Module 1 - Cellular Biology Flashcards
Objectives covering Cellular Biology
1
Q
What are living cells divided into
A
Eukaryotes and Prokaryotes
2
Q
Higher animals, plants, fungi, protozoa and some algae are made of what cells?
A
Eukaryotes
3
Q
Give examples of Prokaryotes
A
cyanobacteria (blue green algea), bacteria, and ricketsaie
4
Q
Cyanobacteria (blue green algae), bacteria, and ricketsaie are made up of what bacteria?
A
Prokaryotes
5
Q
List differences between Eukaryotes and Prokaryotes
A
- Eukaryotes are larger and have more intensive anatomy and organization than prokaryotes
- Eukaryotes have organelles with well defined nucleus. Prokaryotes have no organelles and nuclear materials is not enclosed by nuclear membrane - no distinct nucleus.
- Eukaryotes and Prokaryotes differ in chemical composition and biochemical activity
- Prokaryote’s nuclei carry genetic information in a singular circular chromosomes while eurkaryotes have several or many chromosomes.
- Prokaryotes lack histones
- They also differ in protein production and synthesis
- They differ in mechanisms of transport across the outer cellular membrane
- They differ in enzyme content
6
Q
What class of protein does prokaryotes lack?
A
Histones
7
Q
Which type of cell contains histones?
A
Eukaryotes
8
Q
Which type of cell does not contain histones?
A
Prokaryotes
9
Q
What are organelles?
A
Membrane bound intracellular compartments
10
Q
This is defined as membrane bound intracellular compartments?
A
Organelles
11
Q
Which cell contains organelles?
A
Eukaryotes
12
Q
Which cell does not contain organelles?
A
Prokaryotes
13
Q
What does histones do?
A
They bind with DNA and involved in supercoiling of DNA
14
Q
What process does cells undergo to become specialized?
A
Differentiation or maturation
15
Q
What is differentiation or maturation?
A
Process by which cells become specialized
16
Q
Why do cells differentiate?
A
Cells differentiate so that some cells can do certain function and others do other function.
17
Q
What are the 8 common function of cells?
A
- Movement
- Conductivity
- Metabolic Absorption
- Excretion
- Secretion
- Respiration
- Reproduction
- Communication
18
Q
Function of cell: Muscle cells can generate forces that produce this function.
A
Movement
19
Q
Function of cell: Chief function of nerve cell
A
Conductivity
20
Q
What is the the chief function of nerve cell?
A
Conductivity
21
Q
What happens during conductivity?
A
A stimulus creates an action potential across the cell
Membrane which is propagated to other cells and cell components
22
Q
What cell function describes the following: a stimulus creates an action potential across the cell membrane which is then propagated to other cells and cell components
A
Conductivity
23
Q
Explain cell
Function metabolic absorption
A
All cells can take in and use nutrients and other substances from their surrounding.
24
Q
What cell function matches the following description: all cells
Can take in and use nutrients and other substances from their surrounding.
A
Metabolic absorption
25
Describe Function Secretion
Some cells can synthesize new substances from other substances they absorb and secrete them as new substances than can be used elsewhere.
26
What cell function has the following description: Some cells can synthesize new substances from other substances that they absorb and secrete these new substances to be used elsewhere
Cell function - secretion
27
Describe the cell function excretion:
All cells can create waste products based from the metabolic breakdown of nutrients. Lysosomes contain the enzymes that breaks down or digest larger molecules.
28
Which cell function has the following description: All cells can create waste products resulting from metabolic breakdown of nutrients. The enzyme that breaks down these larger molecules are found in the lysosomes.
Excretion
29
Define Chronic cellular stress
When cell struggles to maintain homeostasis but reverts to an adaptive state
30
List some of cell adaptation
atrophy, hypertrophy, hyperplasia and metaplasia states
31
Cellular adaptation
Adaptive changes as a response to their environmental stressors. Adaptive - reversible changes in cell: size/number/phenotype/metabolic activity and cellular function
32
What is atrophy?
Decrease in cellular size but number can stay the same
33
Give examples of atrophy
Aging, MSK lack of use, hormone loss: post menopausal mucosal tissue
34
Aging, MSK lack of use and hormone loss are examples of what?
