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BIOL1000 Unit 3 > Cell Biology Unit 3 > Flashcards

Cell Biology Unit 3 Flashcards

1
Q

Cell Theory

A

All living things are composed of cells and all cells come from other cells

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2
Q

Light Microscopes (LM)

A
  • Earliest type of microscope
  • Visible light passes through a sample
  • Then through glass lenses
    Objective lens
    Ocular lens
  • Lenses bend the light so that the image of the specimen is magnified
  • Image is projected into your eye or into a camera
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3
Q

Magnification

A

The increase in an object’s image size compared with its actual size

  • This is the ability to distinguish two nearby objects as being separated from each other
  • Example: What look like one star in the sky to the naked eye may prove to be two stars very close when seen through a telescope
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4
Q

Resolution

A

The measure of the clarity of an image

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5
Q

Electron Microscope (EM)

A
  • Came into use in the 1950s and allowed biology to take a huge leap forward
  • Focuses beams of electrons (instead of light) through a specimen sample
  • Electromagnets are used to bend the electron path and magnify the image
    The same way lenses are used in LM
  • EM images are always black and white, colour is added later to highlight or clarify cellular structures
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6
Q

Transmission EM (TEM)

A
  • Electron beam is passed through a very thin section of a specimen
  • Stains containing heavy metals are used to coat certain types of cellular structures
  • Electrons will be scattered by the more dense stained parts
  • The scattered electrons are detected, and an image is produced
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7
Q

Scanning EM (SEM)

A
  • Allows scientists to study the detailed architecture if a cell
  • The sample is usually coated with a thin film of gold
  • An electron beam excites the gold atoms
  • The electrons are scattered and then detected by a device that projects the resulting image onto a video screen
  • Makes the image look 3D
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8
Q

Microscope Problems

A
  • Electron Microscopy
    o Cannot be used to look at live samples
    o Preparing a specimen kills the organisms
    o Scientists must use a light microscope to look at living cells
  • Light Microscopy
    o Many parts of a cell are too small to be seen with a light microscope
    o To see in great detail, an electron microscope must be used
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9
Q

Minimum

A

Large enough to store enough DNA, proteins, and structures to survive and reproduce

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10
Q

Maximum

A
  • Maximum: influenced by geometry
    o Must have enough surface area to service the full cell volume
    o Needs to have flow of oxygen and nutrients and wastes
    o If the cell is too large, the oxygen, waste, and nutrients will bottleneck at the membrane and the cell will be able to handle the molecular traffic
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11
Q

Surface-to-Volume Ratio

A
  • A large cell has more surface area than a small cell but has lower surface-to-volume ratio
  • Some cells in your body can still be very large
    o Example: Nerve cells that run all the way from your spine to your foot
     These cells can be over a metre long
     They are so thin that you still need a microscope to see them
     Being so thin allows them a high enough surface-to-volume ratio to function well
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12
Q

Prokaryotic Cells

A

These were the first cells to evolve and lived for 1.5 billion years before eukaryotic cells evolved

Small and simple structure

No internal membrane-bound structures

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13
Q

Eukaryotic Cells

A

Evolved from prokaryotic cells about 1.8 billion years ago

o Includes all higher life forms such as plants, animals, and fungi
o Larger, more complex cells

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14
Q

Structures Common to All Life

A
  • Plasma membrane: Membrane that surrounds the cell
  • Ribosomes: Machinery for protein synthesis
  • Cytosol: Aqueous solution that fills the cells
  • DNA: one or more chromosomes
  • Cytoplasm: The entire contents of the inside of the cells, excluding the interior of the nucleus
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15
Q

Plasma Membrane

A

The flexible boundary between the living cell and its surrounding environment

Also referred to as the cell membrane

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16
Q

Phospholipids

A

Hydrophobic tail with a negatively charged hydrophilic head

  • Forms a two-layer sheet called a phospholipid bilayer
  • Hydrophilic head face outward
    o In contact with aqueous solution both inside and outside of the cell
  • Hydrophobic tails point inwards
    o Shielded from water
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17
Q

Membrane Proteins

A

Proteins that are embedded in the lipid bilayer

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18
Q

Plasma Membrane (Cell Membrane)

A

Regulates the flow of material in and out of the function of the cells

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19
Q

What can pass through the cell membrane?

