BIOL 2520 - Cell Biology
what are insulator proteins
keep looped domains of DNA separate
Turner's syndrome
lack all or part of chromosome X
what is the function of telomeres
protect ends from nucleases, distinguish ends from broken DNA, prevent fusing of two chromosomes, attachment to nuclear scaffold
prions
proteinaceous infectious particles
why did Dolly the sheep die prematurely
telomeres were 20% shorter than normal sheep, started aging prematurely
why are a fats a good source of energy
they're highly reduced
what is the sequence of a telomere
TTAGGG
what does Arabidopsis thaliana provide as a model organism
fast growing plant with small genome, many mutants
what does C.elegans provide as a model organism
1000 cells, short life cycle
what does Mus musculus provide as a model organism
1000s of mutants, easiest mammal for genetic studies
what does D.melanogaster provide as a model organism
1000s of mutants, well characterized genome
how are the looped domains in the third organizational level of DNA formed
30 nm fibers gather into supercoiled loops which get tethered to the nuclear scaffold (contain 20,000 to 100,000 bases)
what is the second level of DNA organization
30 nm fibers, spontaneous assembly of adjacent nucleosomes (40:1 condensation in length with
how much DNA is left unreplicated at the 3' end after each round of replication
50-200 bp
what is the nuclear matrix
protein fiber framework, major organizing structure or RNA pol, RNA processing and DNA rep
what are the four major categories of macromolecules
proteins, nucleic acids, polysaccharides and lipids (*)
Rudolf Virchow
published Remark's work, cells only arise from other cells
what genes are involved in chronic myelogenous leukemia
reciprocal translocation between chromosome 9 and 22 (producing extra long chromosome 9)
what are factors that contribute to cell aging
telomere shortening, mutations, chronic risk exposures (oxidants, UV), glycation
what does the H5 histone do
the linker histone, links adjacent nucleosome core particles, total of 168 bases per unit, 10nm thick (7:1 packing ratio)
how do translocations effect the phenotype
breaking a gene, moving a gene to region controlled by another regulatory sequence, creating hybrid gene
how are chromosomes held in place
by the nuclear matrix and the nuclear lamina (where they are positioned can affect expression)
HOW does translocation cause chronic myelogenous leukemia
c-abl gene codes for kinase that regulates cell cycle, translocation alters controls to bcr's promoter
nucleotides that can act as regulatory molecules
cAMP (second messenger) and GTP (acts as switch)
facultative heterochromatin
can be activated or inactivated whenever needed
what are HeLa cells
cell cultures from a tumor removed from Henrietta Lacks in 1951 by George Grey
what is cellular senescence
cells no longer divide and will die by triggering apoptosis
structural polysaccharides
cellulose in plants (beta 1,4) and chitin in insects
viroids
circular RNA without a protein coat
metagenomics
collecting enviromental samples and sequencing random DNA
constitutive heterochromatin
condensed at all times, consists of repeat DNA (especially in telomere and centromere)
heterochromatin
condensed during interphase, not transcriptionally active
how does x-ray crystallography lead to protein structure
crystallize protein, look at diffraction patterns, math, electron density map, determine how amino acids fit it
scanning electron microscopes
dead and fixed cells, coated with heavy metals for contrast from one direction, electrons scanned across sample and scattered by metals
euchromatin
dispersed during interphase, transcriptionally active
when are chromosomes visible by light microscopy
during mitosis
DAPI
dye that binds to DNA and fluoresces blue
what is a nucleosome
group of positively charged proteins (histones) that the DNA winds around
purines
A and G
pyrimidines
C, T and U
transmission electron microscopy
thin sections of dead/fixed cells used, coated with heavy metals for contrast, electrons beamed through sample and scattered by metals
monosomy
missing chromosome
what is the fourth level of DNA organization
mitotic chromosomes
how many times does DNA wrap around the nucleosome
1.8 turns or 146 nucleotide bases per nucleosome
heterodimer
two different proteins encoded by different genes
what are MARs (matrix associated regions)
AT rich domains of DNA, affinity for nuclear matrix, can be moved to facilitate transcription
nucleotides that act as agents of energy transfer for metabolism
ATP (P cleaved) and coenzyme NAD
what are the 2 major classes of proteins
globular (usually inside cell) and fibrous (exported out)
three major functions of nucleotides
DNA/RNA, regulatory, energy transfer for metabolism
