Bio 101 Exam 1 Flashcards
(159 cards)
0
Q
Composition of the universe
A
Dark energy 71.4% (can measure, don’t know what it is)
Dark matter 24% (“”)
Atoms 4.6% (Byonic Matter-things we can see on the periodic table)
1
Q
The universe
Diameter, age, etc
A
93 billion light yrs in diameter
13.8 billion years old
Expanding at a rate of 1% per 140 million years
2
Q
Steady state theorem
A
New matter is continually created as the universe expands
No beginning or end
3
Q
Big Bang theory
A
Universe created as singularity and expands outward
Has definite beginning and end
A lot of evidence supporting this
4
Q
Theory (definition)
A
Statements or principles devised to explain something repeatedly tested and widely accepted. Can be used to make predictions about natural phenomena
5
Q
Big Bang theory (the singularity)
A
- not an explosion
- relativity breaks down at 10^-43 seconds, so we don’t actually know what happened
- quantum and string theory offer explanation
6
Q
Big Bang theory (cosmic inflation)
A
- at 10^-36 seconds: gravity separates from the unified force; elementary particles are formed.
- at 10^-32 seconds: strong nuclear force becomes distinct; universe inflates from 1 cm to 18 billon light years.
- at 10^-3 seconds: electromagnetic and weak force separate; matter and antimatter annihilate each other
7
Q
Big Bang theory (hadron and lepton epochs)
A
- by about 1 second, the universe cooled enough to form protons and neutrons (hadrons)
- by about 3 minutes the universe consists of 75% H Nuclei and 25% He nuclei
- antimatter is almost nonexistent
8
Q
The formation of atoms
A
- 300,000 yrs, atomic nuclei capture electrons
- matter consists of 75% hydrogen, 25% helium and < 1% Li
9
Q
Birth of stars
A
- 300 million years, gravity causes pockets of gasses to collapse
- energy triggers nuclear fusion of hydrogen into Helium creating the first stars
10
Q
Formation of heavier elements
A
- H fuses to form He and heavier helium is pulled to core by gravity
- Helium core fuses to form carbon and heavier carbon pulled to core by gravity
- process repeats until iron
- iron stable and absorbs energy from nuclear reaction
- causes the iron core to collapse, releasing protons and neutrons outward
- *star with iron core explodes as supernova
- energy adds protons neutrons from iron decay to outer shells creating all heavier elements
11
Q
Planets and Galaxies
A
- As stars exploded, the heavier elements are dispersed and give rise to planets, moons, asteroids, etc
- planets caught by gravity of stars to form systems
- solar systems formed 4.5 billion yrs ago
12
Q
When did life appear on earth?
A
3.5 billion years ago
Humans pretty recent considering the timeline of the universe
13
Q
Essential elements for life on earth
A
Carbon and water
C and H2O
14
Q
Ionic bond
A
Transfer of electrons creates two oppositely charged ions
-electromagnetic attraction occurs ( two elements with opposite charges want to stick together)
15
Q
Covalent bond
A
Two elements share an electron creating a strong bond that is hard to break
16
Q
Atomic interactions
A
Chemical bonds are mediated by electrons
Outermost electron shell can hold 8 electrons
First electron shell can hold 2 electrons
17
Q
Hydrogen bond
A
An attraction between a slightly positive hydrogen ion and a slightly negative atom (usually O, F, or N)
- the electron is not evenly shared (hydrogen gets the electron a little more), which results in the slightly positive charge for hydrogen and slightly negative for oxygen (or other element)
- causes other things to be attracted to positive or negative charges (why water sticks together)
18
Q
Elements of life
A
- Life on earth uses only 25 of the 118 elements
- 6 are disproportionally represented (CHNOPS)
- carbon, hydrogen, nitrogen, oxygen, phosporous, and sulfer
- make up 96-99% of the human body
19
Q
Water
A
- absolutely essential
- 80-90% ecoli is water (bacteria)
- 95-99% jellyfish is water
- 60-70% human is water
- unique compound cuz has a high boiling point and a great span btwn it and it’s freezing point, allowing water to remain a liquid under a broad range of temperatures
20
Q
3phases of water
A
Solid
- only substance whose solid can float on its liquid state
-becomes less dense as it drops below 4degrees C
Liquid
-one of only a few carbon-less compounds that is a liquid at room temp.
