Lecture 7/8 Flashcards
1
Q
Where did the first cells come from
A
Experimental evidence suggests:
- abiotic (nonliving synthesis) of simple organic compounds
- abiotic polymerization of these monomers
- evolution of molecule(s) capable of both information storage and replication
- enclosure of such molecule(s) within simple membrane(s) to form the first primitive cell
2
Q
Stanley Miller found what organic compounds in his exp
A
Glycine and alanine
3
Q
If subbed CO2 and CO instead of CH4 and NH3 in stanley miller exp what compounds form
A
numerous amino acids, formaldehyde, formic acid, hydrogen cyanide, sugars, and adenine
4
Q
Other possibilities where first cells came from
A
FeS2, deep-sea hydrothermal vents, catalytic surfaces, primitive enzymes
5
Q
Why are most cells small
A
Cells must have adequate surface area/volume ratio (because of the required exchanges between environment: the surface area represent the amount of cell membrane available for uptake and excretion)
If cell too big ur limited by simple diffusion
6
Q
Molecules move by diffusion: the rate of diffusion decreases as the size of molecules
_____, so active transport
is necessary (carrier proteins, vesicles, etc.)
A
increases
7
Q
[reactants and catalysts] ___ through enclosure into organelles = compartmentalization
A
increase
8
Q
Which of the following have nuclei: bacteria, archaea, eukaryotes
A
eukaryotes
9
Q
Fxn of membranes in eukaryotes
A
use of internal membranes to segregate function
10
Q
Fxn of plasma membrane
A
Define cell boundaries and retains contents
11
Q
Plasma membrane composed of
A
Phospholipids, glycolipids, single lipids
12
Q
How is plasma membrane organized in
A
Lipid bi-layer
13
Q
Glycolipids and glycoproteins exposed to the
___ side of the membrane. Fxn?
A
- External
- make it stickier and easier to organize into structures
14
Q
Functions of membrane proteins?
A
- enzymes: catalyze reactions associated with the membrane
- anchors for structural elements of cytoskeleton
- receptors (for external signals that trigger response within the cell)
15
Q
What is the nucleus
A
The cell’s info center
16
Q
What does the nucleus consist of
A
Histones + DNA
17
Q
Nuclear envelope consists of what
A
inner and outer membrane
18
Q
What organelle is continuous with outer membrane of the nuclear envelope
A
Endoplasmic reticulum
19
Q
The space between 2 nuclear membranes is?
A
Perinuclear space
20
Q
Proteins are synthesized on ribosomes in the cytoplasm,
so how do they get into the nucleus?
A
Nuclear pores
21
Q
What are nuclear pores
A
: channels lined up with pore complexes that regulate the movement of macromolecules
(ribosomal proteins, mRNAs, histones, etc.) in and out of the nucleus
22
Q
What are nucleoli
A
rRNA and ribosomal assembly
23
Q
What is the fxn endomembrane system
A
Dynamic system: synthesizes proteins that are destined for various organelles, cellular membranes, or secretion
24
Q
Where are proteins synthesized
A
ribosomes associated w/E.R
25
Where are proteins packaged and processed
Golgi apparatus
26
How do proteins move out of cell
in small membrane-bound vesicles
27
Where are lysosomes derived from? So part of what system
ER, endomembrane system
28
Are peroxisomes part of endomembrane system
no
29
What is the E.R.
Interconnected network (“reticulum”) of tubular membranes and flattened
sacs, or cisternae
(singular: cisterna)
30
Lumen of E.R. continuous with?
nuclear Membrane
31
Characteristics of rough ER
- studded with
ribosomes on the side
of the membrane that faces the cytosol.
- Ribosomes synthesize ER membrane or resident proteins: many of these will be secreted via the endomembrane system
32
Characteristics of rough ER
- studded with
ribosomes on the side
of the membrane that faces the cytosol.
- Ribosomes synthesize ER membrane or resident proteins: many of these will be secreted via the endomembrane system
- synthesize most secretory and membrane proteins
33
Characteristics of smooth ER
- no role in protein synthesis (no ribosomes)
- involved in synthesis of lipids and steroids
- importantly, smooth ER also inactivates and detoxifies drugs
34
Free ribosome vs ribosome on E.R
Free ribosomes synthesize proteins intended for use within the cytosol or for import into organelles, whereas ribosomes on the rough ER synthesize most of secretory and membrane proteins
35
What are dark spots near smooth ER?
Glycogen storage granules
36
What is the golgi apparatus
A stack of flattened discs (cisternae)
37
Fxn of golgi apparatus
processing and packaging secretory proteins and in synthesizing complex polysaccharides (analogy: central post office, processing station, vesicles fuse in – vesicles fuse out, modified and ready for export )
38
Most outer membrane and secretory proteins are ____
Glycoproteins
39
What are glycoproteins
.
