MIDTERM Flashcards
1
Q
What is a reductionist approach? How did it help with the discovery of cells?
A
Reductionist: The premise that studying the parts of the whole can explain the character of the whole. (Small -> big)
Cell biology follows this idea.
2
Q
What is Microscopy?
A
An instrument that provides a magnified image of the tiny object. Allowed cell visualization beyond human vision.
3
Q
What is cell theory?
A
3 major points:
1. All organisms are composed of one or more cells
2. The cell is the structural unit of life
3. Cells arise from pre existing cells
One newer point: Cells contain genetic information that is passed on to the next generation
4
Q
What is the structural unit of life?
A
A CELL!
5
Q
What is it called when a cell is isolated outside of its environment?
A
“In Vitro”
Cultured cells are essential for cell biologists.
6
Q
What do cells from different species share in common?
A
Similar structure, composition, and metabolic features.
7
Q
What are genes?
A
Where Information for building an organism is stored. Genes store info for:
- Constructing cellular structures
- Running cellular activities
- Replication capability.
8
Q
How do cells replicate?
A
Division, contents of a mother cell are distributed into two daughter cells. Cells can be either haploid (n) or diploid (2n).
9
Q
What to cells use in order to function?
A
Energy. Can be in multiple forms (light -> chemical = photosynthesis… OR glucose -> ATP)
10
Q
What does the sum total of chemical reactions in a cell represent?
A
The cells metabolism. Cells function as mini chemical plants.
11
Q
How do cells engage in mechanical activities?
A
Cells can: transport materials, assemble and disassemble, and move from one site to another.
Activities are based on: dynamic, mechanical changes within cells.
12
Q
How do cells respond to stimuli?
A
Most cells are covered with receptors that interact with substances in the environment.
- Cells can also respond by altering metabolism, moving from one place to another, or even self destruction
13
Q
How do cells self regulate?
A
Cells are robust and have feedback loops to maintain homeostasis.
14
Q
How did cells evolve?
A
All organisms evolved from a common ancestral cell that lived more then three billion years ago. Despite this evolution is ongoing and essential for survival.
15
Q
What are the features of a eukaryote?
A
Eukaryotic: plants, animals, fungi, protists
- Have nucleus, specialized organelles, Divide by mitosis, can be uni or multicellular, DNA is in chromosomes.
- Use cytoplasmic movement and cilia and flagella,
16
Q
What are the features of a prokaryotic cell?
A
Prokaryotic - Bacteria
- No nucleus, Small, no membrane bound organelles, unicellular, DNA = long strand
- Divide by fission, Have flagella, do not have spindle
17
Q
What are the similarities between Eukaryotic and prokaryotic cells?
A
They both have: Have ribosomes, DNA, Cytoplasm, Cell membrane, flagella
18
Q
What are the limiting factors in cell size?
A
Surface area to volume ratio..
19
Q
What is a virus?
A
Virus: Pathogen and intracellular obligate parasites.
20
Q
What is a Virion?
A
Virion: Virus particle outside of the host cell. Contains genetic material plus protein subunits.
21
Q
What is a bacteriophage?
A
Bacteriophage: Viruses that infect bacteria
22
Q
What is a viroid?
A
Viroid: Pathogen consisting of a small naked RNA molecule which can cause disease by interfering with gene expression in host cells.
23
Q
What is a Lytic infection?
A
Lytic infection: the virus redirects the host into making more virus particles, host cell lyses and releases the virus
24
Q
What is integration? (in the context of viruses and viroids)
A
Integration: The virus integrates its DNA (provirus) into the host cells chromosomes.
25
What are the basic properties of cells?
- Cells are highly complex and organized
- Cells poses genetic program and a means to use it
- Cells are capable of reproduction
- Cells acquire and use energy
- Cells carry out a variety of chemical reactions
- Cells engage in mechanical activities
- Cells can respond to stimuli
- Cells can self regulate
- Cells evolve
26
What is the difference between polar and non polar molecules?
Polar: Assymetric distribution of charge due to a difference in EN
Non polar: Lacks EN atoms and polar bonds
27
What is an ionic bond?
Attraction between oppositely charged groups in a molecule.
28
What is a Hydrogen bond?
When hydrogen bears a partial positive charge when covalently bonded to an electronegative atom.
29
What is a hydrophobic interaction?
When molecules act differently in the presence of water.
- Polar molecules: Hydrophilic
- Nonpolar molecules: Hydrophobic
30
What is a Vanderwaals force?
When two molecules that have transitionary dipoles are close to another and experience a weak attractive force.
