Exam 2 Flashcards
1
Q
Cell
A
Smallest unit of life
2
Q
Leeuwenhoek
A
One of the first persons to observe single celled organisms
3
Q
Hooke
A
Coined the term cell
4
Q
Schleiden
A
All plants are composed of cells
5
Q
Schwann
A
All animals are composed of cells
Swan is an animal
6
Q
Brown
A
First person to observe the nucleus of a cell
7
Q
Virchow
A
Cells come only from pre-existing cells
8
Q
Cell theory
A
Cells come from pre-existing cells
The cell is the basic unit of life
All organisms are composed of one or more cells
9
Q
Plasma membrane
A
Acts as a boundary between the inside and outside of the cell
Regulates what enters/exits the cell
10
Q
Cell wall
A
Outside the plasma membrane
Add support to cell
Only animals do not have cell walls
11
Q
Cytoplasm
A
Semifluid contents of the cell between the plasma membrane and the nuclear membrane
Includes organelles
12
Q
Cytosol
A
Semi fluid portion of the cytoplasm (doesn’t include organelles)
13
Q
Eukaryotic cells
A
Have membrane bound nucleus
14
Q
Prokaryotic cells
A
Do not have a membrane bound nucleus
Have a nucleoid
15
Q
Small cells are
A
More efficient than big cells when it comes to taking in nutrients and getting rid of wastes
16
Q
Prokaryotic cell
A
Cell wall and plasma membrane
Ribosomes for protein synthesis in cytoplasm
Thylakoids (only in Cyanobacteria)
Nucleoid contains DNA
17
Q
Eukaryotic cells
A
Compartmentalization—keeps cells organized and its various functions separated
Organelles
18
Q
Nucleus
A
Control center of cell
Contains hereditary material (chromosomes), directs activities of the cell
Nuclear envelope separates nucleus from cytoplasm
19
Q
Lysosomes
A
Membranous vesicles containing digestive enzymes
Intracellular digestion
20
Q
Microbodies
A
Membranous vesicles containing specific enzymes
Functions in various metabolic tasks
21
Q
Peroxisomes
A
Microbodies found mainly in kidneys and liver
Contain enzymes that break down alcohol into hydrogen peroxide and then into water
22
Q
Glyoxysomes
A
Microbodies found in plants and especially in plant seeds. The enzymes convert lipids into carbohydrates to enhance seed germination and growth
23
Q
Endosymbiotic Theory
A
Mitochondria and chloroplasts were originally thought to have been free-living prokaryotic cells, which took up residence inside eukaryotes
24
Q
Cytoskeleton
A
Network of protein elements extending throughout the cytosol; function in maintaining cell shape and movement of cell parts
25
Microtubules
Protein structures that make up the cytoskeleton, centrioles, cilia, and flagella
26
Cilia and Flagella
9 + 2 pattern of microtubules
Function in movement of the cell
Flagella—long, few in #
Cilia—short, numerous
27
Centrioles
9+0 patterns of microtubules
| Function in cell division
28
Tight junctions
Create a leak proof seal around cells
| Ex: stomach lining
29
Desmosomes
Anchoring junctions
| Act like spot welds to hold tissues together
30
Gap junctions
Allow for cell to cell communication as ions and other molecules pass through cytoplasmic bridges between cells
31
Plasmodesmata
Gap junctions in plant cells
32
Phospholipid molecules
Ideal for forming plasma membranes because they are both polar and nonpolar at the same time
Form a bilateral with polar heads toward the watery exterior and interior
Nonpolar tails are in the middle
33
Fluid-Mosiac model of cell membrane structure
Bilayer of phospholipids with consistency of olive oil
| Protein molecules are either partially or entirely embedded
34
Phospholipid component
Forms matrix of a membrane
| Hydrophobic, impermeable barrier that prevents movement of polar (most biological) molecules through the plasma membrane
35
Protein component
Carries out most functions of the plasma membrane
| Proteins can move laterally in the cloud bilayer
36
Channel proteins
Have a channel or tunnel that allows ions and small molecules to pass through the membrane
37
Carrier proteins
Helps larger, bulkier molecules cross the membrane
Temporarily bind to the molecule and help it across the membrane
Turns it loose on the other side
38
Cell recognition proteins
Allows one to tell self from nonself
39
Cell receptors
Have branching carbohydratic chains that act as receiving receptacles for hormones and other molecules
40
Receptor proteins
Receive hormones that cause same response by the cell
| The receptors will fit with a hormone having a specific shape
41
Enzymatic proteins
Enzymes that circulate through the cytoplasm, bloodstream, and extracellular fluid. These enzymes are NOT embedded in the plasma membrane
42
Adhesion proteins
Like the desmosomes or anchoring junctions that hold adjacent cells together
43
Selectively permeable