Atrophy
35
Hypertrophy
Increase in cellular size but number stays the same, no new phenotypical cells
36
Definition: Increase in cellular size but number stays the same, no new phenotypical cells
Hypertrophy
37
Examples of hypertrophy
Increases in organ size, often due to excessive demand, hormone or growth factor stimulation. Often is found with hyperplasia
38
Increases in organ size, often due to excessive demand, hormone or growth factor stimulation. Often is found with hyperplasia. These are examples of what?
Hypertrophy
39
Hyperplasia
Increase in number of cells
40
Can hyperplasia grow organ size?
It can, but now always
41
Examples of hyperplasia
Physiologic: Breast tissue for breastfeeding Pathologic: early predisposed cancer cells
42
Metaplasia
One type (phenotype) of cell is replaced by a different type of cell
43
Give examples of Metaplasia
Common in endothelial and connective tissue disorders.
Simple columnar epithelium change to squamous epithelium (squamous metaplasia)
44
Dysplasia
Deranged cellular growth (not true cellular adaptation but atypical hyperplasia)
45
Where is metaplasia common?
Respiratory and GI
46
What are the types of cellular injury?
1. Lack of sufficient oxygen ( hypoxia)
2. Free radicals
3. Chemical agents
4. Infectious agents
5. Physical and Mechanical factors
6. Immunologic factors
7. Genetic factors
8. Nutrition
47
What is the most common cellular injury?
Hypoxia
48
What cell function has the following description: Cells absorb oxygen which is needed to convert nutrients to energy in the form of ATP. This function occur in the organelles called mitochondria
Respiration
49
Describe cell function respiration
Cells absorbs Oxygen. Oxygen is needed to convert nutrients to energy in the form of ATP. Cellular respiration or oxidation occurs in the mitochondria
50
Where does cellular respiration or oxidation occur?
Mitochondria
51
Describe cell function reproduction
Tissue growth occurs when cell enlarges and reproduce. Even without growth, tissue maintenance still require new cells to be produced to replace cells lost through cellular death. Not all cells are capable of continous division
52
What cell function has the following description: Tissue growth occurs when cells enlarge and reproduce. Even without growth, tissue maintenance requires new cells to be produced to replace the cells lost through cellular death. Not all cells are capable of continous division.
Reproduction
53
What cell function has the following description: Communication is vital for cells to survive in a society of cells. Appropriate communication is important to maintain a dynamic steady state.
Communication
54
Describe cell function communication
Communication is vital for cells to survive in a society of cells. Appropriate communication is important to maintain a dynamic steady state.
55
What are the 3 components of a typical eukaryotic cell?
1. Outer membrane called plasma membrane or plasmalemma
2. Cytoplasm - fluid filling
3. Organelles - membrane bound organs of the cell
56
1. Outer membrane called plasma membrane or plasmalemma
2. Cytoplasm - fluid filling
3. Organelles - membrane bound organs of the cell
What are the 3 components of a typical eukaryotes
57
What surrounds the nucleus?
Cytoplasm
58
Where is the nucleus located?
Center of the cell
59
What is the largest membrane bound organelle?
Nucleus
60
What composes the nuclear envelope?
2 pliable membranes
61
What does the nuclear envelope have?
Nuclear pores
62
What is the function of nuclear pores?
It allows chemical messages in and out of the nucleus
63
What allows chemical message to exit and enter the nucleus?
Nuclear pores
64
The outer membrane is continous with what?
Endoplasmic reticulum
65
What does the nucleus contain?
Nucleosus, most of the cellular DNA, and DNA - binding proteins (histones)
66
What is nucleosus?
small dense structure in the nucleus composed mainly of RNA,
67
A small dense structure in the nucleus which contains mostly of RNA
Nucleosus
68
What are the DNA binding - proteins
histones
69
True or false: DNA chain in eukaryotic cells is so long that it is easily broken
True
70
True or false: DNA chain in eukaryotic cells is so long and it is not easily broken
False
71
What are histones?
- DNA binding proteins
- Essential for cells division in eukaryotes
- Binds DNA which causes DNA to fold into chromosomes which decreases risk for breaks in DNA chains
72
These are DNA binding proteins which are essential for cell division. It binds DNA to fold it into chromosomes which reduces risk in breaks in DNA chains.
Histones
73
What happens when DNA folds into chromosomes?
Reduces the risk of breaks in the DNA chains.
