Introduction to Cell and Molecular Biology

fertilization

a joining of two separate cells to produce a single new cell, which then multiplies to produce the embryo

microscope

an instrument that provides a magnified image of a tiny object

Robert Hooke

an English microscopist who, at the age of 27, was credited with the discovery of cells and was awarded the position of curator of the Royal Society of London, England's foremost scientific academy

Antonie van Leeuwenhoek

a Dutchman who earned a living selling clothes and buttons; the first to describe various forms of bacteria; sent rambling letters to the Royal Society of London describing his findings, which were initially met with skepticism, only to be verified by Robert Hooke later

Matthias Schleiden

a German lawyer turned botanist; concluded that, despite differences in the structure of various tissues, plants were made of cells and the plant embryo arose from a single cell

Theodor Schwann

a German zoologist and colleague of Schleiden's; published a comprehensive report on the cellular basis of animal life; concluded that the cells of plants and animals are similar structures and proposed two tenets of cell theory

all organisms are composed of one or more cells; the cell is the structural unit of life

two tenets of Schwann's cell theory

Rudolf Virchow

a German pathologist who proposed the third tenet of cell theory, which challenged Schleiden and Schwann's initial conclusion that cells can arise from noncellular matter

cells can arise only by division from a preexisting cell

the third tenet of cell theory, proposed by Rudolf Virchow

cells contain genetic information in the form of DNA, and that information is passed from parent to daughter cell

the proposed and unofficial fourth tenet of cell theory

abiogenesis

the theory of the spontaneous arising of life from non-living matter

2-lens (20-50x)

specs of the microscope used by Robert Hooke

single lens (275x)

specs of the microscope used by Antonie van Leeuwenhoek

scanning electron microscope (SEM)

scans surfaces with a focused beam of electrons instead of light; electrons interact with the atoms in the sample

transmission electron microscope (TEM)

views the smallest structures in thin specimens through which electrons can pass, generating a projection of images

field emission scanning electron microscope (FESEM)

uses field emission gun (FEG) as electron source; potential gradient is applied to emit the electron beam; provides topographical and elemental info at 10x - 300,000x with unlimited depth; 3-6x better than SEM

life

the most basic property of cells

George and Martha Gey

began the first culture of human cells at Johns Hopkins University in 1951, obtained from a malignant tumor and named HeLa cells after the donor, Henrietta Lacks

Margaret Finney Gey

the true name of Martha Gey, as was originally misprinted; a registered nurse by profession, and a lab technician; cultured the HeLa cells with her husband, George Gey

HeLa cells

the first human cells to be cultured; obtained from a malignant tumor from Henrietta Lacks; descended by cell division from this first cell sample and still being grown in laboratories around the world today

microvilli

long processes on the apical surface of cells which face the intestinal channel; the ability to project outward from the apical cell surface is due to the internal skeleton made of filaments

Levinthal's paradox

if protein folding depended solely on random molecular movements, it would require a period of time greater than the age of the universe for a protein to fold into its native structure

mutation

an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA

daughter cells

cells that result from the division of a single parent cell

oocyte

an immature ovum, an immature egg cell produced in a female fetus in the ovary during gametogenesis

sucrose/starch

energy-rich carbohydrates in which light energy that is converted by photosynthesis into chemical energy is stored

chemical energy

energy stored in the bonds of atoms and molecules

glucose

prepackaged energy for most animal cells; released by the liver into the blood, where it circulates through the body delivering chemical energy to all the cells

adenosine triphosphate (ATP)

the readily available form in which the energy content of disassembled glucose is stored

enzymes

molecules that greatly increase the rate at which a chemical reaction occurs

metabolism

represented by the sum total of the chemical reactions in a cell

motor proteins

one of many types of molecular "machines" employed by cells to carry out mechanical activities

receptors

provide pathways through which external stimuli can evoke specific responses in target cells

apoptosis

an orderly, programmed process of cell death often described as cellular suicide

Hans Driesch (1891)

