Biology: Chapter 1 Flashcards
Eukaryotic cell
-Membrane bound organelles
-Cytosol
-phospholipid bilayer
-DNA in nucleus
-reproduce through mitosis
Cytosol
-semifluid that suspends organelles in eukaryotic cells
-allows for the diffusion of molecules throughout the cell
Nucleus
-Contains all of the genetic material necessary for replication of the cell
-Surrounded by nuclear membrane
-Nuclear pores in the nuclear membrane allow selective two-way exchange of material between the cytoplasm and the nucleus
-The nucleolus is where ribosomal RNA (rRNA) is synthesized
Genes
-coding regions of DNA
-linear DNA is wound around organizing proteins called histones, and is further wound into linear strands called chromosomes
Mitochondria
-Outer membrane: serves as a barrier between the cytosol and the inner environment of the mitochondrion
-Inner membrane: arranged into numerous infoldings called cristae, contains the molecules and enzymes of the electron transport chain
-Mitochondria have cytoplasmic/extranuclear inheritance
Intermembrane space
space between the inner and outer membranes of mitochondria
Mitochondrial matrix
space inside the inner membrane of the mitochondria
Cristae
-infoldings of the inner membrane of the mitochondria
-increase the surface area available for electron transport chain enzymes
Lysosomes
-contain hydrolytic enzymes that are capable of breaking down different substrate
-when hydrolytic enzymes are released, it results in apoptosis
Endosomes
-often function in conjunction with lysosomes
-transport, package, and sort cell materials traveling to and from the membrane
Rough Endoplasmic Reticulum
studded with ribosomes, which permit the translation of proteins destined for secretion directly into its lumen
Smooth Endoplasmic Reticulum
-lacks ribosomes
-utilized primarily for lipid synthesis and detoxification of certain drugs and poisons
-SER also transports proteins from the RER to the Golgi apparatus
Golgi Apparatus
-Materials from the ER are transferred here in vesicles
-cellular products may be modified by the addition of groups like carbohydrates, phosphates, and sulfates once inside here
-After modification and sorting, cellular products are repackaged in vesicles, which are then directed to the correct cellular location
Peroxisomes
-Contain hydrogen peroxide
-Breakdown very long chain fatty acids via -oxidation
-Participate in the synthesis of phospholipids and contain some of the enzymes involved in the pentose phosphate pathway
Cytoskeleton
-Provides structure to the cell and helps it to maintain its shape
-Microfilaments, microtubules, intermediate filaments
Microfilaments
-made up of rods of actin
-Actin filaments are resistant to both compression and fracture
-Actin filaments can also use ATP to generate force for movement by interacting with myosin (muscle contraction)
-Microfilaments also play a role in cytokinesis
Microtubules
-hollow polymers of tubulin proteins
-Provide the primary pathways along which motor proteins like kinesin and dynein carry vesicles
-Cilia and flagella are composed of microtubules
-Cilia are involved in the movement of materials along the surface of the cell
-Flagella are structures involved in the movement of the cell itself
Intermediate Filaments
-involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton
-They are able to withstand tremendous amounts of tension, increasing the structural rigidity of the cell
-They also help anchor other organelles.
Epithelial tissue
-Cover the body and line its cavities. In certain organs, epithelial cells are involved in absorption, secretion, and sensation
-Basement membrane: underlying connective tissue that tightly joins epithelial cells together
-In most organs, epithelial cells constitute the parenchyma, or the functional parts of the organ
-Often polarized: one side faces a lumen (hollow inside of an organ or tube or the outside world) while the other side interacts with underlying blood vessels and structural cells
-Classified by numbers of layers (simple, stratified, and pseudostratified) and shape (cuboidal, columnar, and squamous)
Connective Tissue
-Supports the body and provides framework for the epithelial cells to carry out their functions
-Main contributors to the stroma (support structure)
-Examples include bone, cartilage, tendons, ligaments, adipose tissue, and blood
-Most cells in connective tissues produce and secrete materials such as collagen and elastin to form the extracellular matrix
Prokaryotes
don’t contain any membrane-bound organelles, and their genetic material is organized into a single circular molecule of DNA concentrated in an area of the cell called the nucleoid region
Archaea
-single-celled organisms that are visually similar to bacteria, but contain genes and several metabolic pathways
-Ability to use alternative sources of energy (photosynthetic and chemosynthetic)
-Contain a circular chromosome, divide by binary fission or budding, and share a similar overall structure to bacteria. Also resistant to many antibiotics
Bacteria
-Contain a circular chromosome, divide by binary fission or budding, and share a similar overall structure to bacteria. Also resistant to many antibiotics
-3 Bacteria shapes: cocci (spherical), bacilli (rod-shaped), and spirilli (spiral-shaped)
Obligate aerobes
bacteria that require oxygen for metabolism
Anaerobes
bacteria that don’t require oxygen for metabolism
Obligate anaerobes
bacteria that cannot survive in an oxygen-containing environment
Facultative anaerobes
can switch between using oxygen for aerobic metabolism if present or anaerobic metabolism if its not
Aerotolerant anaerobes
