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

Chapter 3 - Cell Structure Flashcards

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1
Q

What structures are included in the eukaryotic cells for animals?

A
  • nucleus
  • mitochondria
  • rough endoplasmic reticulum (RER)
  • smooth endoplasmic reticulum (SER)
  • golgi apparatus
  • lysomes
  • ribosomes
  • cell surface membrane
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2
Q

Describe the nucleus and its function

A
  • nuclear envelope surrounding chromatin + nucleoplasm

* FUNCTION: stores genetic info to make protein and makes ribosome

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3
Q

Describe the mitochondria and its function

A
  • double membrane
  • inner is highly folded (cristae)
  • FUNCTION: synthesis energy rich ATP molecules during aerobic respiration
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4
Q

Describe the rough endoplasmic reticulum and its function

A
  • network of interjoined sheets studded with ribosomes

* FUNCTION: ribosomes synthesis proteins and channels transport these proteins

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5
Q

Describe the smooth endoplasmic reticulum and its function

A
  • Soft surface and tubular appearance

* FUNCTION: synthesis, store and transports lipids

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6
Q

Describe the golgi apparatus and its function

A
  • from RER then excretes to cell-membrane

* FUNCTION: Modifies proteins or lipids and packages them into vesicles for export

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7
Q

Describing lysosome and its function

A
  • contains hydroletic enzymes

* FUNCTION: Fuses worn out organelles/enzymes digest organelles

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8
Q

Describe ribosomes and its function

A
  • Contains rRNA and protein
  • Occurs in cytoplasm or RER
  • FUNCTION: Makes proteins
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9
Q

Describe cell-surface membrane and its function

A
  • fluid Mosaic model

* FUNCTION:Controls the entry and exit

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10
Q

Calculate magnification

A

Image/actual (IAM)

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11
Q

What structures are included in eukaryotic cells for plants?

A
  • cell wall
  • chloroplast
  • Vacule
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12
Q

Describe a cell wall and its function

A
  • polysaccharides (cellulose)
  • thin layer called middle lamellar makes boundary between adjacent cells and cernents adjacent cells
  • FUNCTION: mechanical strength to prevent bursting of cell allowing only water to pass
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13
Q

Describe chloroplasts and its function

A
  • chloroplast envelope with double plasma membrane and highly selective
  • FUNCTION: harvesting sun light - carries out photosynthesis
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14
Q

Describe a vacule and its function

A

•FUNCTION: stores H2O

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15
Q

What is a transmission electron microscope?

A

Passes electrons through specimen giving 2-D images

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16
Q

What is the scanning electron microscope?

A

Passes electron over the surface of specimens given 3-D imaging (low resolution)

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17
Q

What is an advantage of electron microscope?

A

High resolving power as electrons have a shorter wavelength than light microscopes

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18
Q

What are disadvantages of a lecture microscopes?

A
  • Systems must have a vacuum - Cannot observe living specimen
  • complex staining – yet picture not coloured
  • specimen must be thin
  • may contain artefact - From the way specimen prepared changing appearance
  • expensive
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19
Q

Describe the process of ultracentrifugation

A

•tissue homogenised in a blender in a solution which is: cold (inactivate enzyme)/isotonic (stops gaining/losing water)/buffered(keep the pH the same)
•tube span at high speed (1000 revs min^-1)
•pellet 1 - nucleus
•supernate removed (all except nuclei)
•run at higher speed
•pellet 2 - chloroplast/mitochondria
Repeat

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20
Q

What’s the fluid left after the cells are broken up by homogeniser releasing organelles from cell?

A

Homogenate

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21
Q

The two types of electron microscopes?

A
  • Transmission electron microscope

* Scanning electron microscope

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22
Q

When using a light microscope we can measure the size of objects using…………….

A

An eyepiece graticule

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23
Q

To calibrate an eyepiece graticule you need to use a special microscope slide called a ……………..

A

Stage micrometer

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24
Q

Describe cell specialisation

A

It’s cell adapted to have a particular function and perform it to make it more efficient

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25
Q

Describe a tissue

A

A collection of similar cells for a specific function

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26
Q

Describe an organ

A

A collection of tissues to perform a variety of functions

27
Q

Put an order in organ, cells, tissues and organs system.

