Cells & Organelles Flashcards
1
Q
Define cells
A
The smallest unit of life that contains all the characteristics of life
2
Q
All cells must have which 4 things?
A
- Plasma membrane
- DNA
- Ribosomes
- Cytoplasm
3
Q
What is the cell theory?
A
- All organisms are made of one or more cells
- All cells arise from pre-existing cells
- Cells are the basic unit of life
- Cell structure is correlated to cellular function
4
Q
Describe prokaryotic cells
A
Simple, small (1-10 micrometers) cells relative to eukaryotic cells that do not contain a nucleus or other membrane bound organelles
5
Q
Organisms in which Domains have prokaryotic cells?
A
Domain Archaea
Domain Bacteria
6
Q
Describe eukaryotic cells
A
Larger (10-100 micrometers), more complex cells than prokaryotic cells that contain membrane-enclosed organelles with specific functions
7
Q
Organisms in which domain have eukaryotic cells?
A
Domain Eukarya (includes kingdom Protista, Animalia, Plantae, and Fungi)
8
Q
Define organelles
A
Organelles are USUALLY membrane bound compartments where specific metabolic processes occur in eukaryotic cells
9
Q
T or F: prokaryotic cells have only one kind of organelle
A
True
10
Q
Describe the plasma membrane
A
Made of a phospholipid bilayer with proteins, the plasma membrane surrounds the cell and regulates movement of solutes in and out of cells due to its selective permeability
11
Q
What are the three components of a plasma membrane?
A
Lipids (mostly phospholipids)
Proteins
Carbohydrates
12
Q
Which organelles do eukaryotic animal cells contain?
A
- nucleus
- ribosomes
- lysosomes
- vesicles
- endoplasmic reticulum
- smooth ER
- rough ER
- golgi apparatus
- mitochondria
- centrosomes
13
Q
Which organelles do eukaryotic plant cells contain?
A
- nucleus
- ribosomes
- central vacuole
- vesicles
- endoplasmic reticulum
- smooth ER
- rough ER
- golgi apparatus
- mitochondria
- chloroplasts
- cell walls
14
Q
How do prokaryotic cells control what goes in or out of the cell?
A
they have internal membranes that increase surface area for reactions and control what goes in or out
15
Q
Define nucleus
A
A double membrane bound organelle found only in eukaryotic cells that contains most of the genetic material of a cell.
It controls cell activity by directing protein synthesis
16
Q
Define nuclear envelope
A
The porous double membrane that encloses the nucleus
It allows proteins, macromolecules and RNAs to transfer through
17
Q
Define nucleolus (pl. nucleoli)
A
Where DNA is transcribed to make rRNA
18
Q
Define ribosomes
A
Structures in a eukaryotic cell that are not membrane bound and conduct protein synthesis in two locations:
- Free ribosomes in the cytosol
- Bound ribosomes on the surface of the rough ER
19
Q
What are the two locations where ribosomes carry out protein synthesis?
A
- Free ribosomes in the cytosol
2. Bound ribosomes on the surface of the rough ER
20
Q
Define endomembrane system and state which organelles are included
A
The many different phospholipid bilayers of the eukaryotic cell that are continuous with the nuclear envelop and include:
- vesicles
- endoplasmic reticulum
- Golgi apparatus
- lysosomes (in animal cells)
21
Q
Define vesicles
A
Membrane bound sacs that transport materials throughout the cell
22
Q
Define endoplasmic reticulum
A
A membranous network of sacs and tubes that is continuous with the nuclear envelope and can take two forms:
- Smooth
- Rough
23
Q
Define endoplasmic reticulum
A
A membranous network of sacs and tubes that is continuous with the nuclear envelope and can take two forms:
- Smooth
- Rough
24
Q
Define smooth ER
A
Part of the endoplasmic reticulum that does not have ribosomes attached
25
What are the 4 functions of the smooth ER?
1. synthesizes lipids (steroids, oils, phospholipids)
2. Carbohydrate metabolism
3. stores calcium for muscle contractions
4. detoxifies drugs (especially in liver cells)
26
Define rough ER
part of the endoplasmic reticulum that has bound ribosomes
27
What are the 2 functions of the rough ER?
1. Synthesizes glycoproteins (proteins bound with sugars) for secretion in vesicles
2. Synthesizes membrane proteins and phospholipids
28
Define Golgi Apparatus
Flattened membranous sacs that are continuous with the endoplasmic reticulum
Transport vesicles travel to the GA after leaving the ER
29
What are 4 functions of the Golgi Apparatus?
