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Human Physiology > CC- Cells, Organelles & Plasma membranes > Flashcards

CC- Cells, Organelles & Plasma membranes Flashcards

1
Q

Define nuclear envelope

A

Separates genetic material from cytoplasm

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2
Q

What are the 4 main functions of intrinsic proteins

A

Act as channels

Transporters

Receptors

Enzymes

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3
Q

Define the smooth endoplasmic reticulum

A

Synthesis of lipids

Abundant (lots of them) in cells secreting lipids

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4
Q

What are the 4 ways in which substances may move across the membrane

A

Diffusion

Osmosis

Facilitated diffusion

Active transport

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5
Q

Define the centrioles

A

Consist of 2 hollow cylinders at 90° to each other

They organise microtubules during cell division

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6
Q

Where can hydrophilic pores be found

A

In channel proteins

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7
Q

Can hydrophilic substances diffuse through the membrane?

A

No

instead they cross the membrane via water-filled pores or protein channels.

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8
Q

What is the structure and function of cuboidal tissues

A

1 cell thick, box shaped cells w/ a prominent nucleus.

Involved in absorption or secretion

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9
Q

What are the magnifications and resolutions of the two types of electron microscopes

A

Scanning - medium

Transmission - high

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10
Q

Define the nucleolus

A

Synthesis of ribosomes

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11
Q

What does the reverse transcriptase enzyme do?

A

Converts RNA into DNA

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12
Q

Explain glycolipids in the cell surface membrane

A

Occur on the external surface of cell

CHO part extends into intercellular space + called the glycocalyx.

Cell-cell recognition

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13
Q

What does the cytoplasm of a prokaryotic cell contain?

A

Storage products i.e glycogen and lipids

Ribosomes

Plasmids

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14
Q

Define differentiation

A

Development of a cell into a specific type

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15
Q

Why is the rate of movement for simple diffusion much faster than facilitated diffusion?

A

Because simple diffusion happens via the membrane therefore larger SA.

Facilitated diffusion is limited by no of carrier proteins available

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16
Q

Explain protein production

A

Ribosomes are synthesised in the nucleolus.

mRNA is made by transcription in the nucleus.

Small enough to pass through nuclear pore and into cytoplasm.

Ribosomes then synthesis proteins using the mRNA

RER transports proteins and folds it.

Golgi body modifies protein to then be packaged into a secretory vesicle.

Vesicle migrates towards and fuses with the plasma membrane so that the contents of the vesicle are released by exocytosis.

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17
Q

Define hydrophilic channel proteins

A

Each protein is specific to one type of small ion.

Can close and open if necessary

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18
Q

Explain pinocytosis

A

Active process that extends cell membrane around a FLUID.

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19
Q

What is facilitated diffusion

A

Diffusion that relies on the KE of molecules to move through carrier proteins in the membrane (mol-specific)

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20
Q

Define osmosis

A

Movement of water molecules from an area of high water potential to an area of low water potential across a partially permeable membrane.

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21
Q

What subcellular structures are ONLY found in the mitochondria

A

Matrix

Cristae

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22
Q

What happens to an animal cell in a hypotonic situation

A

Water goes in via osmosis

Lysis

Haemolysis (if in RBC)

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23
Q

What is the structure of cholesterol

A

Hydrocarbon tail

Ring structure region with 4 hydrocarbon rings and a hydroxyl group

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24
Q

Define carrier proteins

A

Allow diffusion of larger polar molecules. I.e glucose

A molecule attaches to binding site, protein changes shape, releases molecule on other side of membrane.

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25
Q

What are the 3 types of lipids found in the cell surface membrane

A

Phospholipids

Glycolipids

Cholesterol

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26
Q

What happens to an animal cell in a hypertonic situation

A

Water moves out via osmosis

CRENATION

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27
Q

Define tissue

A

Groups of layers of similar cells working together to perform a specific function

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28
Q

What is the highest water potential

A

0kPa

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29
Q

What are the 3 most common prokaryotic cell shapes

A

Spheres

Rods

Spirals

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30
Q

What does the phospholipid bilayer allow the diffusion of

A

Lipid soluble

Non polar

BARRIER TO:

Polar molecules as cannot pass through hydrophobic tails unless VERY SMALL. I.e water

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31
Q

What is peptidoglycan made of?

A

Polymers of modified sugars cross-linked by short chain polypeptides.

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32
Q

What is the relative size of a prokaryotic cell?

