WEEK 1 (PART 1) Flashcards
1
Q
What are cells?
A
Complex machines that continuously produce energy and waste
2
Q
What is the energy produced by cells used for?
A
Cell survival, cell repair, and formation of new cells through cell division
3
Q
What happens if there is an interruption to the complex processes in a cell?
A
Premature cell death, failure to give rise to new cells, or cellular disease
4
Q
What are the two major parts of a typical eukaryotic cell?
A
Nucleus and cytoplasm
5
Q
What separates the nucleus from the cytoplasm?
A
Nuclear membrane or envelope
6
Q
What separates the cytoplasm from the surrounding environment?
A
Plasma membrane
7
Q
What is the living content surrounded by the plasma membrane called?
A
Protoplasm
8
Q
What are the five basic substances that compose protoplasm?
A
Water, electrolytes, proteins, lipids, and carbohydrates
9
Q
What percentage of a cell is water?
A
70-85%
10
Q
What is the function of electrolytes in cells?
A
Provide inorganic chemicals for cellular reactions (e.g., electro-chemical impulses in nerves and muscle fibers)
11
Q
What is the function of proteins in cells?
A
Structural (e.g., cell cytoskeleton) or functional (e.g., enzymes that catalyze intracellular chemical reactions)
12
Q
What is an example of a functional protein?
A
Enzymes involved in glucose utilization
13
Q
What is the function of lipids in cells?
A
Form cell membranes and intracellular barriers
14
Q
What is the function of carbohydrates in cells?
A
Play a major role in cell nutrition
15
Q
What are organelles and what are some important ones?
A
Organelles are structures within the cytoplasm that perform specific functions. Important organelles include the endoplasmic reticulum, Golgi apparatus, ribosomes, mitochondria, peroxisomes, and lysosomes.
16
Q
What is the Endoplasmic Reticulum (ER)?
A
A network of membrane-enclosed tubes called cisternae
17
Q
What is the main function of the ER?
A
Synthesis and transport of proteins and lipids for most cell organelles
18
Q
What other important functions does the ER have?
A
Protein folding and sensing cell stress
19
Q
How is the ER connected to the nucleus?
A
The ER membrane is continuous with the outer nuclear membrane
20
Q
What factors can influence the function of the ER?
A
Oxygen levels, glucose levels, temperature, acidity, calcium levels, energy levels
21
Q
What can happen when the ER malfunctions (ER stress)?
A
Disrupted protein folding in the ER lumen
22
Q
How does the cell respond to ER stress?
A
Initiates the unfolded protein response (UPR) to adapt and survive or trigger cell death (apoptosis)
23
Q
How is ER stress linked to diseases?
A
Obesity-induced diabetes, atherosclerosis, and some cancers
24
Q
What is a potential therapeutic approach based on ER stress?
A
Drugs that reduce cellular stress to protect β cells in type 2 diabetes
25
Are there any links between ER dysfunction and neurological disorders?
Yes, ER dysfunction has been linked to Alzheimer's, Parkinson's, Huntington's, multiple sclerosis, and stroke
26
Can repairing ER dysfunction be a potential treatment for neurodegenerative diseases?
Research suggests it may be a way to treat these conditions
27
What are the two main types of ER?
Rough ER (with ribosomes for protein synthesis) and smooth ER (for lipid and carbohydrate metabolism)
28
What is the Golgi apparatus (Golgi complex)?
An organelle with stacked membranes (cisternae)
29
What is the function of the Golgi apparatus?
Processes and packages proteins for transport to specific locations in the cell
30
What is an example of a disease linked to Golgi apparatus dysfunction?
Duchenne's muscular dystrophy (due to abnormal protein processing)
31
What is the main function of mitochondria?
Cellular respiration and energy production (ATP)
32
What does a mitochondrion look like?
Double membrane-bound organelle with a smooth outer membrane and a folded inner membrane (cristae)
33
Where does most of the cell's energy come from?
Oxidative phosphorylation in the mitochondrial matrix
34
What other processes occur in the mitochondria?
Carbohydrate, lipid, and amino acid utilization; urea and heme synthesis
35
Do mitochondria have their own DNA?
