cells Flashcards
1
Q
What is the basic structural unit of all living organisms?
A
Cell
Cells can be unicellular or multicellular.
2
Q
What theory explains the evolution of mitochondria and chloroplasts?
A
Endosymbiotic theory
It suggests that large prokaryotic cells engulfed smaller bacteria.
3
Q
List three facts that support the endosymbiotic theory.
A
- Both organelles have their own DNA
- DNA is arranged like prokaryotic DNA (loop)
- They can divide on their own, like bacteria
4
Q
What are the basic features of eukaryotic cells?
A
- Complex structure
- Can be multicellular or unicellular
- Larger membrane-bound organelles
- Larger ribosomes (80s)
- DNA in a membrane-bound nucleus
5
Q
What is the function of the nucleus in a eukaryotic cell?
A
- Controls activities by controlling transcription of DNA
- Site of DNA replication and transcription
- Contains genetic material
- Nucleolus makes rRNA
6
Q
Fill in the blank: The cell surface membrane is a _______ bilayer.
A
phospholipid
7
Q
What is the primary function of the rough endoplasmic reticulum (RER)?
A
Protein synthesis
Proteins are folded into tertiary structure and packed into vesicles.
8
Q
What is the function of the smooth endoplasmic reticulum (SER)?
A
Synthesis and storage of lipids and carbohydrates
9
Q
What does the Golgi apparatus do?
A
- Processes and modifies proteins
- Packs proteins into vesicles
- Makes lysosomes
10
Q
What is the function of lysosomes?
A
- Digest large molecules into smaller, soluble molecules
- Key role in phagocytosis
- Digest worn-out organelles and invading cells
11
Q
What are ribosomes made of?
A
- 2 subunits
- Proteins
- RNA
12
Q
What is the main function of mitochondria?
A
Site of aerobic respiration to produce ATP
13
Q
What is the structure of chloroplasts?
A
- Double membrane
- Thylakoids with chlorophyll
- Grana (stacked thylakoids)
- Stroma (fluid with starch granules)
14
Q
Fill in the blank: The cell wall in plants is made of _______.
A
cellulose
15
Q
What is the function of the vacuole in plant cells?
A
- Maintains pressure inside the cell
- Keeps the cell rigid
- Isolates unwanted chemicals
16
Q
Define cell specialization.
A
The way cells adapt for their specific function to make that function efficient
17
Q
What are the four phases of interphase?
A
- Gap phase 0
- Gap phase 1
- Synthesis
- Gap phase 2
18
Q
What occurs during the G1 phase of interphase?
A
Cell grows and makes new organelles, proteins, and mRNA
19
Q
What happens during the S phase of interphase?
A
DNA replication occurs, doubling the genetic material (2N → 4N)
20
Q
What is the purpose of checkpoints in the cell cycle?
A
To ensure conditions are right for the cell to proceed to the next phase
21
Q
What occurs during prophase of mitosis?
A
- Chromosomes condense and become visible
- Centrioles move to poles of the cell
- Spindle fibers form
22
Q
Describe the arrangement of chromosomes during metaphase.
A
Chromosomes line up along the equator of the cell and are attached to the spindle fibers
23
Q
What happens during anaphase?
A
Sister chromatids are pulled apart towards the poles by spindle fibers
24
Q
What is cytokinesis?
A
The process of cytoplasmic division following mitosis
25
What is the structure of prokaryotic cells?
* Less complex than eukaryotic cells
* Single-celled
* No membrane-bound organelles
* Smaller ribosomes (70s)
26
What is the function of plasmids in prokaryotic cells?
Carry genes for antibiotic resistance and can be transferred between bacteria
27
What distinguishes Gram-positive bacteria from Gram-negative bacteria?
* Gram-positive: Thick peptidoglycan layer
* Gram-negative: Thin peptidoglycan layer with an outer membrane
28
What is the main difference between light and electron microscopes?