-allows molecules to move around more freely
Gas
-when heated, breaks the hydrogen bonds btwn molecules allowing the molecules to separate
21
Q
More about water
A
- has high surface tension (hydrogen bonding btwn water molecules makes them “sticky”)
- water has high viscosity (thickness)
- intermolecular interaction also makes water unusually viscous
- water as an universal solvent (any solution that dissolves other solutions); more compounds are dissolved in water than any other liquid
22
Q
Carbon
A
- all life on earth is carbon based
- can form long complex chains
- Valence: 4 electrons in outer shell; can make 4 bonds
- Strength: carbon to carbon bonds are strong and stable; ideal to form molecular backbones
- economy: can still be broken by reasonable amount of energy
- double bonds: can form double bonds; two carbon atoms share two electron pairs
- shape: carbon compounds can adopt a number of shapes; rungs and chains common
- flexibility: freedom of rotation around bond allows large molecules to be flexible
23
Q
How to define life
A
Still don't have a universally accepted definition Reproduction Order Evolution Homeostasis Metabolism Stimuli Growth
24
Order
* Life is made up of one or more cells
* Cells in multicellular organisms are ordered
* Structures inside of cells are ordered
* Macromolecules comprising cells are ordered
25
Homeostasis
* Living things maintain an internal environment that is distinct from the external environment
* Examples of homeostasis include maintaining our temperature, maintaining blood glucose levels, maintaining constant pH
26
Metabolism
•Energy-dependent chemical reactions used for growth, reproduction, homeostasis, etc.
•Catabolism breaks down organic matter to liberate energy
•Anabolism uses energy to build organic structures
Metabolism
Many animals like tardigrades can go long periods without growth or metabolism
27
Growth
•The changing of size and shape in a predictable manner
| -lots of no living things grow (fire, crystal)
28
Response to stimuli
•Changing behavior in response to the environment
•Response to light, chemicals, temperature, etc.
-robots can respond to stimuli
29
Reproduction
Cloning or mating to transfer genetic material from one generation to the next
-Turritopsis nutricula is immortal and can alternate between juvenile and adult stages indefinitely
30
Evolution
•The change in genetic material over time
| - viruses and computer programs can evolve but aren't alive
31
Organic compounds
- organic means made of carbon
- most life on earth is made primarily of carbon-based compounds
- molecules that contain backbones of covalently bonded carbon are called this
- carbon can form a greater variety of compounds than any other element
- responsible for structure of living cells or tissues, metabolism, information transmission, energy production and evolution (basically everything living organisms do)
32
Hydrocarbons
Contain only carbon and hydrogen
33
Hydrophobic compounds
- hydrocarbons are hydrophobic (compound that has no charge, thus is doesn't want to interact with water)
- carbon and hydrogen share electrons equally
- neutral charge (so doesn't wanna interact with water)
34
Hydrophilic
Has a charge, thus likes to interact with water
35
Acid
Any substance that can donate a proton (H+) to another substance (proton typically a hydrogen ion)
36
Base
Any substance that can accept a proton (H+) from a donor
37
Acids and bases
Neutralize each other
Result usually in formation of salt and water
pH is a scale for measuring acidity (amnt of protons in a substance)
pH= -log[H+]
Water is neutral
Lower- more acidic
Higher-more basic
38
Functional groups
```
Determine the chemical reactions the compound participates
Hydroxyl (-OH)
Carbonyl (C=O)
Carboxyl
Amino
Phosphate
```
39
Hydroxyl
- oxygen and hydrogen bound to carbon
- water soluble
- found in alcohols and sugars
40
Carbonyl
- forms double bond with oxygen and carbon loses a hydrogen
- hydrophilic functional group
- found in all sugars
41
Carboxyl
- carbon double bonded to oxygen and single boned to hydroxyl
- H+ can be stripped from -OH making it a weak acidic
42
Amino group
- carbon bonded to nitrogen and two hydrogens (NH2)
- NH2 can accept a proton forming NH3+
- weak basic
43
Phosphate group
- carbon bonded to phosphorous double bonded to oxygen and single bonded to two hydroxyls
- can donate one or both H+
- weakly acidic
44
Macromolecules
Any molecule that can be made by piecing smaller sub units together