Yes, they have DNA that codes for some of their enzymes
36
What other cellular functions are mitochondria involved in?
Calcium control and cell death regulation
37
What are reactive oxygen species (ROS)?
Byproducts of oxidative phosphorylation, acting as signaling molecules at low levels but causing damage at high levels
38
What factors can increase ROS levels?
Hypoxia, injury, and mitochondrial aging
39
What else do mitochondria do besides produce ATP?
Regulate cell survival and death (necrosis and apoptosis)
40
Where do lysosomes originate from?
Golgi complex
41
What do lysosomes contain?
Digestive enzymes (hydrolases) that break down various molecules
42
What is the function of lysosomes?
Cellular digestion (breaking down proteins, lipids, nucleic acids, and carbohydrates)
43
What protects the cell from the digestive enzymes in lysosomes?
The lysosomal membrane
44
What happens if the lysosomal membrane ruptures?
Digestive enzymes leak into the cytoplasm and break down cellular components, leading to cell death
45
What are lysosomal storage diseases?
Conditions where lysosomes malfunction and accumulate undigested material
46
What is an example of a lysosomal storage disease?
Pompe disease (accumulation of glycogen)
47
How can lysosomes be damaged?
Through various treatments, cellular injury, pancreatitis, or gout
48
What happens when lysosomes are damaged in gout?
Undigested uric acid accumulates, damaging the lysosomal membrane and causing cell death and tissue injury (gout pain)
49
What are peroxisomes?
Membrane-bound organelles containing oxidative enzymes
50
What is the main function of peroxisomes?
Detoxification by neutralizing poisons and free radicals
51
How do peroxisomes neutralize poisons?
By using enzymes to convert them into harmless byproducts, including hydrogen peroxide (H2O2)
52
What enzyme breaks down hydrogen peroxide in peroxisomes?
Catalase
53
Analogy for peroxisome function?
Miniature sewage treatment plant for the cell
54
What other functions do peroxisomes have?
Break down fatty acids and amino acids, metabolize lipids, and synthesize phospholipids for nerve cell myelination
55
Why are peroxisomes abundant in liver cells?
Liver is the primary organ for detoxifying blood
56
What are free radicals and why are they important?
They are harmful molecules that can damage cells, and peroxisomes help neutralize them
57
Are there any diseases associated with peroxisome dysfunction?
Yes, rare genetic diseases like Zellweger Syndrome and neonatal adrenoleukodystrophy can occur
58
How can abnormal metabolism lead to disease?
Disrupts normal cell function and can cause severe tissue dysfunction
59
Why is glucose used in intravenous therapy?
Because all bodily functions require energy, and glucose is a readily available energy source
60
Why can't an obese ICU patient necessarily be put on a diet?
The body still needs energy for basic functions even at rest
61
What is the basal metabolic rate?
The rate of energy expenditure at rest
62
How is cellular metabolism controlled?
Primarily by enzymes that speed up chemical reactions
63
What are the two main pathways in cellular metabolism?
Catabolism (breaking down molecules) and anabolism (building new molecules)
64
What is a key energy source for cells?
Glucose
65
How is energy extracted from glucose?
Through a complex series of reactions involving breakdown and oxidation (controlled burning) of glucose molecules
66
What process uses glucose for energy production?
Cellular respiration
67
How do cells use the energy from glucose?
ATP, an energy-transferring molecule produced from glucose breakdown, powers cellular functions
68
What is oxidation?
The process of a molecule gaining oxygen or losing hydrogen or electrons
69
What is the opposite process of oxidation?
Reduction
70
What is ATP and how is it produced?
ATP is an energy-transferring molecule produced through a metabolic pathway involving breakdown of carbohydrates, proteins, and lipids.
71
What is the main dietary source of glucose for cells?
Glucose from carbohydrates, absorbed from the gastrointestinal system.
72
How is glucose regulated in the liver?
Glucokinase (positively regulated by insulin, negatively regulated by starvation and diabetes) phosphorylates glucose for storage or use.
73
Where is excess glucose stored in the body?
Excess glucose is stored as glycogen mainly in the liver and skeletal muscle.
74
What are the two main pathways for glucose breakdown?