A

Small non-polar molecules pass directly through the membrane

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20
Q

Channel Proteins

A

Forms a tunnel through the membrane that shields molecules as they pass through the hydrophobic layer

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21
Q

Nucleiod

A

Region of the cell where the chromosome is coiled

Nucleiod = ‘nucleus-like region

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22
Q

Cell wall

A

Rigid, chemically complex shell surrounding the plasma
o Protects the cell
o Maintains the cells shape

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23
Q

Capsule

A

Sticky outer coat around the cell wall
o Helps glue the cells to surfaces or to other cells
o Only some prokaryotes have a capsule

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24
Q

Flagella

A

Long projection that propels a cell through its environment
o Only some prokaryotes have flagella

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25
Q

Organelles

A
  • Organelles: “Little organs”
    o Membrane-bound structures that perform specific tasks
    o A cell may contain many copies of each organelle
    o The proportion of different organelles depends on the specialized function of the cell
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26
Q

Cellular Metabolism

A

The chemical activities of the cell

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27
Q

Organelles only found in animal cells

A
  • Lysosomes and centrosomes
  • Flagella and cilia
    o Sometimes found in animal cells very rare in plant cells
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28
Q

Organelles found only in plant cells

A
  • Rigid cell walls
    o This cell wall is different than what it seen in prokaryotes
    o Made mostly of the polysaccharide

Plasmodesma: Cytoplasmic channels that link adjacent cells together
Chloroplasts: Location of photosynthesis

  • Large central vacuole that stores large amounts of water and various chemicals
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29
Q

The Nucleus

A
  • Contains the cells genetic instructions (DNA)
  • Control the cells activities by directing protein synthesis
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30
Q

DNA Organization

A
  • DNA is organized into chromosomes
    o The DNA associates with many proteins
    o The proteins help coil the long strands of DNA to form a chromosome
    o A human cell has 46 separate chromosomes
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31
Q

Chromatin

A

The complex of protein and DNA

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32
Q

Nuclear Envelope

A

Double membrane enclosing the nucleus

o Each of the two membranes is separate phospholipid bilayer
o Proteins are associated with nuclear envelope
o Control the flow of materials in associated with nuclear envelope
o Control the flow of materials in and out of the nucleus
o Pore proteins regulate the flow of large molecules and connect the nucleus to the endoplasmic reticulum

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33
Q

Nucleolus

A

The site where a specialized RNA molecule called ribosomal RNA (rRNA) is synthesized

  • Proteins made in the cytoplasm are brought into the nucleus to be assembled with rRNA to make ribosomes
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34
Q

Ribosomes

A

The cellular components that use instructions from the nucleus to build protein

  • A cell may contain millions of ribosomes
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35
Q

Non-Membranous Organelle

A

Not contained inside a membrane

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36
Q

Location of Ribosomes

A
  • Free ribosomes are suspended in the cytosol
  • Bound ribosomes are attached to the outside of the endoplasmic reticulum and nucleus
  • both types are structurally identical and can function in either location
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37
Q

Free Ribosomes

A

o Proteins made here generally function in the cytosol
o Example: Enzymes that break down sugar for use in cellular respiration

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38
Q

Bound ribosomes

A
  • Make proteins that will be exported from the cell
  • Ribosomes interact with mRNA to build a protein
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39
Q

Endomembrane System

A
  • Internal membranes are involved in most cellular functions
    o Synthesis, storage, distribution, and export of molecules
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40
Q

Vesicle

A

Sac made of membrane

  • Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, plasma membrane
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41
Q

Endoplasmic Reticulum (ER)

A

An extensive network of flattened sacs and tubules that functions as a major manufacturing site in the cells

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42
Q

Smooth Endoplasmic Reticulum (SER)

