MCAT Biology Review

cell theory

states that all living things are composed of cells, the cell is the basic functional unit of life, cells arise only from preexisting cells, and cells carry genetic information in the form of deoxyribonucleic acid (DNA) and this genetic material is passed on from parent to daughter cell

living, cells, cell, functional unit, cells, preexisting cells, cells, genetic, deoxyribonucleic acid (DNA), genetic, mother, daughter cells

cell theory:

• all _____ things are composed of _____

• the _____ is the basic _____ _____ of life

• _____ arise only from _____ _____

• _____ carry _____ information in the form of _____ _____ (_____). this _____ material is passed on from _____ to _____ _____

reproduce, invading, ribonucleic acid (RNA)

cell theory has created a dilemma with respect to viruses:

• viruses are small structure that contain genetic material, but are unable to _____ on their own

  • can only replicate by _____ other organisms

  • use _____ _____ (_____) as their genetic information

eukaryotic cell

cell that contains a true nucleus enclosed in a membrane; organisms can be unicellular or multicellular

prokaryotic cell

cell that does not contain a nucleus; organisms are always single celled

cytosol, membrane, compartmentalization, phospholipid bilayer, hydrophilic, hydrophobic, selective, cytosol, nucleus, deoxyribonucleic acid (DNA), chromosomes, mitosis, identical

membrane-bound organelles:

• each cell has a membrane enclosing a semifluid _____ in which the organelles are suspended

• in eukaryotic cells, most organelles are _____ bound, allowing for _____ of functions

• membranes of eukaryotic cells consists of a _____ _____

  • surfaces are _____, electrostatically interacting with the _____ environments inside and outside of the cell

  • inner portion is _____, which helps to provide a highly _____ barrier between the interior of the cells and the external environment

• the _____ allows for the diffusion of molecules throughout the cell

• within the _____, genetic material is encoded in _____ _____ (_____), which is organized into _____

• eukaryotic cells reproduce by _____, allowing for the formation of two _____ daughter cells

nuclear membrane, envelope, double, nuclear pores, nuclear membrane, selective, cytoplasm, nucleus, genes, linear, histones, linear, chromosomes, DNA transcription, RNA translation, nucleolus, ribosomal RNA (rRNA)

the nucleus:

• surrounded by the _____ _____ or _____, a _____ membrane that maintains a nuclear environment separate and distinct from the cytoplasm

• _____ _____ in the _____ _____ allow _____ two-way exchange of material between the _____ and the _____

• the genetic material (DNA) contains coding regions called _____

• _____ DNA is wound around organizing proteins known as _____, and is then further wound into _____ strands called _____

• the location of DNA in the nucleus permits the compartmentalization of _____ _____ separate from _____ _____

• there is a subsection of the nucleus known as the _____, where the _____ _____ (_____) is synthesized

nuclear membrane/envelope

a double membrane surrounding the nucleus that maintains a nuclear environment separate and distinct from the cytoplasm

nuclear pores

pores in the nuclear membrane that allow selective two-way exchange of material between the cytoplasm and the nucleus

genes

coding regions contained in the genetic material (DNA)

histones

organizing proteins that linear is wound around

chromosomes

linear strands formed by further wounding of DNA and histones

nucleolus

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

two, outer, inner, cytosol, inner, cristae, electron transport chain, cristae, surface area, electron transport chain, intermembrane space, mitochondrial matrix, semi-autonomous, genes, binary fission, cytoplasmic, extranuclear inheritance, aerobic prokaryote, anaerobic prokaryote, electron transport chain, apoptosis

mitochondria:

• contains _____ layers: the _____ and _____ membranes

  • the outer membrane serves as a barrier between the _____ and the _____ environment of the mitochondrion

  • the inner membrane, which is arranged into numerous infoldings called _____, contains the molecules and enzymes of the _____ _____ _____

    • the _____ are highly convoluted structures that increase the _____ _____ available for _____ _____ _____ enzymes

  • the space between the inner and outer membranes is called the _____ _____

  • the space inside the inner membrane is called the _____ _____

• different from other parts of the cell in that they are _____

  • contain some of their own _____

  • replicate independently of the nucleus via _____ _____

    • paradigmatic examples of _____ or _____ _____: the transmission of genetic material independent of the nucleus

  • thought to have originated when the engulfing of an _____ _____ by an _____ _____ resulted in a symbiotic relationship

• also capable of killing the cell by release of enzymes from the _____ _____ _____

  • this release kick-starts a process known as _____, or programmed cell death

outer membrane

the outer layer of the two layers of the mitochondrion that serves as a barrier between the cytosol and the inner environment of the mitochondrion

inner membrane

the inner layer of the two layers of the mitochondrion, which is arranged into numerous infoldings called cristae, that contains the molecules and enzymes of the electron transport chain

cristae

numerous and highly convoluted infoldings of the inner membrane of the mitochondria that increase the surface area available for electron transport chain enzymes

intermembrane space

the space between the inner and outer membranes of the mitochondria

mitochondrial matrix

the space inside the inner membrane of the mitochondria

cytoplasmic or extranuclear inheritance

the transmission of genetic material independent of the nucleus; mitochondria are paradigmatic examples of this

apoptosis

programmed cell death; another function/role of the mitochondria by releasing enzymes from the electron transport chain

membrane, hydrolytic enzymes, endosomes, lysosomal membrane, autolysis, apoptosis, degradation

lysosomes:

