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Mock Revision Topic 2 Flashcards

Cells, Transport + Immunity

1
Q

Briefly describe the structure and function of the cell-surface membrane

A

Phospholipid bilayer containing proteins which controls the movement of substances into and out of the cell

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2
Q

Describe the nucleus (3)

A
  1. Contains chromosomes consisting of protein-bound, linear DNA.
  2. Has one or more nucleoli surrounded by a double membrane/nuclear envelope
  3. Which contains nuclear pores
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3
Q

Describe the mitochondria (include the terms double membrane, cristae, matrix, ribosome, DNA) (5)

A
  1. Surrounded by a double membrane
    Inner membrane folded and called cristae.
  2. Folding provides a larger surface area so more ATP synthase present.
  3. Matrix contains enzymes involved in aerobic respiration
  4. Contains 70S ribosomes
  5. DNA is short, circular and not associated with proteins.
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4
Q

Describe the chloroplast
(include the terms double
membrane, grana, lamellae,
stroma, ribosome, DNA) (8)

A

1.Flattened disc shape surrounded by a double membrane
2. Contain membrane inside called thylakoid membranes with chlorophyll embedded inside
3. Stacks of thylakoids are called grana
4. Lamellae are thylakoid membrane linking grana to each other
5.Stroma contains enzymes involved in photosynthesis
6. Also present in the stroma are starch grains and lipid droplets
7.Contains 70S ribosomes
8. DNA is short, circular and not associated with proteins.

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5
Q

Describe the function of the golgi apparatus include golgi vesicles (3)

A
  1. Packages lipids and proteins into vesicles for secretion
  2. Modifies lipids and proteins (e.g. produces glycolipids and glycoproteins)
  3. Produces lysosomes
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6
Q

What is a lysosome and what is its function ? (4)

A
  1. Vesicle containing lysozyme/hydrolytic enzymes
  2. Involved in secretion of lysozyme/hydrolytic enzymes from the cell
  3. Fuses with phagocytic vesicle to release hydrolytic enzymes to hydrolyse the contents of the phagocytic vesicle
  4. Fuses with vesicle containing worn out/old organelles to digest them – autophagy.
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7
Q

What is a ribosome, where are they found, what is their function? (4)

A
  1. Made from protein and rRNA
  2. Composed of two sub units
  3. Found in the cytoplasm or on rough endoplasmic reticulum
  4. Protein synthesis
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8
Q

What are the functions of smooth and rough endoplasmic reticulum?

A

Rough – Synthesises /produces (secretory) proteins
Smooth – produces and transports lipids

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9
Q

What is the cell wall made of in:
Plants
Algae
Fungi
Prokaryotes

A

Plants – cellulose
Algae – Cellulose and glycoprotein
Fungi – Chitin
Prokaryotes - Murein

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10
Q

What is the role of the cell vacuole in plants?

A
  1. Contains cell sap - water, sugar and salts (may also contain pigment)
  2. Helps maintain pressure inside the cell and keep the cell turgid.
  3. Provides support for non-woody plants and prevents them from wilting.
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11
Q

How are specialised cells organised? (4)

A
  1. Cells
  2. Tissues - similar cells that perform a specific function and have a common origin
  3. Organ - different tissues performing a specific physiological function
  4. Organ system - Several organs working together to form a system
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12
Q

List 4 ways ALL prokaryotic cells differ from eukaryotic cells

A

Prokaryotic - Circular DNA
Eukaryotic - Linear DNA
Prokaryotic - 70S ribosomes
Eukaryotic - 80S ribosomes
Prokaryotic - No membrane bound organelles
Eukaryotic - Membrane bound organelles (e.g. nucleus, mitochondria etc)

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13
Q

List 3 things that some prokaryotic cells have

A

Capsule
Flagellum
Plasmid (s)

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14
Q

Describe the structure of virus particles (4)

A
  1. Contains DNA or RNA / nucleic acid
  2. Genetic material contained inside a capsid
  3. Has attachment proteins
  4. May have a lipid envelope
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15
Q

What are the limitations of optical microscopes?

A

Lower resolution because the wavelength of light is longer than that of an electron beam.

