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OCR AS/A Level Biology A > Module 2.1 Cell Structure > Flashcards

Module 2.1 Cell Structure Flashcards

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1
Q

Magnification🔎

A

How much bigger an image appears compared with the original object

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2
Q

Resolution

A

The ability to be able to distinguish between 2 points that are very close together

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3
Q

Advantages of light microscopes🔬

A

Relatively cheap, easy to use, portable, can study living specimens

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4
Q

Max magnification of a light microscope 🔬

A

1500 times

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5
Q

Max resolution of a light 🔬

A

200nm

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6
Q

How do you calculate total magnification

A

Magnifying power of the objective lens TIMES BY magnifying power of the eyepiece lens

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7
Q

Disadvantages of electron microscopes

A

Large, expensive, needs a great deal of skill and training to use, specimens need to be dead

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8
Q

Image formed by transmission electron microscopes

A

2D Black and White image

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9
Q

Image formed by scanning electron microscope

A

3D Black and White (although false colour can be added)

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10
Q

Acetic oncein binds to DNA and stains chromosomes

A

Dark red🌶👹👺💃🏿🎒🦀🍎🍒🍷

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11
Q

Name an example of an all purpose stain

A

Methylene blue 💤🐟💦👖👕🐳🐬☄️🎽🚙🛢

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12
Q

How would you prepare a specimen?

A

Dehydrate the specimen, embed it in wax (to prevent distortion) and section the specimen

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13
Q

Calculations involving magnification formula

A

Magnification = Image DIVIDED BY Actual size

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14
Q

Features of a generalised animal cell

A 
Ribosomes
Mitochondria
Nucleolus
Nucleus
Smooth Endoplasmic Reticulum
Plasma membrane 
Golgi apparatus 
Lysosomes
Nuclear envelope 
Rough Endoplasmic Reticulum
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15
Q

Features of a generalised plant cell 🌱

A 
Chloroplast 
Amyloplast containing starch 
Golgi apparatus
Smooth Endoplasmic Reticulum 
Ribosomes
Nucleolus
Nucleus
Nuclear envelope 
Rough Endoplasmic Reticulum 
Plasma membrane
Cell wall 
Vacuole
Mitochondria
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16
Q

🌟Describe the stages in the production of extracellular proteins

A
  • mRNA copy of the gene is made in the nucleus 〰 (transcription)
  • mRNA leaves the nucleus through a nuclear pore
  • mRNA attaches to a ribosome (e.g. attached to the rough endoplasmic reticulum). The ribosome reads the instructions to assemble a protein (translation)
  • Molecules are “pinched off” in vesicles and travel towards the Golgi apparatus
  • Vesicle fuses with the Golgi apparatus
  • Golgi apparatus processes and packages 📦 the molecules ready for release
  • Packaged molecules 📦are “pinched off” in vesicles from Golgi apparatus and move towards the plasma membrane
  • Vesicle fuses with the plasma membrane
  • Protein released out of the cell by exocytosis
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17
Q

Light microscopes can be used to observe dead specimens? True or false

A

False

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18
Q

Light microscopes can be used to observe tissue in colour? True or false

A

True

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19
Q

Light microscopes can be used to observe organelles of cells? True or false

A

True

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20
Q

Light microscopes can be used to observe the movement of cells? True or false

A

True

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21
Q

What features of a 🌱 cell would you expect to be able to see under a light microscope?

A

The cell wall, the nucleus, the cytoplasm and the chloroplasts

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22
Q

Explain why you can only see limited organelle when looking at a 🌱cell under a light microscope

A

The resolution of a light microscope is 200nm and the max magnification is 1500 times. The magnification and resolution are too low to observe most organelle of the cell.

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23
Q

Scanning electron microscopes can be used to observe 2D images, true or false?

A

False

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24
Q

Scanning electron microscopes can be used to observe cell surfaces, true or false?

A

True

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25
Q

Scanning electron microscopes can be used to observe cells in colour, true or false?

A

False

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26
Q

Scanning electron microscopes can be used to observe cells in real time, true or false?

A

False

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27
Q

Strengths and weaknesses of light and electron microscopes

A

Light microscopes strengths:
Cheap, portable, easy to use, can study living or dead specimens with them

Light microscopes weaknesses:
Limited resolution and magnification, most organelles are too small to see at this power

Electron microscopes strengths:
High magnification and resolution

Electron microscopes weaknesses:
Large, needs skills and training to operate, specimen must be dead

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28
Q

Which of these statements are true?

