Chapter 3 - Cellular Organization Flashcards
What is the approximate diameter of a typical cell?
0.1nm
Did Robert Hooke actually see cells?
No - just the outline of them
In what century were microscopes invented?
17th century (1665)
Name the 4 components of the cell theory
- Cells are the building blocks of all plants and animals
- All cells come from the division of preexisting cells
- Cells are the smallest units that perform all vital physiological functions
- Each cell maintains homeostasis at the cellular level. (Homeostasis at the tissue, organ, organ system, and organism reflects the combined action of many cells)
The human body contains _____ of cells
trillions
cytology is part of the broader discipline of …?
cell biology
cell biology integrates aspects of which 3 sciences?
chemistry
biology
physics
The human body contains how many general classes of cells and what are they
2 - somatic cells
sex cells (germ cells)
Name the 4 functions of the plasma membrane
- Physical isolation
- Regulation of exchange with the environment
- Sensitivity to the environment
- Structural support
What is the 1st part of the cell affected by changes in composition, pH, etc of the extracellular fluid?
cell membrane
The plasma membrane contains a variety of _______ that allow the cell to recognize and respond to specific molecules in its environment
receptors
Is the plasma membrane thin or thick? How many nm is it?
EXTREMELY THIN. ranges from 6-10nm in thickness
The cell membrane contains which 3 biomolecules?
carbohydrates, lipids, proteins
Which biomolecule makes up most of the SURFACE AREA of the plasma membrane?
lipids
What % weight is lipids in a cell membrane
42%
Why is isolation between the cytoplasm and extracellular fluid so important?
Because the compositions of the 2 are very different and the cell cannot survive if the differences are eliminated
Proteins account for about ____% of the weight of the plasma membrane
55%
Which are denser - proteins or lipids?
proteins
What are the 2 structural classes of membrane proteins?
Integral proteins and peripheral proteins
Can integral proteins be removed?
Not without damaging the cell membrane. It’s part of the membrane structure
Integral proteins are also known as …..? Why?
Transmembrane proteins because they span the width of the membrane one or more times
Can peripheral proteins be removed from the membrane?
Yes - they are bound to either the inner or outer surface of the membrane and are easily separated from it
Which are more abundant - peripheral or integral?
integral
Membrane proteins can have which 6 functions?
- Channel
- Carrier
- Anchoring
- Recognition
- Enzyme
- Receptor
What do anchoring proteins do? Where do they attach:
-Inside the cell
-Outside the cell
attach the plasma membrane to other structures and stabilize its position
inside the cell: cytoskeleton
outside the cell: another cell or extracellular protein fibers
Recognition proteins are also known as…?
Identifiers
Recognition proteins are crucial in the…?
immune system
Many important recognition proteins are…?
glycoproteins
Are enzymes in the plasma membrane peripheral or integral proteins?
could be either
Receptor proteins are sensitive to the presence of…?
ligands
What is a ligand?
extracellular molecule. Could be a small ion or a complex hormone
The binding of insulin to a receptor protein leads to….?
increase in the rate of glucose absorption by the cell
What do carrier proteins do?
bind solutes and transport them across the plasma membrane
Carrier proteins may require ___ as _______
ATP as an energy source
Do carrier proteins that transport glucose need ATP?
no
What does a channel do?
Permits the movement of water and small solutes across the plasma membrane
Why can ions not cross the plasma membrane??
They do not dissolve in lipids
Many channels are highly _______
specific
Membranes are neither ___ nor ____
rigid nor uniform
Carbohydrates account for about ___% of the weight of the plasma membrane
3
Carbohydrates in the plasma membrane can be components in _____, ______, or _____
protoglycans, glycoproteins, glycolipids
What is the glycocalyx?
portions of proteoglycans, glycoproteins, or glycolipids that extend beyond the outer surface of the membrane
What are 4 functions of the glycocalyx?
- Protection and Lubrication
- Anchoring and Locomotion
- Specificity in binding (receptors)
- Recognition
Cytoplasm is a general term for the material located between the _____ and the ____ surrounding the ______
plasma membrane and the membrane surrounding the nucleus
Which contains more proteins - cytoplasm or extracellular fluid??
cytoplasm
Cytoplasm is a _____ with a ___like consistency
colloid with a gel like consistency
Cytoplasm =
cytosol + organelles
Another name for cytosol is _____ fluid
intracellular fluid
Cytosol contains …?
dissolved nutrients, ions, soluble/insoluble proteins, and waste products
What are organelles?
structures suspended within the cytosol that perform specific functions for the cell
What are 3 differences between the cytosol and extracellular fluid??
- Concentration of potassium ions is much higher in the cytosol than extracellular fluid. Sodium conc is much higher in extracellular fluid
- Cytosol has many more suspended proteins
- Cytosol has small reserves of amino acids and lipids while extracellular fluid is a transport medium ONLY - no reserves
What is fluid within tissues called?
interstitial fluid
What are inclusions?
masses of insoluble material within the cytosol
cellular organelles can be divided into 2 broad categories:
- nonmembranous organelles
- membranous organelles
What are the cell’s membranous organelles?
ER, golgi, lysosomes, peroxisomes, mitochondria, nucleus
What are the 3 components of the cytoskeleton?
microtubules, intermediate filaments, microfilaments
Which component of the cytoskeleton is the smallest?
microfilaments
Microfilaments are made up of _____
actin
microfilaments are generally less than ___nm in diameter
6
What are the 3 main functions of microfilaments?