1. Can add carbohydrates
2. Sorts proteins
3. Ships materials in transport vesicles to other destinations
4. Produces and secretes some macromolecules (like pectin)
30
Define lysosome and its functions
A membranous sac found only in animal cells that contains hydrolytic enzymes in a low pH fluid that are used to:
1. digest macromolecules (intracellular digestion)
2. Recycle cellular components (including organelles)
3. Program cell deaths
31
Define central vacuole and its function
A membrane bound sac found only in plant cells that has hydrolytic abilities to:
1. Store waste, water, and metabolic products
2. Help cells grow by filling up with water and expanding
32
Define mitochondria (s. mitochondrion) and its function
A double membrane bound organelle that is the site of cellular respiration in cells
33
Describe the structure of a mitochondrion
Outer membrane surrounds organelle
Inner membrane is extensively folded into cristae containing enzymes to produce ATP
Matrix is inclosed by inner membrane which contains mitochondrial DNA, ribosomes, and enzymes
34
What 3 things does the matrix of a mitochondrion contain?
1. Mitochondrial DNA
2. Ribosomes
3. enzymes
35
T or F: DNA is ONLY found in the nucleus
FALSE
DNA is also found in mitochondria and chloroplasts
36
T or F: DNA is ONLY found in the nucleus
FALSE
DNA is also found in mitochondria and chloroplasts
37
Define chloroplasts
A triple membrane bound organelle found only in plant and algae cells that is the site of photosynthesis
38
Define thylakoids
Stacked membranous sacs within chloroplast organelles that contain chlorophyll
39
Define a granum (pl. grana)
Stacks of the membranous sacs, thylakoids
40
Define stroma
The internal fluid surrounding thylakoids in a chloroplast organelle
41
What 3 components does the stroma contain?
DNA
Ribosomes
enzymes
42
Define cytoskeleton and its 4 functions
A network of fibres that extends throughout the cytoplasm to:
1. provide mechanical support
2. provide anchorage for organelles
3. assist in cell movement
4. involved in cell division
43
What are the 3 components of a cytoskeleton?
1. microtubules
2. microfilaments
3. intermediate filaments
44
Define centrosomes
Found only in animal cells
Where microtubules grow from and is considered to be the site of organizing microtubules
Contains 2 centrioles
45
How many centrioles does a centrosome contain?
2
1 mother and 1 daughter centriole from cell division
46
Define cell walls
The rigid structure that protects and supports plant, prokaryote, fungi, and some protist cells
47
T or F: only plants have cell walls
FALSE
prokaryotes, fungi, and some protists have cell walls too
48
T or F: Composition of cell walls depends on the taxa
TRUE
49
What are some examples of molecules that a cell wall can be composed of?
Chitin
Cellulose
Lignin
Silica
50
How many cell walls can plants have?
All plant cells have at least primary cell walls but some can have secondary cell walls too
51
Which organelle secretes the components to make cell walls?
The plasma membrane
52
Describe the primary cell wall
Thin, flexible, stretchy and made first by the cell
53
Describe the secondary cell wall
Thick and strong cell wall that some cells make between the cell membrane and the primary cell wall
54
What holds plant cells together?
The middle lamella
55
Define the middle lamella
A think layer rich in sticky polysaccharides called pectins that forms between the primary and secondary cell walls of cells
56
Define intracellular connections
Neighbouring cells communicate and interact
57
What method of intracellular connections do plant cells use?
Plasmodesmata (s. plasmodesma)
58
Define plasmodesmata
Membrane lined channels through cell walls filled with cytoplasm for neighbouring plant cells to communicate and interact
59
What 3 methods of intracellular connection do animal cells use?
1. tight junctions
2. desmosomes
3. gap junctions
60
Define tight junctions
A method of intracellular connection used by animal cells to bind neighbouring cells together to make tissues watertight
61
Define desmosomes
A method of intracellular connection used by animal cells to fasten cells together against mechanical stress
62
Define gap junctions
A method of intracellular connection used by animal cells to provide cytoplasmic channels between adjacent cells to allow things to move between two cells
63
Which form of animal intracellular connection is most like the method plants use?