A
  • The smooth ER and its enzymes are responsible for many functions
    o Synthesis of lipids (oil, phospholipids, steroids)
    o Storage of calcium ions
    o Detoxification
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43
Q

Rough Endoplasmic Reticulum (RER)

A
  • Proteins produced by ribosomes attached to the rough ER are often excreted from the cell
    o These are called secretory proteins
    o Examples: Cells in the pancreas secrete insulin which is produced by ribosomes on the rough ER
  • The rough ER synthesizes new membrane fragments
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44
Q

Secretory Proteins

A
  1. A polypeptide produced by a bound ribosome enters the rough ER
  2. Short sugar chains may be attached to the polypeptide to make a glycoprotein
  3. The glycoprotein is packaged in a transport vesicle
  4. The vesicle buds off from the ER membrane to be passed to the golgi apparatus for further processing
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45
Q

Golgi apparatus

A
  • Stack of flattened sacs
  • A cell may contain hundreds of this organelle
  • Cells that are more active in protein excretion will have higher concentrations of golgi apparatuses
  • After leaving the ER, transport vesicles travel to the golgi apparatus
  • This apparatus acts as a warehouse and processing station for molecules produced by the ER
  • Each flattened sac is not connected to the other ones around it
  • After processing, products will be transported to the plasma membrane
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46
Q

Processing in the Golgi apparatus

A
  1. One side of the sac serves as a docking station for a transport vesicle
  2. The vesicle fuses with a golgi sac, adding its membrane and its contents to the sac
  3. Products are modified as they travel through the stack from one sac to the next
  4. The last sac acts as the shipping side of the golgi apparatus. Here the final products are dispatched in vesicles that bud off and travel to other sites in the cell
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47
Q

Processing in the Golgi apparatus

A
  1. One side of the sac serves as a docking station for a transport vesicle
  2. The vesicle fuses with a golgi sac, adding its membrane and its contents to the sac
  3. Products are modified as they travel through the stack from one sac to the next
  4. The last sac acts as the shipping side of the golgi apparatus. Here the final products are dispatched in vesicles that bud off and travel to other sites in the cell
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48
Q

Lysosomes

A

Membrane-enclosed sac of digestive enzymes

48
Q

Lysosomes

A

Membrane-enclosed sac of digestive enzymes

49
Q

Lysosomal Diseases

A

Diseases where lysosomal enzymes are missing

50
Q

Vacuoles

A
  • Large vesicles with a variety of functions
    o Food vacuoles as food particles are engulfed by the cell
    o Contractile vacuoles

o In plant seeds vacuoles store reserve of proteins for starting growth

51
Q

Peroxisomes

A
  • Metabolic, membrane-bound compartment that does not originate in the endomembrane system
  • How they are related to other organelles is unknown
  • Functions
    o Break down fatty acids to use as a cellular fuel
    o Detoxification of harmful compounds in your liver
51
Q

Peroxisomes

A
  • Metabolic, membrane-bound compartment that does not originate in the endomembrane system
  • How they are related to other organelles is unknown
  • Functions
    o Break down fatty acids to use as a cellular fuel
    o Detoxification of harmful compounds in your liver
52
Q

Inter-membrane space

A

o Region in between the inner and outer membranes

53
Q

Mitochondrial matrix

A

o Region inside the inner membrane
o Contains mitochondrial DNA, ribosomes and enzymes that catalyze some reactions of cellular respiration

54
Q

Chloroplast

A
  • Converts solar energy to chemical energy (photosynthesis)
  • Similar in structure to the mitochondria
    o 2 membranes (inner and outer) separated by a thin intermembranous space
  • Inside the inner membrane is a thick fluid called stroma
    o Contains chloroplast DNA, ribosomes, and enzymes
    o Similar to the mitochondrial matrix
55
Q

Thylakoids

A
  • Thylakoids are suspended in the stroma
    o Network of interconnected membranous sacs
    o Thylakoids are often stacked like poker chips
    o Each stack is called a granum
  • The space inside the thylakoid is called the thylakoid space
  • Chlorophyll is embedded in the thylakoid membranes to trap solar energy
56
Q

