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Neuron size?
up to 2 meters long
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Human cell size?
10-15 micrometers in diameter
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Egg cell size?
100 micrometer
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Limitations on cell size
cell growth increases volume more than surface area
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Plasma membrane
surrounds cell, made of proteins and lipids
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Cytoplasm contains?
organelles, cytoskeleton, cytosol (ICF), ECF
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Membrane Lipids
98% of molecules in plasma membrane are lipids
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Phospholipids
75% of membrane lipids are phospholipids
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Hydrophilic heads
face water on each side of membrane
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Hydrophobic tails
directed toward the center avoid water
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Cholesterol
20% of the membrane lipids, stiffen membrane
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Glycolipids
5% of the membrane lipids, contributes to glycocalyx
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Membrane proteins
2% of the molecules in plasma membrane, 50% of its weight
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Transmembrane proteins
pass through membrane
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Peripheral proteins
adhere to one face of the membrane, help anchor the membrane
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Receptors
surface proteins on plasma membrane of tarfet cell
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Channel proteins
transmembrane proteins with pores that allow water and dissolved ions to pass through membrane in response to stimuli, Ligand, Voltage-regulated, mechanically regulated gates
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Channelopathies
family of diseases that result form defects in channel proteins
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Carriers or pumps
Transmembrane proteins bind to glucose, electrolytes, and other solutes
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Down a gradient
it is a carrier and no ATP is required
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Up a gradient
it is called a pump and ATP is required
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Glycoproteins
are the identity markers for our immune system, are part of the surface gel called the glycocalyx
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First messenger
the chemical that binds to a receptor is the first messenger, activates G-protein,which signals enzyme Adenylate Cyclase, which converts ATP to cAMP (Second messenger)
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Second messenger
cAMP activates a kinase in the cytosol, kinases add phosphate group to other enzymes and turn on internal cell
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Modern drugs
up to 60% of modern drugs work by altering activity of G-protein
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Glycocalyx
Cell identity marker
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Cilia
airlike processes 7-10 micrometers long, on surface of respiratory tract and uterine tubes
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Axoneme
core of cilia that is the structural basis for ciliary movement
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Has 9+2 structure of microtubules
Nine triplets of microtubules form the basal body inside the cell membrane, anchor cilium, Dynein arms crawl up adjacent microtubule, bending the cilia
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Active transport (consumes ATP)
Active transport, vesicular transport, carrier mediated transport
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Filtration
a process in which particles are driven through a selectively permeable membrane by hydrostatic pressure
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Simple diffusion
the net movement of particles from area of high concentration to low
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Factors affecting diffusion
temperature, concentration, surface area, membrane permeability, and weight decreases rate
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Osmosis
flow of water form one side of a selectively permeable membrane to the other
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Aquaporins
channel proteins in plasma membrane specialized for passage of water
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Osmolality
number of osmoles of solute per kilogram of water
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Osmolarity
number of osmoles of solutes per liter of solutions
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Tonicity
ability of a solution to affect fluid volume and pressure in a cell
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One Osmole
1 mole of dissolved particles
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Hypotonic solution
cell bursts
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Hypertonic solution
cell shirvels
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As the solute concentration rises, the rate of transport rises, but only to a point
Transport maximum
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Uniport
carries only one solute at a time
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Symport
carries two or more solutes simultaneously in same direction (contransport)
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Antiport
carries two or more solutes in opposite directions (countertransport)
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Carrier mediated transport
facilitated diffusion, active transport
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Facilitated diffsion
carrier mediated transport of solute through a membrane down its concentration gradient, does not consume ATP
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Active transport
carrier mediated transport of solute through a membrane up (against) its concentration gradient, ATP is consumed
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Secondary active transport
steep concentration gradient maintained between one side of the membrane and the other, does not consume but relies on Na/K pump
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Vesicular transport
processes that move larged particles fluid droplets, or numerous molecules at one through the membrane
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Endocytosis
vesicular processes that bring material into the cell
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Phagocytosis
"cell eating", engulfing large particles, pseudopods, phagosomes, macrophages
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Pinocytosis
"cell drinking" taking in droplets of ECF containing molecules useful in the cell
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Clathrin
coated vesicle, uptake of LDL of bloodstream
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Cytoskeleton
collection of filaments and cylinders, composed of microfilaments 6nm terminal web, intermediate fibers 8-10nm support, microtubules 25nm tubulin
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Membraneous organelles
nucleus, mitochondria, lysosomes, peroxisomes, ER, golgi
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Nonmembraneous organelles
ribosomes, centrosomes, centrioles, basal bodies
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Smooth ER
lack ribosomes, detoxify alcohols and drugs, manufactures all membranes of the cell, synthesizes steroids
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Ribosomes
made in nucleoli, they read genetic code of mRNA
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Lysosomes
package of enzymes bound a single unit membrane
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Autophagy
digest and dispose of worn out mitochondria and other organelles
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Autolysis
cell suicide, some cells are destroyed once their job is completed
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Peroxisomes
produced by Smooth ER
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Centriole
a short cylindrical assemby of microtubules arranged in nine groups of three microtubules each, play a role in cell division
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Inclusions
stored cellular product, foreign bodies, not essential for cell survival
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Stored cellular products
glycogen granules, pigments, and fat droplets
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Foreign bodies
viruses, intracellular bacteria, dust particles
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Enucleate cells
no nucleus (mature RBC)
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Multinucleate cells
2-50 nuclei (skeletal muscle)
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Nuclear envelope
surrounds nucleus, has two membranes
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Nuclear pores
perforate nuclear envelope
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Nucleoplasm
material within nucleus
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Chromatin
DNA and associated proteins
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Nucleoli
dark staining, produce ribosome subunits
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What do nuclear pores do?
