UNIT 1 Flashcards
1
Q
What is cell biology?
A
The study of cells and their structure, function and behaviour
2
Q
What is a reductionist view?
A
Studying the parts can explain the whole
3
Q
The cell is a:
A
Fundamental unit of life, arises from pre-existing cell
4
Q
Cells are the smallest units _
A
exhibiting the characteristics of LIGE
5
Q
Why do we say that cells exhibit the characteristics of life?
A
They are able to reproduce themselves by their own efforts
6
Q
Are organelles the smallest units exhibiting the characteristics of life?
A
Organelles are NOT the smallest units exhibiting the characteristics of life: They are NOT able to reproduce themselves by their own efforts outside of the host cell
7
Q
Organelles are:
A
Specialized structure in a cell that performs a specific function
8
Q
Are viruses the smallest units exhibiting characteristics of life?
A
Viruses are NOT the smallest units exhibiting the characteristics of life they are NOT able to reproduce themselves by their own efforts: they use the host reproductive machinery
9
Q
The cell is:
A
The fundamental unit of life, the building block from which all organisms are constructed
cells –> tissues –> organs –> multicellular organisms
10
Q
cells are typically __ in diameter
A
Cells are typically 5-20 um (0.005 - 0.02mm) in diameter
11
Q
Convert 1m to um and nm and Angstrom units
A
1m = 10^6 um = 10^9 nm = 10^10A
12
Q
__ is the most basic property of cells
A
Life
13
Q
Basic properties of cells: Liife is the most basic property of cells: Cells can _ and _ in cultrure for extended periods of time
A
cells can grow and reproduce in culture for extended periods of time
14
Q
HeLa cells are:
A
Cultured tumor cells isolated from a cancer patient (henrietta Lacks) by George Gray in 1951. - first human cells for extended culturing
15
Q
__ are an essential tool for cell biologists
A
Cultured cells
16
Q
What are the 10 basic properties of cells?1
A
- Life is the most basic property of cells
- Cells are highly complex and organized
- Cells possess a genetic program and the means to use it
4.Cells are capable of producing more of themselves - Cells acquire and utilize energy
6.Cells carry out a variety of chemical reactions, the sum of which is called metabolism - Cells engage in mechanical activities
- Cells are able to respond to stimuli
- Cells are capable of self regulation
- cells evolve
17
Q
What does the 2nd basic property of cells “Cells are highly complex and organised” entail (2) ?
A
(1) Cellular processes are highly regulated
(2) Cells from different species share similar structure, composition, and metabolic features that have been conserved throughout evolution
18
Q
What does the 3rd basic property of cells “ Cells possess a genetic program and the means to use it” entail (2) ?
A
(1) Genes encode information to build each cell, and the organism
(2) Genes encode information for cellular reproduction, activity and structure
19
Q
What does the 4th basic property of cells “cells are capable of producing more of themselves” entail?
A
Cells reproduce, and each daughter cell receives a complete set of genetic instructions
20
Q
What does the 5th basic property of cells “ cells acquire and utilize energy” entail (3) ?
A
-Photosynthesis provides fuel for all living organisms
-Animal cells derive energy from the products of photosynthesis mainly in the form of glucose
- Cell can convert glucose into ATP - a substance with readily available energy
21
Q
Basic properties of cells #6: Cells carry out a variety of chemical reactions, the sum of which is called:
A
metabolism
22
Q
Basic properties of cells #6: Cells engage in :
A
mechanical activities
23
Q
Basic properties of cells #8: Cells are able to respond to :
A
stimuli
24
Q
Basic properties of cells #9: Cells are capable of :
A
Self - regulation
25
Basic properties of cells # 10 : cells __
cells EVOLVE
26
What are the two main types of cells?
