Exam 9, 6, 51 Flashcards
what is the relationship between visible light and the electromagnetic spectrum (EM)?
visible light is a small portion of the EM spectrum
how does radiation travel along the EM spectrum?
as waves
what is a wavelength?
the distance from one peak to the next
what are photons?
small particles which make up light
what is the difference in energy per photon for shorter wavelengths versus longer wavelengths?
shorter wavelength of light have more energy per photon
when a molecules absorbs a photon of light, what happens to an electrons?
electrons become energized
when a molecules absorbs a photon and electrons become energized, what happens?
-atoms may return to ground state and release energy as heat of fluoresces
-the electron may leave the atom and be accepted by an electron acceptor molecule (redox)
what encloses chloroplast?
an outer and inner membrane
what does stroma contain?
enzymes required to produce carbohydrates
the inner layer of the chloroplasts encloses what?
fluid filled stroma
what is suspended within the stroma?
a third system of membranes called the thylakoids
how are thylakoid sacs arranged?
in stacks called grana (granum for singlular)
what is the inside of a thylakoid called?
the thylakoid lumen
what is found inside the thylakoid membrane?
pigments called chlorophyll
what do pigments absorb differently?
different pigments absorb light of different wavelengths
what is chlorophyll?
the main pigment of photosynthesis, which absorbs red and blue light but reflects green light
what is the function of chlorophyll a?
to initiate light dependent reactions of photosynthesis (forms the reaction center)
what is chlorophyll b?
an accessory pigment
what are carotenoids?
yellow and orange accessory photosynthetic pigments which absorb different wavelengths form chlorophyll
equation for photosynthesis?
6CO2 + 6H2O –> C6H12O6 + 6O2
what are the two phases that divide photosynthesis?
light dependent reactions and carbon fixation reactions
what is the function of light dependent reactions?
to convert light energy to chemical energy
where do light dependent reactions occur?
the thylakoid
when do light dependent reactions begin?
as soon as chlorophyll captures light energy
what happens during light dependent reactions?
energized electrons are transferred to an acceptor molecules and replaced by an electron from H2O, H2O is then split and oxygen is released
during light dependent reactions what is the energy of energized electrons used for?
to phosphorylate ADP forming ATP
during light dependent reactions coenzyme NAD+ is reduced to?
NADPH
where are ATP and NADPH used after being made by light dependent reactions?
in the energy requiring carbon fixation reactions
what do carbon fixation reactions “fix”?
carbon atoms from CO2 to existing skeletons of organic molecules
during carbon fixation how are ATP and NADPH used?
energy is transferred from ATP and NADPH to chemical bonds in carbohydrates
where does carbon fixation take place?
the stroma of chloroplast
how many pigment molecules make up the antenna complex?
250-400
what forms the photosystems?
clusters of antenna complexes
what are the two types of photosystems?
photosystem 1 (P700) and photosystem 2 (P680)
what do pigment molecules in an antenna complex do?
absorbs a photon of light energy
what happens within a photosystem?
energy is transferred from one pigment to another until it reaches the reaction center
what happens after energy reaches the reaction center of a photosystem?
it excites an electron to a higher energy level and the electron is transferred to an acceptor molecule
what does the reaction center of photosystem one consist of?
two chlorophyll a molecules (and other proteins) with an absorption peak of 700nm
what does the reaction center of photosystem two consist of?
two chlorophyll a molecules (and other proteins) with an absorption peak of 680nm
what are reaction centers?
a pair of chloropyll a’s with a accessory protein
photosystem one electron passage?
passed along an ETC to ferredoxin, transfers the electrons to NADP+ in the presence of a specific enzyme
photosystem two electron passage?
transferees to a primary electron acceptor and passed alone an ETC to photosystem 1
how are the electrons of photosystem two replaced and what are the products?
by the splitting of H2O; 2 electrons, 2 H+, 2 O2
in the presence of light there is a continuous?
one way flow of electrons from H2O to NADP+
energy of the proton gradient from the ETC is used to produce?
ATP by chemiosmosis
Noncylic Electron Transport abbreviation
ETC
electrons lost from photosystem one are replaced by?
photosystem 2
how does the ETC produce NADPH?