31
What are Acids, bases, and buffers?
Acid: releases protons
Base: accepts protons
Buffers: resist PH changes.
32
What are functional groups?
Units within a molecule that give molecules their physical properties, reactivity, and solubility.
33
What are Carbohydrates?
Carbohydrates: Include simple suars and polysaccharides. Function primarily ad stores of chemical energy.
34
What are nutritional polysaccharides? (Examples)
Polysaccharide: polymers of sugar joined by glycosidic bonds.
- Glycogen: animal product made of glucose polymers
- Starch: plant made of branched and I branched glucose polymers
35
What are examples of structural polysaccharides?
Cellulose, Chitin, sand GAGs/
36
What are fats?
Fats: Glycerol linked by ester bonds to three fatty acids (Triacylglycerol)
- Use hydrophobic interactions to their advantage
- differ in length and saturation.
- Saturated = lacks double bonds, unsaturated = has double bonds
37
What are steroids?
Steroids: built around a four ringed hydrocarbon skeleton. (Ex. Estrogen)
38
What is a phospholipid?
Phospholipid: Resembles a fat but only has two fatty acids, the third hydroxyl group of glycerol is bonded to a phosphate group.
- Membrane
39
What are Amino acids?
Amino acids: building blocks of proteins, all have carboxyl and amino group separated by alpha carbon.
40
What are the levels of structure in a protien?
Primary structure: AA sequence (Sickle cell)
Secondary structure: conformation of portions of polypeptide chain (a helices)
Tertiary structure: Conformation of entire polypeptide chain. (Myoglobin)
Quaternary structure: Subunits of proteins coming together. (Hemoglobin)
41
What is Denaturation?
The unfolding of a protein.
42
What is a helper protien?
Bind to short stretches of AA to help unfolded proteins achieve proper 3D conformation.
43
What is Proteomics?
The entire inventory of proteins that is produced by an organism.
44
What are nucleic acids? What are nucleotides?
Nucleic acid: Polymers of nucleotides that store and transmit genetic information.
Nucleotide: five carbon sugar, phosphate group, and nitrogenous base.
45
What are Purines? What are pyrimidines?
Purines: adenine and guanine in BOTH DNA and RNA
Pyrimidines: cytosine and uracil in RNA and cytosine and thymine in DNA
46
What are the differences between RNA and DNA?
- RNA is single stranded and DNA is double stranded
- RNA may fold on itself to make ribosomes, ribosomes have catalytic activity.
47
What is the plasma membrane?
Plasma membrane: Outer boundary of the cell that separates it from the world. Is a thin fragile structure.
48
What are the major functions of the membrane?
- Compartmentalization
- Scaffold for biochemical activities
- Selectively permeable barrier
- Transport solutes
- Response to external stimuli
- Cell-cell communication
- Energy transduction
49
What are Phospholipids?
- Type of membrane lipid with a phosphate group.
- Phosphoglycerides are phospholipids with a glycerol backbone.
50
What are Sphingolipids?
- Derivatives of sphingosine, an amino alcohol that contains a long hydrocarbon chain
- Ceramides = basic unit of all sphingolipids. Consists of sphingosine linked to fatty acid by its amino group.
51
What is Cholesterol?
- Smaller, less ampipathic molecule.
- Sterol that makes up 50% of animal membrane lipids.
- Stiffens bilayer
52
What are membrane carbohydrates?
- Have glycoproteins and glycolipids.
- Ogliosaccharides: may be attached to AA by two types of links (O and N links)
- Glycolipid carbs determine blood type
53
How do blood types work?
A: Enzyme adds N acetylgalactosamine to end the chain
B: Enzyme adds galactose to chain terminus
AB: Both enzymes present
O: lacks enzymes capable of attaching either terminal sugar
54
What is an integral membrane protein?
- Function as receptors that bind ligands, channels or transporters to move ions/solutes across membrane
- Amphipathic, and on both sides of the membrane
55
What are peripheral membrane proteins?
- Associate with membrane by weak electrostatic bonds
- Have dynamic relationship with membrane being recruited and released as needed.
56
What are lipid anchored membrane proteins?
- Covalently bonded to a lipid group that resides within the membrane
Two kinds:
1. Located on external face of plasma membrane linked to membrane through Glycosyl-Phosphatidylinositol linkage (GPI proteins)
2. Other group is present on the cytoplasmic side of the plasma membrane and anchored by one or more long hydrocarbon chain in the inner membrane.
57
How do cells maintain membrane fluidity?
- Altering composition by adding and removing double bonds, the cell changes the types of phospholipids being synthesized in favour of ones containing more unsaturated fatty acids.