* Light microscopes use light to form an image
* Electron microscopes use beams of electrons
29
What is the purpose of cell fractionation?
To separate cellular components for analysis
30
What are the three main steps of cell fractionation?
* Homogenization
* Filtration
* Ultracentrifugation
31
What is the maximum magnification of light microscopes?
x1500
32
What is the primary structure of viruses?
* Acellular
* Nucleic acids surrounded by a protein coat (capsid)
* May have an envelope
33
What attaches chromosomes to the mitotic spindle during metaphase?
Centromeres
## Footnote
Centromeres are crucial for proper chromosome alignment.
34
What is the purpose of the checkpoint during metaphase?
To ensure all chromosomes are on the metaphase plate
## Footnote
This is important to ensure each daughter cell receives the same number of chromosomes.
35
What happens during anaphase of mitosis?
Spindle fibers contract, pulling sister chromatids towards the poles
## Footnote
Centromeres are pulled first, causing a V-shape appearance.
36
What occurs during telophase of mitosis?
Chromatids reach the poles, uncoil, and new nuclear envelopes form
## Footnote
This results in the formation of two genetically identical daughter nuclei.
37
What is cytokinesis?
The physical separation of the cell and cytoplasm splits
## Footnote
A contractile ring forms, creating a cleavage furrow that pinches the cell into two.
38
How does cancer relate to mitosis?
Mitosis is a controlled process; cancer is uncontrolled cell division
## Footnote
Mutations in genes controlling cell division lead to tumor formation.
39
What distinguishes malignant tumors from benign tumors?
Malignant tumors grow rapidly and invade tissues, while benign tumors grow slowly and do not spread
## Footnote
This difference is crucial for treatment approaches.
40
What is the role of chemotherapy in cancer treatment?
Prevents synthesis of enzymes needed for DNA replication
## Footnote
This disrupts the cell cycle and induces cell death.
41
How does radiation therapy work?
Damages DNA during the synthesis phase, leading to cell death if severe damage is detected
## Footnote
This prevents further tumor growth.
42
What is binary fission?
The process of cell division in prokaryotes
## Footnote
Involves replication of circular DNA and plasmids, followed by cell splitting.
43
What is the function of cell membranes?
Surrounds cells, acts as a barrier, and regulates substance movement
## Footnote
Cell membranes are partially permeable.
44
What is the structure of the phospholipid bilayer?
Composed of hydrophilic heads and hydrophobic tails
## Footnote
This arrangement allows for selective permeability.
45
How does cholesterol function in cell membranes?
Maintains fluidity, stability, and strength of membranes
## Footnote
Cholesterol restricts movement of phospholipids.
46
What are glycolipids and their functions?
Polysaccharide chains covalently bonded to lipids
## Footnote
They help cells attach, serve as recognition sites, and maintain membrane stability.
47
What role do glycoproteins play in cell membranes?
Bonded to extrinsic proteins, extending into the aqueous environment
## Footnote
They assist in cell recognition and tissue formation.
48
What are intrinsic proteins?
Proteins that span the membrane and interact with hydrophobic tails
## Footnote
They can function as channels or carriers.
49
What is the fluid mosaic model?
Describes the flexible structure of cell membranes
## Footnote
It highlights the dynamic arrangement of phospholipids and proteins.
50
What is simple diffusion?
Net movement of particles from high to low concentration without energy
## Footnote
It occurs through a partially permeable membrane until equilibrium is reached.
51
What factors affect the rate of simple diffusion?
* Concentration gradient
* Surface area
* Distance/thickness
* Temperature
* Particle size/mass
## Footnote
Each of these factors influences how quickly substances can diffuse.
52
What is facilitated diffusion?
Passive movement of particles through a membrane via transport proteins
## Footnote
This occurs down a concentration gradient.
53
What is osmosis?
Movement of water from high water potential to low water potential
## Footnote
This process occurs over a partially permeable membrane.
54
What are aquaporins?
Special protein channels that facilitate water diffusion
## Footnote
They are important in kidney cells for water reabsorption.
