Cells Flashcards
1
Q
What is a eukaryotic cell?
A
A cell with a nucleus and membrane-bound organelles.
2
Q
What is the main feature of the cytoplasm?
A
The matrix that contains all of the different organelles.
3
Q
What are centrioles?
A
Structures that consist of 2 hollow cylinders and are involved in cell division.
4
Q
What is the function of the nuclear envelope?
A
Encloses nucleoplasm and controls entry/exit of materials.
5
Q
What is the role of the nucleolus?
A
Site of RNA synthesis.
6
Q
What is chromatin composed of?
A
DNA and protein.
7
Q
What do ribosomes do?
A
They are the site of protein synthesis.
8
Q
What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?
A
Rough ER is covered with ribosomes; Smooth ER has no ribosomes.
9
Q
What is the structure of mitochondria?
A
Double membrane with inner folds called cristae.
10
Q
What is the primary function of mitochondria?
A
ATP production through the Krebs cycle.
11
Q
What are lysosomes?
A
Small membrane-bound organelles containing hydrolytic enzymes.
12
Q
What is the function of the Golgi body?
A
Processes and packages proteins and forms secretory vesicles.
13
Q
What is the primary composition of the cell wall in plant cells?
A
Cellulose.
14
Q
What are chloroplasts responsible for?
A
Photosynthesis.
15
Q
What is a vacuole?
A
A large fluid-filled sac surrounded by a membrane.
16
Q
Fill in the blank: Prokaryotic cells have _______ present.
A
No nucleus.
17
Q
True or False: Eukaryotic cells contain circular DNA.
A
False.
18
Q
What are the two types of stem cells?
A
Embryonic stem cells and adult stem cells.
19
Q
What is the role of transcription factors in cell specialization?
A
They control gene expression allowing differentiation.
20
Q
What is the main difference between light and electron microscopes?
A
Electron microscopes use electrons for higher resolution.
21
Q
What is the resolution of a Transmission Electron Microscope?
A
0.17nm.
22
Q
What is the function of the tonoplast?
A
Surrounds the vacuole and helps maintain turgor pressure.
23
Q
What is the process of homogenisation?
A
Breaking cells open to release cell contents.
24
Q
What is the formula for calculating magnification?
A
M = I / A.
25
Fill in the blank: The diameter of organelle Y is _______.
0.5μm.
26
What are the main features of prokaryotic cells?
No nucleus, no mitochondria, no Golgi body, smaller ribosomes.
27
What is the significance of plant stem cells?
They allow plants to regenerate following substantial damage.
28
What are the main components of a virus?
Genetic material, capsid, attachment proteins.
29
What is the role of the apoplast pathway?
Provides a pathway for water movement through the plant.
30
What type of cell division produces 2 cells?
Mitosis
31
What type of cell division produces 4 cells?
Meiosis
32
In which type of cell division are all cells genetically identical?
Mitosis
33
In which type of cell division are the cells genetically different?
Meiosis
34
During which process does cell division occur for growth, repair, and asexual reproduction?
Mitosis
35
During which process does cell division occur for sex cell production?
Meiosis
36
What is the chromosome number in each cell after mitosis compared to the original cell?
The same number of chromosomes as the original
37
What is the chromosome number in each cell after meiosis compared to the original cell?
Half the number of chromosomes as the original
38
Define haploid.
A cell with half the number of chromosomes
39
What are the main roles of mitosis?
Growth, Repair
40
What is a chromosome?
DNA wrapped around protein & tightly coiled
41
What does the centromere do?
Holds sister chromatids together
42
What happens to chromosomes during prophase?
Chromosomes shorten and thicken
43
What forms during metaphase?
Spindle fibres across the cell
44
What occurs during anaphase?
Sister chromatids are pulled to opposite poles
45
What is the result of telophase?
Two identical daughter cells
46
What is cytokinesis?
The cytoplasm splits into two
47
Fill in the blank: The phase of the cell cycle where DNA replication occurs is _______.
Interphase
48
How many chromosomes are present in human body cells?
46
49
What is the function of centrioles during cell division?
Form spindle fibres
50
What is cancer?
A condition where cells grow & reproduce uncontrollably
51
What causes cancer at the genetic level?
A mutation in genes that control the cell cycle
52
What is the difference between benign and malignant tumors?
* Benign: slow growing, remain in one place
* Malignant: fast growing & can spread
53
What is binary fission?
A process prokaryotes use to reproduce asexually
54
What does the generation time refer to in bacteria?
Time taken for a bacterial population to double
55
How many bacteria will be present in the 9th generation if starting with 1 bacterium?
512
56
What is the role of viral attachment proteins?
To attach to complementary receptors on the host cell
57
What happens to the host cell after a virus replicates?
The cell lyses, releasing new viruses
58
What occurs during the evidence stage of interphase?
