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cells Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

eukaryote cells

A

animals, plants, fungi
DNA contained in a membrane-bound nucleus.
Nucleus has a double membrane.
DNA is tightly wrapped around proteins called histones.
Their DNA is a linear molecule.

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2
Q

Examples of prokaryote cells

A

bacteria, archae

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3
Q

Function of plasma membrane

A

Made of lipids and proteins
Controls movement of substances in and out the cell

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4
Q

Function of the nucleus

A

Controls the cells activities with instructions on how to make proteins.
Contains pores which allow substances to move between cytoplasm and nucleus.
Contains nucleolus which makes ribosomes.

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5
Q

Function of the mitochondrion

A

site of aerobic respiration and production of ATP

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6
Q

Function of chloroplast

A

Site of photosynthesis
Some in grana and some in stroma

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7
Q

Function of golgi apparatus

A

Makes lysosomes
Processes and packages lipids and proteins

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8
Q

Function of golgi vesicles

A

Made by golgi apparatus
Stores lipids and proteins made by golgi apparatus and transports them out of the cell

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9
Q

Function of lysosome

A

produces hydrolyic enzymes and stored in a membrane bound nucleus

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10
Q

Function of ribosomes

A

Site of protein synthesis

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11
Q

Function of rough endoplasmic reticulum

A

System of membranes that is continuous with the nucleus, with ribosomes on the outer surface. Site of synthesis and transport of proteins & glycoproteins.

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12
Q

Function of cell wall

A

In plants and algae it is made of cellulose and in fungi it is made of chitin
Supports cell and prevents it changing shape

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13
Q

Function of smooth endoplasmic reticulum

A

System of membranes with no ribosomes on the outer surface.

Site of synthesis, storage and transportation of lipids and carbohydrates.

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14
Q

Equation for magnification

A

size of image/ size of real object

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15
Q

What is resolution?

A

How sharp an image is. Higher resolution means u can see in more detail.

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16
Q

optical microscopes

A

Image is formed by passing light through specimen. Max resolution of 0.2 micrometres so you should use long wavelengths. No small organelles such as ribosomes can be seen.

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17
Q

electron microscopes

A

electrons are used to form an image. more detailed and can see organelles. max resolution of 0.0002 micrometres so use short wavelengths. max useful magnification + x1500000.

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18
Q

transmission electron microscopes (TEMs)

A

Focuses a beam of electrons which are transmitted through the specimen by a condenser electromagnet. Denser parts absorb more electrons so look darker on the image. Gives high resolution images and allows you to see internal structures. Only can view in a vacuum (dead specimens). Specimens must be thin. Image produced is a photomicrograph.

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19
Q

scanning electron microscopes (SEMs)

A

Scan a beam of electrons across the specimen which are collected in a cathode ray tube to form an image which is in 3D and shows the surface of the specimen. Can be used on thicker specimens.

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20
Q

eyepiece graticule

A

Placed into the eyepiece of an optical microscope.
No units.
Must be calibrated at each magnification using a stage micrometre.

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21
Q

stage micrometre

A

slide which is used to calibrate the scale on the eyepiece graticule at each magnification.
has units

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22
Q

how to measure cells?

A
  1. Line up the eyepiece graticule scale and stage micrometre scale on the objective lens.
  2. Count the no. of divisions on the eyepiece graticule as it = no. of divisions on the stage micrometre.
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23
Q

Method to study cells

A
  1. small drop of liquid on middle of slide
  2. place a thin specimen on top of liquid
  3. add a drop of stain (to identify parts of cell)
    4.stand coverslip upright next to specimen and gradually lower (no bubbles)
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24
Q

what are artefacts?

A

things you see as you look through a microscope that aren’t part of the specimen
eg. fingerprints and air bubbles.

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25
Q

steps in cell fractionation

A
  1. homogenisation
    2.filtration
  2. ultracentrifugation
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26
Q

homogenisation

A

Cells are mixed with an isotonic and ice cold solution and can be broken up in various ways such as using a blender.
A buffer solution is added to maintain pH.
Resultant fluid = homogenate.

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27
Q

why must the solution be isotonic, buffer and ice cold?

A

ice cold- to prevent enzyme activity so organelles aren’t digested
buffer- to maintain pH preventing the denaturing of enzymes
isotonic- prevents damage to the organelles through osmosis.

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28
Q

filtration

A

Homogenate solution is passed through a gauze to separate the large cell debris from the organelle.