NADP+ is reduced to NADPH and released into the stroma
ATP Synthesis By Chemiosmosis: what is used to pump protons from the stroma
energy from electrons passing through ETC, forms a proton gradient across the thylakoid membrane
how do protons diffuse from thylakoid lumen to the stroma?
through channels formed by ATP synthase
what does ATP synthase catalyze?
the phosphorylation of ADP to ATP
during carbon fixation what is the energy of ATP and NADPH used to form?
organic molecules of CO2
carbon fixation reaction formula?
12 NADPH + 18 ATP + 6 CO2 –> C6H12O6 + 12 NADP+ + 18 ADP + 18 Pi + 6 H2O
what do most plants use to fix carbon?
the Calvin cycle
what are the three phases of the Calvin cycle?
CO2 uptake, carbon reduction, RuBP regeneration
G3P significance in plants?
it is the basis of chemical synthesis throughout the plant
what do enzymes do with G3P?
convert G3P to glucose and starch
what is are some G3P converted to?
amino acids fatty acids, and other organic molecules the plant may need
where are some G3P exported?
to the cytosol and then they are converted to disaccharide sucrose which is used is various synthesis
what is the importance of photosynthesis?
to produce energy and carbon sources used by plants and organisms, removes CO2 from the atmosphere and add O2
what is the importance of photosynthesis?
to produce energy and carbon sources used by plants and organisms, removes CO2 from the atmosphere and add O2
how do organisms communicate with members of their own species?
through chemical signals
how do cells of multicellular organisms communicate?
by a means of chemical signals
organisms of different species can communicate with one another by?
chemical signals
what are the four processes of cell communication?
signal transmission, reception, signal transduction, and response
for signal transmission a cell must?
synthesize and release signaling molecules
during signal transmission what happens if a target cell is not nearby?
the signal must be transported
what are signal receptors?
large proteins or glycoproteins that bind with specific signaling molecules
where are many receptors?
on the surface of the cell which allows signals to bind without entering the cell
what is signal transduction?
a cell converts extracellular signals into intracellular signals and relays the signal (involved a chain of molecules)
what is a response in cell communication?
alteration of some chemical process
what are the three types of signaling molecules?
neurotransmitters, hormones, and local regulators
what are the ways cells communicate?
release of chemical signals (local or distant)
electrical/energy signals
temporary cell to cell contact
directly though cell junctions
what are some chemical signals?
interleukins, neurotransmitters, growth factors, and hormones
what is the function of interleukins?
involved in communication between cells of the immune system
what is the function of neurotransmitters?
signal between neurons of the nervous system
what is the function of growth factors?
stimulate cell growth, division and development
what is the function of hormones?
like estrogen and testosterone regulate sexual development and reproduction
what is local chemical transmission?
a local regulator diffuses to target cells
local transmission: what is paracrine?
cell 1 to cell 2
local transmission: what is autocrine?
cell 1 back to cell 1
what is distant chemical transmission?
hormones are transported to distant target cells , circulatory systems transporting hormones through the bloods stream
what is a hormone?
a chemical released by a cell or gland in one part of the body that affects cells in other parts of the organism
Electrical/energy signals: give an example using the ears?
cells in the ear receive sound waves and convert them to electrical signals
Electrical/energy signals: give an example using the eyes?
cells in the eyes receive lights waves and convert them to electrical signals
Electrical/energy signals: give an example using neurons?
neurons relay electrical impulses and in some cases can send and receive electrical signals
what is used for temporary cell- cell contact?
cell adhesion molecules (CAM)
what are cell adhesion molecules (CAM)?
found on the surface of certain immune system cells allow for cells to home to sites of damage and infection, allowing immune system cells to find infections
what is cell communication directly through junctions?
some cells are joined together with junctions allowing signals to flow freely between their cytoplasm
what kind of junctions do animals have?
gap junctions
what kind of junctions do plants have?
plasmodemata
what determines the signals cells respond to?
the cells receptors
what is a ligand’s function?
to bind to a specific receptor and trigger a biological response
what allows signaling molecules to trigger a response in cells?
fitting the specific shape of a receptors
what is the relationship between cells type and receptor production?
different cell types produce different receptors and a cell may synthesize many different kinds of receptors which may change with stages in its life cycle
the same signal may have different meanings for what?
various targets
where do hydrophilic molecules bind?
to protein receptors on the surface of target cells