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16
Q

What are the limitations of electron microscopes in general? (3)

A
  1. Requires a vacuum so can’t look at live specimens
  2. Complicated staining techniques so requires training
  3. Image in black and white
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17
Q

What are the limitations of SEM microscopes? (2)

A
  1. Can only see surface structures- cannot see internal structures.
  2. Lower resolution than TEMs
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18
Q

What are the limitations of TEM microscopes? (2)

A
  1. Complicated staining technique can result in artefacts
  2. Can only be used to view very thin samples which can break down over time
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19
Q

What is magnification?

A

How much bigger the image is than the specimen you are viewing

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20
Q

What is resolution?

A

How well the microscope can distinguish between two points which are close together

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21
Q

What is the formula for calculating magnification?

A

Magnification = image size / actual size

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22
Q

What is cell fractionation used for?

A

Separation of organelles from the rest of the cell

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23
Q

What is ultracentrifugation used for?

A

To separate organelles based on their densities. Larger organelles will be spun out at the lower speeds.

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24
Q

During which stage of the cell cycle does DNA replication occur?

A

Interphase

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25
What is the first stage of mitosis and what occurs in it? (2)
Prophase 1. Nuclear membrane and nucleolus break down. 2. Visible chromosomes
26
What is the second stage of mitosis and what occurs in it? (1)
Metaphase Chromosomes line up at the equator of the cell attached to the spindle fibres by their centromeres
27
What is the third stage of mitosis and what occurs in it? (1)
Anaphase Centromeres splits and sister chromatids separate and are pulled apart to opposite poles of the cell
28
What is the fourth stage of mitosis and what occurs in it? (3)
Telophase 1. Chromosomes uncoil to form chromatin 2. Nuclear membrane reforms 3. Two nuclei in one cell.
29
What is the role of the spindle fibres? (2)
1. Attach to centromere of chromosomes and move them to the to the equator of the cell 2. Seperate sister chromatids by pulling them to opposite poles of the cell
30
What is cytokinesis?
Division of the cytoplasm
31
What can uncontrolled cell division lead to?
Tumours
32
What does binary fission in prokaryotic cells involve? (3)
1. Elongation of the cell 2. Replication of DNA and plasmids 3. Division of the cytoplasm / formation of a septum
33
How are viruses replicated? (5)
1. Viral nucleic acid enters the host cell 2. Viral RNA converted to Viral DNA (if required) 3. Viral DNA incorporated into host cell DNA 4. Viral mRNA produced and used make viral proteins 5. New viral particles assembled
34
Describe the structure of cell membrane (7)
1. Phospholipid bilayer 2. Hydrophilic phosphate heads are faced towards the outside and hydrophilic fatty acid tails towards the inside 3. Glycoproteins embedded in the bilayer - act as antigens 4. Channel proteins – facilitated diffusion 5. Carrier proteins – facilitated diffusion and active transport 6. Glycolipids - phospholipids with carbohydrate chains attached 7. Cholesterol provides stability by making the membrane less fluid
35
Describe simple diffusion
Small / lipid soluble / non-polar molecules move down a concentration gradient through the phospholipid bilayer
36
Describe facilitated diffusion
Movement of water soluble / polar / ions down a concentration gradient through channel or carrier proteins
37
Describe osmosis
The net movement of water molecules from a higher to a lower water potential across a partially permeable membrane
38
Describe active transport
Movement of water soluble / polar / ions against a concentration gradient through carrier proteins, requiring ATP
39
How can cells be adapted for rapid transport? (2)
1. Microvilli - increases the surface area for diffusion/facilitated diffusion/active transport 2. Many mitochondria produce ATP for active transport / co-transport
40
Define an antigen
Foreign / non-self protein / glycoprotein which stimulates an immune response (production of antibodies).
41
What do proteins and other surface molecules allow the immune system to identify? (4)
* Pathogens * Cells from other organisms of the same species * Abnormal body cells * Toxins
42
What are lysozymes used for?
Hydrolysis / digestion of pathogens or toxins ingested by phagocytes
43
Describe phagocytosis (3)
1. Pathogen engulfed into a phagocytic vesicle 2. Lysosome fuses with the phagocytic vesicle and releases lysozyme/hydrolytic enzymes 3. Pathogen destroyed/digested by hydrolysis
44