Glycolysis (aerobic) and anaerobic glycolysis (anaerobic).
75
What are the products of glycolysis?
Pyruvate and ATP (not enough to sustain cells).
76
What happens to pyruvate under aerobic conditions?
Pyruvate is converted to acetyl CoA and then citric acid in the citric acid cycle for most ATP production.
77
Where does most ATP production occur?
The majority of ATP is made from oxidations in the citric acid cycle in connection with the electron transport chain in the mitochondria.
78
What are byproducts of oxidative phosphorylation?
Reactive oxygen species (ROS) like superoxide and hydrogen peroxide, which can cause cellular damage.
79
What is the product of anaerobic glycolysis and what happens to it?
Lactate is produced and released into the bloodstream, taken up by the liver and converted back to glucose.
80
Which tissues are most susceptible to hypoglycemia due to limited anaerobic ATP production?
Tissues with low oxygen supply, such as rapidly contracting muscles during intense exercise.
81
How are proteins built?
From amino acids linked by peptide bonds
82
How are proteins absorbed in infants vs adults?
Infants absorb whole proteins, adults absorb individual amino acids
83
What happens to the body's own proteins?
They are constantly recycled and resynthesized
84
What are the major types of proteins in blood plasma?
Albumin, globulins, and fibrinogen
85
What is the function of albumin?
Maintains colloid osmotic pressure in blood plasma
86
What are the functions of globulins?
Enzymatic functions and cell immunity
87
What is the function of fibrinogen?
Forms blood clots to stop bleeding and aid wound healing
88
What happens to excess amino acids?
Broken down in the liver for energy or storage (fat/glycogen)
89
What is the first step in amino acid breakdown?
Deamination (removal of amino groups) in the liver
90
What is a toxic byproduct of deamination and what happens to it?
Ammonia; converted to urea in the liver to prevent brain damage
91
What are ketoacids and how are they used?
Products of deamination; oxidized for energy in the citric acid cycle
92
How can amino acids be converted into glucose or fatty acids?
Through gluconeogenesis and ketogenesis, respectively
93
What happens during severe starvation?
Protein breakdown for energy (deamination and oxidation) leading to cell destruction and organ failure
94
What are the main types of lipids?
Triglycerides, phospholipids, and cholesterol
95
What are the building blocks of triglycerides and phospholipids?
Fatty acids
96
What is cholesterol made of?
Sterol nucleus synthesized from fatty acid parts
97
What is the function of triglycerides?
Energy storage
98
What are the functions of phospholipids and cholesterol?
Fundamental components of cell membranes
99
What does cholesterol do in the body?
Makes hormones, vitamin D, and aids digestion
100
How are triglycerides broken down?
Hydrolysis releases glycerol and fatty acids
101
What happens to glycerol after breakdown?
Converted to glucose
102
What happens to fatty acids after breakdown?
Converted to acetyl-CoA for energy in the citric acid cycle
103
When is carbohydrate the preferred energy source?
When carbohydrates are readily available
104
What happens to excess acetyl-CoA from carbohydrates?
Converted to fatty acids for storage
105
How are fatty acids stored?
Triglycerides in adipose tissue
106
What happens to fatty acid storage when there are excess carbohydrates?
More triglycerides are formed, reducing free fatty acids available for energy
107
What happens to fatty acid storage in the absence of carbohydrates?
Equilibrium shifts, mobilizing fatty acids for energy
108
Why might it be difficult to use stored fat for energy?
Mobilization of fat for energy may be less efficient than using carbohydrates
109
How can excess carbohydrate consumption contribute to obesity?
Increased conversion of carbohydrates to fatty acids for storage
110
When are ketone bodies produced?
During reduced food intake or prolonged carbohydrate restriction (e.g., starvation)
111
What is the source of ketone bodies?
Fatty acids metabolized by the liver
112
What are the three main ketone bodies?
Acetoacetate, β-hydroxybutyrate (β-HBO), and acetone
113
How are ketone bodies normally used for energy?
Converted to acetyl-CoA and enter the citric acid cycle for ATP production
114
What happens if too many ketone bodies are produced?
They accumulate in the blood, leading to ketosis
115
What is the consequence of ketosis?
