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
where do hydrophobic molecules bind?
they move through the plasma membrane and bind with intracellular receptors found in the cytosol or nucleus
what is the function of receptor up-regulation?
to increase the number of receptors synthesized and amplify the signaling molecule’s effect
what is the function of receptor down-regulation?
often involves transporting receptors to lysosomes, where they are destroyed
what are the four receptors?
ion-channel linked receptors, G protein-linked receptors, enzyme-linked receptors, and intracellular receptors
where are ion-channel linked receptors found
the plasma membrane
what is the function of ion channel-linked receptors?
to convert chemical signals into electrical signals, opening and closing in response to binding of the signaling molecules (ligand)
what is an example of ion-channel linked receptors?
acetylcholine which binds to and opens ligand gated sodium ion channels
what are G protein-linked receptors?
transmembrane proteins with an outside binding site for a signaling molecules and an internal binding site for a specific G proteins
what do G protein-linked receptors do?
couple signaling molecules to transduction pathways in the cell
why are G protein-linked receptors important to medicine?
more than 400 are potential target for pharmaceutical interventions
what are enzyme-linked receptors?
transmembrane proteins with a binding site for signaling molecules outside the cell and an enzyme component inside the cell
what do enzyme-linked receptors do?
bind hormones such as insulin and growth factors
what is tyrosine kinase?
(enzyme-linked receptor) an enzymes that catalyzes transfer of phosphate groups (phosphorylation) from ATP to a specific tyrosine that is part of a protein
what are intracellular receptors?
most are transcription factors like estrogen receptor (ER) that binds estrogens and is involved in some breasts cancers
where are intracellular receptors found?
in the cytosol or nucleus
how do signaling molecules more through target cells (intracellular receptors)?
by diffusing across the membrane of the target cell
what are two ways that signaling molecules diffuse across the membranes of target cells?
by combining with receptors in the cytosol and moving to the nucleus or binding to receptors already bound to DNA inside the nucleus
what is the relationship between regulatory molecules and membrane proteins? (Signal Transduction)
regulatory molecules activate ,membrane proteins, which then transduce the signal
what happens when signaling molecules bind with cell-surface receptors? (Signal Transduction)
signling molecules activate cell surface receptors by changing the shape of the receptor tail that extends into the cytoplasm
what happens during signal transduction
regulatory molecules activate membrane proteins, a signal is transduce, signaling molecules bind to cell surface receptors and a signal is relayed through protein kinase
what happens when a signal is relayed through proteins kinase? (Signal Transduction)
a signaling pathway is created which amplifies the signal
how can signaling molecules act ad molecular switches?
each component in a signaling molecules can be active “on” or “off”
what regulates molecular switches?
phosphorylation/dephosphorylation; protein kinase, and protein phosphatase
what is the function of protein kinase?
adds a phosphate to typically activate a target
what is the function of protein phosphatase?
catalyze the removal of a phosphate group
many ion channel gates remain closed until?
a ligand binds to the receptor
GABA receptors bind to?
the neurotransmitter GABA (Gamma-aminbutryric acid)
- ligand gated chloride ion channels
what is GABA when chloride enters the cell?
a neural signal inhibitor which inhibits transmission of neural impulses
what do G protein linked receptors initiate?
signal transduction
what happens when G protein is inactive?
it has one subunit linked to guanosine diphosphate (GDP)
what happen to GDP when a signaling molecules binds to the receptor?
GDP is replaced by guanosine triphosphate (GTP)
when GTP releases energy?
G proteins is deactivated
what are second messengers?
intracellular signaling agents
what is the first messenger and who do signals get the the second messenger?
the signaling molecule is the first messenger and information in relayed by the G protein to a second messenger
what is the function of second messengers?
to amplify signals inside the cell and relay to other signaling/target proteins
importance of second messengers?
produced in large quantities when receptors are activated and they are the last molecules the signaling chain to activate the final response
what is cyclic AMP
a second messenger
what do some G proteins use phospholipids as?
second messengers (PIP2)
PIP2 splits into?
IP3 and DAG
what are calcium ions used for?
neural signaling
how do calcium ions work?
by binding to certain proteins which then activate certain enzymes
what is the function of the calcium ion Calmodulin?
to help regulate metabolism, muscles contraction, memory, inflammation, and apoptosis
what are many activated intracellular receptors?
transcription factors
what is the function of transcription factors?
to regulate gene expression
what happens when a ligand receptors complex binds rot a specific region of DNA?
it activates or repressed genes
what do activated genes produce?
messenger RNA that carries the code for synthesis of a particular protein into the cytoplasm
what is a scaffolding protein?
allow for bonding with multiples enzymes, increases efficiency
what are three types of cellular responses?
ion channels opening or closing, altered enzyme activity, and the turning on/off of specific gene activity
what can a signal signaling molecule lead to?
changes in millions of molecules at the end of a signaling cascade
how are signals terminated?
returning the receptor and each of the component of signal transduction pathway to their in active states
what inactivates cAMP?
phosphodiesterase which convert cAMP to AMP (adenosine monophosphate)
what are some component of signal transduction pathways in most animals?