74
What are the function of nucleus
- Primary are cell division and control of genetic information
- Other include replication and repair of DNA
- Transcription of information stored in DNA
75
Which cellular component has the following functions:
1. Cell division and control of genetic information
2. Replication and repair of DNA
3. Transcription of information stored in DNA
Nucleus
76
Most of the processing of RN occurs in the _____________
Nucleolus
77
Genetic information is transcribed into _______ which can be processed into various forms.
RNA
78
What is cytoplasmic matrix?
Space between the nuclear envelope and plasma membrane
79
Space between the nuclear envelope and plasma membrane
Cytoplasmic matrix
80
What is cytoplasm?
Also called as cytosol, this is an aqueous solution that fills the cytoplasmic matrix.
81
What is another name for cytoplasm
Cytosol
82
This is an aqueous solution that fills the cytoplasmic matrix
Cytoplasms
83
Cytosol represents _____the volume of a eukaryotic cells.
half
84
What represents half the volume of eukaryotic cells?
Cytosol
85
What does cytosol contain?
- Thousands of enzymes involved in intermediate metabolism
- Crowded by ribosomes making protein
86
What part of the cell has thousands of enzymes which are involved in intermediate metabolism and is crowded by ribosomes making protein
Cytosol
87
The organelles embedded in the cytoplasm have their own _____________.
Biological membranes
88
89
What directs the function of the organelles ?
They are directed by coded messages carried from the nucleus by RNA
90
List some of the functions of organelles?
1. Protein and hormone synthesis and transport
2 . Maintenance of cellular structure and motility
3. Cellular metabolism
4. Processing and elimination of waste including cellular debris and foreign antigen and debris
91
Cytosol is a storage unit for ?
Fat, carbohydrates, and secretory vesicles.
92
Fat, carbohydrates and vesicles are stored in what part of the cell?
Cytosol
93
What are Ribosomes?
RNA protein complexes that (nucleoproteins). They are synthesized in the nucleolus and released into the cytoplasm. They provide sites for cellular protein synthesis.
94
Where are ribosomes synthesized ?
Nucleolus
95
Where are ribosomes released once synthesized?
Cytoplasm
96
What does ribosome provide?
Provides sites for cellular protein synthesis
97
What is the endoplasmic reticulum ?
Endoplasmic reticulum is a network of tubular channels or cisternae that extend throughout the outer nuclear membrane. It specializes in synthesis and transport of proteins and lipid components of most organelles.
98
What organelle has the following description? It is a network of tubular channels or cisternae that extends throughout the outer nuclear membrane. It specializes in the synthesis and transport of protein and lipid components of most organelles.
Endoplasmic Reticulum
99
What does endoplasmic reticulum specialize in?
Synthesis and transport of protein and lipid components of most organelles.
100
Describe structure and function of Golgi Complex
Golgi complex is a network of smooth membranes and vesicles that's close to the nucleus. It is responsible for processing and packaging proteins onto secretory vesicles that breaks away from the complex and migrates into various intracellular and extracellular destinations including the plasma membrane. Best known vesicles are those with coats that are largely made up of protein called clathrin. Proteins in the structure bind to cytoskeleton which generates tension that helps organelle function and keep the complex's stretch shape intact.
101
Which organelle has the following description: It is a network of smooth membranes and vesicles that is close to the nucleus. It processes and packages proteins onto secretory vesicles which breaks off the complex and migrates to various intracellular and extracellular destinations including the plasma membrane. The best known vesicles are those with coats that are largely made up of proteins called clathrin. Proteins in the complex binds into the cytoskeleton. This generates tension which helps the organelle function and keep the complex's stretched shape intact.
Golgi complex
102
Describe Lysosomes
Lysosomes are sac like structures that originates from the golgi complex and contain enzymes for digestion of cellular substances to their basic forms (amino acids, fatty acid, carbs). Cellular injury leads to the release of lysosomal enzymes that cause cellular destruction.
103
What organelle has the following description: It is a sac like structure that originates from the golgi complex and contains enzymes for digesting cellular substances to their basic forms (amino acides, fatty acids, and carbs). Cellular injury leads to the release of lysosomal enzymes that causes cellular self-destruction.
Lysosomes
104
What are the best known vesicles in the golgi complex?
Those vesicles that have coats made largely of a protein called clathrin
105
What is the golgi complex responsible for?
It is responsible for the processing and packaging of protein onto secretory vesicles that breaks of the bind and migrates to cellular intracellular and extracellular destinations.