1) Stains can be used to distinguish between different cell types
2) Stains can be used to fix specimens
3) Stains can be used to distinguish different tissue types
4) Stains can be used to highlight particular organelle

A

1, 3 and 4 only

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29
Q

How would you prepare a temporary mount of a specimen for a light microscope?

A

Section the specimen, put it on a slide, stain it, put a coverslip over the specimen

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30
Q

How would you calculate magnification?

A

Image size divided by actual size

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31
Q

How would you calculate the image size?

A

Actual size times by magnification

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32
Q

How would you calculate the actual size of a cell?

A

Image size divided by magnification

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33
Q

Organelle present in animal cells

A 
Nucleolus
Nucleus
RER
SER
Ribosomes
Mitochondria 
Golgi apparatus 
Centrioles
Plasma membrane 
Cytoskeleton
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34
Q

Organelles present in plant cells🌱

A 
Nucleus
Nucleolus
RER
SER
Ribosomes
Mitochondria
Chloroplasts
Golgi apparatus 
Cellulose cell wall
Plasma membrane 
Large central vacuole
Cytoskeleton
35
Q

Prokaryotic cells don’t have a nucleus, true or false?

A

True

36
Q

Prokaryotic cells have many organelles, true or false?

A

False

37
Q

Prokaryotic cells have a cellulose cell wall, true or false?

A

False

38
Q

Prokaryotic cells have ribosomes, true or false?

A

True

39
Q

Describe the differences in function between the RER, SER and Golgi apparatus

A

RER is coated with ribosomes that synthesise proteins
SER synthesises lipids
Golgi apparatus helps 📦 and modify proteins for exocytosis

40
Q

Proteins cross the plasma membrane by what process?

A

Exocytosis

41
Q

Why do the beta cells in the pancreas (beta cells produce insulin, a protein) have lots of RER?

A

RER coated with lots of ribosomes
Ribosomes synthesise proteins
Beta cells of the pancreas produce insulin, a protein

42
Q

Suggest why beta cells in the pancreas need large amounts of ATP

A

Proteins are secreted from the beta cells by exocytosis which requires ATP/is an active process

43
Q

Which are true?

1) The cytoskeleton is made of microtubules
2) The cytoskeleton is involved with the production of protein
3) Flagella and cilia are made of microfilaments
4) Microtubule proteins transport vesicles along microtubules

A

ONLY 1 and 4

44
Q

Role of flagella

A

Movement of the cell

45
Q

Role of cilia

A

Movement of the cell

Movement of substances e.g. Mucus

46
Q

Role of microtubules

A

To maintain the shape of the cell

47
Q

Role of microtubule motors

A

Movement of vesicles along microtubules

48
Q

How is the cytoskeleton involved in movement inside and outside of the cell?

A

Microtubule motors move vesicles along microtubules inside the cell
Flagella/cilia are made from microtubules on the surface of the cell which helps the cell to move
The lengthening and shortening of microtubules inside the cell helps the cell to move

49
Q

Cytoskeleton

A

Network of protein fibres within the cell that give the cell structure and shape

50
Q

🌟Microtubules

A

Hollow cylinders of tubulin

25nm diameter

Maintain cell shape

Anchors organelles

In flagella and cilia, the structure is a cylinder of 9 microtubules in a circle and 2 more microtubules in a central bundle

Can help move microbes

How chromosomes are moved during mitosis (spindle fibres)

How vesicles move from the ER to Golgi using microtubule motors (requires ATP)

51
Q

Flagella and cilia

A

Sticks out of the surface of the cell
Each one is a cylinder with 9 microtubules in a circle and 2 more in a central bundle
Can move using ATP

52
Q

Cilia

A

Large no. of them on ciliated epithelial cells
Moves egg down Fallopian tube
Beat to move mucus

53
Q

🌟Intermediate filaments

A 
10nm
Thick cables of keratin
Maintains cell shape 
Anchors nucleus 
Anchors organelles
54
Q

🌟Actin microfilaments

A 
2 intertwined strands of actin
7nm diameter
Maintains cell shape 
Causes muscle contractions 
Involved in cytokinesis 
Allows pseudopodia seen by amoeba and some WBCs
55
Q

