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189 Cards in this Set

  • Front
  • Back
what does duplication of cells require
2)segregation of each chromosome
3)cytoplasmic division
how do prokaryotic cells divide and what is the beginning site and ending site of replication called?
binary fission (origin of replication-->terminus)
what protein contracts the middle of a cell to divide the cell into two during binary fission?
ring of FTsZ proteins
define a centromere
centromeres are the constrictions seen at the center of chromosomes
define a kinetochore
protein found at the centromere that attaches to the microtubule during mitosis
define cohesin
protein that holds two sister chromatids together
define a nucleosome
a histone octamer wrapped with with about 200 base pairs
what is the name for a tightly coiled string of nucleosomes
what is the level of organization of chromatin
"30nm fiber" solenoid
name all the phases of the cell cycle
G1, S, G2, mitosis (prophase, prometaphase, anaphase, telophase), cytokinesis
describe prophase
chromosomes finish condensing
centrioles move to poles of cell
nuclear envelope disappears
spindle apparatus appears
describe prometaphase
chromosomes attach to spindle apparatus
chromosomes begin to migrate
describe anaphase
chromosomes split and move toward oppostie poles
describe telophase
spindle apparatus disassembles
chromosomes start uncoiling
nuclear envelope reassembles
define what a cyclin is
proteins that are produced and destroyed in synchronization with the cell cycle
define what a Cdk is
cdk's are enzymes that control the progress of cell division by phosphorylating proteins needed for division
a signal activates a complex to initiate the splitting of the chromosomes. name it
anaphase promoting complex
the APC activates what protein that hydrolyzes cohesin
what elaborate structure do homologous chromosomes line up on during meiosis 1?
synaptonemal complex/metaphasic plate
what was the general name of the view of genetics prior to Mendel
blending inheritance-offspring was a mix of the parents' features
define particulate inheritance
idea that discrete physical units carry the traits from each parent and don't blend (now called genes)
define a locus
the physical location of a gene on a chromosome
define a marker
a known locus being used to keep track of what is going on genetically
define an allele
a particular form of a gene that exists
describe the principle of independent assortment
different genes will behave independently of one another during the production of gametes
what genotype is always needed to perform a test cross
a homozygous recessive
describe incomplete dominance and give an example
phenotype appears intermediate between the two homozygotes.
example: black cow and white cow make brown cow
describe codominance and give an example
full phenotypes of both genes are visible. example: calico cats
define pleiotropy
a single gene product influences multiple traits
define epistasis
one gene obscures the action of another genes.
ex: when an animal has a homozygous recessive for one gene and the phenotype of the other gene isn;t seen at all
define sex-linkage
alteration in patterns of inheritance based on the sex
which sex will always show the recessive sex-linked traits
the heterogametic sex (the one with different sex chromosomes)
describe genetic recombination
crossing over occurs on a chromosome, producing recombinant offspring
describe the correlation between genetic map distance and recombination
the farther apart two loci are, the more frequent recombination will be
what is the relationship between percentage recombinant offspring and map units between two loci
1% recombination=1 map unit
indpendent assortment is more likely if genes are __________
farther apart
define an anonymous marker
a molecular marker that does not produce any phenotypic change, but at a molecular DNA level, changes can be seen
define a SNP
a single nucleotide polymorphism that is used as an anonymous marker in genetic mapping
cross breeding of a true breeding round tall strain with a true breeding wrinkled short strain will produce what ratios in the F1 and F2 generations?
F1: all heterozygous
F2: 9 round tall, 3 round short, 3 wrinkled tall, 1 wrinkled short
what does semiconservative mean in terms of DNA replication
each strand of an old "template" are copied to make a new copy with one old strand and one new strand
name the 5 basic requirements for DNA replication
1: Template
2: Synthesizing enzyme
3. Nucleotides
4. Something to open helix
5. Something to relieve torsional strain of unwinding
Name the enzyme that unwinds the helix
Name the type of enzyme that relieves torsional strain and the specific one that is used in humans
topoisomerase enzyme
In what direction are bases added to the existing DNA strand?