New filtered solution is the supernatant.

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29
Q

ultracentrifugation

A

The supernatant is poured into a tube. This is put into a centrifuge machine. Heavy nuclei gets flung to the bottom and forms a pellet. Rest of organelles stay in supernatant.

Supernatant is poured into another tube and centrifuged at a higher speed and the next heaviest organelle (mitochondria) goes to the bottom. Supernatant is drained.

Process is repeated until all organelles are separated.

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30
Q

What is the function of mitosis?

A

Growth, repair and reproduction

31
Q

Interphase

A

DNA replicated.

32
Q

Prophase

A

Nuclear envelope breaks down.
Chromosomes condense.

33
Q

Metaphase

A

Chromosomes line up along the middle of the cell. Attached to the spindle by the centromere.

34
Q

Anaphase

A

Chromosomes break down into two chromatids. Sister chromatids break at the centromere. Spindles contract and pull chromatids to opposite poles.

35
Q

Telophase

A

Chromatids decondense and become chromosomes again. Nuclear envelope re forms. Cytoplasm splits and two identical daughter cells formed.

36
Q

Binary fission

A

Circular DNA and plasmids replicate. Cell membrane pinches inwards dividing cytoplasm in two. New cell wall forms.

37
Q

What are channel proteins?

A

Form water filled tubes allow water soluble ions to diffuse across the bilayer.

38
Q

Carrier proteins

A

Bind to ions or molecules such as glucose or amino acids. They change shape to carry molecules across the bilayer by active transport.

39
Q

Receptor proteins

A

Detect chemicals released from other cells

40
Q

What are phagocytes?

A

White blood cells which carries out phagocytosis.
They are some of the first to respond to an immune system trigger:
1. Phagocyte recognises a foreign antigen on a pathogen
2. Surrounds and engulfs pathogen
3. Pathogen contained in a vacuole in the cytoplasm of the phagocyte
4. A lysosome fuses with the vacuole and releases lysozymes which destroy the pathogen through hydrolysis
5. Phagocyte presents the pathogens antigens. Activates other immune system cells to respond. Becomes an antigen presenting cell

41
Q

What are lymphocytes?

A

T-cells and B-cells.
Some are responsible for killing bacteria and viruses. Other’s target the body’s own cells that are not properly working

Too many or too few lymphocytes can be a sign of disease.

42
Q

What are T-cells?

A

Mature in the thymus.
Have receptor proteins to bind to complementary antigens.

43
Q

Helper T-cells

A

Release chemical signals which activates B-cells

44
Q

Cytotoxic T-cells

A

Kills virally infected cells and tumours. Produces perforin which makes holes on the surface membrane. Makes cell permeable and it dies.

45
Q

What are B-cells?

A

Mature in bone marrow.
Covered in antibodies.
Each B-cell has a different shaped antibody on it’s surface membrane. When antibody meets a complementary antigen, it binds to it. Antigen enters the B-cell by endocytosis and gets presented on the surface of the B-cell. Helper T-cells bind to presented antigen. T-cells activate B-cells to reproduce by mitosis so B-cells clone into plasma cells.

46
Q

What are antibodies?

A

Proteins which bind to antigens to form an antigen-antibody complex.
Makes 2 light and 2 heavy polypeptide chains.
Soluble in blood and tissue fluid.
Have same constant sites but unique variable sites.

47
Q

What are monoclonal antibodies?

A

Created from B-cells and makes antibodies all identical in structure.
They can bind with anything you like and it will become the target molecule.

48
Q

What can monoclonal antibodies be used for?

A

Anti- cancer drugs
Pregnancy tests
ELISA tests

49
Q

Anti-cancer drugs

A

Cancer cells have tumour markers. It is possible to attach anti- cancer drugs to the antibodies and when the antibodies come into contact with cancer cells they will bind to tumour markers.
Drugs will build up in areas of the body where cancer is. Lesser side effects.

50
Q

Pregnancy tests

A

Designed to detect hCG which is found in the urine of pregnant women.
1. The application window contains monoclonal antibodies which attach to hCG and have blue beads attached.

  1. When window is urinated on, the hCG will bind to these antibodies.

3.They move along the strip

  1. Further up are a second set of monoclonal antibodies which are immobilised but also bind to hCG.

5.Blue line is seen.