unable to use oxygen for metabolism, but aren’t harmed by its presence in the environment
Cell wall (prokaryotic cell structure)
-Provides structure and controls the movement of solutes into and out of the bacterium
-Cell wall and cell membrane are known as the envelope
Gram-positive cell wall
consist of a thick layer of peptidoglycan. Offers structural and barrier functions and aids a bacterial pathogen by providing protection from a host organism’s immune system. These cell walls also contain lipoteichoic acid
Gram-negative cell wall
very thin and contain much smaller amounts of peptidoglycan. Also contain lipopolysaccharides that trigger immune response in human beings
Flagella (prokaryotic cell structure)
-Can be used to move toward food or away from toxins or immune cells
-Composed of a filament, a basal body, and a hook
-Filament: a hollow, helical structure composed of flagellin
-Basal body: anchors the flagellum to the cytoplasmic membrane and is also the motor of the flagellum
-Hook: connects the filament and the basal body so that, as the basal body rotates, it exerts torque on the filament, which then spins and propels the bacterium forward
Binary Fission
-simple form of asexual reproduction
-proceeds more rapidly than mitosis
Genetic recombination
plasmids are extrachromosomal materials that carry genes that impart some benefit to the bacterium such as antibiotic resistance
Transformation
results from the integration of foreign genetic material into the host genome which usually comes from other bacteria that spill their contents into the vicinity of a bacteria capable of transformation
Conjugation
bacterial form of mating (sexual reproduction). Involves two cells forming a conjugation bridge between them that facilitates the transfer of genetic material. Transfer is unidirectional from the donor male (+) to the recipient female (-)
Transduction
the only genetic recombination process that requires a vector- a virus that carries genetic material from one bacterium to another. When a bacteriophage infects another bacterium, it can release its trapped DNA into the new host cell and this transferred DNA can then integrate into the genome, giving the new host additional genes
Transposons
genetic elements capable of inserting and removing themselves from the genome. Can be seen in both prokaryotes and eukaryotes.
Lag phase (growth of prokaryotic cell)
in the new environment, bacteria first adapt to the new local conditions
Exponential/log phase (growth of prokaryotic cell)
as the bacteria adapt, the rate of division increases, causing an exponential increase in the number of bacteria in the colony
Stationary phase (growth of prokaryotic cell)
as the number of bacteria in the colony grows, resources are often reduced. The reduction of resources slows reproduction and this phase result
Death phase (growth of prokaryotic cell)
After the bacteria have exceeded the ability of the environment to support the number of bacteria, this phase occurs, marking the depletion of resources
Viral structure
-Composed of genetic material, a protein coat (capsid), and sometimes an envelope containing lipids. The envelope is very sensitive to heat, detergents, and desiccation; thus, enveloped viruses are easier to kill
-Viruses must express and replicate genetic information within a host cells because they lack ribosomes to carry out protein synthesis
-After hijacking a cell’s machinery, a virus will replicate and produce viral progeny, called virions, which can be released to infect additional cells
Bacteriophages
-viruses that specifically target bacteria. They inject their genetic material, leaving the remaining structures outside the infected cell
-Contain a tail sheath and tail fibers
-Tail sheath can act like a syringe, injecting genetic material into a bacterium
-Tail fibers help the bacteriophage recognize and connect to the correct host cell
Positive sense (single-stranded RNA virus)
genome may be directly translated to functional proteins by the ribosomes of the host cell, just like mRNA
Negative sense (single-stranded RNA virus)
negative-sense RNA strand acts as a template for protein synthesis of a complementary strand, which can then be used as a template for protein synthesis. Must carry and RNA replicase in the virion to ensure that the complementary strand is synthesized
Retroviruses
enveloped, single-stranded RNA viruses and usually, the virion contains two identical RNA molecules. Carry an enzyme known as reverse transcriptase, which synthesizes DNA from single-stranded RNA
Viral life cycle
-Viruses infect cells by attaching to specific receptors, and then enter the cell by fusing with the plasma membrane, being brought in by endocytosis, or injecting their genome into the cell
-The virus reproduces by replicating and translating genetic material using the host’s ribosomes, tRNA, amino acids, and enzymes
-Viral progeny are released through cell death, lysis, or extrusion
Lytic cycle (life cycle of bacteriophage)
bacteriophage produces massive numbers of new virions until the cell lyses. Termed virulent
Lysogenic cycle (life cycle of bacteriophage)
virus integrates into the host genome as a provirus or prophage, which can then reproduce along with the cell. The provirus can remain in the genome indefinitely, or may leave the genome in response to a stimulus and enter the lytic cycle
Prions
infectious proteins that trigger misfolding of other proteins, usually converting an -helical structure to a -pleated sheet. This decreases the solubility of the protein and increases its resistance to degradation
Viroids
plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and, potentially, cell death