55
What are the types of solutions in relation to water potential?
* Hypotonic: Higher water potential than the cell
* Isotonic: Same water potential as the cell
* Hypertonic: Lower water potential than the cell
## Footnote
These terms describe how cells respond to different external environments.
56
What is active transport?
Movement of substances from low to high concentration, requiring ATP
## Footnote
It involves carrier proteins and is selective for certain molecules.
57
What happens to the difference in water potential during osmosis over time?
The difference in water potential on either side of the membrane decreases, so the rate of osmosis levels off over time.
58
How does the thickness of the exchange surface affect the rate of osmosis?
Thinner = faster.
59
What is the effect of a larger surface area of the exchange surface on osmosis?
Larger = faster.
60
What is active transport?
Movement of substances from an area of low concentration to an area of high concentration, against the concentration gradient, requiring energy from ATP and carrier proteins.
61
What is the process of active transport?
1. A molecule binds to a receptor on the carrier protein. 2. ATP binds to the carrier protein. 3. ATP hydrolyzed into ADP and Pi. 4. Pi attaches to protein causing phosphorylation. 5. Conformational change occurs, releasing the molecule on the other side.
62
What is the role of ATP in active transport?
A lot of ATP is required; it is released in mitochondria during respiration.
63
What is co-transport?
Transport of two molecules, one going down the concentration gradient and one against the concentration gradient.
64
What is symport in co-transport?
If the two molecules are transported in the same direction.
65
What is antiport in co-transport?
If the two molecules are transported in opposite directions.
66
How is glucose absorbed in the ileum?
1. High concentration of glucose in ileum. 2. Low concentration in epithelial cells. 3. Glucose enters by facilitated diffusion and active transport.
67
What is the sodium-potassium pump?
A carrier protein that actively transports Na+ from the epithelial cell to the bloodstream and K+ from blood to epithelial cells.
68
What is the role of the sodium-glucose co-transporter?
Na+ ions enter epithelial cells from ileum via facilitated diffusion, allowing glucose to be absorbed against its concentration gradient.
69
What is the immune system's primary function?
To distinguish native cells (self) from pathogens (foreign bodies) and eliminate these pathogens.
70
What are pathogens?
Microorganisms that cause disease.
71
What is the role of phagocytes?
Involved in phagocytosis which is immediate response to pathogens.
72
What are the two types of lymphocytes?
B cells and T cells.
73
What are antibodies?
Proteins that bind to antigens to form an antigen-antibody complex.
74
Define antigens.
Specific molecules found on the surfaces of all cells that stimulate an immune response.
75
What do antigens allow the body to identify?
* Pathogens * Abnormal body cells * Toxins * Cells from other individuals
76
What is the most common blood group?
Blood group O.
77
What determines whether blood is RhD positive or negative?
The presence or absence of the RhD antigen.
78
What is a blood transfusion?
When blood from a donor is given to a recipient.
79
What are the risks of blood transfusion?
Immune response to incompatible blood types, allergic reactions, and bloodborne diseases.
80
What is antigenic variation?
Frequent mutations in a pathogen's DNA that change the primary structure of antigens.
81
What does influenza's antigenic variability lead to?
Short-lived immunity and repeated bouts of influenza.
82
How do lymphocytes recognize cells?
Each B lymphocyte recognizes a specific antigen; self cells are suppressed to prevent immune response.
83
What is the Major Histocompatibility Complex (MHC)?
A protein marker on self cells used to distinguish self from non-self.
84
What are the two types of MHC molecules?
* MHC I: Found on normal body cells. * MHC II: Found on immune system cells.
85
What is devil facial tumour disease (DFTD)?
An aggressive non-viral, transmittable parasitic cancer affecting Tasmanian Devils.
86
What are the two main types of phagocytes?
* Neutrophils * Macrophages
87
What is phagocytosis?
The process of engulfment of pathogens by phagocytes.
88
What attracts phagocytes to pathogens?
