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Biology > Unit 2 - Cells > Flashcards

Unit 2 - Cells Flashcards

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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
Q

What happens in the S phase?

A

chromosomes are replicated with the assembly of new DNA

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26
Q

What are chromatids?

A

two copies of each chromosome

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27
Q

What is the centromere?

A

where the chromatids remain attached to each other

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28
Q

What is G2?

A

new organelles are synthesised, cell growth continues, microtubules start to form

29
Q

What are the stages of mitosis?

A

prophase, metaphase, anaphase, telophase

30
Q

What happens in prophase?

A

chromosomes condense and become visible, centrioles split and move to opposite ends of the cell, the nuclear envelope disintegrates

31
Q

What are the spindle fibres?

A

a series of microtubules that organise the position and movement of chromatids during cell division

32
Q

What happens in the metaphase?

A

nuclear envelope disappears, spindle fibres attach to the chromosomes, chromosomes line up at the equator

33
Q

What happens in anaphase?

A

the chromosomes break apart at the centromere, chromosomes are split into V-shaped chromatid structures

34
Q

What happens in the telophase?

A

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
Q

What is the final stage of the cell cycle?

A

cytokinesis

36
Q

What happens in cytokinesis?

A

the cell invaginate to form two identical daughter cells

37
Q

What two genes control cell division?

A

proto-oncogene and tumour suppressor gene

38
Q

What does the proto-oncogene do?

A

stimulates cell division

39
Q

What does the tumour suppressor gene do?

A

slows or inhibits cell division

40
Q

What do you find in a cell membrane?

A

phospholipids, proteins, carbohydrates, glycolipids, glycoproteins and cholesterol

41
Q

What two types of transport proteins are found in the cell membrane?

A

channel and carrier

42
Q

Functions of phospholipids?

A

allow lipid-soluble substances to enter/leave, prevent water-soluble substances to enter/ leave, make the membrane flexible and self-sealing

43
Q

What are the functions of proteins?

A

structural support, channels for transporting substance, active transport (carrier), adhere together, receptors for hormones, cell surface receptors for identification

44
Q

What are the functions of cholesterol?

A

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
Q

Why is the cell-surface membrane not freely permeable to all substances?

A

too large, not lipid soluble, polar, same charge

46
Q

What are the two types of electron microscope?

A

Transmission electron microscope (TEM) and Scanning electron microscope (SEM)

47
Q

How does a TEM work?

A

An electromagnetic beam of electrons is projected through the sample, and a 2D image is formed

48
Q

How does a SEM work?

A

directs an electron beam across a sample, 3D image is formed

49
Q

What is a benefit of using a TEM?

A

produces a very high resolution image

50
Q

What is a limitation of using a TEM?

A

can only be used on thin specimens in a vacuum

51
Q

What is a benefit of using a SEM?

A

produces 3D images and can be used on thick specimens

52
Q

What is a limitation of using a SEM?

A

lower resolution images

53
Q

Definition of simple diffusion

A

Net movement of molecules/ions from a region where they are more HIGHLY CONCENTRATED
to one where their CONCENTRATION IS LOWER

54
Q

What factors affect the rate of diffusion?

A

Temperature
Concentration gradient
Stirring/moving
Surface area
Distance/thickness
Size of molecule

55
Q

What are protein channels?

A

water-filled hydrophilic channels which are shaped for a specific ion

56
Q

What are carrier proteins?

A

specific molecule fits in, the protein changes shape to allow the molecule through

57
Q

How does phagocytosis work?

A

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
Q

What is found in a cell membrane?

A

lipid bilayer, glycoproteins. glycolipids, cholesterol, channel protein

59
Q

Describe how HIV is replicated

A

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
Q

Describe the role of antibodies in producing a positive result in an ELISA test.

A

antibody binds to antigen, antibody with enzyme attached is added, antibody attaches to antigen, colour changes

61
Q

Where are T cells and B cells made?

A

both made in bone marrow

62
Q

Where do T cells and B cells mature

A

T cells - thymus
B cells - bone marrow

63
Q

What do T cells do?

A

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
Q

What is the role of cytotoxic T cells?

A

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
Q

What is the role of helper T cells?

A

stimulate B cells to divide and secrete antibodies

66
Q

What are antibodies?

A

proteins that have binding sites (variable regions) complementary in shape to antigens

67
Q

What are antibodies made up of?

A

four polypeptide chains, two heavy and two light chains

68
Q

Which cells produce antibodies?

A

plasma cells

69
Q

What is agglutination?

A

clumping cells together to make it easier for phagocytes to locate

Biology (8 decks)

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