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Biology > Chapter 3 - Cells > Flashcards

Chapter 3 - Cells Flashcards

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1
Q

What is the equation for magnification?

A

Magnification = size of image / size of real object

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2
Q

What is magnification?

A

Magnification is how many time bigger the image is

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3
Q

What is resolution?

A

Resolution is the minimum distance between 2 objects without appearing blurred

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4
Q

What is cell fractionation?

A

Cell fractionation is the process where cells are broken up and the different organelles they contain are separated out.

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5
Q

What 3 conditions are required for cell fractionation?

A
  • cold - to reduce enzyme activity that might break down the organelles
  • isotonic - to prevent organelles bursting or shrinking as a result of osmotic gain or loss of water
  • buffered - so that the pH does not fluctuate to not affect enzymes or organelles
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6
Q

What are the 3 stages of cell fractionation?

A
  • Homogenation
  • Filtration
  • Ultracentrifugation
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7
Q

What is homogenation?

A

Cells are broken up by a homogeniser (blender) to open the cell membrane up and release organelles

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8
Q

What happens during filtration?

A

The homogenate is filtered to remove any complete cells and large pieces of debris that may sink to the bottom

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9
Q

What is ultracentrifugation?

A
  • Organelles are spun at a low speed so the heaviest organelles form a pellet at the bottom on the centrifuge (spinning machine)
  • The supernatant (residue liquid) is remove and respun at a faster speed to seperate organelles further
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10
Q

Order the organelles from heaviest to lightest

A
  • nuclei
  • chloroplasts
  • mitochondria
  • lysosomes
  • endoplasmic reticulum
  • ribosomes
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11
Q

How do light microscopes work?

A

A beam of light is passed through convex glass lenses to magnify the object

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12
Q

What are 3 disadvantages of the light microscope?

A
  • some organelles cannot be seen due to longer wavelength
  • the specimen has to be very thin
  • staining is needs to distinguish organelles
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13
Q

What are 2 main advantages of electron microscopes?

A
  • electrom beam has a short wavelength, so it has a high resolving power
  • electrons are negatively charge, so higher focus through use of electromagnets
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14
Q

What is the magnification and resolution of a light microscope?

A

1500x
0.2um

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15
Q

What is the usual magnification and resolution of an electron microscope?

A

2,000,000x
0.1nm

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16
Q

What is a transmission electron microscope?

A
  • beam of electrons with use of EM radiation show image
  • very high resolution
  • 2D image
  • no colour
  • internal parts of organelles can be seen
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17
Q

What is a scanning electron microscope?

A
  • focused beam of electrons which reflect off the surface of structures
  • 3D image
  • sampels do not need to be thin
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18
Q

Why do electron microscope need to be in a vacuum?

A

Air particles would interfere with beams of electrons so the specimens must always be dead

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19
Q

What is the photomicrograph?

A

Photograph of an image produced by a microscope

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20
Q

What are 5 disadvantages of electron microscopes?

A
  • cannot be living material
  • image is only 2D (TEM)
  • specimen must be very thin (TEM)
  • specimen take a long time to prepare
  • image may contain artefacts, blocking organelles from view (TEM)
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21
Q

What type of microscope would be sued to study replication of E.coli bacteria?

A

Light microscope because it is living.

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22
Q

RDR

What are 3 roles of nucleus?

A
  • control centre via production of mRNA + tRNA
  • contain genetic material of cells
  • produces ribosomes and ribosomes RNA
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23
Q

What are 5 components of the nucleus?

A
  • nuclear envelope - double membrane controlling exchange of substnaces
  • nuclear pores - allow passage of molecules in and out of nucleus
  • nucleoplasm - jelly material
  • chromomes
  • nucleolus - small sphere that makes ribosomes RNA
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24
Q

What are 3 components of mitochondria?

A
  • double membrane - control exchange of substances
  • cristae - extensions of inner membrane to increase SA
  • matrix - remainder liquid containing mitochondrial DNA and enzymes
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25
Q

What are 3 components of chloroplasts?

A
  • chloroplast envelope - double membrane
  • grana - stroage of thylakoids (contain chlorophyll)
  • stroma - fluid matrix when sugar synthesis occurs (photosynthesis)
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26
Q

What 3 ways are chloroplasts adapted to their function?

A
  • grana provide large SA for chlorophyll attachments
  • stroma contains many enzymes
  • chloroplasts contain DNA and ribosomes to make more photosynthetic enzymes
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27
Q

What is the rough endoplasmic reticulum?

A
  • ribosomes present on surface + cisternae
  • provides large SA for protein + glycoprotein synthesis
  • provides pathway for transport of materials
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28
Q

What is the smooth endoplasmic reticulum?

A
  • cristernae + no ribosomes - more tubular shape
  • lipid synthesis, transport and storage
  • carbohydrate synthesis, transport and storage
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29
Q

What is the structure of the golgi apparatus?

A

Flattened sacs (cristernae) with small rounded hollow structures (vesicles)

30
Q

What are 5 functions of the golgi apparatus?

A
  • add carbohydrates to proteins to form glycoproteins
  • produces secretory enzymes
  • secretes carbohydrates
  • forms lysosomes
  • modifies + labels proteins and lipids
31
Q

What are 4 functions of lysosomes?

A
  • hydrolyses material ingested by phagocytic cells
  • exocytosis - releases enzymes outside cells to destroy materials
  • digests worn out organelles - contain useful chemicals
  • autolysis
32
Q

What is autolysis?

A

A process where cells are broken down after they die

33
Q

Describe the structure in ribosomes in all types of cells

A

80S - eukaryotic cells
70S - prokaryotic cells
consists of 2 subunits

34
Q

What is the structure of a cell wall?

