Plasma phospholipids and cholesterol. How does structure affect function?

Plasma membrane: Figs 11-1,
11-4, 11-5, 11-7, 11-11, 11-12; pp. 359-366

Are
all cell membranes composed of a lipid bilayer? Yes,
all cell membrane are composed of a lipid bilayer.
Define
hydrophilic/hydrophobic. 

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-Hydrophilic- dissolves in water because it is “water-loving” and
polar

-Hydrophobic- does not dissolve in water because it is “water-fearing”
and nonpolar

Define
polar/non-polar.

-Polar- unequal electron distribution between 2 atoms

-Nonpolar-equal electron
distribution between 2 atoms

Compare
the structure of phospholipids and cholesterol. How does structure affect
function?

Phospholipids
and cholesterol have a hydrophobic, nonpolar tail (made of fatty acids) and a hydrophilic,
polar head (made of glycerol). The difference between them is that
phospholipids have a phosphate group substituted for one of the fatty acids.  Phospholipids and cholesterol maintain the
cell membrane’s fluidity. In addition, Phospholipids allow for
semi-permeability of the membrane due to its amphipathic nature.

Why do
phospholipids spontaneously form bilayers?

Bilayers
are formed to prevent the hydrophilic, nonpolar tails of the phospholipids from
water interaction and because it is energetically favorable as well.

Nucleus:

Nucleolus:  Fig. 5-18; pg.184

§  Function?
Contains ribosomal RNA to make ribosomes

§  What
is its size and shape determined by? Amount of
ribosomal RNA

Nuclear Envelope: Fig. 15-7, pp.
488,495

§  What
provides structural support? Nuclear lamina

§  Function
of nuclear pore complexes?

It
allows molecules to come in and out of the nucleus.

Ribosomes: Figs. 7-31,
7-32, 7-33; pp.244-245

Are
ribosomes organelles? No, because it does not
have a membrane.

Endoplasmic Reticulum:
Figs 1-21, 15-12; pp.489,498-499

Three
major functions of ER?

1. Forms
proteins (made by the ribosomes) and transports them to the Golgi

2.
Forms lipids

3. Forms
steroid hormones and extracellular signals

Structural/functional
difference between smooth and rough ER?

Smooth
ER has not ribosomes, so its function is steroid hormone synthesis, lipid
synthesis, and forming extracellular signals. Rough ER has ribosomes, so it is
the site of protein synthesis.

Where
are smooth and rough ER found?

Both
are found throughout the cell, but the Rough ER is more concentrated near the
nucleus.

Is the
ER connected to the nuclear envelope? 
To the Golgi?

The ER
is connected to the nuclear envelope, not the Golgi.

Golgi: Figs. 1-22,15-26;
pp.19, 510-511

How
does the term compartmentalization apply to the Golgi?

The
Golgi has cisternae, which are multiple layers within it to separate the
various enzymes and process that occur in each layer.

What
is sorted by the Golgi? Proteins

Lysosomes: Figs. 15-35, 15-36;
pp.19, 489, 515, 518-520

What
is the significance of lysosomes having an internal pH ~5?

Having
a pH of 5 is what activates the lysosomal enzymes for digestion.

Define
“endosome”.  How does an endosome
differ in structure and function from a lysosome? …from a phagosome?

-Endosome- organelle that transports molecules from the plasma
membrane to the lysosome

-Endosomes
only transports material (which eventually forms into a lysosome), while lysosomes
and phagosomes ingest the material.

Describe
the three pathways to degradation in lysosomes.

-Phagocytosis:
process where a cell engulfs a specific substance through physical contact
using phagosomes and fused with lysosomes

-Endocytosis:
process where a cell engulfs a substance (not through physical contact) using
vesicles and the contents are delivered to the lysosomes via endosomes

-Autophagy:
Parts of an organelle are packaged into autophagosomes and sent to lysosomes for
ingestion

Mitochondria and Chloroplasts: 
Figs 1-16, 1-17, 1-18, 1-19, 14-1, 14-2, 14-4, 14-5, 14-6, 14-7, 14-8;
pp. 448-453.

Define
chemiosmotic coupling.

Chemiosmotic coupling- process where the energy that is formed as electrons
pass through the ETC is used to create a proton gradient, forming ATP as
protons pass through this gradient

Why is
plasticity of mitochondria needed?

It is
needed to accommodate to each of the cell’s metabolic requirements to create
the proper amount of energy needed.

Compare/contrast
the structure/function of mitochondria and chloroplasts.