- Desaturases = desaturation catalysts
58
What are lipid rafts?
- Cholesterol and sphingolipids pack together to form highly ordered micro domains forming lipid rafts.
- Provide favourable environment for cell surface receptors.
59
What are flippases?
Enzymes that move certain phospholipids from one leaflet to the other (asymmetry)
60
What is cell fusion?
Technique where two different types of cells or cells from two different species can be fused to produce one cell.
61
How do proteins move within the membrane?
- Proteins can be immobile, mobile in a directed manner, or exhibit random movement.
- Movements are slower than predicted by protein size and membrane viscosity
62
What is Brownian movement?
Phospholipids are confined for very brief periods to certain areas.
63
What is single particle tracing?
Experimental demonstration that diffusion of phospholipids within the membrane is confined
64
What are the two faces of the epithelial cell called?
Apical: absorbs substances from the lumen, regulates secretion and Warner intake
Basal: substratum contact, ion gradients
65
What are the major components of the Erythocyte membrane skeleton?
The major component of the internal membrane skeleton is spectrin, spectrin molecules are attached to the membrane surface to ankyrin
66
How does water diffuse across membrane?
Osmosis: diffusion of water through a semipermeable membrane
Hypotonic: Cell swells
Hypertonic: Cell shrink
Isotonic: Cells remain unchanged
67
What are the three main categories of gated channels?
- Voltage-gated channels: Conformational state depends on the difference in ionic charge on the two sides of the membrane
- Ligand-gated channels: Conformational state depends on the binding of a specific molecule
- Mechano-gated channels: Conformational state depends on the mechanical forces that are applied to the membrane.
68
What is facilitated diffusion?
- Diffusion across the membrane with the use of transporters.
- Transport involves a series of conformational changes, the rate of transport is much slower than channels.
69
What is active transport? What are the different E conformations?
- Energy input like ATP is required for this type of transport.
- Cells maintain an imbalance of ions across the plasma membrane, which cannot occur by either simple or facilitated diffusion.
- E1: Ion binding are accessible to the inside of the cell
- E2: Ion binding sites are accessible to the outside of the cell
70
How does the Na/K ATPase work?
- Pumps K in and Na out, the ratio of Na to K is 3:2
- Phosphorylation causes conformational change and ion affinity that allow transport across gradients.
71
What are the other primary ion transport systems?
- P-pump: Ca2+-ATPase, present in the ER to actively transport Ca2+ out of the cytoskeleton into the lumen of this organelle
- V-pumps: H+ across the walls of the cytoplasmic organelles. V = Vacuolar… lysosomes in animal cells.
- ABC- Transporters (ATP binding cassette)
72
What is Cotransport?
A type of Secondary active transport. Where potential energy is stored in ion gradients.
- Can be symport (same direction) or anti port (opposite directions)
73
What are the parts of a neuron?
- Neuron: Specialized cells for the information transmission using changes in membrane potentials.
- Dendrites: Receive incoming information
- Cell body: Contains the nucleus and metabolic centre of the cell
- Axon: Long extension for conducting outgoing impulses
- Node of ranvier: sites where action potentials can be generated, jumping from node to node
74
What is the resting potential?
Resting potential: Membrane potential of a nerve or muscle cell, subject to changes when activated
75
What is the action potential? How does it propagate along a membrane?
- When cells are stimulated Na channels open and the membrane depolarize.
- When cells are stimulated voltage gated Na channels open, triggering the action potential.
- Succession of action potentials passes down the entire length of the neuron without any loss of intensity
76
What is the synaptic cleft?
- The gap between presynaptic and postsynaptic neurons.
- Presynaptic neurons communicate with postsynaptic neurons at the synapse across the synaptic cleft.
- The synaptic cleft is where neurotransmitters are released.
77
What are anaerobes? What are aerobes?
Anaerobes: Capture and utilize energy by oxygen independent metabolism like glycolysis and fermentation.
Aerobes: use oxygen to extract more energy from organic molecules
78
What is mitochondrial fusion and fission?
Mitochondrial fusion: mitochondria fusing with one another
Mitochondrial fission: mitochondria splitting in two.
- can be induced by contact with thin tubules from the ER which encircles mitochondrion like a noose
79
What are the structure and function of mitochondrial membranes?
Outer membrane: outer boundary connecting to the outside world
Inner membrane: two domains
- inner boundary domain is rich in proteins responsible for the import of mitochondrial proteins
- Outer domain is a series of invaginated sheets called cristae
80
What is the mitochondrial matrix?