The passage of most molecules into and out of the cell is regulated
44
Diffusion
Movement of molecules from an area of greater concentration to an area of lesser concentration
No energy required
Small molecules diffuse easily
45
Osmosis
Movement of water from an area of higher water concentration to an area of lower water concentration
No energy required
46
Osmotic pressure
Results when water flows across a membrane to an area where there is a greater solute concentration
47
Turgor pressure
Related to osmotic pressure
As plant cells gain water, the water pushes out against the cell walls. This gives internal support to cells and allows the plant to stand upright
48
Hypotonic
Cell gains water
49
Hypertonic
Cell loses water
50
Protein carriers or transport proteins
Help larger, bulky molecules across the cell membrane
51
Facilitated diffusion
Movement of large molecules down a concentration gradient (high to low) with the help of a carrier protein
No energy required
52
Active transport
Molecules or ions are moved from low to high concentration with the help of a carrier protein
Requires lots of energy
53
Endocytosis
Method of taking substances into cells that would be too large to be transported by protein carriers
54
Phagocytosis
Cell eating
| Solids taken in
55
Pinocytosis
Cell drinking
| Liquids taken in
56
Exocytosis
Method of releasing substances from cells
57
Metabolism
All the chemical reactions hat take place in cells during growth, repair, and reproduction
58
Forms of energy
```
Mechanical
Electrical
Light
Hear
Chemical
```
59
Mechanical
Kinetic energy
60
Electrical
Flow of electrons
61
Heat
Dead end form of energy for cells
| Measure of how fast molecules are moving
62
Chemical
Energy derived from breaking bonds that hold chemical molecules together
Potential energy
ONLY kind of energy cells can use
63
Energy
The ability to do work
64
Ribosomes
Made of protein and RNA
| Protein synthesis
65
Endoplasmic reticulum
Transport system
Rough ER — specializes in protein synthesis
Smooth ER — associated with lipid synthesis
66
Molecules that are moving through the ER system
Are enclosed in vesicles that move to the Golgi apparatus
67
Golgi apparatus
Function is to process, package, and distribute molecules about or from the cell
68
Vacuoles and vesicles
Function is storage of substances
69
1st law of thermodynamics
Energy cannot be created or destroyed, only changed from one form to another
70
2nd law of thermodynamics
Energy conversions are never 100% effective
There will always be some energy released as hear
Energy cannot be recycled
71
The sun is
The primary source for nearly all living things
72
Entropy
A measure of the disorder in a system
Heat has the most entropy
Energy only flows in one direction
73
Exergonic reaction
Reactions that release energy
74
Endergonic reactions
Reactions hat require an input of energy
| Energy released can be used to fuel endergonic reactions
75
Metabolic pathway
A series of stepwise reactions occurring one after another
76
Substrates
Reactants
| Chemicals that participate in chemical reaction
77
Intermediates
Refers to the substances produced between the beginning and end of a metabolic pathway
78
End products
The last substances produced in a metabolic family
79
Enzymes
Organic catalysts (usually globular proteins) that speed up chemical reactions without themselves being changed
80
Coenzymes
Usually inorganic molecules or ions that enhance or help the action of the enzymes
81
Energy carriers
Electron carriers that shuttle electrons from one reaction to another in metabolic pathways
These electron carriers are derived from vitamins
82
Features of enzymes
Enzymes don’t make a reaction happen that couldn’t happen on its own
Not permanently altered or used up in reactions
They can be used over and over again
The same enzyme works in both the forward and reverse directions of a reaction
High key selective about their substrates
83
Active site
Place in the enzyme where the substrates fit
84
Allosteric site
Any place on the enzyme that is NOT the active site
85
Activation energy
The amount of energy that must be supplied to get reactants to form products
86
Enzymes lower
The activation energy so reactions occur more efficiently or quickly
87
Enzymes are
Proteins
88
pH and temperature increase can
Denature enzymes
89
Feedback inhibition (a form of negative feedback)
The product being produced binds with an enzyme (at the active site or the allosteric site) and prevents the substrate from binding
This shuts the process down for a time until the product is used up
90
Negative feedback
A decrease in function, in response to a stimulus.
