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Topic 2 Flashcards

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1
Q

Why is it difficult to see the structures of single celled organisms using optical microscope

A

Resolution too low

Because wavelength of light is too long

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2
Q

Role of a named organelle in digesting bacteria

A

Lysosomes

Fuse with vesicle

Release hydrolytic enzymes

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3
Q

Structures found in all prokaryotic and eukaryotic cells

A

Cell membrane

Ribosomes

Cytoplasm

DNA

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4
Q

Explanation for a faster rate of plasmid replication in cells growing in a culture with high amino acid concentration

A

Amino acids used in respiration

So more energy for plasmid replication

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5
Q

How could a sample of chloroplasts could be isolated from leaves

A

Grind cells AND filter

In cold, same water potential and pH controlled solution

Centrifuge and remove nuclei

Centrifuge at higher speed and chloroplasts will settle out

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6
Q

Contrasting structure of cells visible with different magnifications

A

Magnification show A is bigger than B

A has a nucleus whereas B has free DNA

A has mitochondria whereas B does not

A has Golgi body/endoplasmic reticulum whereas B does not

A has no cell wall whereas B has a murein/glycoprotein cell wall

A has no capsule whereas B has a capsule;

A has DNA is bound to histones/proteins whereas B has
DNA not associated with histones/proteins

A has larger ribosomes

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7
Q

The role of organelles in production, transport, and release of proteins from eukaryotic cells

A

DNA in nucleus is code for protein

Ribosome/RER produce protein

Mitochondria produce ATP for protein synthesis

Golgi apparatus modify protein

Vesicles transport

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8
Q

Why may a nucleus not be visible in an image of a plant cell

A

Nucleus in another part of cell

Nucleus not stained

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9
Q

Advantages of using a TEM compared to SEM

A

Higher resolution

View internal structures

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10
Q

Why would internal structures not be seen on an optical microscope

A

Light has longer wavelength

So lower resolution

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11
Q

What are the properties needed for separating organelles and how do they prevent damage

A

Ice cold - Prevent enzyme activity

Buffered - Prevent denaturing of protein

Isotonic - Prevent bursting of organelles

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12
Q

Main biological molecule in cell membrane

A

Phospholipids

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13
Q

Main biological molecule in prokaryotic cell wall

A

Glycoprotein

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14
Q

Process by which prokaryotic cells divide

A

Binary fission

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15
Q

How do you recognise that an SEM was used

A

3D image

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16
Q

Contrast how optical microscope and TEM work

A

TEM use electrons
Optical uses light

TEM allows a greater resolution

TEM allows for smaller organelles to be observed

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17
Q

Contrast the limitations of TEM and optical microscope

A

TEM can only view dead specimen
Optical can view live specimen

TEM does not show colour
Optical can

TEM requires more time consuming preparation

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18
Q

Why do cells need to be blended and filtered when separating organelles

A

Homogenise

Remove larger debris
Remove unbroken cells

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19
Q

Why might the cell surface membrane appear as 2 dark lines

A

Membrane has phospholipid bilayer

Stain binds to phosphate

On inside and outside of membrane

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20
Q

Structures in eukaryotic cell that cannot be identified using an optical microscope

A

Mitochondria

Ribosome

Cell surface membrane

Lysosome

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21
Q

How to set up a temporary mount of a piece of plant tissue when using optical microscope

A

Add drop of water to slide

Obtain thin section of plant tissue and place on slide

Stain with iodine in potassium iodide

Lower coverslip using mounted needle

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22
Q

Describe binary fission in bacteria

A

Replication of circular DNA

Replication of plasmids

Division of cytoplasm

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23
Q

Suggest and explain environmental variables which could be changed to increase bacteria growth rate