G proteins, protein kinase, and phosphatase
certain disease causing bacteria have signal transduction pathways similar to?
those in eukaryotes
where did cell communication first evolve?
unicellular organisms
what is development?
all the changes that take place in an individual during its life, from fertilization until death
what is a zygote?
a fertilized egg which is totipotent
what is mitosis?
cell division
how is an embryo formed?
a zygote divided by mitosis
how does growth occur in animals?
by the increase in the the number of cells (mitosis)
what contributes to the development of form?
cell determination, cell differentiation, pattern formation, and morphogenesis
which comes first; cell differentiation of determination?
cell determination
what is cell determination?
activities of certain genes are altered to progressively commit a cell to a particular differentiation pathway
what is cell differentiation?
certain cells become biochemically and structurally specialized to carry out specific functions
during development what happens to differentiated cells?
they becomes progressively organized into a multicellular animal (morphogenesis proceeds through pattern formation)
what is morphogenesis?
the creating of shape and form (arms, legs, hands, etc)
what is pattern formation?
a series of steps requiring signaling between cells, changes in cell shape, precise cell migration, interactions with extracellular matrix and apoptosis (the blueprint of the body, determining the front and back end )
what happens as pattern formation and morphogenesis occur?
cells beomce progressively organized into different cell types, tissues, organs, etc (leads to different forms)
what is principle nuclear equivalence?
all somatic cells of an animal contain the same genetic information
each cell expresses? (nuclear equivalence)
a different subset of the same genetic information
what is differential gene expression responsible for?
variation in chemistry, behavior, and structure among cells
what is an example of cells that don’t differentiate?
stem cells which remain undifferentiated and retain the ability to give rise to various cell types
what are the four processes involved in fertilization of a sea urchin?
contact & recognition, entry, activation, and fusion
how is a zygote produced?
in fertilization a motile sperm fuses with a large immotile ovum
what are the three important genetic consequences of fertilization?
restoration of diploid chromosome number, combining genetic instructions from parents and determining sex of offspring
what does fertilization do to the egg?
activates the egg initiating reactions that permit development
what composes the sperm structure?
head (acrosome and nucleus), mid-piece, and tail
what is an egg surrounded by?
a plasma membrane and one or more external coverings
what is the purpose of egg coverings?
to offer protection, ensure fertilization by the sperm of the same species
what is the morphology of an egg?
jelly coat, vitelline envelope, plasmam membrane, and cortical granules
what covers sea urchin eggs?
two layer which interact with sperm, a vitelline envelope and a glycoptrtein jelly coat
what happens when sperm contacts the jelly coat?
sperm undergoes an acrosome reaction (proteolytic enzymes digest through the jelly coat)
what is the fertilization cone?
formed by the plasma membrane, draws the sperm into the egg
what is polyspermy?
fertilization of the egg by more than one sperm rustling int offspring with extra sets of chromosomes, lethal condition
what is fast block to polyspermy?
the egg plasma membrane depolarizes which prevents fusion with additional sperm causing electric shock
what happens when the eggs is depolarized during fast block?
egg becomes negatively charged ion channels open and ions diffuse to depolarize the egg
what is slow block to polyspermy?
a cortical reaction where Ca++ released from the ER triggers the release of cortical granules, the vitelline envelope lifts and forms the fertilization envelope making a physical
what happens during egg activation?
the release of calcium ion into the egg cytoplasm stimulates the cortical reaction and triggers the activation program and a series of metabolic changes within the egg, including the completion of meiosis
what happens during fusion?
the completion of meiosis in the egg forms the female pronucleus and the sperm nucleus swells to form the male pronucleus
what is an echinoderm?
marine ilife, sea urchin
what does mammalian sperm undergo?
capacitation, a maturation process in the female reproductive tract
what is proteins are present in mammalian fertilization and not echinoderms?
binding-like proteins
in mammals, what prevents the attachment of multiple sperm?
cortical reaction which alters “bindin” sperm receptors so no more sperm and attach or enter
mammals do not have a? (fertilization)
fertilization envelope
what is totipotent?
the cell can become anything, gives rise to all cell types of the new individual
what are blastomeres?
clusters of cells
what is the yolk?
nutrients (a mixture of proteins, phospholipids, and fats ) , the energy source for a developing zygote
what is cleavage?
cells divide and separate
during cleavage, what happens to the zygote?
it undergoes rapid mitotic division with no period of growth, producing small blastomeres
during cleavage, how are patterns determined?
by heredity and yolk amount and distribution
what are the sates of cleavage in an echinoderm?
unfertilized egg, 2 cell stage, and 4 cell stage
during 16-64 cell morula, what happens?
embryo starts to fold in on itself at gasturaltion
during cleavage, what does gastrulation initiate?
the formation of germ layers
amount and distribution of yolk?
varies among different animal groups
what is isolecithal?
small amount of yolk uniformly distributed though cytoplasm. cell divide completely (holoblastic)
what is mesolecithal?