4 major macromolecules in life
Carbohydrates, lipids, proteins, nucleic acids
45
Carbohydrates
- sugars, starches,and cellulose
- sugar and starches serve as energy source for cells
- cellulose is the structural component of plant cell walls
- contain one sugar unit (monosaccharide), two sugar units (disaccharide), or more than two sugar units (polysaccharide)
46
Monosaccharide
- subunit of carbs
- hydroxyl bonded to each carbon except one carbonyl
- glucose is most abundant
- hydroxyl and carbonyl groups make hydrophilic
47
Polysaccharide
- most abundant carbohydrates
- macromolecules made of multiple units of monosaccharides (usually glucose)
- starch typically used for energy storage in plants
- glycogen typically used for energy storage in animals
48
Cellulose
- Most abundant carbohydrate on earth
- Accounts for 50% or more of carbon in plants
- structural carbohydrate
- wood is 50% cellulose
- cotton is 90% cellulose
- cannot be digested by humans
49
Lipids
Oily fats and fat-like substances
50
Neutral fats
- Most abundant lipids in living organisms
- primarily serve as fuel storage
- carbs and proteins are stored as fat within adipose cells
- consists of glycerol joined to 1-3 fatty acids
- fatty acids can be saturated or unsaturated
51
Saturated
Means saturated with hydrogens
- single C-C bond
- typically solid at room temperature
- no dietary requirement
- associated with cardiovascular disease
- butter, milk, meat, fried foods
- can lead to health problems
52
Unsaturated
Mono-unsaturated: missing one hydrogen
Poly-unsaturated: missing multiple hydrogens bcuz of double bonds
-double C=C bonds
-typically liquid at room temperature
-small dietary requirement
-increases good cholesterol (HDL); antioxidant
-avacado, olive oil, flax seed, fish, walnut
-typically healthy
53
Phospholipids
- components of cell membranes
- amphipathic molecules: one end hydrophilic (phosphate side) and one is hydrophobic (fatty acid side)
- contains glycerol molecule attached to two fatty acid chains and a phosphate group
- phosphate group is attached to nitrogen containing organic molecule
54
Other biologically important lipids
```
Carotenoids
-plant pigments
-involved in photosynthesis
Waxes
-used as a protective coating in plants and animals
Steroids
-contain 4 attached rings
-distinguished by side chains
```
55
Proteins
- the workhorse of the cell
- proteins are responsible for doing the majority of work in a cell
- comprised of amino acids (monomer)
- polypeptide as a polymer
- unlike carbohydrates and lipids, proteins are different between species
- degree of difference is a measure of evolution
- protein structure determines function
56
Amino acids
- 20 found in proteins
- nonpolar (hydrophobic), polar (hydrophilic, partially positive and partially negative), electrically charged (either acid or base, hydrophilic)
57
Four levels of organization
Primary
-sequence of a chain of amino acids
Secondary
-occurs when the sequence of amino acids are linked by hydrogen bonds
Tertiary
-occurs when certain attractions are present between alpha helices and pleated sheets
Quarternary
-consisting of more than one amino acid chain
58
Nucleic Acids
- DNA and RNA are involved in protein synthesis
- nucleotide subunits as a monomer
- DNA encodes the genetic information (recipe for making proteins)
- RNA is involved in the process of synthesizing proteins from DNA
59
Nucleotide
- monomer for nucleic acid
- comprised of sugar, base, and phosphate group
- DNA : deoxyribose as sugar, thymine as base
- RNA :ribose as sugar, uracil as base
60
Cells
- smallest unit of life
- cell theory :cells fundamental units of all organisms
- New cells are only formed via the division of previously existing cells
- All cells today can be traced back to a common origin
61
Similarities between cells
-All cells have many things in common due to evolutionary history
•Plasma membrane – selectively separates contents inside cell from environment
•Energy conversion – must be able to convert energy to a usable form, usually ATP
•Central Dogma – genetic information flows from DNA to RNA to Protein
62
Cell size
- varies widely
- molecules in cells must be rapidly transported to intercellular locations
- waste products must be quickly eliminated out of cells
- molecules must move in and out through plasma membrane
- more surface area, the faster molecules can transfer
- size limited by surface area to volume ratio