A

Increased glucose concentration
Increased respiration

Increased oxygen concentration
Increased respiration

Increased temperature
Increased enzyme activity

Increased phosphate concentration
Increased ATP

Increased nucleotide concentration
Increased DNA synthesis

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24
Q

Explain the random arrangement of genetic material during mitosis

A

Chromosomes arranged at random

As there is no spindle activity

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25
Role of spindle fibres and chromosome behaviour in prophase
Chromosomes condense Centromeres attach to spindle
26
Role of spindle fibres and chromosome behaviour in metaphase
Chromosomes line up at equator of cell
27
Role of spindle fibres and chromosome behaviour in anaphase
Centromeres divide Chromatids pulled to opposite poles of cell Spindle fibres shorten
28
Why may eggs produced by meiosis be genetically different
Independent segregation Crossing over
29
Why may some offspring be sterile
Too many sets of chromosomes Homologous chromosomes do not pair No meiosis
30
Why would the prevention of spindle fibre formation stop the cell cycle
Chromosomes cannot attach to spindle No metaphase
31
Why would a student use a small section of onion root tip
Where mitosis occurs
32
Why would a student press down firmly on the coverslip
To obtain a thin layer of cells SO light passes through
33
What should the student have done when counting cells to make sure that the mitotic index he obtained for this root tip was accurate
Examine large number of fields of view To ensure representative sample Repeat count To ensure figures are correct
34
Suggest how the structure of the chromosome could differ along its length to result in the stain binding more in some areas
Differences in base sequences Differences in histones
35
Definition of homologous chromosomes
Chromosomes that carry the same genes
36
Describe aseptic techniques a student would have used when transferring a sample of broth culture on to an agar plate.
Keep lid on petri dish To prevent unwanted bacteria contaminating dish Wear gloves/mask Prevent contamination of bacteria onto hands Use sterile pipette To maintain pure culture of bacteria
37
Describe and explain appearance and behaviour of chromosomes during prophase
Chromosomes condense Chromosomes appear as chromatids joined at the centromere
37
Describe and explain appearance and behaviour of chromosomes during metaphase
Chromosomes line up on equator of the cell Chromosomes attached to spindle fibres
38
Describe and explain appearance and behaviour of chromosomes during anaphase
Centromere divides Chromosomes pulled to opposite poles of the cell
39
Describe and explain appearance and behaviour of chromosomes during telophase
Chromosomes uncoil
40
Why is it important to push down hard on cover slip
Spread/squash tissue
41
Why is it important not to push coverslip sideways
Avoid breaking chromosomes
42
Similarities between the regular membrane structure and fluid mosaic model
Both have phospholipid bilayer Both have phosphate groups pointing out Both have protein
43
Differences between the regular membrane structure and fluid mosaic model
No channel/carrier proteins Fluid mosaic has them Cholesterol not present Present in fluid mosaic Glycoprotein/lipid not present Present in fluid mosaic
44
Name and describe five ways substances can move across the cell-surface membrane into a cell
Simple diffusion of small molecules down a concentration gradient Facilitated diffusion down a concentration gradient using protein channel/carrier Osmosis of water down a water potential gradient Active transport against a concentration gradient by carrier protein using ATP Cotransport of 2 different substances using a carrier protein
45
Function of ATP hydrolase in active transport
Releases energy in hydrolysis Energy allows ions to be moved against a concentration gradient
46
Features you would expect to see in a cell specialized for absorption
Microvilli SO large surface areaa Large number of carrier proteins FOR active transport Large number of mitochondria FOR aerobic respiration
47
How is the movement of substances affected by membrane structure
Carrier proteins allow active transport Channel proteins allow facilitated diffusion Number of channels/ carriers determines how much movement Shape of channels/carriers determines which substances move Cholesterol affects fluidity Phospholipid bilayer allows diffusion of lipid soluble substances
48
Why may an increase in temperature cause the release of a red pigment
Damage to cell surface membrane Increased fluidity
49
How is HIV replicated
Attachment proteins attach to receptors on helper T cell RNA enters cell Reverse transcriptase converts RNA to DNA Viral proteins produced Virus assembled and released
50
Describe phagocytosis of a molecule made of a monoclonal antibody linked to a cancer drug
Cell engulfs antibody (and drug) Lysosomes fuse with vesicle (containing drug) Lysozymes breakdown the antibody (and monoclonal antibody to release the drug)
51
If some of the antigens found on the surface of tumour cells are also found on the surface of healthy human cells, how may treatment with drug lead to side effects