“medium” amounted yolk which is concentrated at the vegetable pole
what is telolecithal?
have large amounts of yolk at the vegetal pol and a small amount of cytoplasm at the animal pole
when is cleavage radial?
if the cells sit on top of each other (vertebrates and echinoderms)
when is cleavage spiral?
when cells sit in the cleft, rotate (animals other than vertebrates and echinoderms
pattern of isolecithal cleavage?
fist cell splits into two, then four, then eight
when is the embryo a morula (“solid” ball)
at 32-64 cell stage
what forms the blastula?
64 to several hundred blastomeres
what is a morula?
a “solid” ball
what is a blastula?
a hollow ball with a fluid filled cavity
what are the eggs of amphibians?
mesolecithal; animal hemisphere has many small cells, yolk slows division into vegetal hemisphere (cells are fewer and larger), and an unequal holoblastic
in an amphibian why do cells cleave slower in the vegetal pole?
because of the yolk accumulation the blastocoel is displaced in the animal pole
many vertebrate eggs are?
telocithal; yolk is concentrated a the vegetal pole and opposite animal pole is more metaobolically active
telolecithal eggs of reptiles and birds have?
large amounts of yolk at the vegetal pol and small amount of cytoplasm at the animal pole; yolk never cleaves (cell division occurs in the blastodisc at the animal pole)
what is a blastodisc?
the germinal disc
during patterns of cleavage, what do blasters form?
two layers separated by the blastocoel cavity; an upper epiblast and a lower hypoblast
what is gastrulation?
the process in which blastula becomes a three layered embryo (gastrula)
during gastrulation cells arrange into what three distinct germ layers?
ectoderm (outermost layer), endoderm (innermost layer), and mesoderm (middle layer)
each germ layer develops into?
specific parts of the embryo
what happens during simple gastrulation in echinoderms?
begins when the vegetal pole of the blastula wall flattens and bends inward forming a double walled cup shaped structure
during gastrulation in echinoderms, what lines the newly formed cavity?
the new internal wall lines the newly formed cavity of the developing gut (archenteron and primitive gut)
in echinoderms and vertebrates what is the site of the future anus?
the opening of the archenteron to the exterior blastopore
in amphibians what do large yolk filled cell obstruct?
any inward movement at the vegetal pole (cells from the animal pole move to the interior in a region termed the dorsal lip)
when the c shaped Doral lip is formed during gastrulation on amphibians, what happens?
cells roll in at the dorsal lip, yolk filled cells fill the space enclosed by the lip of the blastopore (forming the yolk plug), and archenterons explains at anterior end of the embryo
during gastrulation in birds, cells of the epiblast?
migrate toward the midline tp form the primate streak
during gastrulation in birds, Hensen’s node formed at the?
anterior end of the primitive streak-cells destined to form the notochord sink and move anteriorly forming a narrow extension of the node
hensen’s node is analogous to?
the dorsal lip
gastrulation leads to?
organogenesis (organ formation)
during organogenesis, what does the ectoderm form?
outer layer of ski and gives rise to the nervous system and sense organs
during organogenesis what does the endoderm form?
tissues that line the digestive tract, and organs that develop as outgrowths of the digestive tract (including liver, pancreas, and lungs)
during organogenesis what does the mesoderm form?
skeletal tissue, muscle and circulatory, excretory, and reproductive systems
what are some of the first organs to form in the early vertebrate embryo?
the notochord, brain, and spinal cord
the notochord forms?
a cylindrical rod of cells, which eventually is replaced by the vertebral column
what do notochord cells stimulate?
differentiation of overlying ectoderm to form precursor of the central nervous system, the neural plate
what happens during the development of the nervous system?
cells of the neural plate move downward and form a depression between two neural fold which meet and fuse to form the neural tube
what is the neural tube?
the anterior portion differentiates into the brain the rest develops into the spinal cord
what are the mesodermal structures?
block or mesoderm (somites) that form on either side of the neural tube give rise to the vertebrates, muscles, kidneys, reproductive structures, and circulatory organs
the transition to terrestrial life required a series of?
membranes to keep the embryo wet, store nutrients, store waste, and aid in respiration
what are the four extraembryonic membranes?
chorion, amnion, allantois, and yolk sace
what is the chorion?
(outermost membrane) which encloses the entire embryo and other membranes; major organ of gas exchange
what is the amnion?
encloses the embryo; secretes protective amniotic fluid that fills the amniotic cavity between the embryo and the amnion also acts as a shock absorber (amniotic fluid can be analyzed for biochemical or chromosomal abnormalities)
what is the allantois?
an outgrowth of the developing digestive tract; in reptiles and birds, it stores nitrogenous wastes in mamas, its blood vessels contribute to the the formation of umbilical vessels joining the embryo to the placenta
what is the yolk sac?
enclosed the yolk, slowly digests it, and makes it avail to the embryo–connected to the embryo by a yolk stalk; walls form blood cells temporarily
