EXAM 1 Flashcards
cell theory
1) all living organisms are made of one or more cells
2) cells are the basic unit of all living organisms
3) cells arise from pre-existing cells
(all cells are essentially the same in chemical composition)
chromosome (DNA) replication
- step 1 of the eukaryotic cell division cycle
- the duplication of the DNA molecules in the nucleus in preparation for mitosis
mitosis
- step 2 of the eukaryotic cell division cycle
- the division of the nucleus
cytokinesis
- step 3 of the eukaryotic cell division cycle
- the division of the cytoplasm and the membrane (the division of the rest of the remaining cell)
polytene chromosomes
the result of multiple rounds of DNA replication without mitosis
syncytium
a polynucleated structure that forms after multiple rounds of mitosis without cytokinesis; may also form from the fusion of multiple mononucleated cells
syncytiotrophoblast
the precursor of the mammalian placenta
prokaryotes
(bacteria and archaea)
- these lack a nuclear envelope, organelles, and a cytoskeleton
- the most diverse group of cells
eukaryotes
have a nuclear envelope, organelles, and a cytoskeleton
photosynthetic bacteria
these cells obtain energy from sunlight
archaea
prokaryotes that are not classified with bacteria because they have more in common with eukaryotes (though they lack nuclei); oxygen-generating photosynthesis cannot occur
endosymbiosis
mitochondria and chloroplasts were prokaryotes that entered eukaryotic cells and became specialized to perform specific cellular functions
mitochondria
- involved in aerobic respiration
chloroplasts
involved in the harvesting of energy from sunlight for carbon fixation
operational genes
metabolism and other cell functions (from ancestral bacteria)
information genes
cell division and gene expression (from ancestral archaea)
single cell living
independent, free living cells (i.e. chlamydomonas)
colonial living
aggregation of cells of the same species but no division of functions (i.e. gonium, pandorina, and eudorina)
colonial living with division of functions
aggregation of cells of the same species with different somatic and reproductive functions, but no recognized true multicellularity because cell functions can be reversed (i.e. pleodorina)
true multicellularity
division of functions (somatic and reproductive), terminal (irreversible) cell identities), and multicellularity (i.e. volvox)
epithelial cells
bound by tight junctions and form sheets that cover body surfaces and form the lining of the internal organs (mouth, bile duct, intestine)
connective tissues
bone, cartilage, adipose tissues, fibroblasts, areolar tissue
blood cell types
red (O2 transport) and white (immunity)
neurons
cells that receive and transmit electrical and chemical signals throughout the body and are capable of generating electrical activity
muscle cells
(fibers) are long, multinucleated cells that generate force and movement (example of a syncytium)
dehydration synthesis
this condensation adds subunits to the one end of a growing chain (macromolecules)
hydrolysis
this reaction breaks covalent bonds and reverses the growth of a macromolecule chain
glycogen
(in animals) energy storage
starch
(in plants) energy storage
cellulose
structural polysaccharide in plants
fatty acids
these are stored as energy reserves (fats and oils) through an ester linkage to glycerol to form triacylglycerols
saturated fatty acids
tend to form aggregates and deposits inside blood vessels
unsaturated fatty acids
contains one or more double bonds
cis unsaturated fatty acids
do not form solid aggregated because a double bond forms a “kink”
trans unsaturated fatty acids
behave similar to saturated fatty acids (they tend to aggregate and form solid deposits) and are major contributors to coronary heart disease (atherosclerosis of coronary blood vessels)
oleic acid
a cis unsaturated fatty acid that comprises up to 80% of olive oil
elaidic acid
a trans unsaturated fatty acid and a major trans fat found in partially hydrogenated vegetable oils
electrostatic interactions
are attractions between ionized groups
hydrogen bond
is the electromagnetic attractive interaction of a hydrogen atom and an electronegative atom, such as nitrogen, oxygen, or fluorine, that is present in another molecule or chemical group
van der Waals forces
are weak interactions between adjacent electrically neutral molecules, caused by the attraction of electron-rich regions of one chemical group and electron poor regions of another
cyclic adenosine monophosphate (cAMP)
is used by cells as a messenger in both intracellular and intercellular signaling
alanine
one of the simplest amino acids
non polar side chains
amino acids that tend to cluster at the core of the protein and away from the aqueous surroundings (in a folded polypeptide), leaving the polar and charged side chains at the surface
protein maturation
involves 5 things:
1) correct folding
2) proteolytic cleavage
3) chemical modifications
4) formation of quaternary structures
5) association with co-factors
elastin fibers
rubberlike elastic meshwork’s present in the extracellular matrix of some tissues; they allow tissues such as skin, arteries, and lungs to stretch and recoil without tearing
quaternary structure
multiple polypeptides
disulfide bonds
the cross links between single elastin molecules
covalent bonds that form between adjacent cysteine side chains; they can link two domains of the same polypeptide or different polypeptide chains
hemoglobin
