Unit Tew Flashcards
(89 cards)
1
Q
What are the distinguishing features of eukaryotic cells?
A
- Cytoplasm containing membrane-bound organelles
- DNA enclosed in a nucleus
2
Q
What is the function of the cell-surface membrane?
A
- Selectively permeable → enables control of passage of substances in/out of cell
- Molecules/receptors/antigens on surface → allow cell recognition/signalling
3
Q
What does the nucleus hold?
A
- Genetic information which codes for polypeptides (proteins)
4
Q
What is the site of DNA replication in the cell?
A
Nucleus
5
Q
What is the function of a ribosome?
A
Site of protein synthesis (translation)
6
Q
What distinguishes rough endoplasmic reticulum (rER) from smooth endoplasmic reticulum (sER)?
A
- rER has ribosomes on its surface
- sER synthesises and processes lipids
7
Q
What does the Golgi apparatus modify?
A
- Proteins and lipids
8
Q
What is the function of lysosomes?
A
- Release hydrolytic enzymes (lysozymes) to break down/hydrolyse pathogens or worn-out cell components
9
Q
What is the primary function of mitochondria?
A
- Site of aerobic respiration to produce ATP for energy release
10
Q
What is the main function of chloroplasts in plants and algae?
A
- Absorbs light energy for photosynthesis
11
Q
What is the composition of the cell wall in plants?
A
Mainly composed of cellulose (a polysaccharide)
12
Q
What is the function of the cell vacuole in plants?
A
- Maintains turgor pressure in cell (stopping plant wilting)
- Contains cell sap → stores sugars, amino acids, pigments and any waste chemicals
13
Q
What is a tissue?
A
Group of specialised cells with a similar structure working together to perform a specific function
14
Q
What characterizes prokaryotic cells?
A
- Cytoplasm lacking membrane-bound organelles
- Genetic material not enclosed in a nucleus
15
Q
How do prokaryotic and eukaryotic cells differ in terms of ribosomes?
A
- Eukaryotic cells have larger (80S) ribosomes
- Prokaryotic cells have smaller (70S) ribosomes
16
Q
Why are viruses described as acellular?
A
- Not made of cells, no cell membrane/cytoplasm/organelles
17
Q
What is the difference between magnification and resolution?
A
- Magnification = number of times greater image is than size of the real object
- Resolution = minimum distance apart 2 objects can be to be distinguished as separate objects
18
Q
What is the principle of cell fractionation?
A
- Homogenise tissue to disrupt cell membrane, breaking open cells and releasing contents/organelles
19
Q
What is the purpose of using a cold, isotonic, buffered solution in cell fractionation?
A
- Cold to reduce enzyme activity
- Isotonic to prevent osmosis-induced damage
- Buffered to keep pH constant
20
Q
Fill in the blank: A _______ is a group of organs working together to perform specific functions.
A
Organ system
21
Q
True or False: All viruses have a lipid envelope.
A
False
22
Q
What are the steps involved in calculating magnification?
A
- Note formula/rearrange if necessary
- Convert units if necessary
- Calculate answer and check units
23
Q
What is the structure of a virus particle?
A
- Nucleic acids surrounded by a capsid
- Attachment proteins allow attachment to specific host cells
24
Q
What is the purpose of filtering the homogenate?
A
To remove large, unwanted debris such as whole cells and connective tissue
This step is crucial before further processing of biological samples.
25
What does ultracentrifugation do?
Separates organelles in order of density/mass
## Footnote
This process involves spinning the homogenate at high speeds to create a pellet of heavier organelles.
26
What is the sequence of organelles separated by ultracentrifugation from heaviest to lightest?
Nuclei → Chloroplasts/Mitochondria → Lysosomes → ER → Ribosomes
27
True or False: Electron microscopes produce clearer images than light microscopes.
False
## Footnote
Electron microscopes have a higher resolution, not just clearer images.
28
What is the significance of wavelength in relation to resolution?
Resolution is related to wavelength; shorter wavelengths provide higher resolution.