a German embryologist; found that he could completely separate the first two or four cells of a sea urchin embryo, and each of the isolated cells would proceed into a normal embryo

last universal common ancestor (LUCA)

a single, common ancestral cell that lived more than three billion years ago; gave rise to all of the living organisms that we know of

prokaryotic cells

structurally simpler; includes bacteria; evidence obtained from rocks approx. 2.7 billion years of age; contain relatively small amounts of DNA; contain a single, circular chromosome; divide via binary fission; occasionally conjugation

cyanobacteria

a prokaryotic organism; recognized as the first organism to have produced oxygen; believed to have first appeared 2.4 billion years ago, when the atmosphere became infused with molecular oxygen

molecular oxygen

the byproduct of the photosynthetic activity of these prokaryotes

nucleoid

contains the genetic material of a prokaryotic cell; a poorly demarcated region of the cell that lacks a boundary membrane to separate it from the surrounding cytoplasm

pro, karyon

etymology of prokaryotic; before, nucleus

600,000 to 8 million base pairs

DNA content of bacteria/prokaryotic cell

500 to several thousand proteins

number of proteins encoded by bacterial base pairs

simple diffusion

accomplishes the necessary movement of materials in prokaryotic cells, where directed intracytoplasmic communication is less important due to their small size

binary fission

a fast form of asexual reproduction where a single prokaryotic cell grows, copies its DNA, and splits into two identical daughter cells

conjugation

in which a piece of DNA is passed from one cell to another; the recipient almost never receives a whole chromosome from the donor, and the condition in which the recipient cell contains both its own and its partner's DNA is fleeting

flagellum

a thin protein filament which accomplishes the movement of prokaryotic cells; protrudes from the cell and rotates

flagellin

a single protein which makes up the bacterial flagellum

biofilms

the complex, multispecies communities in which prokaryotic cells live; e.g. the layer of plaque that grows on our teeth

Escherichia coli

a common inhabitant of both the human digestive tract and the laboratory culture dish has the ability to live and prosper in a medium containing one or two low-molecular-weight organic compounds and a few inorganic ions

domain Archaea

some members are more closely related to eukaryotes than they are to the other group of prokaryotes (the Bacteria); includes several groups of organisms; their evolutionary ties are revealed by similarities in the nucleotide sequences of their nucleic acids

extremophiles

species from domain Archaea that live in extremely inhospitable environments

methanogens

prokaryotes capable of converting CO2 and H2 gases into methane CH4 gas

halophiles

prokaryotes that live in extremely salty environments, such as the Dead Sea or certain deep-sea brine pools that possess a salinity equivalent to 5M MgCl2

Dead Sea

no macroscopic organisms due to high salinity (34.2%, 9.6x saltier than the average ocean); only microbes (halophiles) and fungi can live

plasmolysis

the process in which cells lose water in a hypertonic solution

acidophiles

acid-loving prokaryotes that thrive at a pH as low as 0, such as that found in the drainage fluids or abandoned mine shafts

thermophiles

prokaryotes that live at very high temperatures

hyperthermophiles

live in the hydrothermal vents of the ocean floor

Pyrolobus fumarii

in the hydrothermal vents of the ocean floor (90-113 degrees Celsius)

fumar

Spanish; to smoke

Thermus aquaticus

a heat-loving bacterium famous for providing Taq polymerase used in PCR

Taq polymerase

a heat-stable enzyme used in the polymerase chain reaction (PCR) to make millions-billions of copies of DNA

