chapter 1

4 basic tenets of the cell theory

All living things are composed of cells, The cell is the basic functional unit of life, Cells arise only from preexisting cells, Cells carry genetic information in the form of DNA

have membrane-bound organelles, a nucleus, and may form multicellular organisms

eukaryotes

suspends the organelles and allows diffusion of molecules throughout the cell

cytosol

contains DNA

nucleus

what is dna organized into?

chromosomes

a double membrane that contains nuclear pores for two-way exchange of materials between the nucleus and cytosol

nuclear membrane

a subsection of the nucleus in which ribosomal RNA (rRNA) is synthesized

nucleolus

outer membrane forms a barrier with the cytosol; the inner membrane is folded into cristae and contains enzymes for the electron transport chain

mitochondria

contain hydrolytic enzymes that can break down substances ingested by endocytosis and cellular waste products

lysosomes

a series of interconnected membranes and is continuous with the nuclear envelope

endoplasmic reticulum (ER)

studded with ribosomes, which permit translation of proteins destined for secretion

rough endoplasmic reticulum (RER)

used for lipid synthesis and detoxification

smooth endoplasmic reticulum (SER)

consists of stacked membrane-bound sacs in which cellular products can be modified, packaged and directed to specific cellular locations

golgi apparatus

contain hydrogen peroxide and can break down very long chain fatty acids via beta oxidation

peroxisomes

provides stability and rigidity to the overall structure of the cell, while also providing transport pathways for molecules within the cell

cytoskeleton

composed of actin

microfilaments

provide structural protection for the cell and can cause muscle contraction through interactions with myosin

microfilaments

help form the cleavage furrow during cytokinesis in mitosis

microfilaments

composed of tubulin

microtubules

create pathways for motor proteins like kinesin and dynein to carry vesicles

microtubules

organized into nine pairs of microtubules in a ring with two microtubules at the center

cilia and flagella

found in centrosomes and are involved in microtubule organization in the mitotic spindle

centrioles

involved in cell-cell adhesion and maintenance of the integrity of the cytoskeleton

intermediate filaments

functional parts of the organ

parenchyma

do not contain membrane-bound organelles; they contain their genetic material in a single circular molecule of DNA located in the nucleoid region

prokaryotes

often extremophiles, living in harsh environments (high temperature, high salinity, no light) and often use chemical sources of energy (chemosynthesis) rather than light (photosynthesis)

archaea

have many similar structures to eukaryotes, and have complex relationships with humans, including mutualistic symbiosis and pathogenesis

bacteria

require oxygen for metabolism

obligate aerobes

cannot survive in oxygen-containing environments and can only carry out anaerobic metabolism

obligate anaerobes

can survive in environments with or without oxygen and will toggle between metabolic processes based on the environment

facultative anaerobes

cannot use oxygen for metabolism, but can survive in an oxygen-containing environment

aerotolerant anaerobes

the chromosome replicates while the cell grows in size, until the cell wall begins to grow inward along the midline of the cell and divides it into two identical daughter cells

binary fission

occurs when genetic material from the surroundings is taken up by a cell, which can incorporate this material into its genome

transformation

the transfer of genetic material from one bacterium to another

conjugation

the transfer of genetic material from one bacterium to another via a bacteriophage vector

transduction

genetic elements that can insert into or remove themselves from the genome

transposons

The bacteria adapt to new local conditions

lag phase

Growth then increases exponentially

exponential (log) phase

As resources are reduced, growth levels off

stationary phase

As resources are depleted

death phase

contain genetic material, a protein coat (capsid), and sometimes a lipid-containing envelope

viruses

single-stranded RNA viruses that can be translated by the host cell

positive sense

single-stranded RNA viruses that require a complementary strand to be synthesized by RNA replicase before translation

negative sense

contain a single-stranded RNA genome, from which a complementary DNA strand is made using reverse transcriptase

retroviruses

the bacteriophage produces massive numbers of new virions until the cell lyses

lytic cycle

bacteria in the lytic phase

virulent

the virus integrates into the host genome as a provirus or prophage, which can then reproduce along with the cell

lysogenic cycle

infectious proteins that trigger misfolding of other proteins, usually converting an a-helical structure to a B-pleated sheet

prions

plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and, potentially, cell death

viroids