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Biology 101 > Structure and Function of cells > Flashcards

Structure and Function of cells Flashcards

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1
Q

Approx size of a cell

A

0.1-100 micrometers

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2
Q

Why cant cells be too. small?

A

They must fit DNA and must also fit cellular components to sustain life and reproduce

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3
Q

Why cant they be too big?

A

Needs to exchange w outside environment, the cell needs depend on. the volume

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4
Q

What does the exchange capacity of.a cell depend on?

A

SURFACE AREA

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5
Q

Briefly explain surface to volume ratio and square cube law

A

The more volume a cell has, the more nutrients it requires to get (through surface area) however, volume and surface area do not increase at the same time therefore the nutrients needs cannot be met

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6
Q

What are the parts of the cell theory

A
  • a cell is the basic structural and functional unit of living organisms
  • cells come from pre existing cells
  • cell characteristics are passed from parent to off spring
  • cells have a plasma membrane
  • proteins are produces by ribosomes
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7
Q

What is a cell?

A

Membrane bound structure contained genetic material ,cytoplasm and various organelles

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8
Q

Name the 3 functions of a cell

A

1) Can store and transmit info
2) has a plasma membrane
3) can harness energy from the environment

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9
Q

Explain how the cell membrane is a fluid mosaic

A

It contains different components and it is not uniform.

the membrane contains phospholipids, steroids like cholesterol, proteins and lipid rafts to aggregate)

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10
Q

Why and how is the cell asymmetrical

A

IT is asymmetrical because the two layers (outer and inner) are different because they have different functions/jobs)

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11
Q

Why is the phospholipid bilayer amphipathic

A

it has hydrophilic heads to intereact with the water outside the cells and hydrophobic tails on the inside layer

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12
Q

Explain the movements of phospholipids

A

They can move laterally but usually do not “flip flop” because the hydrophilic heads to not want to interact with the hydrophobic tails.

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13
Q

What are the 2 types of proteins within the membrane

A
  • Integral membrane proteins

- Peripheral membrane proteins

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14
Q

How does cholesterol help in the membrane?

A

Interacts with the phospholipid bilayer and maintains the fluidity of the membrane by preventing the tails to cflump/aggregate when its too cold and to prevent them from moving alot then temp is high.

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15
Q

Explain the integral membrane proteins

A

they can cross the membrane because they have both va hydrophilic region and a hydrophobic region

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16
Q

Explain the peripheral membrane proteins

A

DO NOT cross plasma membrane because the do not have a hydrophobic region. It binds to the polar heads of the lipids and also to the hydrophilic regions of intergtral proteins

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17
Q

What can these two protein types do?

A 
Transport energy
have enzymatic activity
signal transducdtion
cell-cell recognition
intracellular joining
attachement to tje cytoskeleton and extracellular matrix
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18
Q

Explain how the membrane is a selective barrier?

A

It regulates what goes in and what comes out (ions, macromolecules, water)
It requires various means of transport to get across the membrane

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19
Q

What are the two types of membrane transport

A

Passive and Active Transport

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20
Q

Explain Passive transport

A

It includes diffusion and facilitated diffusion

  • normal high to low concentration
  • no outside energy is needed
  • facilitated by channel proteins and carrier proteins
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21
Q

What is the difference between simple diffusion and facilitated diffusion

A

Simple diffusion: straight across membrane, no help needed from proteins
Facilitated diffusion: either by channel mediated or carrier mediated proteins that get the outer molecules inside the cell

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22
Q

What is osmosis

A

a process by which molecules of a solvent WATER tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane.

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23
Q

what are the three types of solutions and explain them

A

Hypotonic: it is lysed therefore has less solute and more water
Isotonic: at equlibrium
Hypertonic: it is shrivelled and has more solute and less water

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24
Q

Why do hydrophobic molecules go straight through the membrane with no aid?

A

Because the membrane itself is also hydrophobic

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25
Q

The diffusion rate of particles is proportional to what?

A

Proportional to the concentration gradient and the hydrophobicity

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26
Q

Do ions easily pass through the membrane?

A

No they need aided diffusion

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27
Q

What will go through the membrane easier

A particle with high hydrophobicity or low hydrophobicity?

A

High hydrophobicity

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28
Q

Facilitated diffusion is aided by what

A

BY TRANSPORT PROTEINS (PERMEASES)

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29
Q

What does active transport do and how does it differ from passive transport

A

It moves ions/molecules across the membrane against the concentration gradient
It differs because it requires carrier proteins and outside energy

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30
Q

What are the 3 kinds of transport part of active transport and what do they mean

A

Uniporter (1 substance in 1 direction)
Antiporter (2 substances in opposite directions)
Symporter (2 substances in in same direction)

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31
Q

what are the two types of active transport

A

Primary and Secondary

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32
Q

explain primary transport

A

Uses chemical energy directly (ATP)

It breaks bonds (to release stored energy)

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33
Q

Explain secondary transport

A

Uses energy from primary

Uses an energetically favourable process to drive an unfavourable one.