A

1-5 micrometers

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33
Q

Define the nuclear pore

A

Allows transport of mRNA out of nucleus

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34
Q

Define endosymbiosis

A

Mutually beneficial relationship in which one organism lives inside the other.

Describes the origin of chloroplasts and mitochondria.

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35
Q

What type of ribosome is found in prokaryotic and eukaryotic cells

A

Prokaryotic - 70s

Eukaryotic - 80s

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36
Q

What is thought to be the site of respiration in prokaryotic cells?

A

Mesosomes

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37
Q

Define amphipathic when talking about phospholipids

A

Meaning they have a dual nature in that one end is hydrophilic whilst the other is hydrophobic.

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38
Q

What transport methods can carrier proteins do?

A

Diffusion

Facilitated diffusion

Active transport

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39
Q

Why aren’t viruses considered to be a cell?

A

Because of their inability to replicate by themselves and lack of nucleus.

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40
Q

Active transport, diffusion and osmosis are for individual molecules. What is the transport known as for larger amounts of molecules?

A

Bulk transport

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41
Q

How does the cell effectively control the amount of water entering across the plasma membrane?

A

By regulating the concentration of ions in the cytoplasm via the sodium/potassium pump

42
Q

Where can mitochondria be found

A

Muscle cells for contraction

Sperm cells for flagella to move

Root hair cells for active transport

43
Q

Define the Golgi body

A

Modifies + packages proteins into vesicles to be transported around or out of cell (exocytosis)

Production of glycoproteins, lysosomes and liposomes

44
Q

Why do organisms have internal cell membranes

A

Provide a transport system

Compartmentalisation

Large SA for attachment of enzymes and other reactants

45
Q

Define extrinsic protein on a cell membrane

A

Usually receptors for chemical messengers i.e hormones

46
Q

Define diffusion

A

Net movement of molecules from a region of higher concentration to a region of lower concentration.

47
Q

Name a connective tissue

A

Collagen and elastic fibres

48
Q

Define water potential

A

Likelihood of water to move out of a solution

49
Q

What is the function of the phospholipids in the membrane

A

Provide stability, fluidity and gives membrane selective permeability.

50
Q

What is the DNA like in prokaryotic cells?

A

Naked

Free

Circular

51
Q

What can the rate of diffusion be affected by?

A

Temp

Concentration gradient

Diffusion distance

52
Q

Define ribosomes

A

Protein synthesis

53
Q

Briefly describe the sodium and potassium ion pump

A

3 Na+ ions move out of cell simultaneously to 2 potassium ions moving into cell = both against their concentration gradients

54
Q

What type of cells have the potential to become any cell type in the body?

A

Stem cells

55
Q

What does the degree of fluidity of a cell surface membrane depend on?

A

Length of FA side chains (longer chains = less fluidity)

Proportion of FA that are saturated (higher sat fats = lower fluidity)

Steroid content (higher = lower fluidity)

56
Q

Where does active transport take place in the cell membrane?

A

Carrier proteins

57
Q

Define the cholesterol on a cell membrane

A

Adds strength and rigidity however too much decreases membrane flexibility to a dangerous level.

58
Q

Define active transport

A

Use of ATP to move substances against their concentration gradients.

59
Q

What are the 3 types of bulk transport?

A

Pinocytosis

Phagocytosis

Exocytosis

60
Q

Define the rough endoplasmic reticulum

A

System of flattened sacs (cisternae) continuous with the nuclear membrane + may link to the Golgi apparatus

Transports proteins synthesised by the ribosomes attached

Manufactures hormones and enzymes

61
Q

What rule is there about pressure potential and solute potential?

A

Pressure pot. = always +ive or zero

Solute potential = Always -ive

62
Q

Eukaryotic cells have a nucleus, what do prokaryotic cells have?

A

A nucleoid.

63
Q

Define electron microscopes

A

Uses electrons

Dead sample in a vacuum

64
Q

List the 4 types of epithelial tissues

A

Squamous

Cuboidal

Columnar or ciliated

Glandular

65
Q

What is the function of columnar or ciliated tissues and where can they be found

A

Absorption +Secretion

i.e Lining of small intestine

66
Q

What is the structure of a squamous tissue and where can it be found

A

Single layer of thin + smooth cells flattened on basement membrane

i.e Alveoli and blood vessels

Permeable to allow filtration or diffusion

67
Q

Who came up with the fluid mosaic model

A

Singer and Nicholson in 1972

68
Q

What is the DNA like in eukaryotic cells

A

Enclosed by an envelope

Linear

69
Q

Define symbiosis

A

Relationship in which organisms from 2 separate species depend on each other for survival.