40
Characteristics of mitochondria
- present in most eukaryotic cells
- Energy production in cells: sites of aerobic respiration- oxidation of sugars and other cellular fuels to CO2 and generation of ATP
- inner and outer membranes
- Mitochondria contain their own ribosomes and circular
dsDNA (mtDNA), inherited only
through the mother (useful in tracing genetic linkages)
41
What are cristae
infolding of inner membrane of mitochondria
42
of mitochondria within a cell can often be related to ___
their role in that cell; e.g., sperm, muscle cells
43
What is the site of photosynthesis
chloroplasts
44
What is photosynthesis
the light-driven process that uses solar energy and CO2 to synthesize the sugars and other organic compounds
45
Characteristics of chloroplasts
Large organelles (~5-10 μm long), large # in the leaves of green plants, double membrane, third membrane system: flattened sacs thylakoids connected by stroma thylakoids and stacked together to form the grana
46
Reactions that depend on solar energy are localized in or on ____
thylakoid membrane system
47
Fxn of stroma
Rxns involved in conversion of CO2 to sugar molecules
48
How is chloroplasts and mitochondria similar
ribosomes and own circular dsDNA in the stroma
49
What is the endosymbiont theory
mitochondria and chloroplasts evolved from ancient bacteria that established a symbiotic relationship with primitive nucleated cells 1 to 2 billion years ago
Phagocytosis (“cell eating”)
Anaerobic vs aerobic metabolism
50
Evidence for endosymbiont theory
- inner membranes have bacterial- type lipids, outer membranes have eukaryotic-type lipids
- mt rRNA sequences match those of aerobic purple bacteria
- chloroplast rRNAs match photosynthetic cyanobacteria
51
Characteristics of lysosomes
- 0.5-1 μm in diameter
- Single membrane, pH~5
- Use by cells as storage containers for hydrolases (enzymes that digest proteins, carbohydrates, or fats) AKA cell’s recycling system
52
Why sequester hydrolases in lysosomes?
They will be digesting things away otherwise. You do not want to be eating your intracellular environment
53
Like secretory proteins, lysosomal enzymes are synthesized in ___, transported through the ___, and then packaged into vesicles that can become lysosomes
- ER
| - Golgi apparatus
54
The inner face of the lysosomal membrane is highly glycosylated. Why?
Want to protect from degradation.
55
Effects of defects in any of ~40 lysosomal enzymes can ?
disrupt normal cellular degradation processes & lead to serious human disease
56
Fxn of each hydrolase?
Breaking down covalent bonds, hydrolysing diff molecules into their constituent parts
57
What happens when hydrolases fail to fxn? What enzyme would you predict to be defective in this condition
- their target molecules accumulate, producing swollen lysosomes (e.g., α-mannosidosis).
- A-mannosidosidase
58
What happens when there is a defect in transport of hydrolases to lysosomes?
A well known example is I-cell disease (life expectancy 7 years, no treatment):
undigested macromolecules accumulate in lysosomes, leading to engorged lysosomes, forming inclusions, coarse facial features,
enlarged liver and spleen, psychomotor retardation, etc.
59
Characteristics of peroxisomes
- Resemble lysosomes in size
and structure: single membrane, but unlike lysosomes, not derived from the ER
- Found in plants, animals, fungi, protozoa, and algae. In animals, especially prominent in liver and kidney cells
60
Fxn of peroxisomes
: generate and degrade H2O2 (a byproduct of several normal metabolic reactions, highly toxic to cells: catalase is involved), oxidative breakdown of fatty acids >12C long, detoxification of other harmful compounds (e.g., methanol, ethanol, formaldehyde), catabolism (break down) of unusual substances (e.g., D-amino acids). Peroxisomes may regulate O2 levels within cells and play a role in aging
61
What is the cytoskeleton
3D array of interconnected proteinaceous structures: an internal framework that
gives a cell its distinct shape and internal organization
62
Fxn of cytoskeleton
Structured yet dynamic, plays
an important role in cell movement and cell division
-a framework for positioning and moving organelles and macromolecules within the cytosol (~80% of the cell proteins are associated with cytoskeleton)
63
3 major structural elements of cytoskeleton
Microtubules, microfilaments (actin), and intermediate filaments
64
cytoskeleton prominent where
cilia, flagella, muscle fibrils
65
Diff between Microtubules, microfilaments (actin), and intermediate filaments
Microtubles tend to be more parallel, micro and intermediate filaments tend to be dispersed
66
What are extracellular structures composed of
Materials transported out of cell across plasma membrane
67
In animals, ECM primarily composed of what
Collagen and proteoglycans
68
Is ECM stiff or elastic
Elastic
69
Plant and fungal cell walls are composed of
Cellulose
70
Bacteria ECM composed of
GlcNAc-MurNAc
71
ECM in animals varies in composition based on
cell type
72
Fxns of ECM in animals
Support, regulation of cell motility and migration, cell division, recognition and adhesion, cell differentiation during development
73
Characteristics of viruses
- Intracellularly life style only
| - DNA or RNA, segments, ss or dd, protein coat and maybe membrane (enveloped viruses, recall Zitka)
74
Characteristics of viroids
Small circles of ssRNA, no protein coat, don't encode proteins, enter nucleus of infected plant and interfere w transcription of DNA
