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

Chapter 3 - Cell Structure Flashcards

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
what are golgi apparatus? (2)
- flattened sacs (cisternae) with vesicles | - adds non protein components and modifies proteins from ER
26
functions of golgi? (4)
- add carbs to form glycoproteins - produce secretory enzymes - secrete carbohydrates - transport, modify, store lipids from lysosomes
27
what are lysosomes?
vesicles containing hydrolytic enzymes
28
function of lysosomes? (4)
- hydrolyse material ingested by phagocytic cells - excocytosis for humoural breakdown - digest worn out organelles - autolysis
29
Types of ribosomes? (2)
80s - eukaryotic cells | 70s - prokaryotic cells
30
what are ribosomes made up of? (2)
2 sub units - 1 large sub unit - 1 small sub unit
31
features of a cell wall? (2)
- polysaccharides e.g. cellulose/chitin | - thin layer called middle lamella marks boundary between cells and cements them together
32
functions of cellulose cell wall? (3)
- mechanical strength - stop bursting - mechanical strength to whole plant - allow water to pass along it through middle lamella
33
what are vacuoles?
fluid filled sac - single membrane
34
functions of vacuoles? (3)
- support herbacious plants by making cells turgid - sugars and amino acids act as temporary food store - pigments colour to attract insects for pollination
35
what is the cell ultrastructure?
the specific internal structure adapted for the cells task
36
how do cells become specialised? (2)
- all contain the same genes | - only certain genes expressed in one cell
37
what is a tissue?
collection of similar cells e.g. epethelial cells
38
what is an organ?
a combination of tissues coordinated to perform a variety of functions usually one major function
39
give 3 examples of organ systems
- digestive - respiratory - circulatory
40
what are eukaryotes?
larger - with a nucleus
41
what are prokaryotes?
smaller - no nucleus or nuclear envelope + plasmids
42
compare the structures of eukaryotes/prokaryotes from the perspective of prokaryotes (9)
- 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
what are viruses?
acellular, non living particles
44
what is the order of mitosis? (6)
``` I P M A T C ```
45
what happens in the cell during interphase? (2)
- DNA replication, chromosomes remain joined at centromere | - replication of organelles
46
what happens during prophase? (2)
- chromosomes become visible, shorten/thicken | - spindle fibres develop
47
what happens during metaphase?
chromosomes line up at equator
48
what happens during anaphase? (3)
- centromeres divide into 2 - pulling apart chromatids - energy for spindle fibres by mitchondria
49
what happens during telophase/cytokinesis? (4)
- chromosomes reach poles - dissapear - spindle fibres disintegrate - nuclear envelope reforms - cytoplasm divides
50
outline the cell division in prokaryotes (6)
- 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
3 stages of the cell cycle?
- interphase - nuclear division - division
52
how do chemotherapy drugs prevent cells replicating? (2)
- prevent DNA replication | - interfering with spindle fibre formation

Biology A level AQA (19 decks)

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