• _____-bound structures containing _____ _____ that are capable of breaking down many different substrates, including substances ingested by endocytosis and cellular waste products

• often function in conjunction with _____, which transport, package and sort cell material traveling to and from the membrane

• the _____ _____ sequester these enzymes to prevent damage to the cell

  • release of these enzymes can occur in a process known as _____

    • like mitochondria, when lysosomes release their hydrolytic enzymes, it results in _____

    • the released enzymes directly lead to the _____ of cellular components

lysosomes

membrane-bound structures containing hydrolytic enzymes that are capable of breaking down many different substrates, including substances ingested by endocytosis and cellular waste products

endosomes

transport, package and sort cell material traveling to and from the cell membrane

autolysis

process that releases the hydrolytic enzymes from lysosomes that results in apoptosis

nuclear envelope, double, central lumen, ribosomes, translation, proteins, lumen, ribosomes, lipid synthesis, detoxification, proteins, RER, Golgi apparatus

endoplasmic reticulum (ER):

• a series of interconnected membranes that are actually contiguous with the _____ _____

• the _____ membrane is folded into numerous invaginations, creating complex structures with a _____ _____

• two varieties of ER:

  • rough ER (RER):

    • studded with _____, which permit the _____ of _____ destined for secretion directly into its _____

  • smooth ER (SER):

    • lacks _____ and is utilized primarily for _____ _____ (such as the _____ in the cell membrane) and the _____ of certain drugs and poisons

    • also transports _____ from the _____ to the _____ _____

endoplasmic reticulum (ER)

a series of interconnected double membranes that are actually contiguous with the nuclear envelope and is folded into numerous invaginations, creating complex structures with a central lumen; two varieties: smooth and rough

rough endoplasmic reticulum (RER)

one of the two varieties of ER that is studded with ribosomes, which permit the translation of proteins destined for secretion directly into its lumen

smooth endoplasmic reticulum (SER)

one of the two varieties of ER that lacks ribosomes and is utilized primarily for lipid synthesis (such as the phospholipids in the cell membrane), the detoxification of certain drugs and poisons, and transportation of proteins from the RER to the Golgi apparatus

stacked, ER, vesicles, vesicles, secretory vesicle, exocytosis

Golgi apparatus:

• consists of _____ membrane-bound sacs

• materials from the _____ are transferred to the Golgi apparatus in _____

• once inside the Golgi apparatus, these cellular products may be modified by the addition of groups like carbohydrates, phosphates, and sulfates

• the Golgi apparatus may also modify cellular products through the introduction of signal sequences, which direct the delivery of the product to a specific cellular location

• after modification and sorting in the Golgi apparatus, cellular products are repackaged in _____, which are then directed to the correct cellular location

• if the product is destined for secretion, the _____ _____ merges with the cell membrane and its contents are released via _____

Golgi apparatus

stacked membrane-bound sacs that receive cellular materials and products from the ER in vesicles and modify and sort these cellular products before being repackaged in vesicles and directed to the correct cellular location

exocytosis

process of secreting a cellular product when a secretory vesicle merges with the cell membrane and its contents are released

hydrogen peroxide, chain fatty acids, B-oxidation, synthesis, lipids

peroxisomes:

• contain _____ _____

• one of the primary functions of peroxisomes is the breakdown of very long ____ ____ ____ via _____-_____

• participate in the _____ of _____ and contain some of the enzymes involved in the pentose phosphate pathway

peroxisomes

contains hydrogen peroxide and functions in the breakdown of very long chain fatty acids via B-oxidation and synthesis of phospholipids

structure, shape, transport, microfilaments, microtubules, intermediate filaments

Cytoskeleton:

• provides _____ to the cell and helps it to maintain its _____

• provides a conduit for the _____ of material around the cell

• three components of the cytoskeleton:

  • _____

  • _____

  • _____ _____

actin, actin, protection, ATP, myosin, muscle contraction, cytokinesis, cleavage furrow, contract

microfilaments:

• made up of solid polymerized rods of _____

• the _____ filaments are organized into bundles and networks and are resistant to both compression and fracture, providing _____ for the cell

• can also use _____ to generate force for movement by interacting with _____, such as in _____ _____

• also play a role in _____, or the division of materials between daughter cells

  • during mitosis, the _____ _____ is formed from microfilaments, which organize as a ring at the site of division between the two new daughter cells