Prokaryotic and eukaryotic
27
Prokaryotic and eukaryotic cells can be distinguished by:
Their size and types of organelles
28
Prokaryotes are all ___
bacteria
29
Prokaryotes are all bacteria which arose __
3.7 billion years ago
30
Eukaryotes include:
Protists, animals, plants and fungi
31
All cells contain __ as a store of genetic information
All cells contain DNA (deoxyribonucleic acid) as a store of genetic information
32
In prokaryotic cells, DNA is ___
not segregated within a defined nucleus
33
In Eukaryotic cells, DNA is ___
segregated within a defined nucleus
34
Prokaryotes comprise:
A single membrane-limited compartment
35
Cytoplams in prokaryotes contains:
30 000 ribosomes (the sites of protein synthesis) which account for its granular appearance)
36
site of protein synthesis
ribosomes
37
sites of protein synthesis
ribosomes
38
Nucleoids are found in:
prokaryotes
39
Nucleoid is a:
Single circular DNA molecule which is NOT surrounded by a membrane seperating it from the cytoplasm, the region of the cell lying outside the nucleoid - in prokaryotes
40
In a prokaryote, the region of the cell lying outside the nucleoid
cytoplams
41
A typical prokaryotic cell is about __ in size
1 um
42
what is an example of a typical prokaryotic cell?
E. Coli
43
What are common features of prokaryotic and eukaryotic cells (5)?
(1) Plasma membrane of similar construction
(2) Genetic information in DNA (identical genetic code)
(3) stored chemical energy in the form of ATP
(4) Shared metabolic pathways (glycolysis, TCA cycle)
(5) Proteasomes (for protein degradation) of similar construction)
44
What are proteasomes?
large protein complexes that break down proteins in cells
45
Do prokaryotes have membrane bound organelles ?
no
46
do prokaryotes have cytoskeleton with associated motor proteins
no
47
do prokaryotes have complex chromosomes that compact into mitotic structures
no
48
Features of eukaryotic cells not found in prokaryotic cells (4):
(1) Nuclear envelope, separating nucleus from cytoplasm
(2) Complex chromosomes that compact into mitotic structures
(3) membrane-bound cytoplasmic organelles
(4) cytoskeleton with associated motor proteins
49
What are three characteristics that distinguish prokaryotic and eukaryotic cells?
(1) complexity (simple vs complex)
(2) cellular reproduction (mitosis vs fission)
(3) Genetic material (packaging, amount, form)
50
Distinguish prokaryotic cells from eukaryotic cells in terms of complexity:
Prokaryotes are relatively simple
Eukaryotes are more complex in structure and function
51
Distinguish prokaryotic cells from eukaryotic cells in terms of cellular reproduction:
Eukaryotes divide by mitosis
Prokaryotes divide by simple fission
52
Distinguish prokaryotic cells from eukaryotic cells in terms of genetic material - packaging
Prokaryotes have a nucleoid region
whereas
Eukaryotes have a membrane-bound nucleus.
53
Distinguish prokaryotic cells from eukaryotic cells in terms of genetic material - amount:
Eukaryotes have much more genetic material than prokaryotes
54
Distinguish prokaryotic cells from eukaryotic cells in terms of genetic material - form:
Eukaryotes have many chromosomes made of both DNA and protein (histones)
prokaryotes have a single, circular DNA with no histone proteins
55
Histones:
Histone proteins are proteins that help package DNA into chromosomes in eukaryotic cells.
56
The nucleus is the __ of the cell
The nucleus is the information store of the cell
57
The nucleus contains molecules of DNA (deoxyribonucleic acid) which are __
extremely long polymers that encode the genetic specification of the organism
58
In eukaryotes, the nucleus is surrounded by:
A double membrane, called the nuclear envelope
59
In eukaryotes, the nucleus communicates with the cytosol via __
nuclear pores that perforate the enveloppe
60
The nuclear envelope consists of (3):
(1) INNER and OUTER NUCLEAR MEMBRANES
(2) NUCLEAR LAMINA
(3) NUCLEAR PORE COMPLEXES
61
the nuclear lamina is:
a fibrous network that provides structural support to the nucleus
62
nuclear pore complexes are:
the only channels through which molecules are able to travel between the nucleus and the cytoplasm
63
The nuclear lamina supports the __ and is composed of _
the nuclear lamina supports the nuclear envelope and is composed of lamins
64
a fibrous network that provides structural support to the nucleus
nuclear lamina
65
the only channels through which molecules are able to travel between the nucleus and the cytoplasm
nuclear pore complexes
66
The integrity of the nuclear lamina is regulated by:
phosphorylation / dephosphorylation (nuclear Intermediate fialments unit 9)
67
What are some human conditions (2) in regards to the nuclear lamina?
