A2.2 SL / HL Flashcards
Cell theory
theory states thatall biological organisms are composed of cells; cells are the unit of life and all life come from preexisting life
Prokaryotes
any organism that lacks a distinct nucleus and other organellesdue to the absence of internal membranes
binary fission
the process of one cell simply dividing into two. It is most commonly used in archaea and bacteria, which are both prokaryotic organisms
Eukaryotes
any cell or organism that possesses a clearly defined nucleus. The eukaryotic cell has a nuclear membrane that surrounds the nucleus
mitosis
a process of cell duplication, or reproduction, during which one cell gives rise to two genetically identical daughter cells
meiosis
a type of cell division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells
Inductive reasoning
a form of logical thinking that uses related observations to arrive at a general conclusion
spontaneous generation
the supposed production of livingorganismsfrom non-living matter, asinferredfrom the apparent appearance of life in somesupposedlysterileenvironments
Deductive reasoning
a form of logical thinking that uses a general principle or law to forecast specific results
Theory
a widely accepted explanation of a biological phenomenon based on sound evidence from rigorous empirical experiments and scientific observations
microscope
an instrument that is used to magnify small objects
Magnification
the increase in size of an object when it is viewed through a microscope or other optical device
Resolution
the ability to distinguish two objects from each other. Light microscopy has limits to both its resolution and its magnification
Field of view (FOV)
the maximum area visible through the lenses of a microscope, and it is represented by a diameter
Compound light microscope
a high magnification microscope that uses 2 lenses to compound (multiply) the level of magnification
Electron microscope
an instrument that uses a beam of electrons to magnify a specimen. It has a higher resolution power of up to 100,000X
Tunneling electron microscope (TEM)
a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image
Scanning electron microscope (SEM)
a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons
Freeze-fracture
physically breaking apart (fracturing) a frozen biological sample
Integral proteins
a type of membrane protein that is permanently attached to the biological membrane
fluid mosaic model
describes the main characteristics of the plasma membrane
Immunofluorescence
a method commonly used in neuroscience to detect viral antigens by directly applying fluorescent dyes to samples, such as nasopharyngeal aspirate or biopsy samples, and observing them under a fluorescent microscope
Fluorescent stains
a pivotal molecular technique that brings to light the structures within biological cells and tissues through fluorescence
antibodies
proteins that protect you when an unwanted substance enters your body
Cryogenic electron microscope
a version of electron microscopy that freezes many copies of a delicate sample into a glassy state and hits them with an electron beam
permeability
the passage of molecules through a biological membrane or a barrier
plasma membrane
amicroscopicmembrane oflipidsand proteins which forms the external boundary of thecytoplasmof a cell orenclosesavacuole, and regulates the passage of molecules in and out of the cytoplasm
Hydrophobic
a property of molecules that do not mix with water
cytoplasm
the gelatinous liquid that fills the inside of a cell. It is composed of water, salts, and various organic molecules
70s ribosomes
In prokaryotes, these subunits are50S(large) and30S(small). The total ribosome with both subunits is 70S in prokaryotes
80s ribosomes
found in the cytoplasm of eukaryotic cells
Capsule
a layer of slime outside the bacterial cell wall, composed mainly of polysaccharides or polypeptides
polysaccharides
long chains of carbohydrate molecules, composed of several smaller monosaccharides
Cell wall
a structural layer that surrounds some cell types, found immediately outside the cell membrane. It can be tough, flexible, and sometimes rigid
peptidoglycan
a polymer consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane of most bacteria, forming the cell wall
Phospholipid bilayer
a two-layered arrangement of phosphate and lipid molecules that form a cell membrane, the hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward
Pili
short, hair-like structures on the cell surface of prokaryotic cells
plasmids
a small, circular, double-stranded DNA moleculethat is distinct from a cell’s chromosomal DNA
Flagellum
hairlike structure that acts primarily as an organelle of locomotion in the cells of many living organisms
metabolic reactions
a chemical process in living systems that transforms molecules to make them more chemically stable, permeable, polar, and less toxic
Nucleoid
an irregularly shaped region within the prokaryotic cell that contains all or most of the genetic material
naked DNA
DNA that is not associated with lipids, proteins, or any other molecule to help protect it
conjugation
the process by which one bacterium transfers genetic material to another through direct contact
antibiotic resistance
occurs when bacteria evolve to evade the effect of antibiotics through multiple different mechanisms
membrane-bound organelles
a membrane bound structure found within a cell
compartmentalization
the separation of the cell interior in distinct compartments with specific local conditions that allow the simultaneous occurrence of diverse metabolic reactions and processes
nucleus
the structure in a cell that contains the chromosomes
nuclear envelope
the nuclear membrane, is made up oftwo lipid bilayer membranes that in eukaryotic cells surround the nucleus
Nuclear pores
a protein-lined channel in the nuclear envelope that regulates the transportation of molecules between the nucleus and the cytoplasm
euchromatin
the less tightly coiled DNA that allows transcription factors and chromatin remodelers access, enabling transcription to occur