29
What happens during interphase of the cell cycle?
DNA replicates semi-conservatively, and the number of organelles and volume of cytoplasm increases.
30
What are the stages of mitosis?
Prophase, Metaphase, Anaphase, Telophase
31
What occurs during prophase?
Chromosomes condense, nuclear envelope breaks down, and spindle fibres form.
32
What is the role of spindle fibres during mitosis?
They attach to chromosomes and help separate sister chromatids during anaphase.
33
What is cytokinesis?
The division of the cytoplasm and cell membrane to form two new genetically identical daughter cells.
34
What is a benign tumour?
A non-cancerous mass of abnormal cells.
35
What is a malignant tumour?
A cancerous mass of cells that can spread (metastasis).
36
Describe binary fission in prokaryotic cells.
1. Replication of circular DNA
2. Replication of plasmids
3. Division of cytoplasm to produce 2 daughter cells
37
How do viruses replicate?
1. Attachment to host cell
2. Injection of viral nucleic acid
3. Host cell replicates virus particles
38
What is the mitotic index?
The proportion of cells undergoing mitosis in a sample.
39
Fill in the blank: The fluid-mosaic model describes the structure of _______.
cell membranes
40
What are the components of a cell membrane?
Phospholipids, proteins, glycoproteins, glycolipids, and cholesterol
41
Explain the role of cholesterol in cell membranes.
It restricts movement of other molecules, decreasing fluidity and increasing rigidity.
42
What is simple diffusion?
Movement of lipid-soluble or very small substances down a concentration gradient through the phospholipid bilayer.
43
What is facilitated diffusion?
Movement of water-soluble or slightly larger substances through specific channel or carrier proteins, down a concentration gradient.
44
What is osmosis?
Movement of water from an area of high to low water potential through a partially permeable membrane.
45
What is active transport?
Movement of substances from lower to higher concentration against a concentration gradient, requiring ATP.
46
What is co-transport?
Movement of two different substances simultaneously via a co-transporter protein.
47
Provide an example of co-transport.
Absorption of sodium ions and glucose by cells lining the mammalian ileum.
48
What is co-transport?
Coupling of the movement of one substance down its concentration gradient with the movement of another against its concentration gradient
## Footnote
Example: Absorption of sodium ions and glucose in the mammalian ileum
49
Describe the process of sodium and glucose absorption in the ileum.
1. Na+ actively transported to blood by Na+/K+ pump
2. Na+ enters epithelial cell down its gradient with glucose against its gradient via co-transporter protein
3. Glucose moves down a gradient into blood via facilitated diffusion
50
How does increasing surface area affect the rate of movement across cell membranes?
Increases the rate of movement
51
What effect does increasing the number of channel or carrier proteins have?
Increases the rate of facilitated diffusion or active transport
52
How does increasing the concentration gradient affect diffusion?
Increases the rate of simple and facilitated diffusion and osmosis until saturation occurs
53
What are adaptations of specialized cells for transport?
1. Membrane folded (e.g., microvilli)
2. More protein channels/carriers
3. Large number of mitochondria
54
True or False: Active transport only uses carrier proteins.
True
55
How do you calculate dilutions?
C1 x V1 = C2 x V2
## Footnote
Where C1 is concentration of stock, C2 is concentration of new solution, V1 is volume of stock used, V2 is volume of new solution
56
What is the first step in creating a calibration curve for water potential?
Create a series of dilutions using a sucrose solution
57
What is the formula for calculating percentage change in mass?
(final mass - initial mass) / initial mass
58
What happens to plant tissue mass in a hypotonic solution?
Increases due to water moving into cells by osmosis
59
What happens to plant tissue mass in a hypertonic solution?
Decreases due to water moving out of cells by osmosis
60
What is phagocytosis?
A process where a phagocyte engulfs a pathogen and digests it using lysozymes
61
Describe the role of T lymphocytes in the immune response.
Recognize foreign antigens and stimulate B cells, cytotoxic T cells, and phagocytes
62
What is the function of antibodies?
