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IB Biology > 1: Cell Biology > Flashcards

1: Cell Biology Flashcards

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1
Q

Outline the cell theory

A
  • all living organisms are made of cells
  • cells are the smallest unit of life
  • cells arise from pre-existing cells
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2
Q

What are the exceptions of the cell theory

A
  • striated muscle
  • giant algae
  • fungal hyphae
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3
Q

Why are striated muscles exceptions to the cell theory

A

they challenge the concept that cells work independently of each other

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4
Q

Why are giant algae exceptions to the cell theory

A

they challenge the idea that most unicellular organisms have to be small in size and simple in structure

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5
Q

Why are fungal hyphae exceptions to the cell theory

A

they challenge the idea that organisms are made of discrete cells

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6
Q

What are the functions of life

A
  • metabolism
  • respiration
  • homeostasis
  • excretion
  • reproduction
  • growth
  • nutrition
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7
Q

Define nutrition

A

ability to obtain food by either synthesising its own organic molecules or the absorbing them to provide energy

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8
Q

Define metabolism

A

the sum of all enzyme-catalysed reactions in a cell/organism

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9
Q

Define growth

A

an increase in size/shape

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10
Q

Define response

A

ability to detect and respond to external and internal stimuli in the environment

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11
Q

Define excretion

A

the removal of metabolic wastes by an organism

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12
Q

Define homeostasis

A

the maintenance of a constant internal environment

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13
Q

Define reproduction

A

the production of an offspring by sexual or asexual reproduction

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14
Q

What are examples of unicellular organisms

A

paramecium & chlorella

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15
Q

Features of Paramecium

A
  • heterotroph
  • contractile vacuole for homeostasis
  • feeds off smaller organisms
  • CO2 released via respiration as waste
  • has cilia for response
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16
Q

Features of Chlorella

A
  • autotroph
  • produces own organic matter via photosynthesis
  • releases O2 as waste product
  • responds to light by moving towards it
  • stores extra glucose as starch
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17
Q

Explain surface area and volume

A
  • surface area affects the rate at which particles enter and exit the cell
  • volume affects the rate of chemical reactions in a cell
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18
Q

Why is there a limit to the cell size

A
  • cell size increases SA:V decreases
  • more substances need to be taken in and out
  • if not able to do this quickly enough, cell will accumulate waste products, overheat and die
  • the cell therefore needs to divide
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19
Q

What are the features of striated muscles

A
  • multiple nuclei
  • larger than most cells
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20
Q

What are the features of giant algae

A
  • consist of one cell very large and multiple nuclei
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21
Q

What are the features of fungal hyphae

A
  • they have no end walls
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22
Q

Features of stem cells

A
  • self-renewal – ability to divide an unlimited amount of times
  • ability to differentiate into any specialised cell
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23
Q

What are emergent properties

A

multi-cellular organisms have greater properties that arise from interactions of cellular components.

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24
Q

Outline differentiation

A

when certain genes are expressed, it determines the function of the cell and the cell becomes specialised
- once a cell has differentiated it cannot change function, it is “committed”

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25
Q

Where can stem cells be found

A
  • embryos
  • umbilical cord
  • adult tissues (ex: bone marrow)
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26
Q

What are stem cells used for + 2 named examples

A

therapeutic uses + embryonic development
- Stargardt disease
- leukaemia
- Parkinson

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27
Q

Outline the use of stem cells in Stargardt’s disease

A

Cause: genetic mutation that impairs retinal photoreceptors
Treatment: replacing dead cells in the retina with functioning ones

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28
Q

Outline the use of stem cells in Parkinson

A

Cause: the death of dopamine-secreting cells in the brain
Treatment: replacing dead nerve cells with living dopamine-producing ones

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29
Q

What are the ethical issues of stem cells

A
  • the use embryonic stem cells signifies the destruction of a potential human life
  • adult tissue and umbilical cord stem cells have limited ability to differentiate
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30
Q