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34
Q

explain the Primary Active Transport Pump (Na/K)

A

SEE DIAGRAM IN SLIDES
Transfers 3 Na+ from cytosol to extracellular space
Up concentration gradient

Transfers 2 K+ from extracellular space to cytosol
Up concentration gradient

Generates membrane potential
Outside of cell becomes more positively charged than inside

Helps maintain cell volume & is involved in signalling & neuron function

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35
Q

explain the Primary Active Transport Pump (H+)

A

SEE DIAGRAM IN NOTES
Uses ATP

Transfers H+ from cytosol to extracellular space, up concentration gradient

Makes it easier for Secondary Active Transport of some ions

Makes it easier for other ions to diffuse into cell later

Generates membrane potential
Outside of cell becomes more positively charged than inside

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36
Q

explain the secondary Active Transport Pump )Na/Glc)

A

SEE DIAGRAM IN NOTES
Transfers Na+ from extracellular space to cytosol
Down concentration gradient

Transfers Glc from extracellular space to cytosol
Up concentration gradient

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37
Q

What are the two different types of vesicle transport and what they do

A

Exocytosis is sending off of vesicles:

  • Secretion of proteins
  • Release of neurotransmitters
  • Turnover of plasma membrane

Endocytosis is taking in larger molecules (vesicles):

  • Phagocytosis (cellular ‘eating’)
  • Pinocytosis (cellular ‘drinking’)
  • Receptor-mediated (specific)
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38
Q

Why have a cell wall?

A
  • Provides protection

- provides structural stability and support

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39
Q

What are the two types of cells and their characteristic?

A 
Eukaryotic
Eu = true	 + Karyon = nucleus
Membrane-bound nucleus
Membrane-bound organelles
Larger: 10-20μm (avg.)
Prokaryotic
Pro = before + Karyon = nucleus
No nucleus
Instead have a nucleoid
No membrane-bound organelles
Smaller: 1-2μm (avg.)
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40
Q

3 main components of a prokaryotic cell

A
  • peptidoglycan cell wall
  • nucleoid
  • plasmids
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41
Q

Describe the cell wall and its functions

A

Surrounds the cell membrane
Protects the cell from bursting due to osmotic pressure
Protects from invasion by viruses
Permeability barrier (allows passage of fluids + small molecules)
Role in cell-cell recognition and adhesion
Structure:
Contains peptidoglycans = sugar polymers linked by short peptides

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42
Q

describe the nucleoid

A

No membrane

Contains large circular chromosome + proteins

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43
Q

Describe plasmids

A

Independent, smaller, circular extra chromosomal DNA, non-essential genes
Transferred through an arm-like pilus

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44
Q

What does the prokaryotic cell used flagellum and pilum for?

A

Motility and movement

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45
Q

How do prokaryotic cells reproduce?

A

asexually

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46
Q

Prokaryotic cells may or may not need O2… what are those called

A

Aerobes (need oxygen)
Anaerobes (do not need oxygen)
facultative anaerobes

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47
Q

Why are prokaryotic cells smaller?

A

TO help with diffusion

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48
Q

What protein is flagella made of

A

Flagellin

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49
Q

what are the 3 parts of flagella and their function

A

Basal body: Anchors the flagellum to the cell wall and acts as the motor
Hook: connects the basal body to the filament
filament: extends into environment and spins

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50
Q

What are the two types of pilli

A

Attachment pili: allow bacteria to attach to surfaces (AKA fimbriae)
Conjugation pili: used to transfer DNA during conjugation or infection by bacteriophage (virus)

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51
Q

Why do cells compartmentalize?

A

Create different “worlds” within the same cell

Can perform different functions in different areas, due to different properties
pH
Solute concentration
Lipid composition

52
Q

Be able to label a eukaryotic cell and its organelles

A

SEE DIAGRAM IN SLIDES

53
Q

What is cytoplasm

A

Mixture of cytosol and organelles

54
Q

What are the parts of a eukaryotic cell (7)

A 
Nucleus
Ribosomes
Endomembrane System
-ER
-Golgi apparatus
-Lysosome
-Vacuole
Peroxisome
Mitochondria
Chloroplast
Cytoskeleton
55
Q

Explain the nucleus and what the components are

A

Stores genetic information (DNA) as chromosomes
-Collection of all chromosomes is called the chromatin