Bind to antigens, forming antigen-antibody complexes
63
What is the difference between primary and secondary immune responses?
Primary response is slower and lower concentration; secondary is faster and higher concentration
64
What is a vaccine?
Injection of antigens from attenuated pathogens to stimulate memory cell formation
65
How do vaccines provide herd immunity?
Large proportion of population vaccinated reduces pathogen spread
66
Fill in the blank: Active immunity involves ________ while passive immunity involves ________.
exposure to antigen, introduction of antibodies from another organism
67
What effect does antigen variability have on disease prevention?
New strains of pathogens can evade immune recognition, making previous immunity ineffective
68
What is the source of antibodies in passive immunity?
Antibodies are received from another organism, e.g., plasma cells, breast milk, or across the placenta from mother.
69
What is the speed of response in active immunity compared to passive immunity?
Active immunity is slower; it takes longer to develop compared to passive immunity, which is faster acting.
70
What is long-term immunity associated with?
Long-term immunity is associated with the ability to produce antibodies.
71
What is short-term immunity associated with?
Short-term immunity is a response to a specific antigen where antibodies are hydrolyzed.
72
Explain antigen variability and its effect on immunity.
Antigens on pathogens change shape due to gene mutations, creating new strains, which can lead to loss of immunity.
73
What happens to B memory cell receptors upon secondary exposure to a changed antigen?
B memory cell receptors cannot bind to or recognize the changed antigen.
74
Give examples of diseases affected by antigen variability.
* Yearly new flu vaccines * No vaccine for HIV * Catching a cold multiple times.
75
Describe the structure of an HIV particle.
HIV particles consist of a lipid envelope, capsid, RNA, and reverse transcriptase.
76
Outline the replication process of HIV in helper T cells.
1. HIV attachment proteins bind to receptors on helper T cell. 2. Lipid envelope fuses with cell membrane. 3. Capsid releases RNA and reverse transcriptase. 4. Reverse transcriptase converts RNA to DNA. 5. Viral DNA integrates into T cell DNA. 6. HIV mRNA is transcribed and translated into new proteins. 7. Virus particles are assembled and released.
77
How does HIV cause symptoms of AIDS?
HIV infects and kills helper T cells, leading to a weakened immune response, making the body more susceptible to infections.
78
Why are antibiotics ineffective against viruses?
Viruses lack structures/processes that antibiotics inhibit, such as metabolic processes and ribosomes.
79
Define monoclonal antibody.
An antibody produced from genetically identical or cloned B lymphocytes or plasma cells.
80
How can monoclonal antibodies be used in medical treatments?
Monoclonal antibodies bind to specific cell types, delivering therapeutic drugs attached to them.
81
In what way can monoclonal antibodies be utilized in medical diagnosis?
Monoclonal antibodies can bind to specific receptors or proteins associated with a diagnosis, often with a dye or marker attached.
82
Describe the direct ELISA test to detect antigens.
1. Attach sample to well. 2. Add complementary monoclonal antibodies with enzymes. 3. Wash well. 4. Add substrate for color change.
83
What is the purpose of a control well in the ELISA test?
To compare and ensure only the enzyme causes the color change and that unbound antibodies have been washed away.
84
Discuss ethical issues associated with vaccine and monoclonal antibody use.
* Animal testing concerns * Potential side effects in clinical trials * Risk of high-risk activities with vaccines * Possible dangerous side effects of drugs.
85
What factors should be evaluated in vaccine and monoclonal antibody methodology?
* Sample size * Participant diversity * Use of placebo/control groups * Study duration * Double-blind trial design.
86
What points should be considered when evaluating evidence for vaccines and monoclonal antibodies?
* Observed side effects and frequency * Statistical significance of results * Standard deviation considerations * Cost-effectiveness of dosage.
87
True or False: Lysosomes and lysozymes are the same.
False
88
True or False: An antibody has an active site.
False
89
What is the mistake regarding HIV replication in T helper cells?
It is too vague; specific processes like transcription and translation should be mentioned.