What is a T lymphocyte and what is its role in the immune system?
Type of white blood cell They have receptors on their surface and are activated when they bind to complementary antigens presented by phagocytes (APCs)
45
What is clonal selection?
Where B lymphocytes with an antibody complementary to the antigen bind to the antigen and are activated to divide by mitosis forming clones
46
What is a monoclonal antibody?
One type of antibody produced by clones of one specific B cell (plasma cell)
47
What is a TH cell and what is its role in the immune system? (3)
Helper T lymphocyte 1. When the receptor in its cell surface membrane binds to a complementary antigen it will activate a specific B lymphocyte to divide by mitosis 2. Activate cytotoxic T cells 3. Also stimulates phagocytes
48
What is a TC cell and what is its role in the immune system? (3)
Cytotoxic T cell 1. Has receptors on its surface. 2. If its receptors bind to a complementary antigen, the cytotoxic T cell will destroy the cell 3. Involved in the cellular response
49
What is a B lymphocyte and what is its role in the immune system? (4)
1. Involved in the humoral response 2. They have antibody in their cell surface membrane. 3. When activated they divide by mitosis and form plasma cells which produce and secrete antibody into the blood plasma 4. Form memory B cells which are involved in the secondary response
50
What is a plasma cell and what is its role in the immune system? (2)
1. Type of B lymphocyte 2. Produces and secretes a specific antibody into the blood plasma
51
Define an antibody and describe its structure (5)
1. Quaternary protein made of four polypeptides (two heavy/two light chains) with specific tertiary structure 2. Produced by (B) plasma cells 3. Chains are joined by disulphide bonds 4. Constant region - sequence of amino acids the same for that group of antibody 5. Variable region - different sequence of amino acid in each different antibody resulting in different shaped binding sites complementary to different antigens
52
What is a memory cell and what is its role in the immune system? (3)
1. Memory cells remain in the body after a primary response. 2. If the body is exposed to the antigen again, a secondary response occurs 3. B cells divide at a faster rate which means antibody is produced at a faster rate and a higher concentration
53
What is agglutination and how does it occur?
Binding of antibodies to complementary antigens on different cells/organisms causing them to ‘clump together’ so that they can be destroyed by a phagocyte
54
What is a vaccine and how does it protect against disease? (3)
1. Injection of an antigen into the body (e.g. dead pathogen, harmless strain of a pathogen, antigens etc) which triggers an immune response against the antigens and the production of memory cells. 2. Provides artificial active immunity 3. If infected by a pathogen with that organism, a secondary response will occur
55
What is a primary response? (2)
When an antigen enters the body for the first time activating the immune system (B cells) to produce antibodies. Memory cells remain
56
What is a secondary response? (2)
1. If the body is exposed to that antigen again, there is a faster and stronger immune response. 2. B cells divide at a faster rate which means antibody is produced at a faster rate and a higher concentration
57
What is herd immunity? (2)
1. Vaccinating a certain percentage of the population (percentage cover) to protect unvaccinated 2. Very low probability of an unvaccinated individual coming into contact with another unvaccinated person so prevents transmission
58
What is active immunity? (4)
1. Immunity gained from exposure to an antigen resulting in the primary response and production of antibodies and memory B/T Cells 2. Slower acting – approx. 72 hours 3. Memory cells are produced 4. Long term
59
What is passive immunity? (4)
1. Immunity gained from receiving antibodies 2. Quick acting 3. Short term 4. No memory cells produced
60
Which cells does the HIV virus infect?
Helper T lymphocytes
61
Name the enzyme HIV inserts along with its genetic material
Reverse transcriptase
62
How does HIV cause the symptoms of HIV? (3)
1. Destroys Helper T lymphocytes 2. So B lymphocytes (and antibody production) 3. And cytotoxic T lymphocytes (and the cellular response) cannot be activated
63
Why are antibiotics ineffective against viruses? (3)
1. Viruses do not have a metabolism (e.g. don’t respire, don’t carry our protein synthesis) 2. Viruses are acellular so don’t have any organelles (e.g. ribosomes which antibiotics can act on) 3. Viruses do not have a cell wall which some antibiotics (e.g. penicillin act on)
64
What is an ELISA test? (2)
1. Enzyme linked immunosorbent assay 2. Uses monoclonal antibodies to detect antigens/proteins or antibodies in a sample
65
Give 2 examples of uses of monoclonal antibodies
1. Targeting medication to specific cell types by attaching a therapeutic drug to an antibody 2. Medical diagnosis e.g. via ELISA

Biology (8 decks)

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