consisted of two alpha globin polypeptides and two beta globin polypeptides; each globin has an oxygen-carrying heme cofactor associated with it
sickle cell anemia
is caused by a single amino acid substitution in the beta chains; a glutamic acid (acidic) is replaced with a valine (Non-polar); the result is sickled (abnormally shaped) erythrocytes, tissues may be deprives of oxygen and there is a high risk of heart attack
denaturants
(such as urea or heat) can unfold (denature) a polypeptide by breaking all non-covalent interactions between amino acids
reducing agents
(i.e. 2-mercaptoethanol) are necessary for breaking disulfide bonds
oxidation
reaction in which a molecule or atom loses electrons
fibrillar collagens
the major structural proteins of connective tissues are built of triple helices of pro collagen polypeptides
TSEs
a family of fatal brain diseases characterized by lesions that appear as small cavities (spongy appearance)
prions
infections agents specific to the brain (TSEs)
prions (PrPsc)
variants of a normal brain protein (PrPc)
can direct a non-infectious PrPc to unfold and re-fold into an identical PrPsc infectious prion
insulin
a pancreatic hormone that regulates blood glucose levels; it is originally synthesized as the single polypeptide preproinsulin
the signal sequence is removed and two disulfide bonds are made resulting in proinsulin
the connecting polypeptide is finally removed resulting in the active insulin protein
gene expression
(regulation of protein activity) determines the amount of protein produced by the cell by limiting transcription and/or translation
protein function
(regulation of protein activity) the protein is synthesized but its activity is restricted according to the needs of the cell
phosphorylation
a covalent modification necessary for the activation or inactivation of many proteins
protein kinase
an enzyme that transfers a phosphate group from ATP to proteins (1. serine/threonine, 2. tyrosine, 3. histidine)
protein phosphates
enzymes that remove phosphate groups from phosphorylated proteins
cAMP
a ligand that activated proteins but is not a cofactor
cofactor
a ligand that participated in the catalytic activities of an enzyme
enzymes
macromolecular biological catalysts
accelerate chemical reactions in cells by converting a substrate into a product
have a specific substrate-binding site (active site)
are not altered in the catalytic process
can catalyze reactions in both directions
allosteric regulation
a change in the conformation of a protein that affects its activity due to the binding of a regulatory molecule
ubiquitin
a small protein that is covalently attached to a target protein and is a label for regulation or destruction
decondensed
(euchromatin) occurs during interphase where most of the DNA is affected; this is necessary for transcription
condensed
(heterochromatin) occurs during metaphase where some of the DNA remains unaffected
nucleolus
the region of the nucleus where the transcription of rRNA genes and the assembly of ribosomes occur
heterochromatin
a DNA that remains condenses and is transcriptionally inactive during the entire cell division cycle, including interphase (epigenetic)
constitutive heterochromatin
are the regions of the chromosomes that are invariably heterochromatic in all cells in an organism
facultative heterochromatin
are the regions of the chromosomes that contain genes but can become heterochromatic depending on the cell type
gene
a segment of DNA that is transcribed and codes for a functional product: a polypeptide (protein) or an RNA species (tRNA, rRNA) as the end product
exons
(a sequence within a gene) coding sequences
introns
(a sequence within a gene) non-coding DNA (intervening sequences)
untranslated regions (UTRs)
( a sequences within a gene) at the 3’ and 5’ ends
regulatory regions
such as promoters, enhancers, and silencers that are not parts of genes
eukaryotic gene expression
following the transcription of the entire gene from DNA, the primary RNA transcript is processed to remove the introns by intron splicing; the mature mRNA contains only exons resulting in the canonic isoform
alpha-tropomyosin
a protein associated with the cytoskeleton in muscle cells and other cell types
the fruitless gene
(in drosophila) the fruitless gene controls male courting behavior; males lacking the wild-type allele do not distinguish between males and females and copopulate with either
interspersed repeats
repetitive sequences that are not clustered but are scattered through the genome
simple sequence DNA
(“satellites”) are tenderly (end to end) clustered repeats)
reassociation assay
1) cut DNA with restriction enzymes
2) denature the DNA fragments by heating
3) allow the DNA to cool and reassociate
4) measure the fraction of DNA remaining single stranded over time (it will decrease as DNA reassociates)
Co
initial molar concentration of single stranded DNA (M)
t
time in (sec)
low Cot
repetitive sequences (reassociate faster)
higher Cot
unique sequences (reassociate slower)
satellites
tandem repeats of short sequences repeated 1000s of times; tend to cluster at the centromeres and telomeres
CsCl Density Gradient
1) Fragment purified DNA with restriction enzymes
2) Place in a tube containing a heavy salt such as CsCl
3) Centrifuge at high speed. This will generate a CsCl density gradient: from lower density (top) to higher density (bottom); the fragments of DNA will migrate to the point within the CsCl density gradient where its density matches the density of CsCl in the tube