How to convert mm in micrometers

A

multiply by 1000

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31
Q

What is the formula to calculate magnification

A

Image size divided by actual size

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32
Q

List the differences between a light and an electron microscope

A

light: colour, poor magnification, low resolution
electron: black&white, high resolution and magnification

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33
Q

List the main features of prokaryotes

A
  • no nucleus
  • 70s ribosomes
  • cell wall
  • Pilli
  • plasmids
  • flagella
  • circular DNA in the nucleoid
  • cell membrane
  • small in size <10 micrometres
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34
Q

What is the function of plasmids

A

they are small loops of genes which can be passed between prokaryotes (ex: antibiotic resistance)

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35
Q

What is the function of the flagellum

A

enables the prokaryote to move

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36
Q

What is the function of Pilli

A

it allows bacteria to adhere to cell surfaces

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37
Q

What is the function of ribosomes

A

synthesis of polypetides

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38
Q

What is the function of cytoplasm

A

site of chemical reactions

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39
Q

How do prokaryotes reproduce

A

asexual reproduction via binary fission

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40
Q

Outline binary fission

A

1) The cell elongates
2) DNA is replicated
3) The cell wall and plasma begin to divide
4) Cross wall forms to separate the 2 cells
5) The 2 cells separate (genetically identical)

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41
Q

What are the two types of eukaryotic cells

A

animal and plant cells

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42
Q

What is the function of chloroplast

A

site of photosynthesis

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43
Q

What is the function of mitochondria

A

produces ATP during aerobic respiration

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44
Q

What is the function of lysosomes

A

breaks down unwanted material using digestive enzymes

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45
Q

What is the function of cell walls

A

prevents the cell from bursting

46
Q

What is the function of the cell membrane

A

controls the entry and exit of substances of the cell

47
Q

What is the function of the vacuole

A

stores water

48
Q

What is the function of the Golgi apparatus

A

it modifies proteins (processes protein into their final 3D shape)

49
Q

What is the function of the phospholipid bilayer

A

controls the movement of substances in and out of the cell

50
Q

Properties of phospholipids

A
  • they are amphipathic
  • hydrophobic tail face inwards
  • hydrophilic head faced outwards
  • made up of 2 fatty acids, 1 glycerol and 1 phosphate
51
Q

Define hydrophobic

A

not attracted to water (insoluble in water)

52
Q

Define hydrophilic

A

attracted to water (soluble in water)

53
Q

What is the main components of the phospholipid bilayer

A
  • phospholipids
  • cholesterol
  • integral and peripheral proteins
  • channel proteins
54
Q

What is the function of cholesterol

A

reduces the fluidity and permeability of the membrane

55
Q

In what 2 categories can membrane properties be grouped in

A

integral proteins: embedded into the bilayer (hydrophobic)
peripheral proteins: on the surface of the bilayer (hydrophilic)

56
Q

List the different types of membrane proteins

A
  • channel/carrier proteins which allow polar molecules to travel through the membrane
  • receptors (hormones)
  • cell-to-cell recognition (ex: glycoproteins allow cells to recognise each other and attach to each other)
  • cell adhesion (allows tight junctions to be formed between cells)
  • immobilised enzymes
57
Q

Describe Davson and Danielli’s model

A

Davson and Danielli’s model of the membrane suggested that the proteins were arranged in layers above and below the phospholipid bilayer

58
Q

What are the different types of membrane transport

A
  • diffusion
  • facilitated diffusion
  • active transport
  • osmosis
  • endocytosis & exocytosis
59
Q

Define diffusion

A

the movement of particles from an area of higher concentration to an area of lower concentration

60
Q

Features of diffusion

A
  • passive movement
  • no ATP needed
61
Q

Define facilitated diffusion

A

movement of particles from an area of higher concentration to an area of lower concentration, through a membrane protein (ex: channel proteins)