- Anchor cytoskeleton to integral proteins
- Determine the consistency of the cytoplasm by interacting with other proteins
- Actin can interact with myosin to produce movement of the cell or change shape
Intermediate filaments range from __to__ nm in diameter
7 to 11nm
Intermediate filaments mainly serve as …?
structural support
List 3 functions of intermediate filaments.
- Strengthen the cell and help maintain its shape
- Stabilize the positions of organelles
- Stabilize the position of the cell with respect to surrounding cells through attachment to cell membrane
Intermediate filaments are.. (soluble/insoluble)
INSOLUBLE
Keratin fibers are which kind of filament?
intermediate filament
Most cells contain ______ built from the globular protein _____?
most cells contain MICROTUBULES built from the globular protein tubulin
microtubules have a diameter of about ___nm
25
Microtubules extend outward from a region near the nucleus known as…?
the centrosome
Name 4 functions of the microtubules.
- Forms the spindle apparatus during mitosis
- serve as a monorail system to move vesicles
- Form centrioles, cilia, flagella
What are thick filaments?
massive bundles composed of myosin
Thick filaments appear only in …?
muscle cells
myosin interacts with ____ to produce powerful contractions
actin
What are the small, finger-shape projections of the plasma membrane?
microvilli
centrioles are composed of….
short microtubules
centrioles are found in which cells?
all animal cells that can undergo mitosis
Which types of cells do NOT contain centrioles?
mature red blood cells, skeletal muscle cells, cardiac muscle cells, and neurons - CELLS THAT CANNOT DIVIDE
What is the heart of the cytoskeletal system?
the centrosome
What is the centrosome?
the cytoplasm surrounding the centriole
the organization of centrioles is what kind of array? why?
9+0 array because there are no central microtubules as they form 3 “triplets”
Cilia are found on the cells lining which 2 tracts?
respiratory and reproductive
What is the array of cilia? why?
9 + 2 array. Nine PAIRS of microtubules surround a central pair
The microtubules in cilia are anchored to a ________ which has the same array as a centriole (9+0)
basal body
Cilium has 2 strokes:
power stroke and return stroke
During what stroke is the cilia relatively stiff?
power stroke
Which are the organelles responsible for protein synthesis?
ribosomes
Before protein synthesis can begin, what 3 things must join together?
small ribosomal subunit, large ribosomal subunit, mRNA
There are 2 types of ribosomes:
fixed ribosomes and free ribosomes
Where do free ribosomes produce proteins?
within the cytoplasm
What are proteasomes?
organelles that contain an assortment of protein-digesting enzymes (proteases)
What is the molecular “tag” attached to proteins for recycling?
ubitiquin
What kind of proteins are degraded by proteasomes?
-damaged/denatured proteins
-abnormal proteins (ex: those infected with viruses)
The ER is connected to the….
nuclear envelope
What are the 4 major functions of the ER?
- Synthesis
- Storage
- Transport
- Detoxification
The ER forms hollow tubes, flattened sheets, and chambers called..?
cisternae
The SMOOTH endoplasmic reticulum synthesizes….
lipids and carbohydrates
The smooth ER in ____ and ____ cells is responsible for the detoxification or inactivation of drugs
liver and kidney cells
What delivers proteins from the rough er to the golgi apparatus?
transport vesicles
is the proportion of rough ER to smooth ER the same in all cells?
NO - vary with the activities of the cell
Pancreatic cells that manufacture digestive enzymes contain more smooth or rough er?
RER
What are 3 major functions of the golgi apparatus?
- Modify and package secretions such as hormones and enzymes for release through exocytosis
- modify the plasma membrane
- package special enzymes within vesicles for use in the cytoplasm
Where are lysosomes produced??
The golgi apparatus
Lysosomes contain…?
digestive enzymes
What are primary lysosomes?
contain inactive enzymes. fuses with the membranes of damaged organelles
Lysosomes function in the deconstruction of…?
bacteria
Which are larger - lysosomes or peroxisomes?
peroxisomes
How are new peroxisomes produced?
From pre existing peroxisomes
What is the most abundant enzyme within the peroxisome?
Catalase
What do peroxisomes absorb and break down?
fatty acids and other organic molecules
In which cells are peroxisomes most abundant?
metabolically active cells such as liver cells
All membranous organelles aside from which one are in communication through the movement of vesicles?
mitochondria
What is the continuous movement and exchange in the cell called?
membrane flow
Which kind of cells lack mitochondria?
red blood cells
Which kind of cells have a LOT of mitochondria
heart muscle cells
Most of the chemical reactions that RELEASE energy occur in the ____ of the cell
mitochondria
Most of the chemical reactions that REQUIRE energy occur in the ____
cytoplasm
The first step of cellular respiration is called _____ and occurs in the _____
glycolysis, cytoplasm
During glycolysis, each ____ molecule is broken down into 2 molecules of ______
glucose is broken down into 2 molecules of pyruvate
Differentiate between the cytoplasm and the cytosol
Cytoplasm is the material between the plasma membrane and the nuclear membrane. Cytosol is the fluid portion of the cytoplasm
What is the function of the centriole??
- movement of chromosomes during cell division
- Organization of microtubules in cytoskeleton
What is the function of the cilia?
- Movement of materials over cell surface
What is the function of microvilli?
Increased surface area to facilitate absorption of extracellular materials