Drug will bind to healthy cells Death of healthy cells
52
How is HIV replicated ONCE INSIDE helper T cells
RNA converted to DNA using reverse transcriptase DNA inserted iunto helper T cell nucleus DNA transcribed into HIV mRNA HIV mRNA translated into viral proteins
53
Describe phagocytosis
Engulfs pathogen Forming phagosome AND fuses with lysosome Lysozymes hydrolyse
54
Evaluate the use of stem cell transplant (BSCT) to treat HIV infections
For: Only one transplant needed Would not need to take daily medicine No receptor so wouldnt get HIV in future Against: Dont know if BSCT alone is effective Might not be long term Dont know if it will work in all people Might be a lack of suitable donors
55
Types of cells that can stimulate an immune response
Cancer cells Cells infected by virus Cells from transplants
56
Role of disulfide bridge in structure of antibody
Joins 2 polypeptide chains
57
How does HIV affect antibody production when AIDS develops
Less antibody produced Because HIV destroys helper T cells So few B cells activated
58
How can determining the genome of a virus allow scientists to develop a vaccine
Scientist could identify proteins Then identify potential antigens
59
How can viruses develop to be able to infect multiple species
Mutation in the viral DNA Altered tertiary structure of viral attachment protein Allows attachment protein to bind
60
How the B lymphocytes of an organism would respond to vaccination
B cell binds to complementary receptor B cell divides by mitosis Plasma cells release antibodies Plasma cells produce memory cells
61
What is a monoclonal antibody
Antibodies with the same tertiary structure
62
Examples of using monoclonal antibodies in a medical treatment
Block antigens on cells OR Binds to specific receptors
63
Describe the role of antibodies in producing a positive result in an ELISA test
First antibody binds to antigen Second antibody with enzyme attached is added Second antibody attaches to antigen Substrate added and colour changes
64
Describe and explain the role of antibodies in stimulating phagocytosis.
Bind to antigen Cause agglutination OR Attract phagocytes
65
Explain how and why it is essential to use passive immunity, rather than active immunity when fighting against toxins such as venom.
In passive immunity antibodies bind to the antigen and cause its destruction Active immunity would be slower
66
Why may a mixture of toxins be used from an animal of the same species
May be different form of antigen Different antibodies needed in the antivenom
67
During vaccination, each animal is initially injected with a small volume of venom. Two weeks later, it is injected with a larger volume of venom. Use your knowledge of the humoral immune response to explain this vaccination programme.
B cells specific to the venom reproduce by mitosis B cells produce plasma cells and memory cells Second dose produces antibodies in higher concentration and quickly
68
How can phagocytosis of a virus lead to presentation of its antigens
Phagosome fuses with lysosome Virus destroyed by lysozymes Antigens from virus are displayed on the cell membrane
69
Describe how presentation of a virus antigen leads to the secretion of an antibody against this virus antigen.
Helper T cell binds to antigen The helper T cell stimulates a specific B cell B cell divides by mitosis Forms plasma cells that release antibodies
70
What is an antigen
Foreign protein That stimulates an immune response
71
What is an antibody
A protein Produced by B cells
72
Why would there be a low mean concentration of antibodies BEFORE the first dose of vaccine
Before vaccination so no antibody released because patients have not yet encountered antigen
73
Why would there be a low mean concentration of antibodies AFTER the first dose of a vaccine
After first dose there is an activation of B cells into plasma cells Plasma cells release antibodies
74
Why would there be a high mean concentration of antibodies after the second dose of a vaccine
After second dose memory cells produce more antibodies
75
Describe how vaccination can lead to protection against bacterial diseases
Antigen on surface binds to surface protein on a B cell B cell divides by mitosis Division stimulated by T cells Plasma cells release antibodies Some B cells become memory cells Memory cells produce antibodies faster
76
When a vaccine is given to a person, it leads to the production of antibodies against a disease-causing organism. Describe how.
Vaccine contains antigen from pathogen Macrophage presents antigen on its surface T cell with complementary receptor protein binds to antigen T cell stimulates B cell With complementary antibody on its surface B cell secretes large amounts of antibody B cell divides to form clone producing same antibody
77
Describe the difference between active and passive immunity.
Active - Involves memory cells Passive - Does not Active - Production of antibody by plasma cells Passive - Antibody introduced into body from outside Active - Long term as antibody produced in response to pathogen Passive - Short term as antibody given is broken down Active - Can take time to develop Passive - Fast acting

Biology (13 decks)

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