| It shuts down or slows down process temporarily
91
Positive feedback
An increase in function in response to a stimulus
| Encourages process to continue or proceed more rapidly
92
NAD+, FAD, NADP+
Energy carriers
Shuttle electrons through electron transport systems
These carriers are derived from vitamins such as niacin and riboflavin
93
Electron transport system
Series of chemical reactions where electrons are shuttle through a series of steps
The electrons have high energy when they enter the system and low energy when they exit
This energy difference is used to produce ATP
94
Function of ATP
Chemical work: synthesis of macromolecules
Transport work: pumping substances across plasma membranes
Mechanical work: beating of cilia and flagella, muscle contraction, movements of chromosomes during cell division, etc
95
Phosphorylation
To add a phosphate to a substance
96
Significance of the ATP/ADP cycle
We can use the neighborhood of 400 lbs of ATP per 24 hours, but only have 1.8 oz on hand at any point in time
97
Cellular respiration
Glucose + oxygen
| Carbon dioxide + water + ATP
98
Glycolysis
Glucose splitting
1st step in the breakdown of glucose
Takes place in the cytoplasm (cytosol)
Does not require oxygen (anaerobic)
End products are 2 ATP (net) & 2 pyruvate molecules
4 ATP are produced total, but 2 ATP are needed to start
99
The role of NAD+ in glycolysis
An electron or energy carrier
100
The 2 molecules of pyruvate produced in glycolysis enter
The mitochondria first for future processing
101
3 steps of cellular respiration
Glycolysis
Krebs cycle (if oxygen)
Fermentation (if no oxygen)
Electron transport
102
Fermentation
Process occurs after glycolysis and only when there is a lack of oxygen in the cells
Takes place in cytoplasm (cytosol)
Does not require oxygen
Generates 2 ATP molecules
103
Lactic acid fermentation
Occurs in the muscles of animals in response to a lack of oxygen in the tissues
The end product is lactate that causes the burning sensation in overexerted muscles. Oxygen debt is the amount of oxygen that must be repaid to the muscle cells in order to convert lactate back to pyruvate
104
Alcohol fermentation
Plants, plant products, and fungi (including yeasts)
| The end product is ethanol (alcohol)
105
2 ATPs are produced for either
Type of fermentation
2 ATPs are better than none at all when oxygen is lacking, thereby preventing the last two steps in the breakdown of glucose
106
Preparatory steps (transition reactions)
Occur just before the Krebs cycle
Occur in mitochondria
Pyruvate is conjoined with coenzyme A to form a 2-carbon molecule of acetyl-coA that enters the Krebs cycle
107
Krebs cycle
A series of 10 reactions that are cyclical
Occurs in mitochondria
Requires oxygen (aerobic)
Releases CO2 (waste)
Produces 2 ATP molecules
Produces 6 NADH and 2 FADH2 energy carrier molecules
The CO2 we exhales originates as carbohydrate
108
Electron transport chain
Requires oxygen (aerobic)
Occurs in mitochondria
Produces 26-28 ATP molecules (net)
The NADH & FADH2 energy carriers produced from the Krebs cycle (and the 2 NADH from glycolysis and 2 NADH from the preparatory steps) enter the electron transport system, where they shuttle electrons through the system
Water is also produced when an oxygen atom combined with a pair of electrons and 2 H+ ions
109
Role of oxygen in aerobic respiration
Final electron acceptor
| Combined with 2 electrons and 2 hydrogen ions to produce water
110
One glucose molecule yields
30-32 total ATP molecules from its complete aerobic breakdown
(ALL 3 processes)