  1. Any antibodies from the application window not bound to the hCG will continue to move along and bind to a diff set on monoclonal antibodies.
51
Q

ELISA tests

A

Enzyme linked immunosuppressant assay

52
Q

How does direct ELISA work?

A
  1. Sample taken from patient and antigens are extracted and bound to the inside of a well in a well tray.
  2. A known complementary antibody with an enzyme attached is added.
  3. If antigen is present in the well sample, the antibody will bind to it.
  4. Well is washed to remove unbounded antibodies.
  5. Substrate solution is added.
  6. If antibody is present solution will change colour.
53
Q

How does indirect ELISA test work?

A
  1. HIV antigen is bound to well in the well plate.
  2. Sample of blood is added which may contain many types of antibodies.
  3. if the body has made any HIV antibodies they will bind to the antigen and stick to the bottom of the plate.
  4. Wash well
  5. Second antibody with an enzyme bound is added to the well.
  6. Well is washed. All secondary antibodies removed.
  7. Solution added.
  8. Colour change shows HIV positive.
54
Q

What is HIV?

A

Human immunodeficiency virus.
Affects the immune system.
Leads to AIDS where the immune system eventually fails and makes those with it more vulnerable to other diseases.

55
Q

HIV host cells

A

Helper T-cells

56
Q

Initial infection of HIV

A

Patient may experience flu like symptoms
After initial infection, replication drops which is the latency period where patient won’t have symptoms.

57
Q

Symptoms of HIV

A

Reoccurring respiratory infections.

Infections of mucus membranes.

In late stages of AIDS there are few white blood cells so patients are susceptible to toxoplasmosis of the brain which is fatal.

58
Q

What does survival period of a patient with aids depend on?

A

The strain, their age, health and access to healthcare.

59
Q

Treatments of HIV

A

Anti viral drugs

60
Q

cellular

A

T-cells and other cells which interact with phagocytes

61
Q

humoral

A

B-cells and clonal selection and the production of monoclonal antibodies

62
Q

primary response

A

1st time a pathogen enters the body it activates the immune system. Slow response as there aren’t that many B-cells. Eventually the body will make enough of the correct antibody to overcome the pathogen. Body will show symptoms.

63
Q

memory cells (secondary response)

A

Memory T-cells remember the antigen
Memory B-cells remember the specific antibodies needed.
Person is now immune

64
Q

secondary response

A

If the pathogen re enters the body it can respond quicker. Clonal selection occurs faster. Memory T-cells divide into the correct type of T-cells to kill the pathogen and Memory B-cells react and divide into plasma cells quicker.

65
Q

what is passive immunity?

A

When you’re given antibodies not made in your own body eg from mothers placenta.
Protection is short term because antibodies given are broken down.

66
Q

what is active immunity?

A

You make your own antibodies after being exposed to a certain antigen eg natural (immune after catching a disease) or artificial (immune after given a vaccination).
Protection is long term because antibody is produced in response to complementary antigen present in the body.

67
Q

Vaccination

A

Introducing a dead or inactive pathogen to the body but antigens on its surface will still produce an immune response. Active immunity and results in the creation of memory b cells.
Booster vaccinations are sometimes taken years later to ensure memory cells have been created.

68
Q

What is a disadvantage of taking a vaccination orally?

A

Enzymes in the digestive system may break it down or molecules are too large to be absorbed.

69
Q

What is herd immunity?

A

If a % of the population have been vaccinated then the chances of those who have not been vaccinated contracting the disease is also reduced.

70
Q

Ethics around vaccines

A

All vaccines are animal tested and animals have no choice and may suffer.
Animal based substances may be used to create a vaccine.

Testing on humans carries risk eg volunteers may think they are immune but the vaccine may not have worked.
Some people do not want vaccines due to allergies and fear of side-effects.

71
Q

What is antigenic variation?

A

Some pathogens can change their antigens due to changes in the DNA of the pathogen when you are infected a second time. Memory cells from the primary infection won’t recognise the antigen. Your immune system will have to start from the beginning. eg HIV.

72
Q

Influenza

A

Changes it’s antigens regularly. Memory cells from a vaccine of one strain will not work on the new strain. The two strains are immunologically distinct. A new vacc needs to be created every year. Vaccines are created against a few different strains and governments needs to decide which to buy for the vaccination programmes.

73
Q

What is peer review?

A

When scientists find new info from a study, they present their research to other scientists in that field.

Biology (7 decks)

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