Chemical products of the pathogen.
89
What are Pathogen Associated Molecular Patterns (PAMPs)?
Unique antigens on pathogens that phagocytes can recognize.
90
What are Pathogen Recognition Receptors (PRRs)?
Specialized receptors on phagocyte membranes that recognize and bind to PAMPs.
91
What is the movement called when cells move in response to chemical signals?
chemotaxis
92
What do pathogens have that are unique and recognized by phagocytes?
Pathogen Associated Molecular Patterns (PAMPs)
93
What are the specialized receptors on phagocytes that recognize PAMPs called?
Pathogen Recognition Receptors (PRRs)
94
What process do phagocytes use to engulf pathogens?
endocytosis
95
What is formed when a lysosome fuses with a phagocytic vacuole?
phagosome
96
What do lysozymes do to pathogens?
hydrolyse/break down
97
What type of immune cell recognizes foreign antigens and presents them to activate other immune cells?
antigen-presenting cell
98
What are the two types of lymphocytes involved in the immune response?
* T-lymphocytes (T cells)
* B-lymphocytes (B cells)
99
Where are T-lymphocytes produced and matured?
produced in the bone marrow, matured in the thymus
100
What do T-helper cells release to stimulate B-cells?
cytokines (interleukin-2)
101
What type of immune response involves T-cells?
cell-mediated response
102
What do cytotoxic T cells do?
destroy abnormal/infected cells
103
What is the term for the cells that produce antibodies?
plasma cells
104
What type of response do B-cells participate in?
humoral response
105
What are antibodies?
proteins that bind to antigens to form an antigen-antibody complex
106
What is the difference between primary and secondary immune responses in terms of the cells involved?
* Plasma cells in primary response
* Memory cells in secondary response
107
What is active immunity?
immunity acquired when the immune system makes its own antibodies after exposure to an antigen
108
What is passive immunity?
immunity received from antibodies made by another organism
109
What is the role of memory cells in the immune system?
provide long-term immunity by rapidly dividing upon encountering the same antigen
110
What is herd immunity?
protection for unvaccinated individuals when a large portion of the population is vaccinated
111
What may cause vaccination to fail in certain individuals?
defective immune systems
112
What ethical concerns surround vaccine testing?
* Animal testing
* Side effects
* Who to test on
* Trials of new vaccines
* Compulsory vaccines
113
Fill in the blank: Antibodies consist of ______ polypeptide chains.
4
114
True or False: Memory cells produce antibodies directly.
False
115
What is the term for the process by which B-cells divide and produce identical clones?
clonal expansion
116
What do antibodies do when they bind to antigens?
form antigen-antibody complexes and cause agglutination
117
What happens to the antibody levels during the primary immune response?
levels rise slowly
118
What is the role of T-helper cells in the humoral immune response?
activate B cells by binding to their MHC molecules
119
What is the main difference between natural and artificial active immunity?
* Natural: immunity from catching a disease
* Artificial: immunity from vaccination
120
What happens to plasma cells after they produce antibodies?
they survive for only a few days
121
What is the consequence of antigenic variation in pathogens?
vaccines may become ineffective due to sudden changes in antigens
122
What is the main health risk associated with HIV?
HIV leads to AIDS, which deteriorates the immune system.
## Footnote
AIDS makes individuals more vulnerable to infections like pneumonia.
123
How is HIV primarily transmitted?
HIV can be spread via unprotected sexual intercourse, infected bodily fluids, and from mother to fetus.
## Footnote
Sharing contaminated needles is another route of transmission.
124
What type of virus is HIV classified as?
HIV is a retrovirus.
## Footnote
Retroviruses have an enzyme called reverse transcriptase.
125
What is the structure of an HIV virus particle?
The virus particle has a spherical structure with a lipid envelope, a matrix, and a capsid.
## Footnote
It contains two single strands of RNA and enzymes like reverse transcriptase, integrase, and protease.