Endosymbiont theory

A

Mitochondria and chloroplasts were once small prokaryotes that began living inside larger cells

57
Q

Mitochondria

A
  • Carries out cellular respiration in all eukaryotic cells
    o Use O2 and release CO2 to transform the chemical energy of food into ATP
  • Enclosed by two membranes
58
Q

Cytoskeleton

A

Networks of protein fibers extending
throughout the cells

59
Q

Microtubules

A

Straight hollow tubes composed of globular proteins
called tubulins

  • Tubulin proteins consist of two subunits
  • Microtubules grow longer by the addition of tubulin
    proteins
  • Can be disassembled and the tubulin proteins
    reused elsewhere

In animal cells microtubules grow out of a region
called the centrosome

60
Q

Intermediate Filaments

A
  • Found in the cells of most animals
  • Made of fibrous proteins that supercoil into
    cables
  • Function
    • Reinforce cells shape and anchor some organelles that should not move
      • Example: The nucleus sits in a cage made of intermediate
        filaments
  • Often a permanent fixture in the cell
  • Outer layer of your skin is made of dead cells
    packed full of intermediate filaments
61
Q

Microfilaments

A

Also called actin filaments
* Rods composed of globular proteins called actin
* Arranged as a twisted double chain

  • Form a network inside the plasma membrane to help
    support the cell shape
    • Important in animal cells because they do not have a cell wall
  • Involved in cell movement
62
Q

Cilia

A

Short, numerous
appendages protruding from
the cell

63
Q

Flagella

A

Long tail-like appendage on cells

  • Typically a cell will only have one or at most a
    few flagella
  • Functions to propel a cell using an undulating
    whip-like motion
  • Commonly found on animal sperm cells
  • Commonly found on motile prokaryotic cells
64
Q

Extracellular Matrix

A
  • Holds cells together in
    tissues
  • Protects and supports the
    plasma membrane
  • Relays signals that affect
    gene expression
  • Directs the movement of
    embryonic cells
65
Q

Integrins

A

The extracellular matrix is bound to
the membrane by membrane
proteins called integrins

66
Q

Tight Junctions

A

Plasma membranes of adjacent cells are knit tightly together
* Prevents fluid leakage between layers of cells
such as in the digestive system

67
Q

Anchoring junctions

A

Intermediate filaments fasten cells together into strong
sheets
* Tissues susceptible to stretching and
mechanical stress such as skin and muscle

68
Q

Gap Junctions

A

Channels or pores that allow the flow of small molecules from one cell to another
* Signal proteins move between heart cells to
coordinate contraction

69
Q

Fluid mosaic model

A

Diverse protein molecules suspended in a fluid phospholipid bilayer
* This structure describes the plasma
membrane

70
Q

Selectively Permeability

A

Some substances can cross the plasma
membrane more easily than others

71
Q

Diffusion

A

The tendency for particles of any substance to spread out into the available space

  • Molecules have thermal energy due to their constant movement. This results in diffusion
  • Molecules will diffuse through air and water and across membranes
72
Q

Passive Transport

A

Diffusion across a membrane with no
energy investment

73
Q

What Substances can easily diffuse through a cell membrane

A

Small non-polar molecules
* This is the only way O2 enters the cells and CO2 exits the cell

Ions and polar molecules
can diffuse freely using simple transport proteins
* They cannot pass directly through the phospholipid bilayer
* They must still move down their concentration gradient

74
Q

Osmosis

A

Diffusion of water across a membrane
* Water will pass through the membrane until the concentration of a solute is equal on both sides
* This occurs when a solute cannot pass through the membrane

75
Q

Tonicity

A

The ability of a surrounding solution to cause a cell to gain or lose water

  • Depends on the concentration of solutes in the environment compared to the concentration of solutes in the cell
76
Q

Isotonic

A

Equal concentration of solutes

77
Q

Hypotonic

A

Lower concentration of solutes

78
Q

Hypertonic

A

Higher concentration of solutes

79
Q

Osmoregulation

A

The control of water balance

  • Prevention of excessive uptake or loss of water, and regulation of the solute concentrations in the body
80
Q

Facilitated diffusion

A

Diffusion through the membrane with the help of transport proteins

Passive transport through a transport protein

  • Does not require energy
  • Solutes move along their concentration gradient
  • Sugars, amino acids, ions, water
81
Q

Channel protein

A

Provides a simple channel for a molecule to pass through

82
Q

Carrier Protein

A

Solute binds the protein, causing it to change shape. The solute is released on the opposite side of the membrane.