106
What are peroxisomes?
Peroxisomes are structures similar to lysosomes. They contain oxidative enzymes that produce and use hydrogen peroxide; reaction detoxifies various wastes
107
What organelle has the following description: Structure like lysosomes that contain oxidative enzymes which produce and use hydrogen peroxide.
Peroxisomes
108
Describe mitochondria?
Structures that contain metabolic machinery that are needed for cellular energy metabolism. Enzymes of respiratory chain which is found in the inner membrane of the mitochondria, generates most of the cell's ATP. They have a role in osmotic regulation, PH control, calcium homeostasis and cell signalling.
109
What cell organelle has the following description?Structures that contain metabolic machinery that are needed for cellular metabolism. Enzymes of the respiratory chain, which is found in the inner membrane of the mitochondria, generates most of the cell's ATP. They have a role in osmotic regulation, PH control, calcium homeostasis, and cell signalling.
Mitochondria
110
Describe Cytoskeleton
Cytoskeleton is the bone and muscle of the cell. It is composed of a network of proteins which includes microtubules and actin filaments (microfilaments). It forms cell extensions such as microvilli, cilia, and flagella.
111
Describe Caveolae
Tiny indentations or caves that can capture extracellular material and shuttle it inside the cell or across the cell. It serves as a storage site for many receptors, provide route of transport into the cell, and act as the initiator for relaying signals from several extracellular chemical/ messenger into the cell's interior
112
Describe Vaults
Cytoplasmic ribonucleoproteins that are shaped like octagonal barrels. They are thought to act like truck that shuttles molecules from the nucleus to elsewhere in the cell
113
What cell organelle has the following description: Bones and muscles of the cell. It is composed of a network of proteins which include microtubules and actin filaments (microfilaments). They form cell extension such as flagella, microvilli, and cilia.
Cytoskeleton
114
What cell organelle has the following description: Indentation or caves that can capture extracellular material and shuttle it inside the cell or across the cell.
Caveolae
115
What cell organelle has the following description: Cytoplasmic ribonucleoproteins shaped like octagonal barrell. They are thought to act like trucks that shuttles molecules from the nucleus to elsewhere in the cell.
Vaults
116
How does membranes exert a powerful influence on metabolic pathways?
By controlling movement of substances from one compartment to another.
117
What is the benefit with the membrane's ability to control movement of substances from one compartment to another?
Through this ability, the membrane is able to exert powerful influence on metabolic pathways.
118
Every cell is contained within an a.)_________ with b.)______, c.)______, and d.)________.
a.) membrane
b.) gates, c.)channel and d.)pumps
119
What are the functions for plasma membrane?
1. Structure
2. Protection
3. Activation of cell
4. Storage
5. Cell to Cell interaction
120
How is directional transport facilitated?
1. Through distribution of charge within a cell
2. Differences in structure of one aspect of the cell when compared to another.
121
What maintains normal cell and tissue structure for numerous function?
Cell polarity and direction of cellular transport.
122
Describe the plasma membrane function: Structure
Plasma membrane is a thicker structure than membranes of organelles. Functions are. Outer surfaces of plasma membranes in many cells are not smooth. They are dimpled with cave like indentations called caveolae. They are also studded with cilia or microvilli - both are capable of movements.
1. Containment of the organelles
2. Maintenance of relationship with cytoskeleton, ER, and other other organelles
3. Maintenance of fluid and electrolyte balance.
123
What membrane function has the following description:Plasma membrane is a thicker structure than membranes of organelles. Functions are. Outer surfaces of plasma membranes in many cells are not smooth. They are dimpled with cave like indentations called caveolae. They are also studded with cilia or microvilli - both are capable of movements.
1. Containment of the organelles
2. Maintenance of relationship with cytoskeleton, ER, and other other organelles
3. Maintenance of fluid and electrolyte balance.
Structure
124
Describe the membrane function Protection?
It acts as a barrier to toxic molecules or macromolecules such as protein, polysaccharides, nucleic acid. It also acts a barrier against foreign organisms and cells
125
What membrane function has the following description: It acts as a barrier against toxic molecules or macromolecules (protein, nucleic acid, polysaccharides). It acts as a barrier against foreign organisms and cells.
Protection
126
Describe the membrane function activation of cell?