(1) Lamin A/C mutation causes Hutchinson-Gilford Progeria syndrome
(2) Lamin B mutation causes leukodystrophy (loss of myelin)
68
Hutchinson-Gilford Progeria syndrome
Lamin A/C mutation in the nuclear lamina
69
leukodystrophy (loss of myelin):
Lamin B mutation in nuclear lamina
70
Emery-Dreifuss muscular dystrophy (elbows, neck and heels become stiff, heart problems)
Mutations in lamin binding protein emerin
71
Mutations in lamin binding protein emerin cause:
Emery-Dreifuss muscular dystrophy (elbows, neck and heels become stiff, heart problems)
72
Leukodystrophy is a condition that causes:
loss of myelin
73
Mutations in lamin binding protein emerin cause
Emery-Dreifuss muscular dystrophy (elbows, neck and heels become stiff, heart problems)
74
Model of a vertebrate nuclear pore complex (NPC). The structure consists of several parts, including
(1) a scaffold that anchors the complex to the nuclear envelope
(2) a cytoplasmic ring
(3 a nuclear ring
(4) a nuclear basket,
(5) eight cytoplasmic filaments.
75
Structure of Nuclear Pore Complex and its Role in Nucleocytoplasmic Trafficking: shape
* Huge complex (15-30X mass of a ribosome) that exhibits octagonal symmetry.
76
Structure of Nuclear Pore Complex and its Role in Nucleocytoplasmic Trafficking: channel width
20-30 nm wide
77
Role of phynylalanine - glycine domains in nuclear pore complex?
* FG (phenylalanine-glycine) domains form a hydrophobic sieve that blocks the diffusion of larger macromolecules (greater than about 40,000 Daltons).
78
Binding of GTP (activation) requires
a protein called a GEF (guanine nucleotide exchange factor)
79
hydrolysis of GTP to GDP (inactivation) requires
a GAP (GTPase activating protein)
80
Proteins synthesized in the cytoplasm are targeted for the nucleus by:
A nuclear localization signal (NLS) having basic resisdues
81
NLS receptors?
importin a/b heterodimer
82
What are the five steps for the import of proteins through the NPC
1. Proteins with an NLS bind to an NLS receptor (importin a/b heterodimer)
2. The protein/importin complex associates with cytoplasmic filaments
3. The protein/ importin complex passes through the NPC
4. ...And associates with a GTPase called Ran
5.The Ran●GTP-importin b complex is transported back to the cytoplasm where Ran is converted to Ran●GDP and brought back in to the nucleus (leaving importin B in cytoplasm).
Importin a is returned to the cytoplasm via a protein called exportin.
83
The outer nuclear membrane is continuous with:
The rough ER
84
the space between the inner and outer nuclear membranes is continuous with:
the lumen of the rough ER
85
GEF (Guanine Nucleotide Exchange Factor): Promotes
GTP binding (activation).
86
GAP (GTPase Activating Protein): Promotes
GTP hydrolysis to GDP (inactivation).
87
Ran-GTP (active):
Binds effectors (e.g., importin β).
88
Ran-GDP
(inactive)
89
What are the ribosomal subunits in prokaryotes?
50S and 30S
90
the assembled ribosome in prokaryotes is:
70S
91
What are the ribosomal subunits in eukaryotes?
60S and 40S
92
What is the assembled ribosome in eukaryotes?