Gap junctions in animal cells are most similar to plasmodesmata in plant cells
64
What are the 2 kinds of microscopes?
light microscopes
| electron microscopes
65
Describe light microscopes
microscopes that transmit light through the sample
66
T or F: the organisms/cells have to be dead for light microscopes
False, they can be alive
67
Describe electron microscopes
microscopes that use beams of electrons and require the organism to be stained with heavy metals (and therefore be dead)
68
What are the 2 kinds of electron microscopes?
Transition electron microscopes (TEM)
Scanning electron microscopes (SEM)
69
How do TEM work?
transmit a beam of electrons through a thin sample
70
How do SEM work?
take images of 3D surface of specimen
71
Define membranes
the thin layer that forms an outer boundary of a living cell or cell compartment
72
What is the fluid mosaic model/hypothesis?
describes how phospholipids and proteins are arranged in the membranes
73
What substance makes the membranes fluid?
cholesterol
74
T or F: membrane molecules are in motion
True
75
What are proteins in a membrane immersed in?
the bilayer
76
Describe how most lipids and some proteins move through the membrane?
they can move quickly through the plane of the membrane (2 micrometres/s)
77
T or F: some membrane molecules can move transversely but this is uncommon
true
78
In comparison to lipids, how quickly do proteins move?
slower because they're larger molecules and are likely directed by motor proteins
79
T or F: some protein molecules do not move at all. why/why not?
true because they are attached to the cytoskeleton or ECM
80
Will unsaturated fatty acids or saturated fatty acids (or both) remain fluid at lower temperatures? explain
Unsaturated fatty acids will remain fluid at lower temperatures because they contain double bonds
81
What is the purpose of cholesterol in animals?
acts as a fluidity buffer
82
How does cholesterol work as a fluidity buffer in animals?
at higher temperatures it makes the membrane less fluid
at lower temperatures, it makes the membrane more fluid
83
Why is it important that membranes remain fluid?
without fluidity, the permeability of the membrane changes and enzymes may stop working
84
Describe the structure and function of the extracellular matrix (ECM)
STRUCTURE:
composed of GLYCOPROTEINS and other molecules that contain carbohydrates
- ex. collagen, proteoglycans, fibronectin
FUNCTION: support, adhesion, movement, and regulation
85
What kind of molecule will bind with the ECM? What is their function?
Integrins are receptor proteins on the cell's surface that can bind with ECM to transmit information between the ECM and cytoskeleton
86
What determines most of the membrane's functions?
membrane proteins
87
Describe integral proteins
Proteins that span the entire membrane (transmembrane) or go to at least into the hydrophobic region
they are amphipathic
88
T or F: integrins can be integrals, but not all integrals are integrins
True
89
Describe peripheral proteins
proteins that are bound to the surface of the membrane and attach to cytoskeleton, ECM, or integral proteins
90
What are the 6 functions of membrane proteins?
1. transport
2. enzymatic activity
3. signal transduction
4. cell-cell recognition
5. intercellular joining
6. attachment to cytoskeleton and ECM
91
What are the 2 kinds of transport proteins in membranes?
1. channel proteins: create channel for substances to cross the membrane
2. carrier proteins: shuttle substances through the membrane
92
How can proteins function in enzymatic activity?
active sites can be exposed to substances in solution
93
How can proteins function in signal transduction?
signalling molecule can bind and change shape of protein, relaying messages to the inside of the cell
94
How can proteins function in cell-cell recognition?
some GLYCOPROTEINS serve as ID tags that are recognized by proteins on other cells
95
How do cells recognize other cells?
by binding to molecules on the ECM surface of the plasma membrane resulting in molecules that contain carbohydrates
96
describe glycoprotein
molecules that are formed when cells covalently bond to PROTEIN molecules on the ECM surface of the plasma membrane
97
describe glycolipid
molecules that are formed when cells covalently bond to LIPID molecules on the ECM surface of the plasma membrane
98
How can proteins function in intercellular joining?
membrane proteins of adjacent cells can hook together
99
How can proteins function in attaching to cytoskeleton and ECM?
microfilaments or other elements can bond with membrane proteins to stabilize the cell shape and locations of proteins
100
T or F: membranes have sidedness
true
101
How are molecules distributed throughout a membrane?
Asymmetrical distribution of proteins, lipids, and associated carbohydrates on the inside and outside of the membrane
102
Describe electrochemical gradient
all cells have voltage across their membrane
the inside of a cell is more negative than the outside
voltage and concentration of ions moves them across membrane
103
How does diffusion move ions in regards to their electrochemical gradient?