1. Hormones (regulation of cellular activity)
2. Mitogens (cell division)
3. Antigens (antibody synthesis)
4. Growth factors (proliferation and differentiation)
127
Describe the membrane function Storage
1. It is a site of storage of many receptors
2. Transport
3. Diffusion and exchange diffusion
4. Endocytosis (Pinocytosis, phagocytosis)
5. Exocytosis (secretion)
6. Active Transport
128
Describe the membrane function cell-to-cell interaction?
1. Communication and attachment at junctional complexes
2. Symbiotic nutritive relationships
3. Release of enzymes and antibodies to extracellular environment.
4. Relationship with extracellular matrix.
129
What is the basic structure of the cell membrane?
The basic structure of the cell membrane if the phospholipid bilayer.
130
Describe the phospholipid bilayer
- It is a complex structure where lipids and proteins are not uniformly distributed but can separate into discrete units called microdomains, differing in their lipid and protein compositions.
- Different membranes have varying percentages of protein and lipids.
- It is composed of 2 layers of lipid molecules - 1 layer with a phospholipid head attached to two fatty acid chains
- Proteins also span the bilayer to form channels and receptors that later processes inside the cell.
131
What are the 3 physical states or phases of the cell membrane?
1. solid gel phase
2. fluid-liquid cystalline phase
3. liquid ordered phase
132
What determines the phases of the cell membranes?
It is determined by the physical bond between the larger proteins in the bilayer.
133
Cell membranes are dynamic and can change under physiological factors such as temperature and pressure fluctuations. True or False
True
134
Cell membranes are a.____________ and change change under physiological changes such as b.___________________ and c.________________.
a. dynamic
b. temperature
c. pressure
135
How can carbohydrates be associated with plasma membrane?
They can be associated with plasma membrane when they are chemically combined with lipids and with proteins.
136
What part of the cell membrane provides storage site for many receptors?
Caveolae
137
What causes the membrane to spontaneously organize itself into 2 layers?
This is caused by the incompatible solubilities. The lipid molecule is polar or amphipathic. This means that one part is hydrophobic and the other part is hydrophilic. The bilayer serves as a barrier to the diffusion of water and hydrophilic substances while allowing lipid soluble molecules (e.g. O2 and CO2) to diffuse through the membrane readily. The structure of the cell membrane also makes it more difficult for water-soluble medications and ionized medications to enter the cell.
138
What are the most abundant lipids in the cell membrane?
Phospholipids
139
What forms self sealing lipid bilayers in the plasma membrane?
Phospholipids and glycolipids
140
What acts as a molecular glue for structural integrity of the membrane and form the membrane lipid rafts (MLRs)
Lipids and associated proteins
141
What does lipids and associated proteins act as?
They act as a molecular glue for the structural integrity of the membrane and forms the membrane lipid raft (MLR)
142
What are MLR
MLR or membrane lipid rafts appears to be functionally and structurally distinct regions of the plasma membrane that has numerous microdomains that form various interaction of protein to protein, lipid to lipid and lipid to protein interactions
143
What are the functions for MLR?
1. Cellular polarity and corresponding communication of cellular signals
2. Platform for ECM adhesions and cellular structure through CAMs (cellular adhesion molecules)
3. Signaling across the membrane which can alter the structure of the cytosol and regulate cell growth, movement and other functions
4. Entry of viruses, bacteria, toxins, nanoparticles
144
What are proteins made from ?
Proteins are made from a chain of amino acids known as polypeptide
145
What are polypetides?
Polypeptides are chains of amino acids that makes up protein
146
How many types amino acids are in proteins?
There are 20 types of amino acids in proteins
147
True or False: Each type of protein has similar sequence of amino acids
False
148
True or False: Each type of protein has unique sequence of amino acids
True
149
How is protein synthesized
Through the translation of RNA
150
A protein might undergo a series of ____________ that further impact and diversify protein function in the cell.
Post Translational modifications (PTMs)
151
What can PTMs do and why is it important?
PTMs can alter the activity and function of proteins and have become important in understanding the nature of disease.
152
Researchers have known for decades that _______can interfere with the host's PTMs.
pathogens
153
Where are membrane proteins synthesized?
ribosomes
154
Membrane structure is determine by ______________.
Lipid bilayer
155
Membrane functions are determine largely by ___________.
