Cells Flashcards
1
Q
What are the distinguishing features of eukaryotic cells?
A
Eukaryotic cells have membrane bound organelles, and their genetic material is enclosed in a nucleus.
2
Q
What is the structure of the cell-surface membrane?
A
The cell surface membrane is a phospholipid bilayer. Phospholipids have hydrophilic phosphate heads and hydrophobic fatty acid tails, so the heads point outwards and the tails point inwards. It also contains intrinsic and extrinsic proteins, glycolipids and glycoproteins on the exterior surface, and cholesterol molecules.
3
Q
What is the function of the cell-surface membrane
A
It is selectively permeable, selectively allowing some substances in and out of the cell. It also has receptors on its surface, allowing recognition of foreign and abnormal cells.
4
Q
Describe the structure of the nucleus
A
The nucleus is surrounded by a double membrane called the nuclear envelope, which has nuclear pores in it. The interior of the nucleus consists of the nucleoplasm, within which is the nucleolus. Also in the nucleoplasm is chromatin.
5
Q
Describe the function of the nucleus
A
Holds and stores genetic information, which codes for proteins. It is also the site of DNA replication as well as the site of transcription, producing mRNA. Also, Ribosomes are produced in the nucleolus.
6
Q
Describe the structure of a ribosome
A
Made up of ribosomal RNA and 2 subunits of protein. It is not membrane bound.
7
Q
Describe the function of a ribosome
A
Site of protein synthesis
8
Q
Describe the function of the RER
A
Ribosomes on the surface synthesise proteins, which are then processed, in the RER and are then packaged into vesicles for transport around the cell.
9
Q
Describe the function of the SER
A
Synthesises and processes lipids
10
Q
Describe the structure of the Endoplasmic Reticulum
A
Consists of a system of fluid filled channel-like membranes. The RER has attached Ribosomes.
11
Q
Describe the function of the Golgi Apparatus and Vesicles
A
The Golgi modifies and packages proteins and lipids, and also produces lysosomes. The Golgi vesicles transport proteins and lipids around the cell.
12
Q
Describe the function of lysosomes.
A
They release hydrolytic enzymes called lysozymes, which hydrolyse pathogens.
13
Q
Describe the structure of lysosomes.
A
They are surrounded by a membrane and contain lysozymes, which are digestive enzymes.
14
Q
Describe the structure of mitochondria
A
Mitochondria consist of an outer membrane, Cristae, which are the inner membrane folds, and the matrix containing small 70S ribosomes and circular DNA
15
Q
Describe the function of mitochondria
A
Mitochondria are the site of aerobic respiration, producing ATP for energy release.
16
Q
Describe the structure of chloroplasts
A
Chloroplasts have a double membrane, and stroma, which contain thylakoid membrane, 70S ribosomes, circular DNA, starch granules and lipid droplets. Chloroplasts also contain lamellae, and grana (stacks of thylakoid)
17
Q
Describe the function of chloroplasts
A
Absorb light energy for photosynthesis
18
Q
Describe the structure of the cell wall
A
Composed of Cellulose in plants and algae. Composed of Chitin in fungi, and of Murein in bacteria.
19
Q
Describe the function of the cell wall
A
Provides structural support to the cell, preventing the cell bursting due to osmotic action.
20
Q
Describe the structure of the vacuole
A
Contains cell sap and is surrounded by a tonoplast membrane.
21
Q
Describe the function of the vacuole
A
Maintains turgor pressure in the cell, stopping the plant wilting. Also contains cell sap which stores sugars, amino acids, pigments and any waste chemicals.
22
Q
What is a tissue?
A
Group of specialised cells with a similar structure working together to perform a specific function.
23
Q
What are the 2 main distinguishing features of prokaryotic cells?
A
They lack membrane-bound organelles, and therefore their genetic material is not enclosed in a nucleus
23
Q
What is an organ?
A
Group of tissues working together to perform a specific function
23
What is an organ system?
Group of organs working together to perform specific functions.
24
Describe the general structure of prokaryotic cells
They consist of cytoplasm, and within the cytoplasm are 70S Ribosomes and circular DNA, which is free in the cytoplasm and not associated with proteins. Sometimes, this DNA is in the form of plasmids. The cells are surrounded by a cell-surface membrane and a murein cell wall. Some prokaryotic cells are also surrounded by a capsule, and some also have flagella.
