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