Matrix: within the interior of the mitochondria
- Contains: ribosomes and circular DNA to manufacture RNA
81
What is ATPs structure and function?
- ATP is the energy currency of the cell, it is composed of an adenine, a ribose, and 3 phosphates.
- ATP can be transformed into ADP and then to AMP through dephosphorylation.
82
What is Glycolysis?
- The first pathway used in the breakdown of glucose to extract energy.
- Glusoce is sepperated into two three carbon pyruvate molecules.
- 2 ATP are used in the first half, 4 ATP molecules are formed in the second half. Resulting in net 2 ATP
- Pyruvate is transported across inner membrane and is decarboxylated to form acetyl CoA which enters TCA
83
What is fermentation?
- ANaerobic process in which NAD+ is regenerated from glucose.
- Happens in the cytsol when muscle has insufficient oxygen supply.
84
What is the TCA cycle?
- Also known as kerbs and citric acid cycle. MAIN SOURCE OF ENERGY FOR CELLS AND AN IMPORTANT PART OF AEROBC RESPIRATION.
- Uses acetyl CoA for energy
***GO ON PPT ON CANVAS***
85
WEEK 4 SLIDE 22/23/24/25
86
What are Flavoprotiens?
Flavoprotiens: Polypeptides bound to either FAD or FMN
- major Flavoprotiens of mitochondria: NADH dehydrogenase (electron transport chain), and Succinate dehydrogenase (TCA cycle)
87
What are Cytochromes?
Cytochromes: contain heme groups bearing Fe or Cu metal ions
- Iron atom of a heme undergoes reversible transition between Fe3+ and Fe2+ oxidation states as a result of the acceptance and loss of a single electron
- There are three distinct cytochrome types (a, B, and c) present in the electron transport chain
88
Wha are three cooper atoms?
Three cooper atoms: located within a single protein complex and alternate between Cu2+/Cu3+
89
What is Ubiquinone?
Ubiquinone: Coenzyme Q is a lipid soluble molecule made of five carbon isoprenoid units.
90
What are iron sulfur proteins?
Iron-sulfur protein: iron atoms are not located within a heme group but instead are linked to inorganic sullied ions as part of an iron-sulfur centre. The most common centres contain either two or four atoms of iron and sulfur—-designated [2Fe-2S] and [4Fe-4S]—- linked to the protein at cysteine residues.
91
What is electron transport complex 1?
Complex I: Catalyzes the transfer of a pair of e- from NADH to Ubiquinone (UQ) to form ubiquinol (UQH2)
- The hydrophilic domain that projects into the matrix
- The hydrophobic portion of the complex e,bedded in the membrane
- These portions of the complex carry out e- transfer and proton translocation.
92
What is electron transport Complex II?
Complex II: consists of - two hydrophobic subunits that anchor the protein in the membrane and two hydrophilic subunits that comprise succinate dehydrogenase.
- Provides pathway for feeding lower energy e- from succinate to FAD to Ubiquinone
- The path from FADH2 to Ubiquinone takes the e- through three iron sulphur clusters
- Contains a heme group, attracts escaped e- to prevent fermentation of destructive superoxide radicals
- e- transfer through complex II is not accompanied by proton translocation.
93
What is electron transport complex III?
Complex III: catalyzes the transfer of e- from ubiquinol to cytochrome c
- Four protons are translocated across the membrane for every pair of e- transferred
- Protons are released in two separate steps
1. 2 protons are derived from molecule of ubiquinol that entered the complex
2. 2 protons are removed from the matrix and are translocated as part of a second molecule of ubiquinol
94
What is electron transport complex IV?
Complex IV: O2 reduction is catalyzed, huge assembly of subunits known as cytochrome oxidase, a redox driven proton pump.
- for every molecule of O2: 8 protons are taken up from matrix, 4 are consumed to form two molecules of water and 4 are translocated to the inter membrane space
95
What is the structure of ATP synthase?
96
What is the proton motive force?
- Concentration gradient between matrix and inter membrane space creates PH gradient…
- Charge sepperation across membrane creates electric potential…
- Energy in both above components is the proton motive force
- This force may be used to pull Ca into the mitochondrion and drive fusion. Many processes rely on the proton motive force for energy
97
What are the roles of glycocalyx?
- mediator of cell cell and cell substratum interactions
- Mechanical protection
- Barrier to molecular movement towards plasma membrane
- Regulatory factory binding site
98
What is the basement membrane?
- surrounds muscles, nerves, and fat cells
- underlies the epidermis of the skin, digestive and respiratory tract, and lining of blood vessels
99
What is collagen?
