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Biology A level AQA > Chapter 3 - Cell Structure > Flashcards

Chapter 3 - Cell Structure Flashcards

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1
Q

What is the formulae for magnification?

A

“I AM” , Image over actual size times magnification

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2
Q

What must be done to a sample before cell fractionation? 3

A

cold - slow enzymes involved in autolysis
isotonic - stop shrinking/bursting (of organelles)
buffered - stop fluctuation in pH, no denatured proteins

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3
Q

What is homogenation?

A

blender, break down of cells

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4
Q

what is the resultant fluid of homogenation known as?

A

homogenate

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5
Q

outline the steps of ultracentrifugation (3)

A
  • homogenate spun at low speed
  • nuclei forced to bottom forming a pellet
  • supernantent removed and spun again at higher speed
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6
Q

what must happen to the homogenate before ultracentrifugation?

A

filtered, removes cell walls/membranes

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7
Q

what is resolution?

A

the minimum distance apart that two objects can be in order for them to appear as separate items

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8
Q

what is the resolving power of TEM

A

0.1nm

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9
Q

what is the resolving power of SEM

A

20nm

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10
Q

what is the resolving power of a light microscope

A

0.2 micrometers

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11
Q

why can the highest resolving power of TEM not always be achieved? (2)

A
  • artefacts from prep

- higher energy electron beam needed which may destroy the specimen

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12
Q

what are the limitations of TEM? (4)

A
  • vacuum (organisms must be dead)
  • complex staining process
  • extremely thin specimen
  • artefacts from extensive prep process and many chemicals
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13
Q

What is the name of the image the TEM produces?

A

photomicrograph

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14
Q

what is an eyepiece graticule?

A

glass disc placed in eyepiece with scale etched on

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15
Q

how would you calibrate the eyepiece graticule? (3)

A
  • use stage micrometer with scale
  • find where both scales line up
  • known value of micrometer allows calculation of graticule units and magnification
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16
Q

state the features of the nucleus (5)

A
  • nuclear envelope (double membrane)
  • nuclear pores (for mRNA)
  • jelly like nucleoplasm
  • chromosomes
  • nucleolus (manufactures ribosomal RNA and ribosomes)
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17
Q

what are the functions of the nucleus? (3)

A
  • control centre of cell, protein synthesis
  • retain chromosomes
  • manufacture ribosomal RNA and ribosomes
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18
Q

what are the structures of the mitochondria? (3)

A
  • double membrane
  • cristae, Large SA for ETC
  • matrix
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19
Q

function of mitochondria? (2)

A
  • site of aerobic respiration

- ATP from glucose

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20
Q

features of a chloroplasts? (3)

A
  • chloroplast envelope , double
  • grana (stacks of thylakoids) which contain chlorophyll
  • stroma, LI
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21
Q

functions of a chloroplast? (3)

A
  • granal membranes = large SA for LD
  • stroma contains all enzymes for LI
  • contain DNA + ribosomes for protein synthesis
22
Q

what is the ER? (2)

A
  • 3D system of sheet-like membranes, continuous with outer membranes of nuclear membrane
  • membrane encloses sacs called cisternae
23
Q

functions of SER?

A

synthesize, store and transport lipids and carbohydrates

24
Q

functions of RER? (2)

A
  • large SA for synthesis of proteins/ glycoproteins

- transport of proteins in cell

25
Q

what are golgi apparatus? (2)

A
  • flattened sacs (cisternae) with vesicles

- adds non protein components and modifies proteins from ER

26
Q

functions of golgi? (4)

A
  • add carbs to form glycoproteins
  • produce secretory enzymes
  • secrete carbohydrates
  • transport, modify, store lipids from lysosomes
27
Q

what are lysosomes?

A

vesicles containing hydrolytic enzymes

28
Q

function of lysosomes? (4)

A
  • hydrolyse material ingested by phagocytic cells
  • excocytosis for humoural breakdown
  • digest worn out organelles
  • autolysis
29
Q

Types of ribosomes? (2)

A

80s - eukaryotic cells

70s - prokaryotic cells

30
Q

what are ribosomes made up of? (2)

A

2 sub units

  • 1 large sub unit
  • 1 small sub unit
31
Q

features of a cell wall? (2)

A
  • polysaccharides e.g. cellulose/chitin

- thin layer called middle lamella marks boundary between cells and cements them together

32
Q

functions of cellulose cell wall? (3)

A
  • mechanical strength - stop bursting
  • mechanical strength to whole plant
  • allow water to pass along it through middle lamella
33
Q

what are vacuoles?

A

fluid filled sac - single membrane

34
Q

functions of vacuoles? (3)

A
  • support herbacious plants by making cells turgid
  • sugars and amino acids act as temporary food store
  • pigments colour to attract insects for pollination
35
Q

what is the cell ultrastructure?

A

the specific internal structure adapted for the cells task

36
Q

how do cells become specialised? (2)

A
  • all contain the same genes

- only certain genes expressed in one cell

37
Q

what is a tissue?

A

collection of similar cells e.g. epethelial cells

38
Q

what is an organ?

A

a combination of tissues coordinated to perform a variety of functions usually one major function

39
Q

give 3 examples of organ systems

A
  • digestive
  • respiratory
  • circulatory
40
Q

what are eukaryotes?

A

larger - with a nucleus

41
Q

what are prokaryotes?

A

smaller - no nucleus or nuclear envelope + plasmids

42
Q

compare the structures of eukaryotes/prokaryotes from the perspective of prokaryotes (9)

A
  • no nuleus
  • no nuclear envelope
  • DNA not associated with proteins
  • plasmids
  • no membrane-bound organelles
  • no chloroplasts
  • smaller ribosomes
  • cell wall made of murien
  • slime capsule
43
Q

what are viruses?

A

acellular, non living particles

44
Q

what is the order of mitosis? (6)

A 
I
P
M
A
T
C
45
Q

what happens in the cell during interphase? (2)

A
  • DNA replication, chromosomes remain joined at centromere

- replication of organelles

46
Q

what happens during prophase? (2)

A
  • chromosomes become visible, shorten/thicken

- spindle fibres develop

47
Q

what happens during metaphase?

A

chromosomes line up at equator

48
Q

what happens during anaphase? (3)

A
  • centromeres divide into 2
  • pulling apart chromatids
  • energy for spindle fibres by mitchondria
49
Q

what happens during telophase/cytokinesis? (4)

A
  • chromosomes reach poles - dissapear
  • spindle fibres disintegrate
  • nuclear envelope reforms
  • cytoplasm divides
50
Q

outline the cell division in prokaryotes (6)

A
  • circular DNA replicate
  • both attach to membrane
  • plasmids also replicate
  • cell membrane grows between DNA molecules - pinch inwards
  • cell wall forms between DNA forming identical daughter cells
  • variable no. plasmids
51
Q

3 stages of the cell cycle?

A
  • interphase
  • nuclear division
  • division
52
Q

how do chemotherapy drugs prevent cells replicating? (2)

A
  • prevent DNA replication

- interfering with spindle fibre formation

Biology A level AQA (19 decks)

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