Proteins
156
Proteins act as a:
1. recognition and binding units for substances going in and out of the cells
2. pores or transport channels for various electrically charged particles called ions or electrolytes and specific carriers for amino acids and monosaccharides
3. specific enzymes that drive active pumps to promote concentrations of other ions particulary K within the cell while keeping concentrations of other ions (Na+) less than concentrations found in the extracellular environment.
4. cell surface markers such as glycoproteins that identify a cell to its neighbor
5. CAMs or proteins that allow cells to hook together and form attachments of the cytoskeleton for maintaining cellular shape
6. Catalyst of chemical reactions
157
What are the different ways membrane proteins associate with lipid bilayer?
1. Transmembrane proteins that extend across the bilayer and are exposed to an aqueous environment on both sides of the membrane.
2. proteins located almost entirely in the cytosol and are associated with the cytosolic half of the lipid bilayer by and alpha helix exposed on the surface of the protein
3. proteins that exist outside the bilayer, on one side or the other and are attached to the membrane by one or more covalently (or chemically bonded) attached lipid groups
4. proteins bound indirectly to one or the other bilayer membrane face, held in place by their interactions with the other proteins
158
True or False: Proteins exist in densely folded molecular configurations rather than straight chains
True
159
True or false: Proteins exist in straight chains rather than densely folded molecular configurations
False
160
Where are most hydrophilic units found?
Surface of the molecule
161
Where are most hydrophobic units found?
Inside the molecule
162
Where are membrane proteins synthesized?
Ribosomes
163
How do membrane proteins make their way to different membrane locations of a cell?
Through the process call trafficking
164
Explain the process Trafficking
Trafficking is the process that helps membrane proteins make their way to different locations of a cell. Trafficking places unique demands on membrane proteins for folding , translocation, and stability.
165
Where is the primary site for protein folding in the cell?
The ER (endoplasmic reticulum)
166
What can alter or decrease the rate of protein folding?
ER or cell stress, mutations, or random errors during protein synthesis.
167
What can disrupt the sensitive ER environment?
Viral infections, environmental toxins, and mutant protein expressions. Natural processes such as large protein synthesizing load placed on the ER can perturb the ER environment.
168
What can ER perturbations cause?
Accumulation of immature and abnormal proteins in cells which leads to ER stress.
169
What is unfolded protein response UPR?
These are pathways. The ER can actually mediate intracellular signalling pathways in response to the accumulation of unfolded or misfolded proteins.
170
What are the key components of energy transduction?
Membrane proteins.
171
What does ATP enzymes affect?
They affect the shape of biological membranes particularly mitochondrial membranes.
172
The cellular protein pool is in a state of __________________.
Constant flux
173
The number of copies of a protein in a cell dependent on what factors?
It depends on how quickly it is made and how long it survives or is broken down.
174
The adaptable system of protein homeostasis is defined by what network?
Proteostasis network
175
What comprises the proteostasis?
ribosomes (makers), chaperones (helpers), and 2 protein break down systems (proteolytic systems).
176
What are the 2 proteolytic systems?
Lysosomes and UPS (ubiquitin proteasome system)
177
What systems regulate protein homeostasis?
Proteolytic systems
178
What conditions does proteolytic systems regulate protein homeostasis under ?
1. Variations in nutrient supply
2. Existence of oxidative stress or free radicals
3. Cellular differentiation
4. Changes in temperature
5. Presence of heavy metal ions and other sources of stress
179
True or false: Malfunction or failure of the proteostasis network is associated with human disease
True
180
True or false: Malfunction or failure of the proteostasis network is not associated human disease
False
181
What are the short chains of carbohydrates that are contained within the plasma membrane bound to?
Membrane proteins (glycoproteins) and lipids (glycolipids).
182
What are proteoglycans?
Long polysaccharide chains that are attached to membrane proteins.
183
What is the glycocalyx?
Carbohydrate coating outside the plasma membrane. These carbohydrates are on the glycoproteins, proteoglycans and glycolipids.
184
Explain some of the function of glycocalyx.
1. Protects cells from mechanical damage
2. Assists with mobility of some cells by making surface layer of the cell slimy (e.g. leukocytes).
3. Specific cell-cell recognition and adhesion
185
What are cellular receptors?
Protein molecules on the plasma membrane, cytoplasm, or on the nucleus that can recognize and bind with specific smaller molecules called ligands.
186
What do you call the region of a protein that associates with a ligand?