A

Cells, tissues, organs and organ system

28
Q

Given two examples of a tissue

A
  • Epithelial tissue - found in animals and consists of sheets of cells
  • Xylem – found in plants transporting water and minerals ions through the plant
29
Q

Give two examples of an organ

A
  • muscle – to churn up the stomach contents

* Palisade mesophyll - made up of leaves palisade cells that carry out photosynthesis

30
Q

Give three examples of an organ system

A
  • The digestive system – digests and processes food
  • Respiratory system - useful breathing and gas exchange
  • The circulatory system - pumps and circulates blood
31
Q

Compare a prokaryotic and eukaryotic cell:

A

Prokaryotic cell – no nucleus/DNA is not associated with proteins/some DNA may be found in circular strand (plasmid)/no membrane/no chloroplast/ribosomes are smaller/cell wall made out of murine

Eukaryotic cell – distinct nucleus/do you need Societie proteins/no plasmid/DNA is linear/mitochondria are presents/chloroplast are present/ribosomes are larger

32
Q

Name the cell structures in a bacterial cell

A
  • cell wall
  • capsule
  • cell-surface membrane
  • circular DNA
  • plasmid
33
Q

Define the role of the cell wall in a bacteria

A

Physical barrier that exclude certain substance and protects against mechanical damages

34
Q

Define the role of a capsule in a bacteria

A

Protects bacteria from other cells and helps groups of bacteria to stick together

35
Q

Define the role of cell-surface membrane in the bacteria

A

Controls what enters and exits chemically

36
Q

Define the role of circular DNA in bacteria

A

Genetic information for replication of bacteria cells

37
Q

Define the role of plasmid in a bacteria cell

A

Possesses genes that may aid aid survival of bacteria in at this condition

38
Q

What structures are in the virus?

A
  • attachment protein
  • capsid
  • lipid envelope
  • matrix
  • reverse transcription
  • genetic material
39
Q

What is mitosis?

A

Produces two daughter cells that have the same number of chromosomes as the parent cell and each other

40
Q

What is meiosis?

A

Produces for daughter cells, each with half the number of chromosomes of the parents cell

41
Q

What are the five stages of mitosis?

A
  • interphase
  • prophase
  • metaphase
  • anaphase
  • telophase
42
Q

What can you use to remember the mitosis stages?

A

IPMAT

43
Q

Describe the interphase stage

A
  • Growth
  • DNA REPLICATION ( 1 chromosome = 2 chromatids)
  • Replicates ATP and organelles
  • Chromosomes invisible
44
Q

Describe the prophase stage

A
  • Chromesomes become visible (Short/condense)

* Nuclear envelope disappears

45
Q

Describe the metaphase stage

A

• chromosomes attached to spindle fibres at the centromere

46
Q

Describe the anaphase stage

A
  • Spindle fibres contract
  • chromatids separate to opposite poles
  • Energy from mitochondria
47
Q

Describe the telophase stage

A
  • Chromatids reached piles
  • Nuclear envelope forms two clusters
  • Cytoplasm divides
48
Q

What are the three stages of the cell cycle?

A
  • nuclear division
  • cytokines
  • interphase
49
Q

What is an object?

A

The material placed under the microscope

50
Q

What is an image?

A

The appearance of the material viewed under the microscope

51
Q

What is resolution?

A

How well a microscope can distinguish between two points that are close together

52
Q

Maximum resolution of a light microscope

A

0.2 micrometres

53
Q

Maximum magnification of a light microscope

A

1500 x

54
Q

Maximum resolution of electron microscopes

A

0.0002 micrometres

55
Q

Maximum magnifiation of electron microscopes

A

1,500,000 x

56
Q

What are artefacts?

A

Things that you can see on the microscope but aren’t part of your specimen

57
Q

How many micrometres are in a millimetre?

A

1,000

58
Q

How many nanometres are in a micrometre?

A

1,000

59
Q

How to calibrate a microscope?

A

1) Divide total length of stage micrometre by how many intervals to find one micrometre unit
2) Find a point where the two lines are equal
3) Work out how many micrometre units equal how many eyepiece units
4) Convert the stage micrometre units to micrometres
5) Divide stage micrometre units by eyepiece units to find the value of one eyepiece unit
6) This can be used in calculations

60
Q

What is cell fractionation?

A

The process where cells are broken up and different organelles they contain are separated out

61
Q

What happens during ultracentrifugation?

A

The filtrate is poured into a test tube, placed in the centrifuge and spun slowly
The heaviest organelles sink to the bottom, forming the pellet, whilst the rest of the organelles stay suspended in a fluid called the supernatant
The supernatant is drained off, poured into another test tube and spun at a higher speed
The next heaviest organelles form the pellet and are removed
The process repeats until the desired organelle forms the pellet, which can then be studied

62
Q

What are grana?

A

Stacks of thylakoid membranes inside chloroplasts

63
Q

What is the stroma?

A

A matrix where the sugars are synthesised during photosynthesis

AQA A-Level Biology (22 decks)

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