62
Q

What are two types of proteins that enable facilitated diffusion

A

channel and carrier proteins

63
Q

Features of carrier proteins

A
  • they are highly specific (only allow 1 type of molecule to pass through)
  • they change shape to allow molecules to move through the membrane
64
Q

Define osmosis

A

the movement of water molecules from an area of higher water potential to an area of lower water potential, through a partially permeable membrane
- up the solute concentration

65
Q

Define active transport

A

the movement of particles from an area of lower concentration to an area of a higher concentration, with the use of ATP from cellular respiration

66
Q

Define osmolarity

A

measurement of the solute concentration in a solution

67
Q

What is the effect of a hypertonic solution on an animal cell

A

The water potential is greater in the cell inside the cell than outside
Water moves out of the cell → cell shrivels

68
Q

What is the effect of a hypotonic solution on an animal cell

A

there is a lower water potential inside the animal cell than outside
Water moves into the cell → cell swells and might burst

69
Q

What is the effect of an isotonic solution on an animal cell

A

the water potential inside and outside the cell is equal
Water does not move into the cell → no change in the cell

70
Q

Outline the sodium-potassium protein pump across the axon membrane

A

1) 3 Na+ located in the cell bind to the pump
2) A phosphate group is removed from ATP and binds to the pump
3) The pump changes shape and transports the 3 Na+ outside the cell (active transport)
4) 2 K- located outside the cell bind to the pump
5) The phosphate group is released and the pump goings back to its original shape
6) The 2 K- are released inside the cell (facilitated diffusion)

71
Q

Define endocytosis

A

The taking of external substances by an inward pinching of the plasma membrane, forming a vesicle

72
Q

Define exocytosis

A

The release of substances from a cell when a vesicle joins with the cell membrane

73
Q

What is the relationship between the fluidity of the cell membrane and vesicles

A

The membrane fluidity allows larger substances to move in and out of the cell in vesicles using ATP to pinch off small regions of the plasma membrane

74
Q

Outline endocytosis

A
  • Part of the plasma membrane is pulled inwards
  • A droplet of fluid containing the material becomes enclosed when a vesicle is pinched off
  • The vesicle moves away from the plasma membrane into the cytoplasm
75
Q

Outline exocytosis

A
  • Polypeptides are created in the RER
  • A vesicle is pinched off the RER with the polypeptide inside
  • The vesicle travels to the Golgi apparatus and fuses with the Golgi apparatus
  • The Golgi apparatus processes the polypeptide in its final 3D shape
  • A vesicle will be pinched off the Golgi apparatus and it moves towards the plasma membrane
  • The vesicle will fuse with the plasma membrane and the polypeptide is released outside the cell
76
Q

What observations supported the Davson-Danielli model

A
  • The membrane has two darker layers surrounding a lighter line
  • Proteins were known to appear darker in electron micrographs
77
Q

What are the falsifications for the Davson-Danielli model

A

Biochemical analysis showed that: proteins were globular, varied in sizes
& had parts that were hydrophobic
- different coloured fluorescent markers had mixed which showed that membrane proteins were free to move within the layer
- non-polar amino acids cause proteins to remain embedded in membranes

78
Q

What is the evidence to support endosymbiotic theory

A
  • Both reproduce by binary fission
  • Both contain their own circularDNA
  • They both have 70S ribosomes to synthesise their own proteins
  • They both have double membranes
79
Q

Outline endosymbiotic theory

A
  • mitochondria and chloroplasts are similar to prokaryotes
  • host cell engulfed a prokaryotic cell but did not digest it
  • chloroplasts and mitochondria were once independent
80
Q

What was the point of the Pasteur’s experiment

A

disproved spontaneous generation, the idea that living things can arise from non-living things

81
Q

Outline the Pasteur’s experiment

A
  • he boiled nutrient broth and place it in two flasks
  • one flask had access to open air, the other did not
  • A sample from each flask was incubated to check for the presence of live bacteria
  • Only the one with the open neck grew bacterial cells
82
Q