Chromosomes are not visible
59
What evidence indicates prophase?
Chromosomes are visible
60
What signifies metaphase?
All chromosomes are in the middle of the cell
61
What is the evidence of anaphase?
Chromatids are on both ends of the cell
62
What is the evidence of telophase?
Two nuclei visible
63
What is the phospholipid bilayer?
A barrier to substances that do not dissolve in or are repelled by lipid.
64
What role does cholesterol play in the membrane?
Strengthens the membrane and makes it less fluid.
65
What are the functions of proteins in the membrane?
Act as receptors.
66
What are glycolipids and glycoproteins?
Can act as receptors or as antigens.
67
Define diffusion.
The net movement of molecules from a high concentration to a low concentration until evenly distributed.
68
Is diffusion a passive or active process?
Passive process.
69
What does Fick's Law relate to?
Diffusion.
70
What is facilitated diffusion?
Transport of water-soluble, polar substances that could not otherwise cross the membrane.
71
What are the two types of trans-membrane proteins involved in facilitated diffusion?
* Channel
* Carrier
72
How do ions diffuse through the membrane?
Through channels.
73
How do other polar molecules diffuse through the membrane?
Through carriers.
74
What is osmosis?
The net movement of water molecules from a dilute solution to a more concentrated solution across a partially permeable membrane.
75
What is another way to define osmosis?
The net movement of water molecules from a higher water potential to a lower water potential across a partially permeable membrane.
76
Can water molecules cross the phospholipid bilayer?
Yes.
77
What is the size and charge of individual water molecules?
Tiny and have very little charge.
78
What happens to water molecules crossing the membrane one way and the other?
As many molecules cross one way as the other, resulting in no net movement.
79
In which conditions do fewer water molecules become 'free' to cross the membrane?
When solutes like Na+ and Cl- are present.
80
What does a hypotonic solution have?
Lower solute concentration, so it has a higher water potential.
81
What happens to cells in a hypotonic solution?
Cells swell and burst.
82
What does a hypertonic solution have?
Higher solute concentration, so it has a lower water potential.
83
What happens to cells in a hypertonic solution?
Cells shrivel or become crenated.
84
What occurs when the water potentials of cells and solution are equal?
No net movement of water by osmosis.
85
What is active transport?
The movement of substances from low concentration to high concentration through carrier proteins.
86
What does active transport require?
ATP.
87
How can a researcher determine if a substance is crossing the membrane by diffusion or active transport?
By inhibiting ATP production or manipulating the concentration gradient.
88
What is co-transport?
A process involving the simultaneous transport of two substances across a membrane.
89
What is phagocytosis?
Uptake of solids.
90
What is pinocytosis?
Uptake of liquids.
91
What is exocytosis?
Bulk transport of substances out of the cell.
92
What can exocytosis be used for?
* Removing waste
* Releasing useful substances (e.g., hormones, enzymes)
93
What is a pathogen?
Microbes that can cause disease
## Footnote
Pathogens cause direct damage to cells and tissues and can release toxins that affect distant sites.
94
What are the two main types of pathogens discussed?
* Bacteria
* Viruses
95
Describe the structure of viruses.
Acellular and non-living, containing genetic material (DNA or RNA), a capsid (protein), and attachment proteins.
## Footnote
Viruses do not have a nucleus, organelles, cell-surface membrane, or cytoplasm.
96
What is the function of viral attachment proteins?
Attach to specific host cells using proteins complementary to receptors on the host cell membrane.
97
How do viruses replicate?
By attaching to host cells, injecting nucleic acid, and directing the production of more virus particles using the host's organelles.
98
What are the methods of pathogen transmission?
* Airborne/droplets
* Food-borne
* Water-borne
* Contact
* Sexual intercourse
99
What are the non-specific mechanisms of defense against pathogens?
* Skin
* Stomach acid
* Respiratory lining
* Tears
* Ear wax
100
What role do phagocytes play in the immune response?
They engulf bacteria and form phagosomes, which fuse with lysosomes containing hydrolytic enzymes to destroy the pathogen.
101
What is phagocytosis?
The process by which phagocytes engulf and digest pathogens.
102
What is antigen presentation?
The process in which phagocytes display parts of digested pathogens on their cell surface to activate lymphocytes.
103
What are antigens?
Glycoproteins with a specific tertiary structure on cell surfaces that can be 'self' or 'foreign'.
104
What is the specific immune response?
An immune response carried out by lymphocytes that can distinguish 'self' antigens from 'foreign' antigens.
105
What are the two types of specific immune responses?
* Humoral (B-cells & antibodies)
* Cell-mediated
106
What are antibodies?
Proteins produced by B lymphocytes in response to a specific antigen, found in blood plasma, tissue fluid, and breast milk.
107
How many polypeptide chains are present in an antibody?
4
108
What are the two types of chains in an antibody?