63
How can cells be studied
-Microscopes are integral for the study of cells
-Microscopes allow us to see objects too small to observe with the naked eye
•Magnification – ratio of the size of the image seen with the microscope to the actual size of the object
•Resolution – the minimum distance between two points where they both can be seen separately
64
Light Microscopes
* Uses visible light (400-700 nm wavelength)
* Resolving power is ~500x greater than human eye
* Can be used to see objects as small as bacteria
65
Fluorescence microscope
* Observes fluorescent signals (substances that absorb light at one wavelength and release it at another)
* Used to detect locations of targets within cells
* Confocal fluorescence microscopy uses computers to improve resolution of fluorescent signal
66
Electron microscopes
* Uses electrons (0.1 – 02 nm wavelength)
* Resolving power is 250,000x better than eye
* Can be used to see objects as small as atom
* TEM sees through slices
* SEM sees surface of object
67
Prokaryotic cells
- "before the nucleus" no nucleus, no organelles
- primarily bacteria
- average .2-10 uM in size
- genetic material in nuclear area lacking membrane
68
Eukaryotes
- has nucleus "true nucleus"
- most other cells besides bacteria
- average 10-100 uM in size
- genetic material in nucleus with nuclear membrane and nucleoli
- has membrane bound organelles
69
Membranes
* Organelles allow for the compartmentalization of cells
* Allows specific activities to be localized within regions of the cell
* Allows gradients to form!
* Organelles are enclosed within membranes
70
Cytoplasm
* The region of the cell outside the nucleus (11)
* Contains fluid, proteins, nucleic acids, molecules, and organelles
* Liquid portion (~80% water) called cytosol
71
Nucleus
* Located near center of cell (2)
* Contains genetic information (DNA)
* Enclosed by two membranes called nuclear envelope
* Material passes between nucleus and cytoplasm through nuclear pores
72
Ribosomes
* Small structures (3) responsible for making proteins encoded by DNA
* Contains two subunits containing rRNA
* rRNA is made in the nucleolus (1)
73
Endoplasmic reticulum
* Network of membranes connected to nucleus
* Smooth ER (8) is responsible for making and storing steroids, lipids, and ions
* Rough ER (5) is site for making membrane and secreted proteins
74
Golgi apparatus
* Stacks of membranes usually located to side of nucleus (6)
* Responsible for processing, sorting, and modifying proteins made in RER
* Glycoproteins
75
Lysosomes
- small sets of digestive enzymes
- break down complex molecules
- acidic environment (pH5)
- break down internal or ingested molecules for food
76
Vacuoles
- fluid filled sacs found in all plant and fungal cells and some animal cells
- Many functions but often used to store waste and toxic material
77
Mitochondria
- Oblong structures located throughout cytoplasm
- convert chemical energy into ATP
- contain inner and outer membrane thought to have arisen by endosymbiosis
78
Chloroplasts
- found in plants and algae
- use chlorophyll to convert light energy into glucose by photosynthesis in stroma
- glucose is converted to ATPin thylakoid
79
Cytoskeleton
* Complex network of fibers that give a cell its shape and allows mobility (7)
* 3 main types
* Actin microfilaments
* Intermediate filaments
* Microtubules
80
Actin Microfilaments
* Thin filament made of small proteins called actin
* Can rapidly lengthen at (+) end and shorten at (-) end
* Involved in muscle contraction, cell division, motility, and organelle movement
81
Intermediate filaments
- over 70 different types
- most are cytoplasmic except nuclear lamins
- help stabilize the cell shape and strengthen the cytoskeleton
- keratin important in hair, skin, nails
82
Microtubules
- hollow cylinders made of protein called tubulin
- microtubule is anchored at end
- have roles in cell structure, serve as roadway for transport, and are important for chromosome separation
83
Microtubule organizing center (MTOC)
* In non-dividing cells, microtubules are anchored to MTOC called centrosome (13)
* Made of two hollow tubes of microtubules at right angles to one another (centrioles)
84
Cilia and flagella
- motile projections (come out of cell) on surface of cells
- flagella are one of few long, whip-like projections
- cilia are many, short appendages
- both are involved in cell movement or to pass liquids over cell surface
85
Membranes define...