Ions move DOWN their electrochemical gradient
104
What are the 6 ways molecules can cross a membrane?
1. simple diffusion
2. facilitated diffusion
3. osmosis
4. active transport
5. electrogenic pump
6. cotransport
105
Define simple diffusion
the spontaneous, random movement of a solute from an area of high concentration to low concentration
ie., solutes move DOWN their concentration gradients
106
Simple diffusion moves what kind of solutes? Does it require input of energy?
small, non-polar solutes
no energy input required (ie., it's passive)
107
What are some examples of solutes that simple diffusion could work on?
CO2, oxygen, small hydrocarbons
108
T or F: small polar solutes will move more slowly by simple diffusion
true like simple sugars or water
109
Why does size and charge of a solute matter in terms of crossing a membrane?
because they must pass between the phospholipid molecules of the cell or organelle membrane
110
Define facilitated diffusion
specific transport proteins help large and/or charged specific solutes cross a membrane DOWN their concentration gradient (high --> low)
ex. glucose, water, amino acids, K+
111
Is facilitated diffusion passive or active? spontaneous or not?
Passive and spontaneous, no energy input is required
112
Define osmosis
the movement of water via aquaporin (water transport protein) that moves water from
areas of high water concentration/low solute concentration to
low water concentration/high solute concentration
113
Does osmosis require energy input?
no
114
Describe aquaporins
channel proteins for water through a plasma membrane
115
Define active transport
Movement of a solute across a membrane from an area of LOW concentration to HIGH
ie, goes AGAINST their concentration gradient and REQUIRES ATP and a transport protein
116
What 2 things are required for active transport?
1. transport protein
| 2. ATP (energy)
117
T or F: active transport can transport any kind of solute
FALSE. not water
118
What is the purpose of active transport?
to allow a cell or organelle to maintain different concentrations of solutes from their surroundings
ex. simple sugars
119
Define electrogenic pump
transport protein that generates the resting voltage potential across a membrane that is powered by ATP
120
What is the function of an electrogenic pump?
to store energy that can be used for cellular work
121
What is an example of an electrogenic pump?
the Na-K pump that moves sodium ions out of the cell and potassium ions into the cell
122
In the Na-K pump, how many ions leave and enter the cell to create the electrical gradient?
for every 3 Na+ leaving the cell, 2 K+ enter the cell
123
Define cotransport and give an example
an ATP powered pump that transports a solute that can indirectly drive the active transport of several other solutes
ex. the gradient created by the H+ pump to drive transport of other substances into the cell
124
Define solution, solute, and solvent
SOLUTION: a liquid mixture in which the solute(s) is(are) UNIFORMLY distributed
SOLUTE: the substance that is dissolved in the solution
SOLVENT: the substance in which the solute is dissolved in to form a solution
125
Define concentration gradient
the region where the density of a chemical substance increases or decreases
126
Define bulk transport
The movement of large molecules through vesicles across membranes that requires ATP input
127
What are the 2 kinds of bulk transport?
1. exocytosis
| 2. endocytosis
128
Define exocytosis
the secretion of macromolecules by fusion of transport vesicles with the plasma membrane
129
Define endocytosis and list the 3 kinds
the intake of molecules by forming new vesicles from the plasma membrane
1. phagocytosis
2. pinocytosis
3. receptor-mediated endocytosis
130
Define phagocytosis
Intracellular digestion in which particles are engulfed in a food vacuole (can fuse with a lysosome)
a type of endocytosis
131
Define pinocytosis
Droplets of extracellular fluid are taken into tiny vesicles to get the solutes in the fluid
a type of endocytosis
132
Define receptor-mediated endocytosis
Ligands (signals) bind to receptor molecules in coated pits and the pits then form a vesicle containing ligands
a type of endocytosis
133
Which types of transport/movement across a membrane requires a transport protein?
1. active
2. facilitated
3. electrogenic
4. cotransport
5. osmosis
134
Which types of transport/movement across a membrane are passive?
1. simple diffusion
2. facilitated diffusion
3. osmosis
135
Which types of transport/movement across a membrane are active and require energy input?
1. active transport
2. electrogenic
3. cotransport
136
Which type of transport/movement across a membrane only applies to one specific substance?
osmosis to water