126
What role does reverse transcriptase play in HIV replication?
Reverse transcriptase catalyzes the production of DNA from RNA.
## Footnote
This is necessary for the replication of the virus.
127
Describe the process of HIV replication within a host cell.
HIV binds to CD4 receptors, fuses with the cell membrane, releases its capsid, and uses reverse transcriptase to convert RNA to DNA, which integrates into the host DNA.
## Footnote
This process leads to the production of new HIV particles.
128
What happens to helper T cells during HIV infection?
HIV infects and kills helper T cells, leading to a decrease in their count.
## Footnote
This deterioration of helper T cells results in a weakened immune response.
129
What are opportunistic infections in the context of AIDS?
Opportunistic infections are diseases that take advantage of a weakened immune system, such as pneumonia and tuberculosis.
## Footnote
These infections can be fatal for individuals with AIDS.
130
What are the initial symptoms of HIV infection?
The initial (acute) stage can cause flu-like symptoms.
## Footnote
This immune response is insufficient to eliminate the virus.
131
How long can the latency period of HIV last?
The latency period can last for years.
## Footnote
During this time, the infected person may not experience symptoms.
132
What is the significance of helper T-cell count in diagnosing AIDS?
AIDS is diagnosed when the helper T-cell count drops below a certain level or symptoms appear.
## Footnote
This threshold varies between individuals.
133
Why do antibiotics not work against viruses?
Antibiotics target bacterial enzymes and ribosomes, which are different from those in human cells.
## Footnote
Viruses utilize the host's cellular machinery for replication.
134
What are antiviral drugs designed to do?
Antiviral drugs target virus-specific enzymes to inhibit their replication.
## Footnote
For example, reverse-transcriptase inhibitors block HIV's replication process.
135
What is a monoclonal antibody?
Monoclonal antibodies are produced from a single group of genetically identical B-cells.
## Footnote
They bind to specific antigens due to their identical structure.
136
How are monoclonal antibodies used in cancer treatment?
Monoclonal antibodies can bind to tumor markers on cancer cells and prevent their growth or deliver drugs directly to them.
## Footnote
Examples include Herceptin for breast cancer.
137
What is the role of monoclonal antibodies in pregnancy tests?
Pregnancy tests detect the hormone hCG using mobile antibodies that bind to it, causing a color change.
## Footnote
If hCG is present, the test strip turns blue.
138
What is the ELISA test used for?
The ELISA test is used to diagnose viral diseases by detecting antigens or antibodies in a sample.
## Footnote
It provides qualitative and quantitative information.
139
What is the difference between direct and indirect ELISA tests?
Direct ELISA tests for antigens using known antibodies; indirect ELISA tests for antibodies using known antigens.
## Footnote
Both methods involve binding and color change to indicate presence.
140
What is added to the well in an indirect ELISA test?
A sample of the patient’s blood plasma
141
What do specific antibodies in the plasma bind to?
The specific antigen stuck to the bottom of the well
142
What is done to remove unbound antibodies after the initial binding?
The well is washed out
143
What is added to the well after washing out unbound antibodies?
A secondary antibody with a specific enzyme attached
144
What does the secondary antibody bind to?
The specific antibody bound to the antigen (primary antibody)
145
What happens if there is no primary antibody in the sample?
All of the secondary antibody will be washed away
146
What is added to the well after the secondary antibody?
A solution containing a substrate
147
What does the substrate solution react with?
The enzyme attached to the secondary antibody
148
What does a color change in the solution indicate?
The patient has specific antibodies to the known antigen in their blood
149
What ethical issue arises from the use of monoclonal antibodies?
Animals are involved in the production, often suffering from induced diseases
150
What must patients be informed about before treatment?
The risks and benefits
151
True or False: The use of monoclonal antibodies has caused deaths in cancer treatment.
True
152
Fill in the blank: The well is washed to remove any ________ antibodies.
unbound
153
Fill in the blank: The secondary antibody is linked to a ________.
specific enzyme