Binding sites
187
Give examples of ligands that bind to receptors
Hormones, neurotransmitters, antigens, complement components, lipoproteins, infectious agents medications, metabolites.
188
What does recognition and binding depend on?
Chemical configuration of the receptor and its smaller ligand, which must fit together somewhat like pieces of a jigsaw puzzle.
189
Binding selectively to a protein receptor with high affinity to a ligand depends of what factors?
1. Formation of weak, noncovalent interactions - hydrogen bonds, electrostatic attractions, and Van der Waals attraction
2. Favourable hydrophobic forces
190
What can happen when ligand binds to receptors?
It can activate or inhibit the receptor's associated signaling or biochemical pathway.
191
How are receptors classified?
Receptors are classified based on their location and function even though the chemical nature of ligands and their receptors differ.
192
What does cellular type determine
It determines overall cellular function.
193
What determines cellular function?
Cellular type
194
What does plasma membrane receptors determine?
It determines which ligand a cell will bind with and how the cell will respond to the binding.
195
What determines which ligand a cell will bind with and how the cell with respond to the binding?
Plasma membrane receptors
196
Receptors for different medications are found where?
Plasma membrane, in the cytoplasm, and in the nucleus.
197
What are the opiate like peptides?
Endorphins
198
What happens with endorphins bind to a receptor?
1.It changes the cell's permeability to ions
2. Increases the concentration of molecules that regulate intracellular protein synthesis
3. Initiates molecular events that modulate pain perception
199
Where are membrane receptors for endorphins found?
It is found in large quantities in pain pathway of the nervous system
200
Aside from serving as outer boundaries of all cells, what is another function of plasma membranes?
It allows groups of cells to be held together robustly, in cell-to-cell adhesions to form tissues and organs.
201
What are the 3 different means that cells are linked?
1. CAMs in the cell's plasma membrane
2. ECM
3. Specialized cell junctions
202
What secretes ECM (extracellular matrix)?
Fibroblasts
203
What do you call the cells and matrix within the ECM?
Connective tissue because they interconnect cells to form tissues and organs.
204
Describe the ECM
ECM is an intricate meshwork of fibrous protein embedded in a watery gel-like substance composed of complex carbohydrates.
205
What are some of the function of the ECM
1. Acts like a glud
2. Provides pathways fer diffusion of nutrients, wastes and water-soluble substances between the blood and tissue cells.
3. Matrix helps regulate the function of the cells within it.
206
What are the 3 macromolecules within the matrix?
1. Fibrous structural proteins - elastin and collagen
2. adhesive glycoproteins - fibronectin
3. proteoglycans and Hyaluronic acids
207
Describe collagen
Forms cablelike sheets or fibers that provides tensile strength or resistance to longitudinal stress.
208
What macromolecule in the matrix has the following description: Forms cablelike sheets or fibers that provides tensile strength or resistance to longitudinal stress.
Collagen
209
Describe Elastin
Rubberlike protein fibre most abundant in tissues that must be capable of stretching and recoiling. For instance, the lungs have an abundance of elastin, which is responsible for the passive recoil of the lungs on expiration
210
What macromolecule in the matrix has the following description: rubberlike protein fibre most abundant in tissues that must be capable of stretching and recoiling. For instance, the lungs have an abundance of elastin, which is responsible for the passive recoil of the lungs on expiration
Elastin
211
Describe Fibronectin
large glycoprotein, promotes cell adhesion and cell anchorage
212
What macromolecule in the matrix has the following description:large glycoprotein, promotes cell adhesion and cell anchorage
Fibronectin
213
What are specialized cell junctions?
Unique membrane regions where cells come into direct physical contact with other cells of the same tissue, and they are classified by their function:
214
What are the functions of cell junctions?
1. Protect the integrity of epithelium through mechanical attachment
2. provide communication of the cells with each other while maintaining cell polarity.
215
List some of the cell junctions and their functions
1. Tight Junctions: some hold cells together and form a tight seal, some maintain polarity across the apical and basal aspects of individual epithelial cells
2. adherens junction, desmosomes, hemidesmosomes - provide strong mechanical attachments
3. Gap junctions: provide a special type of chemical communication which involves the movement of ions and small water-soluble molecules and cause an electrical wave
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Which cell junction does the following:provides a special type of chemical communication which involves the movement of ions and small water-soluble molecules and cause an electrical wave
Gap function
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Which cell junction does the following:provide strong mechanical attachments
adherens junctions, desmosomes, hemidesmosomes
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Which cell junction does the following:provides a special type of chemical communication which involves the movement of ions and small water-soluble molecules and cause an electrical wave
tight junctions
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What are tight junctions
- They are barriers to diffusion,
- they prevent movement of substances through transport proteins in the plasma membrane
- prevents the leakage of small molecules between the plasma membrane of adjacent cells.