-Life forms as distinct entities
•A cell requires a membrane to separate it from the outside world
•Necessary to perform internal chemical reactions
•Can maintain different environments within eukaryotic cell
•Membranes played important role in the formation of life as well as its evolution
86
Composition of cell membrane
* Cell membranes are made of LIPIDS and PROTEINS
* Phospholipids are arranged as a lipid bilayer
* Proteins can span across both layers of lipid bilayer or may be attached to either layer
* Proteins and lipids are often modified with CARBOHYDRATES
87
Phospholipid bilayer
•Amphipathic molecules can spontaneously form a spherical bilayer in water
•The cylindrical shape of the phospholipid makes it assume a bilayer instead of a micelle
-detergents are lipids, round, micelle
88
Biological membranes
- fluid
- behave like liquid crystals
* because they form ordered arrays (hydrophilic heads on the outside, hydrophobic tails on the inside)
* liquid because the lipids can rotate and move freely within their layer
89
Proteins in membrane
```
-are also fluid
•Membrane fluidity also allows for lateral movement of membrane proteins
•Frye and Ediden 1970
-can be transmembrane, integral, or peripheral
-can be modified
-secreted in RER
-transported to Golgi in vesicle
-Golgi adds carbohydrates to protein
-transports from Golgi to membrane
-function
•Membrane transport
•Signaling
•Enzymes
•Attachment
```
90
Membranes must
-Maintain optimal fluidity
•Membrane function can be inhibited if the membrane is too fluid or too rigid
•Can be controlled by degree of fatty acid saturation
91
Cholesterol
- helps stabilize fluidity
- animal cells can insert cholesterol in between lipid bilayer
- at low temperatures, cholesterol acts as a spacer to increase fluidity
- at high temperatures, cholesterol prevents weakening of membrane by holding hydrophilic heads together
92
Vesicles
- lipid membranes can pinch off to form spherical vesicles
- have the ability to carry cargo, such as proteins, or other molecules
- vesicles can then fuse into other lipid bilayers
93
Selective permeability
* Membranes keep inside in and outside out
* Must allow nutrients and molecules in
* Must allow waste and molecules out
* What gets in or out depends on size and charge of particle and on composition of membrane
* Biological membranes are selectively permeable
* Allows some things in but not others
94
Diffusion
* Particles move from areas of [high] to [low]
* Equilibrium is reached when [equal]
* Particles can still move back and forth but no net [change]
95
Osmosis
* The diffusion of water across a membrane is called osmosis
* Water molecules move from areas of [high] to [low]
* Dissolved solute lowers [water] by interacting with water molecules and preventing movement across membrane
* Water moves toward area of high [solute]
96
Osmosis cont
- Cell wall of plants and fungi prevents them from bursting from hypotonic water
- Well watered plants swell and build up turgor pressure
- Plant is supported by tugid cells
- if the plant is placed in a hypertonic medium (such as too much fertilizer), water leaves the cell through osmosis
- The plasma membrane pulls away from the cell wall and the vacuole shrinks
- Plasmolysis ensues and the plant becomes flacid
97
Wrinkled fingers and toes
- Wrinkled fingers and toes are NOT caused by osmosis
- Vasoconstriction is triggered by nervous system to restrict blood flow to fingers and toes
- Loss of blood volume causes wrinkling
- Possibly evolutionary mechanism to help gain traction in wet environment
98
Carrier-mediated transport
* Membrane is impermeable to large polar molecules (glucose, amino acids, nucleic acids, etc.)