what are the 2 hypotheses for how the second level of DNA organization occurs (30 nm fibers)
H1 histones bind adjacent nucleosomes or N-terminal tails of H4 may reach other nucleosome histones
what are the 4 types of histones that make up the nucleosome
H2A, H2B, H3, H4
how are polysaccharides stored for energy in animals
glycogen in muscles (branched alpha 1,4 and 1,6)
anueploydy
abnormal number of chromosomes
what are the three tenants of cell theory
all organisms are composed of one or more cells, cell is structural unit of all life, cells can arise only by division from a preexisting cell
Matthias Schleiden
all plant tissue made of cells, all plant embryos come from single cell
what are centromeres made of
alpha satellite DNA made of non transcribed 171 base repetitive sequences
telomerase
an RNA containing enzyme that adds more nucleotides to the 3' end of the telomere DNA strands
what sort of template does telomerase use to synthesize DNA
an RNA template (weird)
transcriptome
an organism's complete set of mRNA
genome
an organisms complete set of DNA (including all genes)
four ways to get fluorescence
antibodies, DAPI, green fluorescent protein from jellyfish, autofluorescence
what are sister chromatids
attached duplicated chromosomes
biological roles of lipids (4)
energy, hormones, vitamins, structural
roles of protein
enzymes, structural, contractile, gene transcription, transport, carriers, hormones, antibodies
what is epigenetics
external factors that can switch genes on or off, NOT caused by changes in DNA sequence
Down's syndrome
extra chromosome 21
Leeuwenhoek
first to describe living cells in pond water; described prokaryotic cells (called animalcules)
what does E.coli provide as a model organism
first understanding of DNA replication, transcription and translation
what do genomes code for other than protein
functional RNAs, positional sequences, repeat regions
what is the nuclear lamina (lamin IFs)
lamins on the inner part of the nuclear envelope bind telomeres and alpha satellite DNA of the centromere
what is the function of Topoisomerase II
looks for kinks in DNA and untangles them
what is the third level of DNA organization
looped domains (this is the normal state of DNA during interphase)
what is the condensin protein
loops DNA to create more compact DNA (chromosomes vs chromatin)
how is a glycosidic bond formed
loss of a hydroxyl from carbon 1 and a hydrogen from another (releasing water)
what are telomeres
non coding regions at the end of chromosomes (repeated many times, include specialized proteins)
cell cultures are either ...
normal cells from an organism or immortal cancer cell lines
what is the first level of DNA organization
nucleosomes
ploidy
number of sets of chromosomes
Theodor Schwann
observed animal life is all cells
Hooke
observed chambers in cork, called them cells
trisomy
one extra chromosome
how do you define a living cell
organized, autonomous, internally regulated
viruses
reproduce only in cells, inert outside cells, bits of nucleic acid with protein coats
what is the problem with light microscopy
resolution power
what is the function of cohesin proteins
ring shaped proteins that maintain the looped domains of DNA in the third organizational level
genomics
science of sequencing, assembling and analyzing genomes
confocal microscopy
similar to fluorescence but laser scans across at specific depth (only one plane of focus), allows more detail
what does. S.cerevisae provide as a model organism
simplest eukaryote, many mutants
oligosaccharides
small chains of monosaccharides, added to lipids to make glycolipids and glycoproteins, cell recognition
what is resolution power
smallest distance between two separate points of an objects that are still distinguishable (dependent on wavelength of light)
how are polysaccharides stored for energy in plants
starch (alpha 1,4 linked)
how was Dolly the sheep cloned
taking a nucleus from the udder of an adult ewe and transplanting it into a denucleated embryo
why are cells small
to maintain proper area/volume ratios, depend on diffusion for movement of substances
translocations
transfer of a piece of one chromosome to a non homologous chromosome
what types of cells is telomerase present in
tumor, one celled organisms, primordial germ cells, tissue stem cells
homodimer
two proteins encoded by the same gene
what major problem is associated with telomeres?
when the chromosomes are replicated, the telomeres get progressively shorter
when (in terms of telomere size) does apoptosis occur
when the telomere is 4-6 kbp long
non disjunction
where one gamete receives an extra chromosome or is missing one
what are the two main methods to determine tertiary and quaternary protein structure
x-ray crystallography and nuclear magnetic resonance