What other protein complex is needed for DNA synthesis to start?
RNA primer
Describe some polymerases exonuclease activity.
the ability of some polymerases to remove bases from the end of a DNA strand, in either 5--3 or 3--5 direction
What enzyme creates the RNA primer?
What is the function of DNA Pol III?
synthesize new DNA
What is the function of DNA Pol I?
to remove RNA primers after DNA Pol III has initiated its synthesis
What enzyme seals gaps between DNA fragments after the primer has been removed?
DNA Ligase
Describe the replisome.
The replisome is the large complex structure in which all the proteins of DNA synthesis are housed.
study specific and nonspecific repair mechanisms for DNA
DNA polymerase II function
not involved in replication. repair only
Describe the relationship between oncogenes and tumor suppressor genes and cancer.
Oncogene mutation causes proliferation by a gain of function, tumor suppressor gene mutation causes proliferation by way of loss of function
Define homeostasis
the ability of organisms to maintain a constant internal environment despite a constantly changing external environment
Name the 5 methods of cellular communication.
Direct Contact
Define autocrine signalling
a cell sends out a signal that ends up triggering receptors on its own surface
define direct contact signalling
communication that occurs between receptors on cells that are touching each other
define paracrine signaling
release of communication molecules to extracellular fluid to diffuse to nearby cells
define endocrine signalling
release of communication into bloodstream where they travel to target cells in another part of the body
name some endocrine organs/glands
hypothalamus, pituitary, thyroid, thymus, adrenal glands, pituitary, gonads, pancreas
name some organs that are involved in endocrine processes but their main function lies elsewhere
liver, kidneys, skin
define a tropic hormone
a hormone made by one endocrine gland that targets another endocrine gland which, in turn, produces another hormone
define a non-tropic hormone
a hormone that targets an organ or group of cells that is not one of the main endocrine structures
how are hormones differentiated molecularly
what three main classes of lipophilic hormone are there
steroid hormones
thyroid hormones
where do lipophilic hormones travel?
bound to transport proteins in the blood
what three main classes of hydrophilic hormones are there
amino acid derivatives
where do hydrophilic hormones travel
can travel dissolved in the blood stream
how do lipophilic hormones enter the target cell?
diffuse through the membrane and attach to intracellular receptors
how do hydrophilic hormones enter the target cell?
they attach to an extracellular receptor and initiate a signalling sequence inside the cell
name the two main classes of paracrine signallers
growth factors
what class of hormones controls the anterior pituitary
define a neurohormone
neurotransmitters that originate in the hypothalamus but travel through the blood to cells in the anterior pituitary
define a ligand
a signalling molecule
what are the two different types of receptors?
describe the functional domains of steroid hormone receptor
hormone binding domain
DNA binding domain
transcription-activating domain
name the three types of membrane receptors
G-protein couple receptors
how do enzymatic receptors activate enzyme activity?
activation of a protein kinase cascade via phosphorylation
describe the action of a GPCR
G proteins are attached to the membrane receptor and are activated by ligand-binding
how many transmembrane domains do GPCR's have?
describe a MAP Kinase cascade
ligand called a mitogen (growth-stimulating) activates a kinase cascade
G proteins are active when bound to what and inactive when bound to what?
active when bound to GTP, and inactivated by binding to GDP
what subunits are usually part of the G-Protein
what subunit of a G-protein dissociates when a ligand binds to the GPCR?
the G protein beta and gamma subunits do what after the alpha subunit has dissociated?
activate an effector protein that either directly activates a signal transduction cascade or produces a second messenger
how are G-proteins considered self-regulating?
they can hydrolyze GTP back to GDP, shutting off their own activity
name two common effector proteins activated by G-proteins
adenylyl cyclase
phospholipase C
what is the action of the effector protein adenylyl cyclase?
converts ATP to cAMP, a very useful second messenger
what is the action of the second messenger inositol trisphosphate/the action of phospholipase C?
cleaves PIP2 to produce IP3 and DAG
how does the bacteria Vibrio cholera affect human cellular functoin?