* Benefits cell by preventing loss of needed molecules
* Also impermeable to most charged ions (Ca++, K+, Na+, Mg++, etc.)
* Cell uses ions as signals
* Selective permeability allows cell to regulate ion concentration
* Carrier-mediated transport allows cells to pass large polar and ionic particles through membrane
99
Facilitated diffusion
* Particle binds to protein in membrane
* Binding causes protein to change shape and allow particle into cell
* Particles enter cell following concentration gradient
* Ex. Glucose uniporter in red blood cells
100
Active transport
- can move particles against the concentration gradient (areas low to high)
- requires energy to be used in the form of ATP
- Na+ \ K+ pump
- 3 Na+ bind pump
- energy used in form of ATP
- Na+ transported out
- 2 K+ bind pump
- K+ transported in
101
Cotransport
* Gradient of ions generated by active transport can be used to move another molecule against its concentration gradient
* Ex. Glucose symporter in intestine
102
Exocytosis
* Cargo is stored in vesicles in cell
* Waste products
* Hormones
* Vesicle fuses with cell membrane releasing cargo outside cell
* Also way cell membranes grow or are replaced
103
Endocytosis
| Phagocytosis
•Large particles are taken into cell inside pinched off membrane
•The resulting vacuole containing the particle is transported to lysosome
•Vacuole membrane fuses to lysosome membrane
•Particle is digested
(Cell swallowing)
104
Endocytosis
| Pinocytosis
-Tiny droplets of fluid are trapped in pinched off membrane
•Liquid is transferred to cytoplasm
•(engulfing water/drinking)
105
Viruses...
Take advantage of endocytosis
106
Respiration
- all organisms respire
- production of ATP from organic molecules
- aerobic respiration requires oxygen. This is where ventilation and gas exchange come in
107
Energy
- Energy is the capacity to do work
- Work is the change in the state or motion of matter (large scale= breathing, pumping blood, etc. cellular scale= active transport)
- Thus energy is the capacity to change the state or motion of matter
- Usually measures in kilo joules (kJ) or kilocalories (kcal)
- 1kcal=4.184 kJ
108
Potential energy
Stored energy that has the potential to do work
109
Kinetic energy
-Potential energy is converted to this
-Energy of motion
-Living organisms convert kinetic energy into potential energy which can be stored and used to create kinetic energy
(Ex. Food is stored as potential energy and used to move muscles)
110
1st law of thermodynamics
-energy cannot be created or destroyed. Can only change form
111
2nd law of thermodynamics
Disorder increases in the universe
- entropy is the measure of disorder in the universe
- randomized, disordered energy (heat) is not available to do work
112
Metabolism
- all of the chemical reactions that go in a living organism
- anabolism: formation of complex molecules from simpler building blocks
- catabolism: breakdown of larger molecules into smaller ones
113
Energy of activation
-every chemical reaction requires a certain amount of energy to initiate it
114
Exergonic reactions
-energy is released and reaction said to be spontaneous
| C~D -3kcal energy
115
Endergonic
Net input of energy is required and products have more energy than reactants
-often involves the breakdown of adenosine triphosphate (ATP)
A~B +5kcal energy
116
Coupling reactions
Endergonic reactions are usually coupled to Exergonic reactions in cells
A+C~B+D -3 kcal energy
117
ATP
- drive reactions
- saved in chemical bonds of fats or carbohydrates
- energy ATP can be freed by breaking bonds between phosphate groups
- reaction ATP + H2O ~ ADP + P , releases 7.6 kcal of energy
- cannot be stockpiled in an organism (spent almost as soon as it's made)
- bacteria has about 1 second supply of ATP at anytime
- a human has about 100 lbs of ATP per day but only has .002 lbs at any given moment
