Download Honors Biology - UNIT 6

Honors Biology - UNIT 6
Cells & Organelles
Trembly
Cell Membrane:
The cell membrane is in the form of a double layer (lipid bilayer) composed of mainly
lipids (fatty acids) and proteins. There are also some carbohydrates attached to the
outside.
The lipids are mostly phospholipids (fatty acids with phosphate groups), they can be
phospho-monoglycerides, phospho-diglycerides or phospho-triglycerides.
Function:
The membrane is Semi-permeable (allows only specific items into and out of the cell).
Transmembrane Proteins
Integral:
Peripheral:
E face:
P face or C face:
Nucleus:
Organelle that holds the genetic information, has the following items.
Chromosomes:
Chromatin:
Nuclear envelope:
Nucleolus:
Ribosomes (aka. Ribosomal RNA):
Nucleoplasm:
Nuclear Pores:
Nuclear Lamina:
Endoplasmic Reticulum
The general structure of the endoplasmic reticulum is an extensive membrane network of
cisternae (sac-like structures) held together by the cytoskeleton. The phospholipid
membrane encloses a space, the cisternal space (or lumen), from the cytosol.
There are 3 types of endoplasmic reticulum each has a different function. These 3
varieties are listed below.
1) Rough Endoplasmic Reticulum (RER):
2) Smooth Endoplasmic Reticulum (SER):
3) Sarcoplasmic Reticulum: (muscle cells/calcium storage)
1 Nucleus 2 Nuclear pore 3 Rough endoplasmic reticulum (rER) 4 Smooth endoplasmic reticulum (sER) 5 Ribosome on the
rough ER 6 Proteins that are transported 7 Transport vesicle 8 Golgi apparatus 9 Cis face of the Golgi apparatus 10 Trans
face of the Golgi apparatus 11 Cisternae of the Golgi apparatus
Golgi Apparatus or Golgi Bodies
Golgi is structurally composed of membrane-bound sacs known as _______________.
Between five and eight are usually present, however as many as sixty have been
observed.
Golgi Function:
Vesicles
Trans face:
Cis face:
All proteins are sorted and shipped to their intended destinations by their placement into
one of at least three different types of vesicles, depending upon the molecular marker
they carry:
Type
Description
Example
Vesicle contains proteins
destined for extracellular
release. After packaging the
vesicles bud off and
immediately move towards Antibody release
Exocytotic vesicles (continuous) the plasma membrane,
by activated
where they fuse and release plasma B cells
the contents into the
extracellular space in a
process known as
constitutive secretion.
Secretory vesicles (regulated)
Vesicle contains proteins
destined for extracellular
release. After packaging the
vesicles bud off and are
stored in the cell until a
signal is given for their
Neurotransmitter
release. When the
release from
appropriate signal is
neurons
received they move towards
the membrane and fuse to
release their contents. This
process is known as
regulated secretion.
Lysosomal vesicles
Vesicle contains proteins
destined for the lysosome,
an organelle of degradation
containing many acid
hydrolases, or to lysosomelike storage organelles.
Digestive
These proteins include both proteases destined
digestive enzymes and
for the lysosome
membrane proteins. The
vesicle first fuses with the
late endosome, and the
contents are then transferred
to the lysosome via.
Endomembrane System:
The Cytoskeleton:
Functions
Eukaryotic cells contain these three main kinds of cytoskeletal filaments.The
cytoskeleton provides the cell's cytoplasm with structure and shape.
Actin filaments / Microfilaments
Intermediate filaments
Different intermediate filaments are:
- made of vimentins, being the common structural support of many cells.
- made of keratin, found in skin cells, hair and nails.
- neurofilaments of neural cells.
- made of lamin, giving structural support to the nuclear envelope.
Microtubules
Protofilaments
alpha (α) Tubulin
beta (β) Tubulin
They play key roles in:
- intracellular transport (associated with dyneins and kinesins they transport organelles
like mitochondria or vesicles).
- the axoneme of cilia and flagella.
- the mitotic spindle.
- synthesis of the cell wall in plants.
Microtrabeculae; made of short, filamentous structures of unknown molecular
composition in electron micrographs of whole cells. Due to their filamentous appearance
and association with known cytoplasmic structures,
Flagella & Cilia:
Flagellum (plural: Flagella)
(9+2 arrangement). The nine peripheral doublets are linked to each other by proteins
such as dynein, a molecular motor which can cause flagella to bend.
An eukaryotic cell usually has only one or two flagella. As in prokaryotes, the eukaryotic
flagellum may be used in locomotion; one well known example of this is the sperm cell,
in which the "tail" of the sperm (a flagellum) is used to propel the cell forward.
However, all non-dividing eukaryotic cells contain a flagellum (or cilium), not only
sperm cells. Stationary cells (such as kidney, intestine, and nerve cells) also contain
flagella (cilia) which project from the cell body out into the extracellular environment,
these flagella can serve in sensation or in the movement of the extracellular fluid
surrounding the cell.
Cilia:
Cilium (plural Cilia)
There are two types of cilia: motile cilia, which constantly beat in a single direction, and
non-motile cilia, which typically serve as sensory organelles. Along with flagella, they
make up a group of organelles known as undulipodia.
Example of cilia: Our trachea in the respiratory system has cells lined with cilia to remove particles from
the respiratory system and into the digestive system.
.
In the diagram:
The top picture shows how microtubules form the structure of a flagella or cilia with 9
doublets of microtubules surrounding 2 singlets of microtubules. This is termed the 9+2
arrangement of the microtubules as seen with the flagella. Between each doublet are
proteins called dynein arms.