* Light chains
* Heavy chains
109
What binds the chains of an antibody together?
Disulfide bridges
110
How many antigen binding sites does an antibody have?
2
111
What is the significance of antigen-antibody complexes?
They facilitate agglutination and enhance destruction by phagocytosis.
112
What is the role of memory cells in the immune system?
They remain in the blood for decades, providing immunity against pathogens with the same antigen.
113
What occurs after B-cell activation?
The B-cell grows, divides by mitosis, and produces plasma cells that secrete antibodies.
114
What is the process of antibody-mediated response?
Initial binding to an antigen activates B-cells, which then secrete many antibody molecules.
115
What is the difference between 'self' and 'foreign' antigens?
'Self' antigens are recognized as part of the body, while 'foreign' antigens are recognized as invaders.
116
What happens after an antibody on an immature B-lymphocyte binds with an antigen?
The B-lymphocyte becomes activated and undergoes clonal proliferation, producing plasma cells that secrete antibodies.
## Footnote
This process is part of the primary immune response.
117
What are the types of T-cells?
* T-cytotoxic (killer)
* T-helper
* T-memory
## Footnote
Each type has distinct roles in the immune response.
118
What is the role of Cytotoxic T cells?
Destroy pathogen by attaching to specific antigens and secreting chemicals like perforin.
## Footnote
This action leads to the lysis of infected cells.
119
What is the role of Helper T cells?
Stimulate B cells to divide into plasma cells and produce antibodies.
## Footnote
They also assist in activating other immune cells.
120
What do Memory T cells do?
Provide long-term immunity by remaining in the blood and responding quickly to subsequent exposures to the same antigen.
## Footnote
They are crucial for the secondary immune response.
121
What is antigenic variation?
The high mutation rate of pathogens leading to constantly changing antigens, resulting in multiple strains.
## Footnote
This can cause repeated infections, as the immune system may not recognize new strains.
122
What is the difference between active and passive immunity?
* Active: Body produces antibodies in response to infection or vaccination.
* Passive: Antibodies are provided from another source, such as maternal antibodies.
## Footnote
Passive immunity is typically short-term.
123
What is a vaccine?
A substance that stimulates the production of antibodies and memory cells against a target pathogen without causing illness.
## Footnote
Vaccines may contain weakened or dead pathogens.
124
What is herd immunity?
Protection of an individual from a disease due to a high proportion of the population being immune, reducing transmission risk.
## Footnote
It can be achieved naturally or through vaccination.
125
True or False: Vaccines are the most effective way to cure diseases.
False
## Footnote
Vaccines prevent diseases but do not cure them.
126
Why are some groups offered the ‘flu vaccine for free on the NHS?
To protect vulnerable populations who are at higher risk for severe illness or complications from the flu.
## Footnote
These groups often include the elderly, young children, and those with underlying health conditions.
127
Fill in the blank: The first exposure to an antigen leads to a _______ immune response.
primary
## Footnote
This initial response is typically slower than subsequent responses.
128
Fill in the blank: The second exposure to an antigen leads to a _______ immune response.
secondary
## Footnote
This response is faster and more robust due to memory cells.
129
What is the significance of the MMR controversy?
A 1998 paper speculated a link between the MMR vaccine and autism, leading to widespread media coverage and vaccine hesitancy despite the lack of evidence.
## Footnote
The paper was later retracted due to insufficient evidence.
130
True or False: Vaccination only protects the individual.
False
## Footnote
Vaccination also contributes to herd immunity, protecting the community.
131
What can high mutation rates in pathogens lead to?
Antigenic variation, resulting in the emergence of new strains that may evade the immune response.
## Footnote
This can lead to epidemics if the population lacks immunity to the new strains.
132
What does HIV stand for?
Human Immunodeficiency Virus
## Footnote
HIV is the virus that causes AIDS.
133
What does AIDS stand for?
Acquired Immune Deficiency Syndrome
## Footnote
AIDS is the condition caused by HIV.
134
What type of virus is HIV?
Retrovirus
## Footnote
Retroviruses use RNA as their genetic material and reverse transcriptase for replication.
135
What is the role of reverse transcriptase in HIV?
Enzyme that uses RNA template to produce DNA
## Footnote
This process is crucial for the replication of HIV.
136
What is the structure of HIV?
HIV consists of:
* Capsid (protein coat)
* Lipid envelope with glycoprotein ‘spikes’
## Footnote
The spikes attach to T helper cells, which are the host cells.
137
How is HIV transmitted?
Transmission occurs through:
* Blood
* Semen
* Vaginal secretions
* Sexual contact
* Blood transfusions
* Sharing needles
* Mother to baby
## Footnote
These routes allow the virus to enter the bloodstream.
138
What happens during the latent period of HIV infection?
The virus attaches to helper T cells and can remain inactive for up to 10 years
## Footnote
During this time, the individual may not show symptoms.