- a cell makes about 10 million molecules of ATP every second
- energy to make ATP comes from breakdown of lipids and polysaccharides
118
Receptor mediated endocytosis
-specific particles bind to receptors on cell surface
-receptor then pinches off with membrane and cargo
-vesicle travels to endosomes where cargo is sorted
-receptors are recycled back to membrane
Ex) how cholesterol regulated
119
Carbohydrate catabolism
- carbohydrates are broken down into monosaccharides
- then converted to energy
- excess glucose converted to glycogen in liver
- stored as fat for future energy needs
120
complex carbohydrates
- healthy
- veggies, fruits, while grains
- contain vitamins, minerals and fiber
121
Simple carbohydrates
- unhealthy
- refined and processed food
- lacks vitamins, minerals and fiber
- leads to obesity
122
Fat Catabolism
- broken down into fatty acids and glycerol
- chemically converted to energy
- excess fat stored for future energy needs
123
Essential amino acids
- proteins are made from 20 amino acids
- nonessential aa can be synthesized by humans
- essential aa cannot and must be obtained from the diet
124
Enzymes
- spontaneous reactions may take a long time to occur on their own
- breakdown of glucose is Exergonic but could take hundreds of years to occur at room temperature.
- enzymes are protein catalysts that speed up the rate of a reaction
- does not provide energy to the reaction
125
Enzyme cofactors
- some enzymes need additional factors to work
- neither enzyme (aprenzyme) or the cofactor work alone
- can be organic or inorganic
- inorganic : often metals Ca++ Mg++ Zn++ Fe++ Cu++
- organic: called coenzymes, most vitamins
126
Cellular metabolic
- cells process materials constantly through thousands of metabolic reactions
- breakdown large molecules into smaller and synthesize complex molecules from building blocks
- products help cell with growth, reproduction, movement, homeostasis
127
Anabolic reactions
Endergonic, require energy (ATP) to drive them
128
Metabolic Pathways
-cells use enzymes in a series of steps to convert energy from nutrients into ATP
129
3main categories of metabolic pathways
- aerobic respiration
- anaerobic respiration
- fermentation
130
4 stages of aerobic respiration
Glycolysis
Formation of acetyl CoA
Tricarboxylic acid (TCA) cycle
The electron transport chain
131
Stage 1
Glycolysis
- yields 2ATP and 2NADH
- doesn't require oxygen
- occurs in cytoplasm
132
Stage 2
Formation if acetyl CoA
- yields 2NADH
- requires coenzyme
- produce CO2
- occurs in mitochondria
133
Stage 3
Tricarboxylic Acid (TCA) cycle
- yields 2 ATP, 6 NADH, 2 FADH2
- acetyl CoA undergoes a series of conversions
- produces CO2
- occurs in the mitochondria
134
Stage 4
The electron transport chain
- yields 32 ATP
- electrons from NADH and FADH2are paired through 4 complexes
- pumps H+ into intermembrane space
- final electron acceptor is O2
- occurs in mitochondria
135
ATP Synthase
- H+ on intermembrane space diffuses into ATP synthase (protein that makes)
- H+ flow causes rotation of ATP synthase
- produces ATP from ADP
136
Oxygen
- a cell can make 10 mil ATP per second
- in the absence of oxygen, ATP cannot be made in sufficient quantity
- why most organisms can only survive for a short time without oxygen
- cyanide binds to electron transport complexes preventing transfer to oxygen
137
Anaerobic respiration
- some organisms live in environments within which there is little oxygen (stagnant water, soil etc)
- similar to aerobic except uses chemical other than oxygen as final electron acceptor (nitrogen, sulfer)
- produces a significantly less ATP than oxygen
138
Fermentation
- does not require an electron transport chain at all
- all ATP are produced by Glycolysis
- waste products are typically ethanol or lactic acid
- very inefficient because glucose is not completely oxidized