A

Microfibrils of cellulose embedded in a matrix
Middle lamella to join nearby cells together

35
Q

What are cell walls in fungi made of?

A

Chitin (nitrogen based polysaccharide)

35
Q

What is the structure of a vacuole?

A
  • tonoplast - single membrane
  • contains salts and sugars - used as a food source
36
Q

What is a bacterial cell wall used for?

+ what is it made of

A

Protects cell against mechanical damage and osmitic lysis
Made of peptidoglycan (murein) - sugars + amino acids

37
Q

What is the function of a capsule in a bacterial cell?

A

Prevents desiccation (drying out) and protects cell from viruses and antibiotics

38
Q

What is a nucleoid?

A

Circular loop of DNA in bacteria that can’t form chromosomes

39
Q

What is the function of a flagella in a bacterial cell?

A

used for locomotion powered by protein motors

40
Q

What is the function of a mesosome in a bacterial cell??

A

increases SA for enzymes

41
Q

What is the function of pilia in a bacterial cell?

A

used in bacterial conjugation (DNA transfer)

42
Q

What is fungi made up of?

A

Fungi is eukaryotic and have most of the organelles in plant cells, but do not have chloroplasts

43
Q

What is the structure of a virus?

A
  • contain nucleic acids - RNA or DNA
  • capsid - protein coat
  • lipid envelope
  • attachment proteins - used in virus replication
  • reverse transcriptae - found in capsid
44
Q

(3)

What are the roles of a capsid?

A
  • protects nucleic acids from digestion by enzymes
  • contains special sites to attach to a host
  • provides proteins to allow virion to penetrate host cell
45
Q

What is mitosis?

A

Mitosis is cell division where 2 genetically-identical daughter cells are produced

46
Q

What happens during interphase?

A

DNA is replicated
Chromosomes are not yet formed

47
Q

What happens during prophase?

A
  • chromosomes condense and become visible
  • nuclear envelope + nucleolus starts to break down
  • centrioles move to poles of cellsand produce spindle fibres
48
Q

What happens during metaphase?

A
  • nuclear membrane has disappeared
  • spindle fibres attach to centromeres and align chromosomes along equator
49
Q

What happens during anaphase?

A
  • spindle fibres pull centromeres apart
  • chromatid are pulled to opposite ends of the cells
  • cell starts to elongate
50
Q

What happens during telophase?

A
  • cell starts to divide
  • nuclear envelope and nucleolus reforms
51
Q

What is a centriole?

A

Tubular proteins that create spindle fibres

52
Q

What happens during cytokinesis?

A

Cytoplasm and cell membrane splits into 2 daughter cells

53
Q

What are the uses of mitosis?

A
  • growth
  • repair
  • reproduction
54
Q

What are the 3 stages of the cell cycle?

+ which is the longest

A
  1. Interphase - resting phase as no division occurs
  2. Nuclear division - nuclear divides into 2 or 4
  3. Cytokinesis - cytoplasm divides to produce new cells
55
Q

What are the 3 stages of interphase?

A
  • G1 - organelles replicate and cell growths
  • S - DNA synthesis
  • G2 - energy stores replaced and cell growths again
56
Q

What is cancer?

+ what causes it

A

Uncontrolled cell division caused by mutations

57
Q

What are 3 sources of cancer treatments?

A
  • Chemotherapy - prevents synthesis of enzymes required for DNA replication
  • Radiotherapy - damages DNA so it can’t pass the checkpoints in S phase
  • Drugs - prevent spindle fibres from forming so mitosis cannot occur
58
Q

What factors affect rate of cell division?

A
  • Nutrients
  • Oxygen
  • Hormones
  • Genes
  • Risk factors - UV exposure, carcinogens
59
Q

Why do tumours have a low blood supply?

A

The demand for oxygen cannot be kept up by the rate of mitosis

60
Q

What is melalin?

A

Melalin is a pigment that reflects UV radiation

61
Q

What is metastasis?

A

tumours spread out and form secondary tumours

62
Q

What is apoptosis?

A

cells force to kill itself when it doesn’t pass cell cycle checkpoints

63
Q

What are the stages of binary fission?

A
  1. The circular DNA in the cells replicates and both copies attach to the cell membrane. Plasmids also replicate.
  2. The cell membrane then begins to grow between the two DNA molecules and begins to pinch inwards, dividing the cytoplasm in two.
  3. A new cell wall forms between the two DNA molecules dividing the original cell.
  4. The identical daughter cells each have a single copy of the circular DNA and a variable number of copiesof the plasmids.
64
Q

What are the stages of virus replication?

A
  1. They attach to host cell with attachment proteins
  2. Nucleic acid is injected into host cell
  3. Host cell replicates nucleic acid
  4. Viruses form
65
Q

What is in a lysosome?

A

H+ pump maintains acidic conditions to produce hydrolase enzymes

66
Q

How do bacteria store excess food?

A

Food reserve granule suspended in cytoplasm

67
Q

What is the role of mitochondria?

active transport?

A

provides ATP and is the site of aerobic respiration
energy from respiration can be used for active transport against concentration gradient

68
Q

How does DNA condense into chromosomes?

A

Histone proteins coil around the DNA and tighten it into chromosomes

69
Q

How do lysosomes engulf phagocytes?

A

They fuse with a vesicle to release hydrolytic enzymes

70
Q

What is the difference between eukaryotes and prokarytoes in terms of cell membranes?

A

Prokaryotes lack membrane-bound organelles

71
Q
A

Biology (2 decks)

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