25
Name 5 differences between Eukaryotic and Prokaryotic Cells
* Eukaryotic Cells have membrane bound organelles, whereas Prokaryotic Cells have no membrane-bound organelles.
* Eukaryotic Cells have a nucleus which contains DNA, whereas Prokaryotic Cells have no nucleus, so their DNA is free in the cytoplasm.
* In Eukaryotic Cells, the DNA is long, linear, and associated with histone proteins, whereas in Prokaryotic Cells, the DNA is short, circular, and not associated with any proteins.
* Eukaryotic Cells contain larger (80S) Ribosomes, whereas Prokaryotic Cells contain smaller (70S) Ribosomes.
* Prokaryotic Cells have a Cell Wall made of Murein, whereas in Eukaryotic Cells, where present, the Cell Wall is made of Cellulose or Chitin in fungi.
26
Why are Viruses described as acellular and non-living?
They are acellular because they are not made of cells, and they have no organelles. They are non-living because they can not independently replicate.
27
Describe the general structure of a virus particle.
Contains Nucleic acids surrounded by a capsid (protein coat) They have attachment proteins on surface to allow attachment to specific host cells. Some also surrounded by a lipid envelope e.g. HIV
28
What is magnification?
The number of times larger the image is than size of the real object
29
What is the equation for magnification?
Magnification = Size of Image / Size of real object
30
What is Resolution?
Minimum distance apart 2 objects can be to be distinguished as separate objects
31
Optical Microscopes: How do they work, What kind of image do they produce, and what is the resolution and magnification like?
* Light focused using
glass lenses
* Light passes through specimen, different structures absorb different amounts & wavelengths
* Generates a 2D image of a
cross-section
* Low resolution due to long wavelength of light
* Can’t see internal structure of
organelles
* Specimen has to be thin
* Low magnification (x 1500)
* Can view living organisms
* Simple preparation
* Can show colour
32
Transmission Electron Microscopes: How do they work, What kind of image do they produce, and what is the resolution and magnification like?
* Electrons focused using
electromagnets
* Electrons pass through specimen,
denser parts absorb more and
appear darker
* Generates a 2D image of a
cross-section
* Very high resolution due to short
wavelength of electrons
* Can see internal structures of organelles
* Specimen has to be very thin
* High magnification (x 1,000,000)
* Can only view dead / dehydrated
specimens as uses a vacuum
Can only view dead / dehydrated
specimens as uses a vacuum
* Complex preparation so
artefacts often present
* Does not show colour
33
Scanning Electron Microscopes: How do they work, What kind of image do they produce, and what is the resolution and magnification like?
* Electrons focused using
electromagnets
* Electrons deflected / bounce
off specimen surface
* Generates a 3D image
of surface
* High resolution due to short
wavelength of electrons
* Can’t see internal structures
* Specimen does not need to be thin
* High magnification (x 1,000,000)
* Can only view dead / dehydrated
specimens as uses a vacuum
* Complex preparation so
artefacts often present
* Does not show colour
34
What may occur if there are issues in the preparation of microscope slides?
May result in air bubbles or particles of dust etc. in the slide. This could result in artefacts which could be mistaken for cell organelles and other structures that are not actually present.
35
What is the order of units of measurement, getting 1000 times smaller each time?
Metre (m), Millimetre (mm), Micrometre (µm), Nanometre (nm)
36
Describe how the size of an object viewed with an optical microscope can be measured
1. Line up scale of eyepiece graticule with scale of stage micrometre
2. Calibrate eyepiece graticule - use stage micrometre to calculate size of divisions on eyepiece graticule
3. Take micrometre away and use graticule to measure how many divisions make up the object
4. Calculate size of object by multiplying number of divisions by size of division
5. Recalibrate eyepiece graticule at different magnifications
37
Describe and explain how cell fractionation and
ultracentrifugation can be used to separate cell components
1. Homogenise tissue to disrupt cell membrane, breaking open cells and releasing the organelles
2. Place in a cold, isotonic, buffered solution (Cold to reduce enzyme activity → so organelles not broken down / damaged, Isotonic so water doesn’t move in or out of organelles by osmosis → so organelles don’t burst, Buffered to keep pH constant → so enzymes don’t denature
3. Filter homogenate to remove large, unwanted debris
4. Ultracentrifugation - separates organelles in order of density. Centrifuge homogenate in a tube at a relatively low speed. Remove pellet of heaviest organelle and respin supernatant at a higher speed. Repeat at increasing speeds until separated out.