Surrounded by nuclear envelope
Double-bilayer connected to the endomembrane system
Trafficking through Nuclear Pore

Nucleolus is an area of RNA (rRNA) production in the Nucleus

56
Q

What is the function of the nucleolus

A

builds ribosomes

57
Q

Explain ribosomes and their function

A

Built in the nucleolus
End up in the cytoplasm
Composed of proteins + rRNA
Function: protein synthesis

58
Q

what are the two types of ribosomes

A

free ribosomes and bound ribosomes

59
Q

explain free ribosomes

A

Suspended in the cytoplasm

Make proteins that stay in cytoplasm

60
Q

explain bound ribosomes

A

Attached to the outside of the endoplasmic reticulum (ER) + nuclear envelope
Make proteins for export or inclusion in organelles

61
Q

what is the function of the endomembrand system

A

Connects multiple organelles (including nucleus)

62
Q

What are the components of the endomembrane system

A 
Nuclear envelope
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Vesicles
63
Q

What is the interior of the ER called

A

Interior is referred to as “lumen”

64
Q

What. are the two types of ER and what are the main differences. between the two

A

Rough ER has ribosomes associated to it and specializes in producing proteins (especially membrane-bound)

Smooth ER does not have ribosomes and focuses on lipid synthesis

65
Q

Components of rough er

A

Covered by ribosomes on cytosolic side

Function: involved in protein synthesis
Secreted proteins
Integral membrane proteins

66
Q

Proteins that are made in the RER go where and how

A

Proteins generated in the RER are modified and leave the RER in vesicles (pinched-off portions of the RER membrane). The vesicles then migrate to the Golgi apparatus

67
Q

Explain the smooth ER

A 
Lacks ribosomes 
Functions: 
-Synthesises lipids -
-Steroids, phospholipids
-Stores glycogen (involved in carbohydrate metabolism) 
-Detoxifies drugs and poisons
68
Q

What is the function of the golgi apparatus and give an example

A

Functions: modify, store, & route products of ER
‘Sorting Centre’ of the cell (Shipping & Receiving)
e.g. alteration of phospholipids or glycoproteins for secretion

69
Q

Explain the process in the golgi apparatus

A

Cis face (forming face) receives products from ER

Molecules are modified by enzymes in the Golgi as they migrate to the Trans face

Vesicles pinch off from the Trans face → transport molecules to other sites (e.g., plasma membrane, membrane-bound organelles)

70
Q

What do lysosomes contain and what is their per purpose

A

Membrane-enclosed bags of hydrolytic enzymes
Acidic (pH ~5)
Lyse = destroy

71
Q

what do the enzymes in lysosomes do and name the 4 types of enzymes

A 
Digest all major classes of molecules
Include:
Lipases
Carbohydrases
Proteases
Nucleases
72
Q

What are the two processes lysosomes can do?

A

Phagocytosis and Autophagy

73
Q

Explain phagocytosis

A

it is Intracellular digestion:
a vacuole (generated by phagocytosis) fuses with lysosomes; enzymes digest the contents of the vacuole
e.g. human macrophages targetting bacteria

74
Q

explain autophagy

A

If a cell has an old, damaged, or dysfunctional organelle, it can fuse this with the lysosome

75
Q

What is a vacuole

A

Membrane enclosed-sac

Larger than vesicles

76
Q

what are the three types of vacuoles and their function

A
  • Food vacuole: site of intracellular digestion in some protists
  • Contractile vacuole: pumps excess water from some freshwater protists
  • Central vacuole: large vacuole in plants
77
Q

Explain the central vacuole

A

Large vacuole in plants
Often occupies most of the cell volume
30-90%
Holds food reserves, ions, waste, pigments, poisons…

78
Q

What does peroxisome do?

A

Involved in degrading alcohol and long fatty-acids

Produces hydrogen peroxide while doing so, and is specifically designed for eliminating this toxic compound

79
Q

What are the two organelles that process energy?

A

Mitochondria and plasmits

80
Q

Explain mitochondria

A

-Energy producing centre
-Responsible for respiration and producing ATP from glucose in almost all eukaryotes
-has a Double-bilayer that contains many proteins and encloses a liquid area filled with enzymes
Contains some ribosomes and circular DNA

81
Q

explain the function of a plasmic and name one type

A

Photosynthesise or store materials

Chloroplasts are one type of plastid.

82
Q

explain chloroplasts

A

-Energy production centre
-Responsible for photosynthesis and converting CO2 into glucose
-Exist in plants and algae (protists)
Double-bilayer enclose a liquid area filled with enzymes and “thylakoids” – sacs of chlorophyll
ALSO contains some circular DNA

83
Q

where did both mitochondria and chloroplasts come from?