70
Q

Define optical microscopy

A

Uses light and can observe living samples at low magnification

71
Q

List 2 types of endocytosis

A

Phagocytosis

Pinocytosis

72
Q

What type of microscope is needed to see the internal structures of chloroplasts and mitochondria?

A

Electron microscope

73
Q

How much of the cell is vacuole

A

70%

74
Q

Describe the process of phagocytosis

A

Cell surface receptor binds to antigen on bacterium

Cell membrane invaginates + bacterium is taken into a phagosome by endocytosis.

Lysosomes fuse w/ phagosome + secret digestive enzymes onto it.

Productos of digestion are absorbed into cytoplasm.

75
Q

Define organ

A

A collection of different types of tissues working together to perform a specific function.

76
Q

Define the mitochondria

A

Site of aerobic respiration to release energy in the form of ATP

77
Q

Define the glycolipid on a cell membrane

A

Branched carbohydrate attached to a phospholipid

78
Q

What is FD limited by?

A

Number of carrier proteins

79
Q

Explain the transportation of water-soluble substances in regards to the permeability of the membrane

A

Water soluble substances (i.e glucose, polar molecules and ions) can’t diffuse through phospholipids so MUST pass through intrinsic protein molecules.

80
Q

What is the structure of the columnar or ciliated tissues

A

Elongated column shaped cells

Some have cilia, some have microvilli

81
Q

Where can cuboidal tissues be found

A

In the kidney tubule

82
Q

Define cotransport

A

Type of FD in which 2 substances are simultaneously transported across a membrane by 1 protein.

83
Q

What is the structure of a phospholipids bilayer membrane known as?

A

Fluid mosaic model

84
Q

Why is it called the fluid mosaic model

A

Fluid = phospholipids and proteins move around each other

Mosaic = arrangement of proteins within phospholipid bilayer

85
Q

Define the glycoprotein on a cell membrane

A

Branched carbohydrate attached to a membrane protein

86
Q

What do the different electron microscopes look at

A

Scanning - 3D surface

Transmission - Internal cross section

87
Q

How big is the Golgi body

A

1 x 1 micrometers

88
Q

Define viral DNA

A

Enclosed in a protein coat called capsid

Has enzymes attached ready to convert DNA into RNA once in host cell

89
Q

Define the intrinsic protein channel of a cell membrane

A

Passes through both layers of the cell membrane

Maintains different concentrations of ions on either side of the membrane.

Essential for the sodium/potassium pump.

90
Q

How thick is the cell surface membrane?

A

7.5 nm thick

91
Q

Why do liver cells contain more mitochondria than fat storage cells?

A

Because liver cells are metabolically active due to secretion therefore require large supply of ATP

Fat storage cells are metabolically inactive so need less ATP

92
Q

List 3 structural differences between phospholipid and triglyceride

A

PL only has 2 fatty acid chains, TG has 3.

PL has a phosphate group, TG don’t.

PL has a hydrophilic and hydrophobic region, TG is entirely hydrophobic

93
Q

What is the role of the glycoproteins and glycolipids on the cell membrane?

A

Allow cells to recognise and attach to each other.

94
Q

What are the basics to a virus structure

A

All have genetic material (either RNA or DNA)

Protein coat (caspid)

Some have a lipid bilayer

95
Q

Define cell membrane

A

Protection - Separating cell contents from outside environment

Cell recognition and signalling

Receptor sites

Regulation transport of materials into or out of cells, selectively permeable

96
Q

Define the nucleus

A

Contains DNA coding for protein synthesis

97
Q

What is the function of a glandular tissue and where can it be found?

A

Striated + Closely packed together

Secrete hormones, saliva + enzymes

i.e Digestive system

98
Q

What are the levels of organisation

A

Cell

Tissue

Organ

Organ system

99
Q

How is the structure of a virus different to that of a bacteria?

A

Virus has a lipid bilayer whereas bacterium just has a cell membrane

100
Q

What are the 2 major biochemical components present in ALL viruses

A

Proteins

DNA/RNA

101
Q

Do viruses have plasmids or mitochondria?

A

NO

Human Physiology (16 decks)

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