38
What order do the organelles separate during Ultracentrifugation?
1. Nuclei
2. Chloroplasts and Mitochondria
3. Lysosomes
4. Endoplasmic Reticulum
5. Ribosomes
39
Describe the stages of the cell cycle in eukaryotic cells.
1. Interphase - DNA undergoes semi-conservative replication, leading to 2 sister chromatids joined at the centromere. Also, the number of organelles and the volume of cytoplasm increases.
2. Mitosis - The nucleus divides to produce 2 nuclei with identical copies of DNA
3. Cytokinesis - The cytoplasm and cell membrane divide to form 2 new genetically identical daughter cells.
40
What happens in Prophase?
The Chromosomes condense, becoming visible. They will appear as 2 sister chromatids joined at the centromere. The nuclear envelope breaks down and the centrioles move to opposite poles, forming the spindle network.
41
What happens in Metaphase?
The spindle fibres attach to the chromosomes at the centromere, and chromosomes align along the equator.
42
What happens in Anaphase?
The spindle fibres contract and the centromere divides, pulling sister chromatids to opposite poles of the cell.
43
What happens in Telophase?
Chromosomes uncoil, and the nuclear envelope reforms to form 2 new nuclei. Spindle fibres and centrioles are broken down.
44
Explain the importance of mitosis in the life of an organism
Cells divide to produce 2 genetically identical daughter cells for:
* Growth
* Replacing cells in damaged tissue
* Asexual reproduction
45
How do tumours and cancers form?
Mitosis is a controlled process. Mutations in the gene controlling mitosis (oncogenes) can lead to uncontrolled cell division. This may result in a mass of abnormal cells, forming a tumour. If this tumour metastasises, it becomes malignant and cancerous.
46
Suggest how cancer treatments control rate of cell division.
Some cancer treatments disrupt spindle fibre formation and activity, so that the spindle fibres can not attach to the chromosomes at the centromere, and the chromatids can't be separated to opposite poles during anaphase, therefore preventing mitosis. Others prevent DNA replication by inhibiting DNA Polymerase, so that cells can't make 2 copies of each chromosome, so prevents mitosis.
47
What is the main issue with most cancer treatments?
Most cancer treatments kill cells or prevent mitosis, therefore healthy cells will also be destroyed or their cell cycle will be disrupted.
48
Describe how prokaryotic cells replicate.
They replicate via Binary Fission:
* Replication of Circular DNA and any Plasmids that are present.
* Division of the cytoplasm, producing 2 new daughter cells
* The 2 new daughter cells each contain a single copy of the Circular DNA and a variable number of copies of plasmids.
49
How do viruses replicate?
1. Attachment proteins attach to the complimentary receptors on host cell
2. They inject viral nucleic acid into host cell
3. Infected host cell replicate the virus particles nucleic acid, producing viral proteins.
4. The virus is assembled then released.
50
Explain the role of cholesterol in cell membranes.
Restricts movement of other molecules making up the membrane, increasing rigidity
51
Suggests how cell membranes are adapted for other functions (not transport)
The phospholipid bilayer is fluid, so it can bend for vesicle formation and phagocytosis. The glycoproteins and glycolipids on the surface act as receptors and antigens, involved in signalling and recognition.
52
Describe how movement across membranes occurs by simple diffusion
Lipid-soluble, non-polar or very small substances move from an area of higher concentration to an area of lower concentration down the concentration gradient across the phospholipid bilayer. This is a passive process, meaning it requires no energy from ATP.
53
Describe how movement across membranes occurs by facilitated diffusion
Water-soluble, polar, large molecules move down the concentration gradient through specific channel and carrier proteins. This is a passive process, meaning it requires no energy from ATP.
54
Explain the role of carrier and channel proteins in facilitated diffusion
Channel proteins have a hydrophilic pore filled with water which allows water-soluble molecules to diffuse across the membrane. Carrier proteins facilitate the diffusion of larger molecules. When complimentary substances bind to the binding site, the carrier protein will change shape via conformational change to transport the substance across the membrane.