activates a specific G-protein and keeps it turned on, allowing ions to be continuously transported out of the gut, resulting in dehydration
define cleavage
the stage of early cell divisions in an embryo
what is the name for the group of cells left at the end of cleavage?
what cells compose a blastocyst?
blastomere cells
what is the name of the central cavity of a blastocyst?
define a stem cell
cells that can mature into a range of specialized cells and can divide indefinitely
name the four tupes of stem cells
define a totipotent stem cell
can mature into any cell type, including placenta
define a multipotent stem cell
can mature into any of a group of specialized cell, such as any type of blood cell
define a pluripotent stem cell
can mature into any type of cell of the embryo(excludes placenta)
define a unipotent stem cell
can mature into only one specialized cell type
define a morphogen and its function
a morphogen is a biomeolecule that can influence the development of cells, serve as signalling molecules during development (proteins, nucleic acids)
what two types of morphogens are there?
cytoplasmic determinants
induction agents
define a cytoplasmic determinant
a molecule found in the cytoplasm of the embryo before fertilization, are usually unevenly distributed in the egg, highly localized
define an induction agent
a molecule released by a cell to the cells around it to influence the developmental fate of the cells around it
define differentiation
cells that have differentiated have taken on the physical characteristics of the cells they are determined to be
define determination
determined cells are already destined to be a certain cell type, but yet lack the physical characteristics of that cell
describe pattern formation in embryonic development
establishment of axes and segments in the embryo, establishment of the cell's polarity
name the succession of pattern formation genes activated in a growing embryo
gap genes-->pair-rule genes-->segment polarity genes
why is segmentation of an embryo important
cells in each segment know where they are because of the induction agents recieved by surrounding cells in that segment
what genes determine the identity of each segment in an embryo?
Hox genes
define morphogenesis
the process of creating non-identical cells, (formation of an ectoderm, endoderm, mesoderm)
what protein is very important to cell migration in embryonic development?
cadherin proteins that help cells stick to each other
what protein is very important in keeping a cell where it belongs?
integrin proteins that help cells stick to their foundation
what proteins are responsible for bringing about apoptosis and how do they do it?
proteases that hydrolyze, or break down, other proteins
what two things are absolutely necessary for the nervous system?
a way to sense stimuli, and a way to respond to those stimuli
define neuroglia
support cells that nourish neurons
where are the resting membrane charges on the neuron
positive outside, negative inside
name the factors essential to maintenance of the resting potential
NA+/K+ pump that transports NA out and K in. diffusion of K+
look up NA+/K+ resting potential characteristics
what two anions are important in neurons
Cl- and negatively charged proteins
why are Cl- and negatively charged proteins important in the neuron
depolarization is making the membrane more _________
hyperpolarization is making the membrane more _________
define a graded potential
a change in polarization of the membrane
look up exact graded potential definition
what is the combination of graded potentials called?
define a voltage gated channel
a channel that opens and closes in response to changes in membrane potential
look up stages of an action potential
what is the all-or-none principlcle
the action potential can either be all the way completed, or not done at all
what does the membrane potential travel from and to during an action potential
goes from -70mV to 50mV
what are the two gates of the NA+ voltage gated channel responsible for
activation gate responsible for large influx of ions, inactivation gate slowly closes to terminate the rising phase after depolarization
what causes repolarization
slow opening of the K+ channel that causes K+ to flow outward
what causes the undershoot
the K+ gate also closes slowly
how does action potential stay unidirectional?
the inactivation gates of channels "behind" the potential remain closed for a short period of time
what three ways can action potential speed be increased?