83
Q

Aquaporin

A

Allows the passage of water

  • Slow diffusion of water directly through the membrane is adequate most of the time, if faster diffusion is required aquaporin is necessary
84
Q

Active transport

A

A cell expends energy to move a solute against its
concentration gradient

  • Solute will move from an area of low concentration to an area of high
    concentration
  • ATP supplies the energy
85
Q

Exocytosis

A

fusion of secretory vesicles with the plasma membrane

86
Q

Endocytosis

A

The process by which large molecules and fluids are
taken up by the cell

87
Q

Phagocytosis

A

“cellular eating”

88
Q

Pseudopodia

A

Extensions of the membrane that engulf a particle

89
Q

Receptor Proteins

A

are embedded in the membrane in an area that is lined by coat proteins

90
Q

Energy

A

The capacity to cause change, especially to do work

91
Q

Kinetic Energy

A

The energy of motion

  • Moving objects perform work by transferring motion to other matter
92
Q

Thermal Energy

A

Kinetic energy associated with the random motion
of atoms or molecules

  • Thermal energy transferred from one object to another is called heat
93
Q

Light Energy

A

Kinetic energy harnessed for photosynthesis

94
Q

Potential Energy

A

Energy that matter possesses based on its location or structure

95
Q

Chemical energy

A

potential energy available for release in a chemical
reaction

  • This is transformed to power the work in a cell
96
Q

ATP

A
  • Adenosine triphosphate (ATP)
  • Energy carrying molecule
  • Organic molecule called adenosine bound to a triphosphate
  • Triphosphate: Chain of three phosphate groups
  • The phosphate groups are all negatively charged
97
Q

Hydrolysis

A

The addition of water

98
Q

Exergonic Reaction

A

Reaction that releases energy

99
Q

Endergonic reactions

A

Reactions that require an input of energy

100
Q

Phosphorylation

A

The phosphate group broken off of ATP is
transferred to another molecule

101
Q

Chemical work

A

Phosphorylation of reactants provides the energy required for endergonic reactions to form the products

102
Q

Transport work

A

ATP drives the active transport of solutes across a
membrane against their concentration gradients

103
Q

Mechanical work

A

Phosphorylation by ATP allows a protein to move

104
Q

Activation barrier

A

Energy barrier that must be overcome for any
chemical reaction to begin

105
Q

Activation energy

A

Energy required to contort or weaken bonds so that they
can break and new bonds can be formed

106
Q

Substrate

A

The reactant that an enzyme acts on

107
Q

Active site

A

The region of the enzyme that a substrate fits into

  • Typically a pocket or groove on the surface of the enzyme
108
Q

Catalytic Cycle

A

A reaction that proceeds with the help of an enzyme

  • The enzyme is the catalyst
109
Q

Induced fit

A

Active site may change shape to hold the substrate more tightly

110
Q

Denaturation

A

The protein unfolds so that its shape is changed

111
Q

Cofactors

A

non protein molecules that aid enzymes

112
Q

Coenzyme

A

cofactor that is organic

  • Example: Vitamins
113
Q

Inhibitor

A

A chemical that interferes with an enzyme’s activity

114
Q

Competitive Inhibitor

A

Chemical compound that resembles an enzyme’s normal substrate

115
Q

Non-competitive inhibitor

A

Inhibitor that binds to a spot on the enzyme outside of the active site

116
Q

Feedback inhibition

A

If a cell is producing more product than it needs,
the product itself may become an inhibitor

BIOL1000 Unit 3 (1 decks)

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