80S
93
A suborganelle of the nucleus is :
the nucleolus
94
The nucleolus, a suborganelle of the nucleus is a factory where:
ribosomes are assembled
95
What are the 5 steps involved in the ribosome assembly in the nucleolus:
(1) Ribosomal proteins are imported to the nucleus from the cytoplasm
(2) These ribosomal proteins are then delivered to the nucleus and assemble on pre-rRNA (pre-ribosomal RNA)
(3) The pre-rRNA is cleaved to form several rRNAs
(4) Ribosomal proteins and rRNAs assemble to form the 40S and 60S ribosomal subunits
(5)The subunits are exported to the cytoplasm (fully assembled ribosome is too large to fit through pore, ensuring protein synthesis takes place in cytoplasm)
96
The complexes composed of eukaryotic DNA and proteins are
called
chromatin
97
do ribosomes assemble in nucleus or cytoplasm
in cytoplasm - subunits exported from nucleus : fully assembled to big to fit through nuclear pore
98
Chromatin contains about __ protein as DNA
twice as much
99
The major proteins of chromatin are the:
histones
100
chromosome vs chromatin:
Chromatin is the loosely packed form of DNA found during interphase, allowing access for gene expression and replication. Chromosomes are the tightly condensed form of chromatin that appear during cell division to ensure accurate DNA segregation.
101
Important facts chromatin (5):
(1) complexes composed of eukaryotic DNA and proteins are
called chromatin
(2) Chromatin contains about TWICE AS MUCH protein as DNA
(3)The major proteins of chromatin are the HISTONES
(4) Histones are small proteins (11 to 23 kDa) containing a high proportion of BASIC AMINO ACIDS (arginine and lysine) that facilitate binding to the negatively charged DNA molecule
102
Histones are
Small proteins (11 to 23 kDa) containing a high proportion of BASIC AMINO ACIDS (arginine and lysine) that facilitate binding to the negatively charged DNA molecule
103
What are the 5 major types of histones:
H1
H2A
H2B
H3
H4
104
__ are very similar among different species of eukaryotes
Histones
105
Chromatin also contains
an approximately equal mass of nonhistone chromosomal proteins (more than a 1000 different types)
106
The basic structural unit of chromatin is called the:
nucleosome
107
Describe (2 main parts) of the basic structural unit of chromatin called: the nucleosome
-The DNA is wrapped around an octamer of histones H2A, H2B, H3 and H4 in a NUCLEOSOME CORE PARTICLE, and sealed by histone H1. This produces a 7-fold compaction of the DNA
- Non-histone proteins bind to the LINKER DNA between nucleosome core particles
108
nucleosome core particle
DNA is wrapped around an octamer of histones H2A, H2B, H3 and H4
sealed by histone H1
109
As a cell prepares to divide into two daughter cells, its chromatin
condenses into chromosomes that can be distinguished in the light microscope
110
Chromosomes can be arranged in a
karyotype
111
karyotype
a preparation of homologous pairs ordered according to size; may be used to screen chromosomal abnormalities
112
Euchromatin
returns to a dispersed state after mitosis.
113
Heterochromatin
is condensed during interphase.
114
Constitutive heterochromatin
remains condensed all the time.
115
Constitutive heterochromatin found mostly around
centromeres and telomeres.
116
Constitutive heterochromatin
Consists of highly repeated sequences and few genes.
117
Facultative heterochromatin
inactivated during certain phases of the organism’s life (X- inactivation)
118
Mitochondria play a critical role in:
the generation of metabolic energy in eukaryotic cells
119
Mitochondria play a critical role in the generation of metabolic energy in eukaryotic cells: they:
oxidize carbohydrates and lipids to produce; the basic chemical fuel adenosine triphosphate (ATP) by a process called oxidative phosphorylation
120
Mitochondria play a critical role in the generation of metabolic energy in eukaryotic cells
* They oxidize carbohydrates and lipids to produce the basic chemical fuel adenosine triphosphate (ATP) by a process called:
oxidative phosphorylation
121
ATP is used in
a variety of energy-requiring reactions within cells
122
Because mitochondria consume oxygen and release carbon dioxide in the course of ATP production, the entire process is called
cellular respiration, from its similarity to breathing
123
Mitochondria can appear as
a highly branched, interconnected tubular network.
