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Unit 2 - Cells Flashcards

1
Q

Function of nuclear pores

A

to allow mRNA and ribosomes to travel out of the nucleus and to allow enzymes to travel in

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2
Q

What is chromatin?

A

the material from which chromosomes are made

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3
Q

What is the nucleolus?

A

the site of ribosome production

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4
Q

Structures of mitochondria

A

cristae, matrix, inner and outer membrane

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5
Q

What is found in the chloroplast?

A

thylakoids (granum), stroma, lamellae, starch, DNA, ribosomes

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6
Q

Why do chloroplast contain small circular pieces of DNA and ribosomes?

A

to synthesise proteins needed in chloroplast replication and photosynthesis

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7
Q

What is the function of the Golgi apparatus?

A

modifies proteins and lipids before packaging them into Golgi vesicles, add carbohydrates to proteins (glycoproteins), produced enzymes, form lysosomes

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8
Q

What do the vesicles do?

A

transport the proteins and lipids to their required destination

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9
Q

What are the functions of the smooth ER?

A

synthesise, store and transport lipids and carbohydrates, drug detoxification

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10
Q

What are the functions of lysosomes?

A

hydrolyse materials, release digestive enzymes, digest worn out organelles, break down dead cells

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11
Q

What are cell walls made of (plant and fungi) ?

A

plant- cellulose
fungi- chitin

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12
Q

What is the membrane called in the vacuole?

A

tonoplast

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13
Q

What are the steps of cell fractionation?

A

homogenisation, filtration, ultracentrifugation

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14
Q

What type of solution is used in cell fractionation?

A

cold, isotonic, buffer solution

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15
Q

Why does the solution have to be cold?

A

to reduce enzyme activity so organelles don’t break down

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16
Q

Why is a buffer used?

A

so the pH doesn’t fluctuate as it could affect structure of organelles

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17
Q

Why is an isotonic solution used?

A

so the water potential is equal to prevent organelles from bursting/ shrinking

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18
Q

What does homogenisation do?

A

releases organelles (breaks cells open)

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19
Q

Why is the homogenate filtered?

A

to remove whole cells/ debris

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20
Q

What is ultracentrifugation?

A

fragments are separated by spinning at a high speed

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21
Q

What is a prokaryotic cell wall made of?

A

murein

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22
Q

What structures are presents in all prokaryotic cells?

A

cell wall, plasma membrane, ribosomes, cytoplasm, nucleoid region

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23
Q

What are the three stages of interphase?

A

G1, S, G2

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24
Q

What happens in G1?