55
Describe how movement across membranes occurs by osmosis
Water moves from an area of high water potential to an area of low water potential down a water potential gradient through a partially permeable membrane until equilibrium. This is a passive process, meaning it requires no energy from ATP.
56
What is the maximum water potential and what substance would have this amount?
0ψ or 0kPA, distilled water
57
Describe how movement across membranes occurs by active transport
Substances move from an area of lower concentration to an an area of high concentration, against the concentration gradient. This requires energy from the hydrolysis of ATP and also requires specific carrier proteins
58
Describe the role of carrier proteins and the importance of the hydrolysis of
ATP in active transport
The complementary substance binds to specific carrier protein, and ATP also binds to the carrier protein, resulting in it being hydrolysed into ADP + Pi, releasing energy. This energy is used to change the shape of the carrier protein, transporting the substance to the other side of the membrane. Then, the inorganic Phosphate is released, causing the protein to return to the original shape
59
Describe how movement across membranes occurs by co-transport
Two different substances bind to a
co-transporter protein (type of carrier protein) and move through it simultaneously. Often this involves movement of one substance against its concentration gradient and the movement of the other down its concentration gradient
60
Name 4 factors affecting the rate of movement across cell membranes and explain how they affect it.
* Surface area of membrane: Increasing surface area increases the rate of movement
* Number of channel/carrier proteins: Increasing number of channel / carrier proteins increases rate of facilitated diffusion / active transport
* Concentration gradient: Increasing concentration gradient increases rate of facilitated diffusion (until number of channel / carrier proteins becomes a limiting factor as all are saturated), simple diffusion and osmosis.
* Water potential gradient: Increasing water potential gradient increases rate of osmosis
61
Explain the adaptations of some specialised cells in relation to the rate of transport across their membranes
* The membrane is folded, for example in microvilli in ileum. This increases surface area, increasing the rate of transport.
* More protein channels / carriers for facilitated diffusion or active transport (Carrier Proteins only)
* Large number of mitochondria to release more ATP and therefore releasing more energy by aerobic respiration for active transport
62
What is an antigen?
A foreign protein which stimulates an immune response, leading to the production of a complimentary antibody.
63
How are cells identified by the immune system?
Each cell has specific antigen on it’s cell surface. These antigens are proteins and have a specific tertiary structure, which help the immune system to recognise them as self or foreign.
64
What types of cells and molecules can the immune system identify?
* Pathogens (microorganisms that cause disease)
* Cells from other organisms (e.g. organ transplants)
* Abnormal body cells (e.g. tumour cells or virus infected cells)
* Toxins (Harmful chemicals release by some bacteria)
65
What is the non-specific immune response?
Phagocytosis
66
What are the specific immune responses?
Cellular and humoral response.
67
Describe phagocytosis of pathogens
1. Phagocyte is attracted to chemicals made by pathogen or recognises it’s foreign antigens on cell surface membrane.
2. Phagocyte engulfs pathogen by endocytosis, surrounding it with its cell membrane.
3. Pathogen contained in phagosome within the cytoplasm of the phagocyte.
4. Lysosome fuses with phagosome to produce a phagolysosome and releases lysozymes.
5. Lysozymes hydrolyse the pathogen and the products are absorbed into the phagosome if they are soluble, but are expelled from the cell if they are insoluble.
68
How does phagocytosis lead to the cellular and humoral responses?
Phagocytosis leads to presentation of antigens, where antigens are displayed on the phagocyte cell-surface membrane, stimulating the specific immune response (cellular and humoral response).
69
Describe the response of T lymphocytes to a foreign antigen (the cellular response).
T-Lymphocytes recognise antigens on the surface of antigen presenting cells. Specific T-Helper cells with complimentary receptors on their cell surface bind to the antigen on the antigen-presenting cell, causing the T-Helper cells to divide rapidly by mitosis, which then stimulate the production of Cytotoxic T Cells (which produce chemicals such as perforin to kill infected cells and pathogens), Specific B Cells (which stimulate the humoral response, including the production of antibodies) and Phagocytes (which engulf pathogens by phagocytosis).
