bilayer