139
What are the four phases of HIV symptoms?
1. Flu-like illness and antibody production
2. Antibody-positive phase
3. AIDS-related complex (ARC)
4. Infections of body organs
## Footnote
The severity and symptoms can vary based on treatment.
140
What characterizes the AIDS-related complex (ARC)?
Bacterial, viral, and fungal infections; loss of weight; severe diarrhea
## Footnote
These symptoms indicate a reduction in T helper cells.
141
What are common complications of AIDS?
Common complications include:
* Kaposi’s sarcoma
* Pneumonia
* Cancer of skin cells
## Footnote
Opportunistic infections are prevalent due to a weakened immune system.
142
True or False: Antibiotics are effective against HIV.
False
## Footnote
Antibiotics only target bacteria, not viruses.
143
Fill in the blank: HIV particles are assembled and the _______ is destroyed.
helper T cell
## Footnote
This destruction allows new viral particles to infect other T cells.
144
What happens to T helper cells as HIV progresses?
Many helper T cells are destroyed, leading to reduced stimulation of B cells and less antibody production
## Footnote
This breakdown of the immune response can lead to death.
145
What is the effect of anti-viral drugs on HIV patients?
They can prevent the virus from replicating, leading to a much longer life expectancy
## Footnote
These drugs help manage the infection.
146
What is the significance of glycoprotein spikes on HIV?
They attach to T helper cells, allowing HIV to enter these cells
## Footnote
This is crucial for the virus's ability to infect the host.
147
How does reverse transcriptase contribute to HIV's replication?
It makes DNA copies of viral RNA, which are then integrated into the host's DNA
## Footnote
This allows the virus to hijack the host's cellular machinery.
148
What is the diameter of an HIV particle?
80 nm
## Footnote
This size is significant for understanding how the virus interacts with cells.
149
What happens when memory T cells are destroyed by HIV?
The immune response is impaired, leading to opportunistic infections
## Footnote
This is a critical factor in the progression from HIV to AIDS.
150
What is the link between AIDS and HIV?
HIV = virus which can lead to AIDS
151
What is the name of the enzyme found in HIV?
Reverse transcriptase
152
What does reverse transcriptase do?
Uses viral RNA as a template to build DNA
153
What allows HIV to attach to human cells?
Via glycoproteins that are complementary to host cell receptors
154
What type of cell does HIV infect?
T lymphocytes – helper T cells
155
How is HIV transmitted?
Sexual transmission / blood products / needle sharing, placenta / child birth / breast milk
156
What happens to someone who is infected with HIV during phase 2?
Phase 2 = HIV+ phase – no clinical signs of disease
157
Why can’t we treat HIV with antibiotics?
Antibiotics target cellular structures of bacteria. HIV is a virus
158
What are monoclonal antibodies?
Identical antibodies produced from clones of a single B cell
159
What is a direct ELISA used for?
Determine if a pathogen is present in a sample
160
What is an indirect ELISA used for?
Determine if an individual has antibodies against a pathogen
161
Describe the first step in a direct ELISA.
Plastic tray divided into wells, each well coated with a specific monoclonal antibody
162
What happens if the specific antigen is present in a direct ELISA?
It binds to the monoclonal antibodies, forming an antibody-antigen complex
163
What is the role of the second monoclonal antibody in a direct ELISA?
It binds to the antigen of interest and has an enzyme attached
164
What indicates a positive result in a direct ELISA?
Colour change occurs if the enzyme converts the substrate to a coloured product
165
What does a colourless well indicate in a direct ELISA?
No enzyme present to convert substrate into coloured product, indicating negative result
166
What is the significance of washing the wells in ELISA procedures?
Prevents false positives by removing unbound antibodies
167
What is the purpose of a calibration curve in ELISA?
To determine the precise amount of antigen or antibody in a sample
168
What is the first step in an indirect ELISA?
Antigen coated well
169
What does the enzyme-linked antibody bind to in an indirect ELISA?
It binds to the antibody of interest if present
170
What is a potential ethical issue associated with the use of monoclonal antibodies?
Reduce risk of harm / no credit for ‘playing God’
171
What is involved in risk assessments for experiments?
Valid control variables, repeats, control experiment, control group, large representative sample
172
What is the role of hybridoma cells in monoclonal antibody production?
They are immortal, antibody-producing cells formed by fusing plasma cells and cancer cells
173
Fill in the blank: ELISA stands for _______.
Enzyme Linked ImmunoSorbent Assay
174
What is the outcome if there is a lot of antigen in the sample during a direct ELISA?
Deeper colour due to more antibody binding and enzyme presence
175
What is the significance of the tertiary structure in monoclonal antibodies?
It determines the specific binding site for the antigen
176
True or False: Monoclonal antibodies can only target one specific antigen.
True