formed by ring shaped complex of proteins, regulate traffic through envelope, holds nuclear evelope together
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Nucleosomes
cluster of eight proteins, histones, serve as spools to protect and organize DNA
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Supercoils of DNA
preparation for cell division
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Nucleotides consist of?
Sugar-ribose, deoxyribose, Phosphate group, Nitrogenous Base
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Purines
double carbon nitrogen ring, Adenine, Guanine
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Pyrimidines
single carbon nitrogen ring, Uracil, Thymine, Cytosine
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Gene
sequence of DNA nucleotides that codes for one polypeptide
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Genome
all the genes for one person
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mRNA size?
over 10,000 bases
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DNA size?
over a billion bases
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Meiosis
cell reproduction (gametes)
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Base triplet
sequence of DNA nucleotides that codes for 1 amino acid
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Start codon
AUG Methionine
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Introns
nonsense portions (must be removed)
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DNA and Peptide Formation Six Step
1.DNA Double Helix, 2.DNA Coding Strand, 3.Codons of mRNA, 4.Anticodons of tRNA, 5.Amino Acids, 6.Peptide
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Chaperones
Assist is proper folding of new proteins, may escort protein to destination in cell, stress or heat shock proteins
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Signal peptide
amino acid sequence that causes polyribosome to migrate to rough ER and enter cisterna
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Modifications in RER cisterna
signal peptide removed, may remove amino acids, fold protein, form disulfide bridges, or add CHO groups
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DNA unwinds (DNA Replication)
from histones
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DNA Helicase (DNA Replication)
opens short segments, called replication fork
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Replication by (DNA Replication)
DNA polymerase
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Semiconservative replication
each new DNA has one new helix and the other helix conserved from parent DNA
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Error rates in bacteria
3 errors per 100,000 bases copied
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Error rates in DNA
1 per 1,000,000,000
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Mutations
changes in DNA structure due to replication errors or environmental factors
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Mutations cause
no effect, kill cell, turn it cancerous, cause genetic defects
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Interphase is divided into
G1, S, G2
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G1
Normal cellular function, gain full set of organelles
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G2
Preparation for mitosis, replicates centrioles, synthesizes enzymes for cell division
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M Phase
nuclear and cytoplasmic division
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G0 Phase
cells that have left the cycle
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Functions of mitosis
embryonic development, tissue growth, replacement of old and dead cells
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Mitosis Prophase
chromatin supercoils into chromosomes, nuclear envelope disintegrates, centrioles sport microtubules (mitotic spindle) and move to poles, nucleoli disintegrates, spindle apparatus is completed
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Mitosis Metaphase
chromosomes line up at equator, spindle fibers attach to centromere, asters anchor centrioles to plasma membrane
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Mitosis Anaphase
centromeres divide, spindle fibers pull sister chromatids to opposite poles
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Mitosis Telophase
chromatin uncoils, nuclear envelope forms and nucleoli form, mitotic spindle breaks down
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Cytokinesis
division of cytoplasm (cleavage furrow)
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Cells divide when
cells are large enough, DNA replicated, adequate supply of nutrients, growth factor stimulation, open space in tissue
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Cell stop dividing when
loss of growth factor, contact inhibition
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Tumors
abnormal growth, when cells multiply faster than they die
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Carcinogens chemical
cigarette, food preservatives
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Carcinogens viruses
type 2 herpes simplex in uterus, hepatits B in liver
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Defenses against mutagens
scavenger cells, peroxisomes, nuclear enzymes, tumor necrosis factor TNF
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Karyotypes
chart of chromosome at metaphase by size, structure
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Homologous chromosome
22 pairs autosomes, sex chromosome, 2 chromosomes in each pair one from each parent
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Germ cell
Gamete, sperm and egg cells, haploid
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Somatic cells
all other cells beside reproductive, diploid
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Allele
two homologous chromosomes have some gene at same locus, may be different forms of gene
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Dominant allele
produces normal, functional protein
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Recessive allele
when both alleles are recessive produces abnormal protein or no protein
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Gene pool
collective genetic make-up of whole population
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Multiple alleles
more than 2 alleles for a trait
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Codominant
both alleles expressed, like AB blood type
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Incomplete dominance
phenotype intermediate between traits for each allele (pink flower)
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Polygenic inheritance
2 or more genes combine their effects to produce single phenotype trait such as skin color
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Pleiotropy
single gene causes multiple traits, such as sickle cell disease, anemia, weakness
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Penetrance
% of population to express predicted phenotype
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