Metabolic acidosis if the body can't keep up with removing the acid produced by ketone bodies
116
Why do ketone bodies cause acidosis?
Two ketone bodies (acetoacetate and β-HBO) are anions of moderately strong acids
117
How does the body normally handle small amounts of ketone bodies?
By buffering their protons to maintain blood pH
118
What happens if the body can't buffer enough ketone bodies?
Buffering capacity is lost, and metabolic acidosis develops
119
How does blood pH affect enzymes?
Enzymes have optimal pH ranges for function
120
What are the optimal conditions for enzymes involved in energy production?
A stable blood pH is necessary for optimal enzyme function
121
What is cell division?
A process where a parent cell duplicates its DNA and divides to form two daughter cells
122
Why does cell division occur?
For growth, repair, and replacement of tissues
123
What are the four phases of cell division?
G1 phase, S phase, G2 phase, and M phase
124
G1 phase
Cell growth and preparation for DNA replication
125
S phase
DNA synthesis (replication of chromosomes)
126
G2 phase
Additional growth and preparation for mitosis
127
M phase
Mitosis (nuclear division) and cytokinesis (cytoplasmic division)
128
Interphase
Period between mitoses (G1, S, and G2 phases)
129
How is cell division regulated?
Tightly controlled process
130
How do chemotherapeutic drugs work?
By interfering with specific stages of cell division, often targeting DNA replication or mitosis
131
How can targeting multiple stages be beneficial?
To reduce tumor survival and resistance to treatment
132
What happens to injured cells?
They either recover or die (necrosis or apoptosis)
133
What is necrosis?
Cell death caused by sudden injury
134
What is apoptosis?
Programmed cell death
135
When does apoptosis occur during development?
Patterning of tissues (e.g., human fingers)
136
When does apoptosis occur in adults?
Involution of hormone-dependent tissues, removal of autoreactive immune cells, shedding of intestinal cells, and elimination of old cells
137
When does apoptosis occur in pathological conditions?
To eliminate damaged cells, cells with abnormal proteins, virus-infected cells, and atrophied cells in organs
138
Cell shrinkage
Cell shrinks in size
139
Chromatin condensation
DNA condenses in the nucleus
140
Cytoplasmic blebbing
Formation of bubble-like protrusions on the cell surface
141
Apoptotic bodies
Fragments of the apoptotic cell engulfed by phagocytes
142
Activation of caspases
Enzymes that break down cellular components
143
Initial phase
Caspases become active
144
Execution phase
Caspases trigger a series of events leading to cell destruction
145
How can caspases be activated?
Through two main pathways: intrinsic (mitochondrial) and extrinsic (death-receptor)
146
When is the intrinsic pathway activated?
After cellular damage from growth factor withdrawal, DNA damage, or protein misfolding
147
How is the intrinsic pathway initiated?
By BCL2 family proteins that control mitochondrial permeability
148
What happens after mitochondrial permeability increases?
Death-inducing molecules like cytochrome C are released into the cytoplasm
149
How does cytochrome C activate caspases?
By forming complexes that activate caspase-9, the initiator caspase
150
What do executioner caspases do?
Fragment the nucleus and break down the cytoskeleton
151
How is the extrinsic pathway initiated?
By activation of cell death receptors on the plasma membrane
152
What happens after a death receptor is activated?
A signaling complex forms, activating caspase-10 (human)
153
How does caspase-10 work?
Activates executioner caspases, leading to cell destruction
154
What is necroptosis?
A programmed form of necrosis occurring when apoptosis is insufficient
155
When does necroptosis occur?
In brain ischemia, neurodegenerative diseases, and viral infections
156
How is necroptosis different from apoptosis?
It doesn't involve caspase activation
157
What are some effects of necroptosis?
Decreased ATP production, increased ROS production, lysosomal membrane damage, and cell death resembling necrosis
158
What is autophagy?
A process where cellular components are degraded by lysosomes
159
How does autophagy work?
Cellular organelles are engulfed by autophagosomes, which fuse with lysosomes for breakdown
160
What is the role of autophagy in diseases?
It's linked to cancer, neurodegenerative disorders, and pathogen degradation