124
Observations of fluorescently labeled mitochondria within living cells have shown them to be
DYNAMIC ORGANELLES capable of dramatic changes in shape (through FUSION and FISSION)
125
Observations of fluorescently labeled mitochondria within living cells have shown them to be dynamic organelles capable of dramatic changes in shape:
- they can (2):
fuse with one another (fusion) or split into two (fission)
126
The balance between fusion and fission is a major determinant of mitochondrial morphology: fission is induced by:
contact with endoplasmic reticulum (ER) tubules.
127
Mitochondria arise from
preexisting mitochondria by fission
128
Mitochondria are surrounded by
a double-membrane system, consisting of INNER and OUTER mitochondrial membranes separated by an intermembrane space.
129
mitochondria:The inner membrane forms:
numerous folds (CRISTAE).which extend into the interior (or MATRIX) of the organelle.
Its surface area is substantially increased by its folding into cristae.
130
the surface area of mitochondria is substantially increased by
its folding into cristae.
131
The mitochondrial MATRIX contains (3):
* ENZYMES responsible for the oxidative breakdown of carbohydrates and lipids via the CITRIC ACID CYCLE, and enzymes required for the EXPRESSION OF MITOCHONDRIAL GENES
* Several identical copies of CIRCULAR DNA MOLECULES (mitochondrial genome)
* Special MITOCHONDRIAL RIBOSOMES
132
Inner mitochondrial membrane:
The principal site of ATP SYNTHASE
133
ENERGY (ATP) production in the mitochondrion: this electron transport generates:
a proton gradient across the inner membrane (uses to drive the production of ATP by ATP synthase)
134
Energy (ATP) production in the mitochondrion: in the process of oxidative phosphorylation, high energy electrons from __ and __ are then passed along the electron transport chain in the inner membrane to oxygen (O2)
NADH and FADH2
135
Energy (ATP) production in the mitochondrion: PYRUVATE and fatty acids:
enter the mitochondrion, are broken down to acetyl CoA, and are then metabolized by the citric acid cycle, which produces NADH and FADH2
136
glycolysis generates
2 ATP
2NADH
water
G
Pyruvate
137
glycolysis: fate of pyruvate: oxygen vs no oxygen
Oxygen present: oxidative phosphorylation to generate lots ATP
no oxygen: fermentation: regenerates NAD+ so the cells can further metabolize glucose and produce small amounts ATP (Yeast: ethanol produced, muscle cells under stress: lactic acid)
138
Outer membrane mitochondria contains:
ENZYMES that CONVERT LIPID SUBSTRATES into forms that are subsequently metabolized in the matrix
139
Overall ATP yield from a single molecule of glucose
about 30
140
Mitochondrial disorders
Disorders that are due to abnormalities in mitochondrial structure
and function most dramatically affect muscle and nerve tissues because of their high demand for ATP.
141
Each pyruvate that enters the mitochondrion generates (*glycolysis generates two pyruvates):
4 NADH (3 from the TCA cycle, 1 from production of Acetyl-CoA)
1 FADH2
1 GTP
142
including glycolysis, after the TCA cycle there is a TOTAL of:
10 NADH
2 FADH2
2 ATP
2 GTP
143
glycolysis products (per glucose)
2ATP
2NADH
2PYRUVATE
144
conversion of pyruvate to acetyl coa takes place where?
mitochondrial matrix: as pyruvate enters the mitochondrion, each pyruvate is converted to acetyl coA
145
including glycolysis, after the TCA cycle there is a TOTAL of:
10 NADH
2 FADH2
2 ATP
2 GTP
146
during oxidative phosphorylateion, each NADH generates:
2.5 ATP molecules
147
during oxidative phosphorylation, each FADH2 molecule generates:
1.5 ATP
148
where the TCA cycle occurs.