Microtubules can also form triplets as they do in the basal body seen in the bottom
picture. These basal bodies form the portion of the flagella or cilia found inside the main
body of the cell. While the doublets forms the flagella or cilia itself which extends
beyond the main body of the cell.
What is the function of:
Basal Bodies:
Flagella:
Difference between the flagella and cilia:
Molecular Motor Proteins
Dynein and Kinesin are proteins can that move along microtubules, they sort of walk on
the microtubule. Vesicles formed by the golgi or endoplasmic reticulum having a cargo
inside of vesicle often can move around the cell by the action of these motor proteins
using ATP as the energy (fuel) to move them. The motor proteins also play other role,
movement functions, for example in flagella and cilia as specified above.
Other ways motor proteins function to move: (all need ATP for energy to move):
Muscle movement: Walking of myosin & actin past each other to shorten muscle fibers.
Cytoplasmic streaming/amoeboid movement: The interaction of myosin with actin
filaments squeezes the cytoplasm into other sections of the cell. Amoeba use this process
to make pseudopodia “false feet” where the cytoplasm pushes out a pocket of the cell to
form an appendage, the cell then uses this to pull itself forward.
Cytoplasmic streaming of organelles in plant cells: Some cytosol move around the cell
by motor proteins attaching the organelles to actin filaments.
Centrosomes:
These organelles play a role in cell division and in making cilia and flagella. They are
always found in cells which have flagella and cilia, they are also found in all other animal
cells. The centrosomes are very small organelles, they are composed of a pair of
centrioles. Surrounding the centrioles is the pericentriolar material which radiate long
strands of microtubules during cell division this is called the microtubule-organizing
center, microtubules form into large clusters around this material, the mirotubules are
called asters. Plant cells also have a microtubule-organizing center but no centrioles.
Lysosomes
Small organelles composed hydrolytic enzymes surrounded by a single membrane. The
lysosome also has acid inside since the hydrolytic enzymes work best in an acidic
environment.
Function:
Vacoules
These are organelles made of a single lipid bilayer membrane with different types of
materials inside of it. There are different types of vacuoles depending on the materials,
molecules they hold inside:
Functions of:
- food vacuoles:
- water vacuole (central vacuole
What is Cell Sap?
Tonoplast
The membrane surrounding the central vacuole holds the cell sap. It is the same as any
other membrane surrounding a vacuole, however it is the largest of the vacuole
membranes so it is given a special name.
Mitochondria:
The mitochondria (singular: mitochondrion) found in both animal and plant cells.
This organelle is composed of a double lipid bilayer (2 double membranes) like the
nuclear envelope. The outer membrane is smooth, but the inner membrane is convoluted
with many infoldings called cristae. Inside the cristae is the matrix or mitochondrial
matrix. The matrix is a gel-like material full of enzymes which carry out ATP
production. The space between the inner and outer membrane is called the
intermembrane space.
Function:
Chloroplast
Found in plant cells, not in animal cells. Chloroplasts are another organelle surrounded
by a double bilayer. Inside the inner membrane are small, thin disc shaped parts called
thylakoid discs. The inner membrane 0f these discs are full of many proteins (enzymes)
which play a role in photosynthesis, converting light into food energy. These discs are
stacked on top of each other to compose a granum, there are many of these stacks, the
plural is called grana. These grana are all interconnected by extensions of the discs
called lamellae. Surrounding the grana and lamellae is a gel inside the inner membrane
called the stroma. The stroma contains enzymes needed for important reactions of
photosynthesis, also termed the Calvin cycle.
Function:
* Both the mitochondria and the chloroplasts contain DNA, these are the only organelles
which contain DNA other than the nucleus. The reasons for this are the source of debate
and differing theories. The most accepted theory is that these organelles were from other
cells engulfed by a larger cells but not broken down, instead they were used for energy
production, but the maintained their DNA. This occurred early in the history of cells and
became part of the origin of eukaryotic cells.
The chloroplast is only 1 of 3 types of plastids. The plastid organelles all contain a
specialized molecules. Chloroplasts contain chlorophyll,
Chromoplasts:
Amyloplasts:
Peroxisomes:
Glyoxysomes are found in fat-storing portions of plants, like seeds. These convert the fat
to sugar, to form energy for the seed to develop into a plant.
Cell Wall (in plants)
The cell wall is found in plant cells but not in animal cells. Other types of cells which
have a cell wall include: bacteria, algae and fungi, however, except for algae these cells
have different types of cell walls made of different material.
Plant and algae cell walls are composed mostly of the polysaccharide cellulose. Many
plants have two cell walls for added strength such as woody plants. The first cell wall is
thin and flexible called the primary cell wall it is mostly cellulose mixed with a
substance called lignin for added support and another substance called pectin which is a
glue-like substance that is also found in the middle lamella. The middle lamella is found
between primary cell walls of different plant cells, the pectin helps the cell walls stick
together.
The secondary cell wall is made in cells which will stop growing and become the
structural component of the plant as in the wood of tree trunks. The secondary cell wall is
made of many layers of cellulose for additional strength. It is formed between the cell
membrane and the primary cell wall.
Cell Junction Organelles: Give functions of each
Plasmadesmata:
Tight Junctions:
Gap Juctions:
List below which organelles have a single membrane, double membrane or
no membrane?
SINGLE MEMBRANE DOUBLE MEMBRANE
NO MEMBRANE
Explain the contribution to cell biology from of each of the scientists below:
Robert Hooke
Anton Von Leuwenhoek
Rudolph Virchow
Theodore Schwann
Matthias Schleiden
Robert Brown
Draw a bacterial cell, include all the organelles from class:
Give the cell wall components of:
Plants:
Fungi:
Bacteria:
Explain the relationship to cell volume and surface area and how does this affect cell
size?