Vesicles

A

Membrane bound sacs

Carry substances

56
Q

Features of prokaryotic cells

A

Mesosomes - inner folding, large SA for respiration
Ribosomes - synthesise proteins (smaller than in eukaryotes)
Plasmid - genetic material
Pilli - for conjugation
Slime capsule - keeps cell moist
Chromosomal DNA - contains instructions to make proteins
Cell wall - made of murein/peptidoglycan

57
Q

Nucleus

A 
Surrounded by nuclear envelope
Nuclear pores allow mRNA and nucleotides through
Contains genetic material (chromatin)
Contains nucleolus 
Controls cell
58
Q

Mitochondria

A

2 membranes separated by inter-membrane space
Inner membrane folded = cristae
Aerobic respiration takes place in mitochondria to release ATP

59
Q

RER

A

System of cisternae
Ribosomes line it
Involved w/ protein synthesis and transport

60
Q

SER

A

System of cisternae
Lacks ribosomes
Involved w/ synthesis and transport of lipids

61
Q

Ribosomes

A 
Involved w/ protein synthesis 
Move along mRNA 
Read nucleotide code to synthesise proteins
Ribosomes are made of rRNA + protein 
1 large + 1 small subunit
62
Q

Golgi apparatus

A

More compact that SER
Made of flattened membrane sacs
Modifies and packages 📦 proteins
Forms lysosomes

63
Q

Lysosomes

A

Membrane sac
Contains digestive enzymes
Destroys worn out parts of cell

64
Q

Cytoplasm

A

Aqueous

Contains simple ions, amino acids, ATP, sugars, fat droplets

65
Q

Cell membrane

A 
Boundary between cell + environment 
Fluid mosaic model
Phospholipid bilayer
Proteins 
Cholesterol
Glycolipids 
Glycoproteins
66
Q

Centrioles

A

ONLY in animal cells

Migrate to poles of cell during mitosis and produce microtubules (spindles) to pull chromosomes apart

67
Q

Chloroplasts

A 
PLANTS ONLY 
Stroma
Thylakoids 
Grana
Intergranal lamellae
Chlorophyll 
Site of photosynthesis
68
Q

Starch granules

A

PLANTS ONLY

temporary stores of carbohydrates

69
Q

Cell wall

A

Made of cellulose
Provides strength
Allows water to move through the plant

70
Q

Plasmodesmata

A

PLANTS ONLY
gaps that allow neighbouring cells to link
Continuation of cytoplasm

71
Q

Average diameter of prokaryotic cell

A

0.5-5 micrometers

72
Q

Average length eukaryotic cells

A

20-40 micrometers

73
Q

Ribosome diameter in prokaryotes

A

18nm

74
Q

Ribosome diameter in eukaryotes

A

22nm

75
Q

A structure associated with the cytoskeleton that can help cells move

A 
Flagellum
Cilia
Microtubules 
Microfilament
Undulipodium
76
Q

2 processes inside the cell that rely on cytoskeleton for movement

A

Chromosomes moving
Cytokinesis
Movement of organelles
RNA in protein synthesis

77
Q

What events happen following production of extracellular proteins until they are released?

A 
Protein pinched off by Vesicle 
Moves to Golgi apparatus
Golgi processes and packages 
Moves in Vesicle to plasma membrane 
Exocytosis
78
Q

What structure secretes mucus?

A

Golgi Vesicle

79
Q

Why do ciliated cells have lots of mitochondria?

A

They need a lot of energy to waft mucus

V active

80
Q

Vacuoles

A

Large, permanent organelle in plants

Tonoplast filled w/water and sugars to keep the cell turgid

81
Q

🌟Stages of exocytosis

A

Vesicle moves towards cell surface membrane along microtubules

Vesicle fuses with the cell surface membrane

Protein released out of the cell by exocytosis

Movement of vesicles on microtubules and fusion of vesicles with the membrane requires ATP

82
Q

🌟Stages of endocytosis

A

Molecule binds w receptor

Cell surface membrane invaginates (requires ATP)

Membrane fuses w itself to form a vesicle

Vesicle moves through cytoplasm to destination organelle

83
Q

🌟Roles of the cytoskeleton

A

Cell support + stability to maintain cell shape

Movement of cilia

Movement of flagellum to move cell

Changing cell shape e.g. endocytosis and exocytosis

Moving organelles around inside a cell

Anchoring organelles

Moving chromosomes and mRNA

OCR AS/A Level Biology A (14 decks)

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