70
Describe the response of B lymphocytes to a foreign antigen (the humoral response)
B Lymphocytes can recognise free antigens. When they come across a foreign antigen, specific B-Lymphocytes with complimentary receptors bind to the antigens, and is stimulated by T-Helper cells to divide rapidly by mitosis. Some of these clones differentiate into B-Plasma cells, which secrete large amounts of antibodies, which are specific to the foreign antigen. Others differentiate into B-Memory cells, which remain in the blood until the secondary immune response.
71
What are antibodies?
Antibodies are quaternary structure proteins and they consist of 4 polypeptide chains. They are secreted by B-Plasma cells in response to specific antigen. They are complimentary to their specific antigen, and when bind to it, they form an antigen-antibody complex.
72
Draw and label the structure of an antibody.
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.thesciencehive.co.uk%2Fimmune-response-a-level&psig=AOvVaw18Tp-0NiivX2iWLKfl9f_u&ust=1712164476099000&source=images&cd=vfe&opi=89978449&ved=0CBIQjRxqFwoTCMizj-2DpIUDFQAAAAAdAAAAABAE
73
How do antibodies lead to the destruction of pathogens?
Antibodies bind to complimentary antigens on the surface of pathogens . Each antibody can bind to 2 pathogens at a time, causing agglutination. This allows the antibodies to attract phagocytes, which destroy the pathogens via phagocytosis.
74
What are the differences between the primary and secondary immune response?
The primary response refers to the immune response which occurs upon the first exposure to an antigen. Antibodies are produced slowly and at a lower concentration as it takes time for specific B-Plasma cells to be stimulated to produce the specific antibodies. Memory cells are produced in the primary response. The secondary response refers to the immune response that occurs upon the second exposure to an antigen. In the secondary response, antibodies are produced faster and at a higher concentration. This is because B memory cells are present in the blood, and they rapidly undergo mitosis in order to rapidly produce specific antibodies.
75
What is a vaccine?
The injection of antigens from dead, weakened or inactive pathogens, stimulating a weak immune response, producing memory cells.
76
How do vaccines provide protection to individuals against disease?
1. Specific B lymphocyte with complementary receptor binds to antigen
2. Specific T helper cell binds to antigen-presenting cell and stimulates B cell
3. B lymphocyte divides by mitosis to form clones
4. Some differentiate into B plasma cells which release antibodies
5. Some differentiate into B memory cells
6. On secondary exposure to antigen, B memory cells are already present, so they can rapidly divide by mitosis to produce B plasma cells
7. These release antibodies faster and at a higher concentration
77
How do vaccines provide protection for entire populations against disease?
Herd Immunity - If a large proportion of the population is vaccinated, then the majority of people will not become ill from infection. This results in fewer infected people to pass the pathogen, and therefore unvaccinated people are less likely to come into contact with someone with the disease. This helps to protect vulnerable people such as young children and elderly people, as well as other people who do not get vaccinated due to personal or medical reasons.
78
What are the differences between active and passive immunity?
* In active immunity, the person is exposed to the antigen, either natural (via primary infection) or artificially (via vaccination), whereas in passive immunity, the person has not been exposed to the antigen.
* In active immunity, the antibodies were produced and secreted by the person’s own B-plasma cells, but in passive immunity the antibodies that are introduced into the body were produced by another organism (e.g. through breast milk)
* Active immunity is slower as it requires a full immune response. Passive immunity is much quicker as the antibodies can act immediately.
79
Explain the effect of antigen variability on disease and disease prevention.
The tertiary structure of the antigens on the surface of pathogens changes due to a mutation, causing a change in shape. Therefore, the B-memory cells can no longer bind to the antigen when exposed to the antigen, and the specific antibodies are no longer complimentary so can not bind to the antigen. Therefore, there is no more immunity.
80
Draw and label the structure of a HIV particle.
https://images.squarespace-cdn.com/content/v1/5c5aed8434c4e20e953d6011/1591278433693-1D7XKEM9RC99Y8B861EY/hiv+structure.jpg
81
Describe the replication of HIV in helper T-Cells.
1. HIV attachment proteins attach to receptors on helper T cell.
2. Lipid envelope fuses with T-Helper cell-surface membrane, releasing capsid into cell.
3. Capsid breaks down, releasing RNA and reverse transcriptase into the cell.
4. Reverse transcriptase converts viral RNA to DNA.
5. Viral DNA is inserted into helper T cell DNA, so it is replicated when cells replicate.
6. DNA is used to make HIV RNA and proteins at the host ribosomes.
7. Virus particles are assembled, which bud off from the cell membrane and continue infecting other cells.
82
How does HIV cause AIDS?