What was the conclusion of the Pasteur’s experiment

A

cells arise from pre-existing cells (they disproved spontaneous generation)

83
Q

Outline Urey and Miller’s experiment

A
  • they re-created conditions on Earth before life and demonstrated the synthesis of organic matter from non-living things
84
Q

What are the main stages of cell division

A
  • interphase
  • mitosis
  • cytokinesis
85
Q

Outline interphase

A

G1: organelle duplication
S: DNA replication
G2: protein synthesis and active metabolic reactions

86
Q

Outline the first phase of mitosis

A

Prophase:
- DNA supercoils & becomes condensed
- Nuclear membrane breaks down
- Spindle microtubules start to form

87
Q

Outline the second phase of mitosis

A

Metaphase:
- chromosomes line up to the equator
- spindle microtubules attach themselves to the centromeres of the chromosomes

88
Q

Outline the third phase of mitosis

A

Anaphase:
- the spindle microtubules contract separating the sister chromatids
- the sister chromatids are moved to opposite poles of the cell (now chromosomes)

89
Q

Outline the fourth phase of mitosis

A

Telophase:
- chromosomes uncoil
- spindle microtubules break down
- the nuclear membrane breaks down

90
Q

What are the uses/functions of mitosis

A

growth, asexual reproduction, tissue repair and embryonic development

91
Q

Outline the differences in cytokinesis in plant and animal cells

A

animal: a cleavage furrow forms and separates the daughter cells
plant: a cell plate forms and separates the daughter cells

92
Q

What is the function of cyclins

A

proteins that control the progression of the cell cycle

93
Q

What is the mitotic index

A

the ratio of cells that are undergoing mitosis

94
Q

Define tumour

A

agents that cause mutation in one’s DNA which can lead to cancer

95
Q

Define carcinogens

A

agents that cause cancer

96
Q

Define metastasis

A

the spreading of cancerous cells through the body via the blood or other mechanisms

97
Q

Define primary tumour

A

a mass of cells that are dividing at abnormally fast rates

98
Q

Define secondary tumour

A

the tumour that forms in other parts of the body after metastasis of the primary tumour

99
Q

Define benign tumour

A

do not cause cancer

100
Q

Explain the role of cyclin and cyclin-CDK complexes in controlling the cell cycle

A
  • a cyclin and CDK form a complex are activated
  • the cyclin-CDK complex phosphorylates a target protein
  • it causes it to perform a specific function
  • there are 4 types of cyclins
101
Q

how to calculate the mitotic index

A

the number of cell in mitosis divided by the total number of cells X100

102
Q

What is the correlation between smoking and cancer

A

There is a positive correlation between smoking and cancer. The more cigarettes smoked per day the higher the chance of developing certain cancers

103
Q

Why is the genetic code considered universal

A

all species use the same four bases A,T,C and G, and each base sequence codes for the same amino acid in all species.

104
Q

Which prokaryotic cell evolved first?

A

heterotrophic (respiring aerobically) and then autotrophic prokaryotes (photosynthesis)

105
Q

Draw a Davson-Danielli and Singer-Nicholson Model

A

Davson: two layers of proteins above and below the phospholipids
Singer-Nicholson: integral and peripheral proteins in the structure

106
Q

What is a feature that is found in eukaryotes and photosynthetic prokaryotes?

A

70s ribosomes because eukaryotes have 70s ribosomes in their mitochondria

107
Q

What are the functions of cyclin D

A

it is present first and it triggers cells to move from G1 to S phase

108
Q

What is the function of cyclin E

A

it has the highest concentration at the start of S phase and it prepares the cell for DNA replication during S phase

109
Q

What is the function of cyclin A

A

it has the highest concentration in G2 phase and it triggers DNA replication and prepares the cell for mitosis

110
Q

What is the function of cylin B

A

it has the highest concentration at the beginning of mitosis and it promotes the formation of the mitotic spindle

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