A

the cell increases in size/mass and synthesises additional organelles

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25
What happens in the S phase?
chromosomes are replicated with the assembly of new DNA
26
What are chromatids?
two copies of each chromosome
27
What is the centromere?
where the chromatids remain attached to each other
28
What is G2?
new organelles are synthesised, cell growth continues, microtubules start to form
29
What are the stages of mitosis?
prophase, metaphase, anaphase, telophase
30
What happens in prophase?
chromosomes condense and become visible, centrioles split and move to opposite ends of the cell, the nuclear envelope disintegrates
31
What are the spindle fibres?
a series of microtubules that organise the position and movement of chromatids during cell division
32
What happens in the metaphase?
nuclear envelope disappears, spindle fibres attach to the chromosomes, chromosomes line up at the equator
33
What happens in anaphase?
the chromosomes break apart at the centromere, chromosomes are split into V-shaped chromatid structures
34
What happens in the telophase?
the chromatids reach opposite poles of the cell, nuclear envelopes reforms around the chromosomes, the cell prepares to split the cytoplasm and its contents
35
What is the final stage of the cell cycle?
cytokinesis
36
What happens in cytokinesis?
the cell invaginate to form two identical daughter cells
37
What two genes control cell division?
proto-oncogene and tumour suppressor gene
38
What does the proto-oncogene do?
stimulates cell division
39
What does the tumour suppressor gene do?
slows or inhibits cell division
40
What do you find in a cell membrane?
phospholipids, proteins, carbohydrates, glycolipids, glycoproteins and cholesterol
41
What two types of transport proteins are found in the cell membrane?
channel and carrier
42
Functions of phospholipids?
allow lipid-soluble substances to enter/leave, prevent water-soluble substances to enter/ leave, make the membrane flexible and self-sealing
43
What are the functions of proteins?
structural support, channels for transporting substance, active transport (carrier), adhere together, receptors for hormones, cell surface receptors for identification
44
What are the functions of cholesterol?
strengthens and stabilises the membrane, hydrophobic (prevents water and ion loss), reduced fluidity of the membrane at high temperatures, increases fluidity of the membrane at low temperatures
45
Why is the cell-surface membrane not freely permeable to all substances?
too large, not lipid soluble, polar, same charge
46
What are the two types of electron microscope?
Transmission electron microscope (TEM) and Scanning electron microscope (SEM)
47
How does a TEM work?
An electromagnetic beam of electrons is projected through the sample, and a 2D image is formed
48
How does a SEM work?
directs an electron beam across a sample, 3D image is formed
49
What is a benefit of using a TEM?
produces a very high resolution image
50
What is a limitation of using a TEM?
can only be used on thin specimens in a vacuum
51
What is a benefit of using a SEM?
produces 3D images and can be used on thick specimens
52
What is a limitation of using a SEM?
lower resolution images
53
Definition of simple diffusion
Net movement of molecules/ions from a region where they are more HIGHLY CONCENTRATED to one where their CONCENTRATION IS LOWER
54
What factors affect the rate of diffusion?
Temperature Concentration gradient Stirring/moving Surface area Distance/thickness Size of molecule
55
What are protein channels?
water-filled hydrophilic channels which are shaped for a specific ion
56
What are carrier proteins?
specific molecule fits in, the protein changes shape to allow the molecule through
57
How does phagocytosis work?
receptors on he phagocyte bind to antigens on the pathogens. Phagocyte engulfs the pathogen and is contained within a phagosome. Lysosomes fuse with the phagosome. Lysozymes digests the pathogen and destroy it. Digested pathogen is removed from the phagocyte by exocytosis
58
What is found in a cell membrane?
lipid bilayer, glycoproteins. glycolipids, cholesterol, channel protein
59
Describe how HIV is replicated
attachment proteins attach to receptors on helper T cell, RNA enters cell, reverse transcriptase converts RNA to DNA, viral protein produced, virus assembled and released from cell
60
Describe the role of antibodies in producing a positive result in an ELISA test.
antibody binds to antigen, antibody with enzyme attached is added, antibody attaches to antigen, colour changes
61
Where are T cells and B cells made?
both made in bone marrow
62
Where do T cells and B cells mature
T cells - thymus B cells - bone marrow
63
What do T cells do?
Receptors on the T cells will bind onto the antigens on antigen-presenting cells and cause the T cell to divide rapidly by mitosis
64
What is the role of cytotoxic T cells?
kill abnormal cells and infected body cells. They release a protein called perforin which creates pores (holes) in the cell membrane. This allows all substances to move into the cell and causes cell death.
65
What is the role of helper T cells?
stimulate B cells to divide and secrete antibodies
66
What are antibodies?
proteins that have binding sites (variable regions) complementary in shape to antigens
67
What are antibodies made up of?
four polypeptide chains, two heavy and two light chains
68
Which cells produce antibodies?
plasma cells
69
What is agglutination?
clumping cells together to make it easier for phagocytes to locate
70
Describe the process of facilitated diffusion
movement of polar molecules down a concentration gradient via carrier/ channel protein
71
Describe the process of active transport
movement against a concentration gradient via carrier protein using ATP
72
describe binary fission in bacteria
replication of DNA, replication of plasmids, division of cytoplasm
73
Suggest and explain how two environmental variables could be changed to increase the growth rate of cells.
increase temperature, increased enzyme activity increase conc of phosphate, increase DNA increase conc of glucose, increased respiration
74
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope
Add drop of water to (glass) slide; 2. Obtain thin section (of plant tissue) and place on slide / float on drop of water; 3. Stain with/add iodine in potassium iodide; 4. Lower cover slip using mounted needle;
75
Give 3 structural features found in all virus particles
genetic material, capsid, attachment proteins
76
Why are viruses described as acellular and non-living?
no cell membrane, no metabolism, cannot replicate without host cell
77
Why are antibiotics not effective against viruses?
do not have a murein cell wall
78

Biology (8 decks)

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