- yield only 2ATP per glucose
139
Anabolic reactions
- Energy harvested is typically used for anabolic processes
- each cell has to produce protein, nucleic acids, lipids, etc
- chemical synthesis of molecules typically uses ATP as energy source
- many of the building blocks are produced in Glycolysis and TCA cycle
- anabolic and catabolic reactions are constantly occurring
140
Photosynthesis
- plants are carbon-based
- get carbon from air (CO2)
- CO2 transformed into glucose and other organic molecules (Endergonic) using sunlight as energy (photosynthesis)
- photosynthetic organism convert > 110 bil tons of CO2 info organic compounds each year (supports all life)
141
Chloroplasts
- bound by 2 membrane like mitochondria
- stroma contain enzymes to make carbohydrates
- thylakoid (one disk)
- Grana (stacks of thylakoids)
- chlorophyll in thylakoid
142
Autotrophs
- Organism that can make organic molecules from inorganic matter (plants)
- heterotrophs- cannot make their own organic compounds and must eat other organisms to obtain them
143
Thylakoid
Light-dependent reaction take a place here
- split H2O
- electrons sent to electron transport chain
144
Light
-form of electromagnetic energy
145
Chlorophyll
- exists in thylakoid membrane
- absorbs light in blue-red spectrum,
- reflects green light
- accessory pigments absorb other spectra light for broaden range
- carotenoids (yellow or orange), absorb blue light
146
ATP synthase is coupled to
Electron transport
147
Carbon fixation
-takes place in Stroma
-carbon molecules from CO2 are incorporated into carbon backbone of organic molecules
-carbon fixation
-dark fixation
-energy to fix carbons comes from products of light reaction
-energy is stored in bonds of organic molecules
(Calvin cycle, C4 pathway, CAM pathway)
148
Calvin Cycle
- CO2 and water react with RUBP to form 2 molecules of phosphoglycuate (PGA )
- ATP and NADPG (from light reaction) is spent to convert PGA to G3P
- 2 G3P are removed from cycle to form sugars
- remaining G3P are used to make more RUBP
- cycle repeats
149
Photorespiration
Toxic buildup of oxygen feeding through cycle instead of photosynthesis
150
C4 pathway
- uses CO2 at low concentrations
- occurs prior to C3 pathway (but does not replace)
- special enzyme with a high affinity for CO2 forms 4 carbon molecule
- can be converted back to CO2 and stored in high concentrations
- can then be used by Calvin Cycle using C3 pathway
151
C4 pathway continued
Carbon is up to 60 x greater
- allows Calvin cycle to close even when stromata are closed
- includes corn sugar came, and many grasses
152
CAM pathway
- fixes CO2 at night
- stromata only open at night (temp cooler)
- fix carbon and store it as 4 carbon molecule
- during day stromata close (exchange cant occur)
- stored CO2 fixed into sugar by Calvin cycle
- desert plants
153
C3 plants
- most plants
- fix carbon in Calvin cycle (attach CO2 to RuBP)
- enzyme: rubisco
- most energy efficient
- loses water through photorespiration
153
C3 plants
- most plants
- fix carbon in Calvin cycle (attach CO2 to RuBP)
- enzyme: rubisco
- most energy efficient
- loses water through photorespiration
154
C4 plants
- tropical grasses like corn, sugar cane
- fix carbon in cytoplasm (attach CO2 to PEP)
- enzyme: PEP-ase
- 1/2 way between C3 and CAM
- loses less water than C3
154
C4 plants
- tropical grasses like corn, sugar cane
- fix carbon in cytoplasm (attach CO2 to PEP)
- enzyme: PEP-ase
- 1/2 way between C3 and CAM
- loses less water than C3
155
CAM plants
- succulents, pineapple, agave
- fix carbon at night only (fix it to organic molecules)
- enzyme: PEP-ase
- best water conservation
- loses least water
155
CAM plants
- succulents, pineapple, agave
- fix carbon at night only (fix it to organic molecules)
- enzyme: PEP-ase
- best water conservation
- loses least water