A

ORIGINATED as BACTERIA become endosymbionts of larger prokaryotic cells

84
Q

What is the function of the cytoskeleton

A

provides structural framwork for cells and movementt system

85
Q

3 parts of cytoskeleton

A

1) microtubules
2) microfilaments
3) intermediate filaments

86
Q

What are microfilaments made of

A

Actin

87
Q

what are microfilaments involved in?

A

cell movement
cell contraction
vesicular transport

88
Q

explain process of cell movement

A

1) add actin to the edge of the cell and the microfilaments elongate and push the cell membrane forward
2) at the same time, actin is removed from the back end of the end

89
Q

What is the process of removing and adding actin called

A

DYNAMIC INSTABILITY

90
Q

explain treadmilling

A

unidirectional

removed actin gets added to the front

91
Q

What are microtubules made of

A

tubullin

92
Q

what do microtubules use for cell movement?

A

cilia and flagella

93
Q

Where do microtubules come from>

A

centrosome

94
Q

What two proteins are involved in muscle movement?

A

actin and myosin

95
Q

Explain how myosin works in muscle movement

A

myosin binds and unbinds from actin polymers (always move toward the positive end)
This movement results in the shortening of the muscle cell (contraction)

96
Q

Where do kinesis and dynein work

A

within the microtubules

97
Q

what direction does dynine go in

A

negative end (towards centrosome)

98
Q

What is the function of the centrosome

A

it is a microtubule organizing centre

99
Q

explain spindle fibres

A

Important during cell division
Attach to chromosomes
Made of microtubules

100
Q

what is the structure of a centriole

A

Cylindrical structures

Ring of 9 sets of 3 microtubules

101
Q

what is the form of intermediate filaments

A

sturdy cable like structure

102
Q

functions of intermediate filaments

A

help maintain structure

can link multiple cells

103
Q

what is the ECM

A

A gel-like area filled with proteins and carbohydrates

104
Q

what is the purpose of the ECM

A

provides support and motility

105
Q

what does the ECM contain and their function

A

Collagen: Strong, helical protein, huge quantities
Elastin: Looser chain of protein in skin, lungs, gut
Proteoglycans: mostly sugar that capture and retain water
Integrins: integral cell proteins that anchor to ECM
Fibronections: binds integrals and collegians involved in adhesion and migration

106
Q

BE ABLE TO LABEL THE ECM COMPONENTS

A

see diagram on slides

107
Q

does the cell wall exist in animals?

A

no

108
Q

where is the cell wall?

A

external to the cell membrane

109
Q

In plant cells, what is the cell wall made of

A

cellulose (part of glucose) and other polysachhcaries and proteins like lignin and pectin

110
Q

In fungi ,what is the cell wall made of

A

chitin

111
Q

what are the functions of the cell wall. (4)

A

Protects cell
Maintains shape
Prevents excess water uptake (can’t expand)
Allows turgescence (water pressure pushing against the wall

112
Q

what are the three classes of membrane junctions

A

Desmosomes
Tight Junctions
Gap Junctions

113
Q

What are desmosomes formed from

A

cadherin

114
Q

describe the interaction in desmosomes junctions

A

Cadherin-cadherin interactions at a specific point between two cells
Localised spot-like adhesions FOCAL POINT

115
Q

what is the function of desmosome junctions

A

Resist shearing forces

116
Q

What is the function of a tight junction

A

Hold cells together
Block movement of integral membrane proteins
Prevent passage of molecules & ions through space between cells

117
Q

are desmosomes attached to the cytoskeleton?

A

yes

118
Q

are tight junction attached to the cytoskeleton

A

no

119
Q

how can a substance pass a tight junction?

A

MUST GO THROUGH IT

120
Q

Explain gap junctions

A 
Integral protein channels
Attach between two cells
Allow material (molecules, ions) to flow from the cytosol of one cell to another
121
Q

are viruses living, if not give a reason why

A

no because they cannot produce of use energy

122
Q

what are viruses made of and give an example of one

A
  • Nucleic acid (RNA or DNA)
  • Protein coat (capsid): surrounds the nucleic acid
  • Envelope (for some viruses): membrane derived from the host cell, + usually proteins and glycoproteins of viral origin
    e. g., influenza virus
123
Q

how can a virus reproduce?

A

To reproduce, they must infect cells (host cells)
Plants
Animals
Bacteria

124
Q

explain reproduction process of a virus

A

Viral genome inserted into host cell

Cell replicates viral particles based on the information contained in the viral genome

125
Q

what does active transport do?

A
  • Regulation of cell volume
  • cell signalling
  • neuron functiom
  • taking in needed resources (amino acids, carbs, minerals)

Biology 101 (15 decks)

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