HIV infects and kills T-Helper cells. Therefore, T-Helper cells can’t stimulate Cytotoxic T Cells , B-Cells and Phagocytes. This means that B Plasma cells can’t release as many antibodies, leading to the deterioration of the immune system. This makes the patient more susceptible to opportunistic infections, leading to many of the patient’s healthy body cells being destroyed.
83
Name the 3 main ways that HIV can be transmitted
* Having unprotected sex with an infected person.
* Close contact with the blood of an infected person (via the sharing of needles for drug use or the use of infected blood in blood transfusions)
* Mother to child (Shared through the placenta or through breast milk).
84
Why are antibiotics ineffective against viruses?
Viruses do not have structures and processes that antibiotics inhibit. Viruses do not have metabolic processes and they do not have bacterial enzymes or a murein cell wall.
85
How can monoclonal antibodies be used in medical treatments?
Monoclonal antibodies have a specific tertiary structure and therefore their antigen binding site is complementary to the receptor of an antigen found only on a specific cell type (e.g. cancer cell). Therapeutic drugs can be attached to the monoclonal antibodies, so the antibody will bind to the specific cell, forming antigen-antibody complex, delivering the drug to the specific cell.
86
How can monoclonal antibodies be used in medical diagnosis?
Monoclonal antibodies have a specific tertiary structure and therefore their antigen binding site is complementary to the receptor of the antigen associated with diagnosis. Fluorescent markers can be attached to the monoclonal antibody, and if the antibody binds to the receptor of the specific antigen, it will form an antigen-antibody complex which will be visible so that scientists can diagnose diseases by identifying which antigen is present.
87
Explain the use of antibodies in the ELISA test to detect antigens.
1. Attach sample with potential antigens to well
2. Add complementary monoclonal antibodies with enzymes attached. They will bind to antigens if present.
3. Wash well to remove unbound antibodies (to prevent false positive)
4. Add substrate so that the enzymes create products that cause a colour change (positive result)
88
Explain the use of antibodies in the ELISA test to detect antibodies.
1. Attach antigens to well that are complimentary to the antibody you are testing for.
2. Add sample with potential antibodies, wash to remove unbound antibodies.
3. Add complementary monoclonal antibodies
with enzymes attached, which will bind to antibodies if
present,
4. Wash well to remove unbound antibodies.
5. Add substrate so that enzymes create products that
cause a colour change (positive result).
89
What is the purpose of a control well in the ELISA test?
So that you can compare it to the test well to ensure that only the enzyme caused the colour change and that all unbound antibodies had been washed away.
90
How do pregnancy tests use monoclonal antibodies?
1. Mobile monoclonal antibodies that are complimentary to the hCG protein are attached to a coloured bead.
2. If there is any hCG in the urine (indicating pregnancy) then it will bind to the antibodies, forming a HCG-antibody complex.
3. The urine moves up the strip, until in reaches a line of immobilised monoclonal antibodies which only binds to the HCG-antibody complex. If the test is positive, this first this line will change colour.
4. The urine continues up the test strip to a line of immobilised monoclonal antibodies which only bind to the mobile monoclonal antibodies, regardless of whether there in hCG attached or not. This line indicates that the test worked.
91
Suggest some points to consider when evaluating methodology relating to the use of vaccines and monoclonal antibodies.
* Was the sample size large enough to be representative?
- Were participants diverse in terms of age, sex, ethnicity and health status?
* Were placebo / control groups used for comparison?
* Was the duration of the study long enough to show long-term effects?
* Was the trial double-blind to reduce bias?
92
Suggest some points to consider when evaluating data relating to the use of vaccines and monoclonal antibodies.
* What side effects were observed, and how frequently did they occur?
* Was a statistical test used to see if there was a significant difference between start & final results?
* Was the standard deviation of final results large, showing some people did not benefit?
* Did standard deviations of start & final results overlap, showing there may not be a significant difference?
* What dosage was optimum? Does increasing dose increase effectiveness enough to justify extra cost?
* Was the cost of production & distribution low enough?
* What are the ethical issues surrounding the use of vaccines and monoclonal antibodies?