-Similarities:
-both take part in metabolic processes

                      -both have double
membrane

                      -both have circular DNA

-Differences:
-mitochondria takes part in oxidative phosphorylation, while chloroplasts

                      take part in
photosynthesis

                      -mitochondria found in plant &
animal cells, while chloroplasts only found

                       in plant cells

                      -chloroplasts have
photosynthetic pigments, while mitochondria does not

                      -chloroplasts have an extra
compartment (thylakoid)

                      -mitochondria are smaller,
chloroplasts are larger

Purpose
of a double membrane?

To increase
the surface area needed for metabolic processes to occur, so more energy can be
generated.

Why is
it postulated that mitochondria/chloroplasts contain DNA?  Does it code for the same proteins as
nuclear DNA?

It is postulated
that mitochondria/chloroplasts contain DNA due to the Endosymbiotic Theory,
which states that they were engulfed by Eukaryotic cells (which also contained
DNA). It does not code for the same proteins as nuclear DNA.

Why
are mitochondria mostly
maternally inherited in higher animals? What is the significance of this?

Mitochondria
is maternally inherited because it is passed through the egg from the mother to
the offspring. This is significant because we can trace back the lineages of
various animals using this mitochondrial DNA.

How
are mitochondria made? 

Mitochondria
can be made through mitochondrial DNA, or through cell division (using
mitochondrion).

Peroxisomes: pp.19,
489-490, 498

Function?
Use hydrogen peroxide to break down fatty
acids.
How do
peroxisomes function differently from lysosomes?

Peroxisomes
break down substances, while lysosomes ingest waste products

Cytoskeleton: Fig 1-26,
17-1, 17-2, 17-5; pp.21, 565-566

Ø  Define
“cytoskeleton”.

-Cytoskeleton- composed of proteins which provide shape and structure to
a cell

Ø  For
microfilaments, microtubules, intermediate filaments-

-Microfilaments:

            -Major
proteins: actin

            -Size
(diameter): 3-6 nm

            -Stability:
are stable

            -Functions:
muscle contraction, cytokinesis, pseudopod formation

 

-Microtubules:

     -Major Proteins: tubulin

     -Size (diameter): 20-25 nm

     -Stability: are stable

     -Functions: compose mitotic spindles,
cilia, flagella; used for intracellular transport

-Intermediate filaments:

     -Major Proteins: many different proteins

     -Size (diameter): 10 nm

     -Stability: most stable of the three

     -Function: provide structure for the cell

 

Extracellular matrix (ECM) structures: Figs 20-2, 20-3, 20-5,
20-8, 20-19, 20-20, 20-21, 20-22, 20-31; pp.683, 686, 688, 694-695

§  Do
plant cells have an ECM? Yes, plant cells have an
ECM.

§  How
does a tissue differ from a cell? 

Tissues are made of similar cells that share a common
function.

§  Define
“connective tissue”.

Connective
tissue- connects other
tissues/organs with a matrix (composed of elastic tissue, cartilage, of fatty
tissue)

§  List
the 3 major components of connective tissue. 
What are two main proteins associated with connective tissue?

-3 major components:

1. fibers

2. ground substances

3. cells

            – 2 main proteins= reticular
proteins & collagen

§  What
comprises the extracellular matrix of bone? Cartilage? Tendon? Blood?

-Bone’s
ETC:  water, minerals, collagen fibers

-Cartilage’s
ETC: proteoglycan, elastin fibers, collagen fibers

-Tendon’s
ETC: collagen, proteoglycans, water

            -Blood’s ETC: contains plasma
(proteoglycans, water, minerals, fibers)

§  Describe
the structure of epithelial tissue.

The epithelial tissue contains cells that are packed
together as sheets that are closely connected. It also contains glands,
junctions, and the basal lamina.

§  What
is a basal lamina?  Function?

The basal lamina a layer beneath the epithelium which
contains the extracellular matrix secreted by the epithelial cells. Its
function is to separate the epithelial cells from other tissues and also acts
as a selectively permeable filter.

§  Describe
the functions of at least 3 different cell junctions.

Cytosol: Fig 1-25; pp.21-22

Is the cytosol liquid? No, it is considered more of a water-based gel than
a liquid.
Describe the internal
environment of the cell.  Is it
static?

The
cell’s internal environment is not static. It has various molecules and
proteins that are constantly in motion.

 

 

Ø 
List three ways plant cells differ from animal
cells. Panel 1-2, pg. 25

1)
Plant cells have a chloroplast, while animal cells do not.

2)
Plant cells have a cell wall, while animal cells do not

3)
Plant cells have vacuoles, while animal cells do not

Ø 
Describe the main difference between prokaryotic
and eukaryotic cells. pp. 12-22

Eukaryotic
cells contain membrane-bound organelles (which includes the nucleus), while
prokaryotic cells do not. 

x

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