75
What are prions
infectious protein molecules
76
What is Alzheimers disease
Disease characterized by degradation of brain cells due to excessive aggregation of proteins outside (amyloid plaques) and inside brain cells
77
What are amyloid plaques
Insoluble fibrils of amyloid-beta peptide (AB), produced in plasma membrane on amyloid precursor protein (APP_
78
How do normal vs. alzheimer's patients differ in their apoE
Most patients have defective apolipoprotein E (apoE): normal function of apoE is cholesterol transport, but defective apoE stimulate amyloid plaque formation
79
Unlike bacterial and yeast cells, most animal cells will grow only when attached to ____
solid surface
80
What to cell cultures (in vitro) need to grow
- cell culture flask or scaffold material (i.e., chemically modified plastic or coated with ECM proteins)
- suspension culture/nutrients (aka culture media)
- environment mimicking in vivo conditions (CO2, temperature 37oC, humidity, oxygen tension maintained at atmospheric, but can be varied depending on cell type)
- sterility (aseptic technique, antibiotics, and antifungals) – GMP, QC/QA
81
Cell morphologies vary depending on ___
cell type
- (fibroblasts, cells of the connective tissue, typically divide/grow the fastest and will become the predominant cell type, unless removed)
82
What was Basal Eagle Media developed for
HeLa cells
83
Use of Basal Eagle Media
- Maintain pH and osmolarity
| - Provide nutrients and nrg source
84
Components of Basil Eagle Media
Inorganic Salts
- Maintain osmolarity
- Regulate membrane potential (Na+, K+, Ca2+)
- Ions for cell attachment and enzyme cofactors
pH Indicator – Phenol Red
- Optimum cell growth approx. pH 7.4
Buffers (Bicarbonate and HEPES)
- Bicarbonate buffered media requires CO2 atmosphere
- HEPES chemical buffer range pH 7.2 – 7.6 (is better at maintaining physiological pH in cell culture, when compared to bicarbonate buffers despite the changes in [CO2])
Glucose
- Energy Source
Vitamins, trace elements, supplements: antibiotics, antifungals, etc.
FBS provides growth factors and hormones, aids in cell attachment
85
Practically speaking, how do we culture cells in the laboratory?
1. Revive frozen cell population (see ATCC), OR isolate cells from tissue
2. Maintain in culture (passing/sub-culture under aseptic technique when confluent)
3. Count cells (see slide 11)
86
If dont have antifreezing what happens to cultured cells
Your ice will expand and ur cell will lyse
87
What is a cell strain
A lineage of cells originating from one initial primary culture
88
What is senescence
Most of the primary cells will divide a finite number of times and then cease growing
89
Exception to finite life span?
embryonic stem cell (ES), derived from an embryo. These cells will divide and give rise to all tissues during development: ESs can be cultured indefinitely under the appropriate conditions
90
What are transformed cells
Rare cells in a population of primary cells may undergo spontaneous oncogenic mutations. These transformed cells can grow indefinitely in culture
91
What is a cell line
A culture of cells with indefinite life span is considered immortal (recall HeLa cells)
92
What does FACS stand for
fluorescence-activated cell sorter
93
Fxn of FACS
both analyze the cells and select the few fluorescent cells from thousands of others and sort them into separate dishes
94
Common use of FACS and example
FACS is commonly used to purify the different types of white blood cells (WBCs), each of which bears on its surface one or more distinctive proteins and so will bind monoclonal antibodies specific for its proteins
Example: only T cells of the immune system have both CD3 and Thy1.2 proteins on their surfaces, and may
be separated from other types of blood cells because on these “molecular markers”
11
95
What are antibodies
proteins secreted by B cells that bind with high affinity to their antigens
96
What is monoclonal
Each normal antibody-producing B-cell forms a clone of cells in the spleen, or lymph notes, with each cell producing the identical antibody
97
What is polyclonal antibodies
Because most natural antigens contain multiple epitopes, however, exposure of an animal to an antigen usually stimulates the formation of multiple B-cell clones, each producing a different antibody (so, there is a mixture of antibodies
circulating in the blood
98
How to produce and purify monoclonal antibodies
hybrid cells called hybridomas are made. Individual B-cells are fused with immortal cells called myelomas and the surviving hybridomas are selected/tested for the production of the desired (monoclonal) antibody
99
What should you do if cell fractions obtained by differential and equilibrium density-gradient centrifugation still contains more than one type of organelle
Monoclonal antibodies for various organelle- specific membrane proteins are a powerful tool for further purifying such fractions
Example: purification of vesicles whose outer surface is covered with the protein clathrin; these coated vesicles are derived from coated pits at the plasma membrane during
receptor-mediated endocytosis (more on this later in the course)
An antibody to clathrin, bound to a bacterial carrier/magnetic beads, can selectively bind these vesicles in a crude preparation of membranes, and the antibody complex can then be isolated by low-speed centrifugation/attachment to magnets on the side of tubes