Mitochondrial Matrix
149
Site of the Electron Transport Chain (ETC).
Inner Membrane
150
where is there a high concentration of H+ in mitochondria
intermembrane
151
Disorders that are due to abnormalities in mitochondrial structure
and function most dramatically affect
muscle and nerve tissues because of their high demand for ATP.
152
Myoclonic Epilepsy and Ragged Red Fibers (MERRF) disorder.
Ragged-red fibers in skeletal muscle of a patient
The red-stained “blotches” just beneath the cells’ plasma membrane are due to abnormal proliferation of mitochondria that have decreased cytochrome c oxidase (complex IV) activity.
153
mitochondrial disorders: Yeast “petite” colonies arise from
loss of mitochondrial DNA. can only utilize fermentable carbon sources (e.g. glucose) but not non-fermentable carbon sources (e.g. glycerol, ethanol).
154
Endosymbiont theory:
mitochondria (and chloroplasts) are derived from smaller prokaryotic cells that took up residence in a eukaryotic cell
155
Support for the endosymbiont theory:
1. Outer membrane of bacteria and mitochondria contain porins
2. Inner membrane of bacteria and mitochondria contain the lipid cardiolipin
3. Mitochondria arise from pre-existing mitochondria via fission
4. Mitochondria and bacteria contain a single, circular DNA
5. Mitochondrial ribosomes are similar to those of bacteria (70S)
156
Chloroplasts resemble mitochondria in that
both contain a permeable outer membrane and a relatively impermeable inner membrane
157
Stroma in mitochondria is analogous to
mitochondrial matrix.
158
sites of photosynthesis
Chloroplasts:
159
Chloroplasts:third membrane is formed by
the thylakoids (orderly stacks are called grana).
160
the largest and most characteristic organelles in the cells of plants
Chloroplasts:
161
photosynthesis
series of light-driven reactions that creates organic molecules from atmospheric carbon dioxide (CO2)
162
Chloroplast sperform photosynthesis during the day light hours and thereby produce
ATP and NADPH, which in turn are used to convert CO2 into sugars inside the chloroplast
163
for most of its ATP production, the plant relies on
an export of sugars from its chloroplasts to the mitochondria that are located in all cells of the plants.
164
Three of four stages in photosynthesis (the “light reactions”) take place in the thylakoid membranes:
1. Absorption of light by green pigments (chlorophylls) attached to proteins
2. Electron transport to generate a H+ gradient
3. Synthesis of ATP and NADPH
165
Each photosynthetic unit contains
several hundred chlorophyll molecules.
166
reaction- center chlorophyll
transfers electrons to an electron acceptor.
167
Yeast “petite” colonies arise from
loss of mitochondrial DNA. They cannot respire and hence can only utilize fermentable carbon sources (e.g. glucose) but not non-fermentable carbon sources (e.g. glycerol, ethanol).
168
Cellular Respiration Equation:
C6H12O6 +6O2 →6CO2+ 6H2O+ATP
169
An activated carrier is
a molecule that stores energy or chemical groups in a high-energy form and transfers them to other molecules in metabolic reactions.
170
Which activated carriers carry electrons
NADH / FADH₂ (ETC -> ATP)
FADH2 (calvin cycle, photosynthesis)
171
The proton gradient creates a proton motive force that
drives ATP synthesis as H⁺ flows back into the matrix through ATP synthase.
172
Ion Concentration in Mitochondria (esp. H⁺): matrix:
H+ concentration low
Basic pH
Protons pumped out
173
ion concentration in intermembrane space:
high H+ concentration
acidic pH
accumulates H+ from ETC
174
example of electron transport uncoupling
Electron transport can be “uncoupled” from ATP synthesis by endogenous proteins (uncoupling proteins) such as UCP1 in brown adipose tissue. UCP1 dissipates the H+ gradient and the energy of electron transfer is released as heat rather than a high- energy ATP molecule.
175