1) raise temperature
2) increase axon diameter
3) insulate with myelin
what neurotransmitter stimulates muscle tissue?
the central region of the sarcomere occupied by myosin is which band
the A band
the region that action doesn't overlap myosin is what band
the I band
name the 4 steps of muscle contraction
1)myosin hydrolyzes ATP
2)Myosin releases Pi, binding actin
3)myosin releases ADP, power stroke
4) ATP binds to myosin, releasing actin
look up muscle contraction steps
what does the poison curare do?
prevents the reception of acetylcholine at the neuromuscular junction
describe cooperativity in relation to oxygen binding
the second and third of the 4 oxygens that bind to hemoglobin bind more easily than the first, but the 4th binds more slowly because there is only one spot left for it to bind
the fetal hemoglobin binding curve is different from the adult binding curve how?
shifted left
what animal has a left shifted curve?
what does a left shifted curve result in?
saturation at a lower pO2
why do llamas and fetuses need saturation at a lower pO2?
less O2 in the environment but still need just as much oxygen delivered to tissues
describe the Bohr shift
pH causes the hemoglobin binding curve to shift to the right
what does a right shift of the curve do?
causes less saturation at the same pO2, resulting in more O2 released into the tissues
what two types of cells make up the xylem?
dead tracheids, vessels
what types of cells is phloem made of?
living sieve tube cells that resemble tracheids
what are the three pathways that water enters the root?
symplast, apoplast, transmembrane
describe symplast transport
water and minerals move through cytoplasm and plasmodesmata
describe apoplast transport
passive, water diffuses through cell walls and between the spaces between cells
what protein composes the outer cells of the root endodermis
what is the name for these suberin-containing cells found on the outside of the endodermis?
Casparian strip
what benefit does the Casparian strip have?
forces water and minerals to pass through selective membranes, allowing control of what enters and exits the cell
how do plants move water from root hair tips to the xylem?
root pressure as solutes are pumped closer and closer to the xylem/move through the plasmodesmata, creating water potential gradient
what are the 4 forces that allow water to move up the xylem
what structure controls gas exchange in plants?
what is a stomata made of?
two guard cells with vacuoles inside that are open when the vacuoles are full and closed when the vacuoles are empty
describe the pressure flow model
photosynthetic areas pump sugars into the phloem, which is followed by water, increasing pressure. nonphotosynthetic areas pump sugars out, which is followed by water, reducing pressure. this pressure difference is what causes water to flow through the phloem
the peritubular capillaries surround what tubular structures?
proximal convoluted tubule, distal convoluted tubule
define an interferon
a protein based cytokine used in the immune system
what "patterns
do the innate immune system recognize
pathogen associated molecular patterns (PAMPs)
define a PAMP
a molecule that isn't made at all in the human body like double stranded RNA, lipopolysaccharides
what receptors do PAMPs bind to?
pattern recognition receptors, PRRs
what are the three cpmponents of the innate immune system?
1) three types of leukocytes
2)inflammatory response
3) complement activation
name the three types of leukocytes involved in the innate immune system
macrophages, neutrophils, NK cells
define chemotaxis
attraction of other white blood cells to an area of pathogenic activity via a chemical signal (usually cytokines)
define an opsonin
a special marker protein used by complement to mark a pathogen for destruction by another WBC
what type of molecule are fragments of foreign pathogens displayed on on the outside of a dendritic cell
MHC II molecules
what two types of cells does clonal expansion create?
some cells capable of fighting a specific pathogen, others that specialize in remembering and can respond very quickly next time that pathogen enters the system
what two types of T cells are there and what protein receptors do they each express
Helper T cells-CD4
Cytotoxic T cells-CD8
what is the main difference in the way the T and B cells recognize foreign antigens
T cells bind to a short peptide that is bound to MHC II, but B cells recognize a protein, lipid, or carb on the cell surface of a pathogen
what different things can immunoglobulins due to shut down a pathogen
they can bind to the cell, inhibiting its function; they can act as an opsonin, or they can aggultinate pathogens
define somatic recombination
production of new Ig's or TCR's with the encounter of a new pathogen
what are the 4 different segments of the genes that code for TCRs
Variable (50)
Diversity (30)
Joining (5)
Constant (2)
describe the process of somatic recombination
one each of the VDJ segments are selected and joined during B cell or T cell maturation. The C segment selection occurs as an mRna transcriptional modification during splicing
define the order of segment selection in somatic rearrangement
first a D and J are randomly chosen and joined, then a V segment is joined to the DJ, the both C regions are transcribed into the receptor, but one is deleted during intron removal