111
Autotroph
Self feeder
Organism that can make their own food
Photoautotrophs use sunlight to make their own food through the process of photosynthesis
Chemoautotrophs strip electrons from hydrogen atoms or other atoms to make their own food ex: bacteria deep in the ocean
112
Heterotroph
Other feeder
Organism that cannot make its own food
These organisms must eat or prey upon other organisms or absorb nutrients from organic materials ex: fungus
113
Photosynthesis
Carbon dioxide + water + sunlight(energy) = carbohydrate (glucose) + oxygen
114
Plants use visible light portions of be electromagnetic spectrum for photosynthesis. The blue and red wavelengths are
Absorbed best
115
Leaves appear green because
They reflect the green wavelengths of light
116
Structure of a chloroplast
Bound by a double membrane
| Contains 2 portions: liquid stroma and membranous grana (made of thylakoids)
117
The light dependent reactions take place
In the thylakoids
| Function is to capture the energy of sunlight
118
The light independent reactions take place
In the liquid stroma
| Function is to reduce or convert CO2 to carbohydrate
119
Light dependent reactions
Sunlight is absorbed by chlorophyll. This energizes electrons, which are sent to acceptor molecules
Water is split. One atom of oxygen is released to the atmosphere, 2 hydrogen ions are released to the thylakoid space and the electrons from this splitting H2O replace those that were boosted in energy from the chlorophyll molecule
An acceptor molecule sends electrons to the ETC. The electrons have high energy going in and low energy coming out. The energy lost from these electrons is used to make ATP
Electrons leaving the ETC are picked up by P700. The electrons are again boosted to a high energy level where another acceptor molecule passes them to NADP+
120
NADP+ + 2e- + H+ = NADPH
NADPH is used in the stroma to produce carbohydrate and ATP
| Oxygen is a by product
121
Chemiosmotic ATP synthesis
H+ ions are pumped to one side of a membrane. This creates a concentration gradient of H ions. There is a lot of potential energy here (like water behind a dam)
H+ ions are allowed to flow back across the membrane through a protein channel. An enzyme is activated that allows the 3rd phosphate to be put back on ADP to make ATP
122
Light independent reactions
ATP and NADPH that were produced in the light dependent reactions are used here
CO2 combined with a 5 carbon molecule of RuBP. This is the first of a cyclical series of chemical reactions in the conversion of carbon dioxide into sugar.
It takes 6 turns of the Calvin-Benson cycle along with 6 molecules of CO2 to produce one molecule of sugar (glucose)
123
Photorespiration
Opposite of photosynthesis
In the presence of light, oxygen is taken up and CO2 is released. This happens when the weather is hot and dry. The plants close their stomata to prevent water loss. This causes the concentration of CO2 to be low inside the plant leaves, so photosynthesis cannot proceed as usual.
This is a protective mechanism to prevent water loss. When the conditions are right, the plant’s stomata will open again and photosynthesis will proceed normally
124
C3 Plants
Fix their carbon into a 3 carbon molecule. They do best in mild to moderate climates
Ex: peas, beans, radishes
125
C4 plants
Fix their carbon into a 4 carbon molecule
They do best in warmer, drier climates
Ex: bamboo, corn
126
CAM plants
Fix most of their carbon at night when temperatures are cooler and the plant is not in as much danger of losing H2O
Ex: succulents