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What are gap junctions:
clusters of communicating tunnels or connexons that allow small ions and molecules to pass directly from the inside of one cell to the inside of another
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What are connexons?
Connexons are communicating tunnels , are made of small protein molecules connexins spanning the cell membrane. It extends outwards from each of the adjacent plasma membranes.
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These are communicating tunnels , are made of small protein molecules connexins spanning the cell membrane. It extends outwards from each of the adjacent plasma membranes.
Connexons
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What factors regulate the gap junction intracellular communication
1. Voltage across the junction
2. intracellular pH
3. Intracellular Ca++ concentration
4. Protein phosphorylation
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What is the most abundant human connexin ?
Cx43
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What is Cx43
Tumor Suppressor, important prognostic maker and target for therapy
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What is the junctional complex?
- Highly permeable part of the plasma membrane.
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What controls the permeability of the junctional complex?
It is controlled by a process called gating
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Describe the process gating
This is where increased levels of cytoplasmic calcium from injured cells cause decreased permeability at the junctional complex. Gating enables uninjured cells to protect themselves from injured neighbouring cells.
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What does the gating process enable?
It enables uninjured cells to protect themselves from injured neighbouring cells.
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What are the 4 main reasons why cells need to communicate?
1. For the maintainance of a stable internal environment or homeostatis
2. Regulation of growth and division
3. Development and organization of cells into tissues
4. Coordination of their functions
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What are the 3 main ways cells communicate with each other?
1. they display plasma membrane–bound signalling molecules (receptors) that affect the cell itself and other cells in direct physical contact
2. they affect receptor proteins inside the target cell, and the signal molecule has to enter the cell to bind to them
3. they form protein channels (gap junctions) that directly coordinate the activities of adjacent cells
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What does alterations in cell communication do?
It affects the disease onset and progression.
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Paracrine
Hormones working on nearby cells
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Autocrine
Hormones from the cell target the same cell
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Give examples of neurohormonal
renin-angiotensin-aldosterone and sympathetic nervous system
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Give examples of neurotransmitter
norepinerphone and acetylcholine
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What does contact dependent signalling require?
It requires cells to be in close membrane - membrane contact
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This type of signalling requires cells to be in close membrane-membrane contact.
Contact-dependent signalling
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Explain Paracrine signalling
In this type of signalling, cells secrete local chemical mediators that are quickly taken up, destroyed, or immobilized. Paracrine signalling usually involves different cell types;
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Explain autocrine signalling
In this type of signaling, cells also can produce signals to which they alone respond.
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Explain Hormonal Signaling
Involves specialized endocrine cells that secrete chemicals called hormones; hormones are released by one set of cells and travel through the bloodstream to produce a response in other sets of cells
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Explain neurohormonal signaling
Hormones are released into the blood by neurosecretory neurons. Like endocrine cells, neurosecretory neurons release bloodborne chemical messengers, whereas ordinary neurons secrete short-range neurotransmitters into a small discrete space (
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What are the types of plasma membrane receptors?
1. Ion channel coupled
2. Enzyme coupled
3. G-protein coupled
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Describe ion channel coupled
- Also called transmitter-gated ion channel
- Involve rapid synaptic signaling between electrically excitable cells
- Channels open and close briefly in response to neurotransmitters, changing ion permeability of plasma membrane of post-synaptic cell
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Describe enzyme coupled
Once activated by ligands, function directly as enzymes or associate with enzyme
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Describe G-protein coupled
- indirectly activate or inactivate plasma membrane enzyme or ion channel
- interaction mediated by GTP-binding regulatory protein
- May also interact with inositol phospholipids which are significant in cell signaling and with molecules involved in inositol-phospholipid transduction pathway.
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What are transduction pathways
They are communication pathways or signalling cascades
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What happens when cells are deprived of appropriate signals?
Most cells undergo a form of call suicide known as programmed cell death, or apoptosis