Geogemma barossii (strain 121)

the record holder among hyperthermophiles; able to grow and divide in superheated water at a temperature of 121 degrees Celsius, which just happens to be the temperature used to sterilize surgical instruments in an autoclave

domain Bacteria

all other prokaryotes that are not members of domain Archaea; includes the smallest known cells; present in every conceivable habitat on Earth, from the permanent ice shelf of the Antarctic to the driest African deserts, to the internal confines of plants and animals

mycoplasma

the smallest known cells (0.2 um diameter); in domain Bacteria

cyanobacteria

the most complex prokaryote; contain elaborate arrays of cytoplasmic membranes, which serve as sites of photosynthesis; also capable of nitrogen fixation

nitrogen fixation

the conversion of nitrogen gas into reduced forms of nitrogen (such as ammonia), which can be used by the cells in the synthesis of nitrogen-containing organic compounds, including amino acids and nucleotides

eukaryotic cells

structurally more complex; include protists, fungi, plants, and animals; contain considerably more genetic information; possess several separate chromosomes, each containing a single linear molecule of DNA; divide via mitosis and meiosis

ribosomes

nonmembranous particles that function as "workbenches" on which the proteins of the cell are manufactured; found in both prokaryotic and eukaryotic cells

nucleus

found only in eukaryotic cells; a region bounded by a complex membranous structure called the nuclear envelope

nuclear envelope

a complex membranous structure which bounds the nucleus

eu, karyon

etymology of eukaryotic; true, nucleus

chromatin

a complex nucleoprotein material

endosymbiotic theory

explains how complex cell structures called eukaryotic cells evolved from simple single cells called prokaryotic cells; proposed by Lynn Margulis

Lynn Margulis

an American biologist who was the primary modern proponent for the significance of symbiosis in evolution; proposed the symbiotic theory in 1967

prokaryotes > FECA > LECA > LUCA

the stages of evolution of eukaryotes

first eukaryotic common ancestor (FECA)

the theoretical ancestral population or lineage that emerged after the eukaryotic line split from its closest prokaryotic relatives; with internal membrane compartments

last eukaryotic common ancestor (LECA)

a complex, single-celled organism that lived roughly 1.5 to 2 billion years ago; the most recent common ancestor shared by all plants, animals, fungi, and protists alive today; possessed modern hallmark features like mitochondria, cilia, intron splicing, and meiosis

intron

a non-coding part of a gene; copied into RNA during gene transcription, but it is cut out before the RNA makes a protein

exon

a segment of a DNA or RNA molecule containing information that codes for a protein or persists in mature messenger RNA (mRNA)

codon

a DNA or RNA sequence of three nucleotides (a trinucleotide) that forms a unit of genomic information encoding a particular amino acid

AUG

codes for methionine (met)

CCA

codes for proline (pro)

UUU

codes for phenylalanine (phe)

12 million base pairs encoding about 6200 proteins

DNA content of a simple baker's yeast/eukaryotic cell

mitochondria

where chemical energy is made available to fuel cellular activities

cristae

the inward folds of the inner membrane of a mitochondrion; dramatically increase the surface area of the membrane, allowing the cell to produce more chemical energy efficiently

endoplasmic reticulum

where many of a cell's proteins and lipids are manufactured

Golgi complexes

where materials are sorted, modified, and transported to specific cellular destinations

chloroplasts

for plant cells only; the sites of photosynthesis, and often a single large vacuole that can occupy most of the volume of the cell

cytosol

the soluble phase of the cytoplasm

centromere

the narrow, pinched middle part of a duplicated chromosome that holds two identical sister chromatids together

sister chromatids

two identical copies of a single chromosome

histone proteins

basic proteins that pack and order DNA into structural units called nucleosomes

meiosis

a specialized type of cell division that reduces the chromosome number by half, producing four unique haploid sex cells (gametes like sperm and eggs) from one diploid parent cell

mitosis

a complex process within eukaryotic cells in which duplicated chromosomes condense into compact structures that are segregated by an elaborate microtubule-containing apparatus

mitotic spindle

a microtubule-containing apparatus which allows each daughter cell to receive an equivalent array of genetic material

Louis Pasteur (1862)

discovered microbes that cause fermentation and disease; originated pasteurization; pioneered in developing vaccines (rabies and anthrax- which is flu-like, caused by Bacillus anthracis)

Bacillus anthracis

a Gram-positive and rod-shaped bacterium that causes anthrax, a deadly disease to livestock and, occasionally, to humans