  • as the actin filaments within this ring _____, the ring becomes smaller, eventually pinching off the connection between the two daughter cells

microfilaments

one of the components of the cytoskeleton that are made up of solid polymerized rods of actin, organized into bundles and networks and are resistant to both compression and fracture, providing protection for the cell, can also use ATP to generate force for movement by interacting with myosin, such as in muscle contraction, and also play a role in cytokinesis

myosin

motor proteins that can interact with microfilaments (actin filaments) to generate force for movement, such as in muscle contraction

cytokinesis

the division of materials between daughter cells; microfilaments (actin filaments) play a role by forming the cleavage furrow at the site of division between the two new daughter cells

cleavage furrow

organization of microfilaments as a ring at the site of division between the two new daughter cells during cytokineses

hollow, tubulin, kinesin, dynein, cilia, flagella, surface, cell, nine pairs, outer, two, 9+2, eukaryotic, centrosome, organizing, nine triplets, mitotic spindle, kinetochores

microtubules:

• _____ polymers of _____ proteins

• radiate throughout the cell, providing primary pathways along with motor proteins like _____ and _____ carry vesicles

• _____ and _____ are motor structures composed of microtubules

  • cilia:

    • projections from a cell that are primarily involved in the movement of materials along the _____ of the cell

  • flagella:

    • structures involved in the movement of the _____ itself

  • share the same structure, composed of _____ _____ of microtubules forming an _____ ring, with _____ microtubules in the center

    • known as a _____ structure

    • seen only in _____ organelles of motility

• centrioles:

  • found in the region of the cell called the _____

  • _____ centers for microtubules and are structured as _____ _____ of microtubules with a hollow center

  • during mitosis, the centrioles migrate to opposite poles of the dividing cell and organize the _____ _____

  • the microtubules emanating from the centrioles attach to the chromosomes via complex called _____ and ever force on the sister chromatids, pulling them apart

microtubules

one of the components of the cytoskeleton that are hollow polymers of tubulin proteins that radiate throughout the cell, providing the primary pathways along with motor proteins like kinesin and dynein carry vesicles

kinesin, dynein

motor proteins that carry vesicles along primary pathways provided by microtubules

cilia, flagella

motile structure composed of microtubules

cilia

projections from a cell that are primarily involved in the movement of materials along the surface of the cell; one of the motile structures composed of microtubules

flagella

structure involves in the movement of the cell itself; one of the motile structures composed of microtubules

9+2

structure of cilia and flagella composed of nine pairs of microtubules forming an outer ring, with two microtubules in the center

centrioles

organizing centers for microtubules found in a region of the cell called the centrosome and are structured as nine triplets of microtubules with a hollow center

centrosome

region of the cell where centrioles are found

kinetochores

complexes where the microtubules emanating from the centrioles attach to the chromosomes and force is exerted on the sister chromatids to pull them apart

keratin, desmin, vimentin, lamins, cell-cell adhesion, organelles, nucleus

intermediate filaments:

• diverse group of filamentous proteins, which includes _____, _____, _____ and _____

• involved in _____-_____ _____ or maintenance of the overall integrity of the cytoskeleton

  • able to withstand a tremendous amount of tension, increasing the structural integrity of the cell

• help anchor other _____, including the _____

intermediate filaments

one of the components of the cytoskeleton that are a diverse group of filamentous proteins (includes keratin, desmin, vimentin, and lamins) and involved in cell-cell adhesion, maintenance of the overall integrity of the cytoskeleton, and anchoring other organelles

epithelial, connective, muscle, nervous

four tissue types

body, cavities, protection, absorption, secretion, sensation, basement membrane, parenchyma, polarized, lumen, outside world, blood vessels, structural cells, number, shape, simple, stratified, pseudostratified, cuboidal, columnar, squamous

epithelial tissue:

• cover the _____ and lines its _____, providing a means for _____ against pathogen invasion and desiccation

• in certain organs, epithelial cells are involved in _____, _____, and _____

• to remain as one cohesive unit, epithelial cells are tightly joined to each other and to an underlying layer of connective tissue known as the _____ _____

• in most organs, epithelial cells constitute the _____, or the functional parts of the organ

• epithelial cells are often _____, meaning that one side faces a _____ (the hollow inside of an organ or tube) or the _____ _____, while the other side interacts with the underlying _____ _____ and _____ _____

• classified according to the _____ of layers and _____ of the cells

  • _____ epithelia have one layer of cells

  • _____ epithelia have multiple layers

  • _____ epithelia appear have multiple layers due to differences in cell height but are, in reality, only one layer

  • _____ cells are cube-shaped

  • _____ cells are long and thin

  • _____ cells are flat and scale-like

epithelial tissue

tissue type that covers the body and lines its cavities, providing a means for protection against pathogen invasions; in organs, constitutes the parenchyma, the functional parts of the organ

basement membrane

underlying layer of connective tissue that allow for epithelial cells to be tightly joined to each other and to remain as one cohesive unit

parenchyma

functional parts of the organ that epithelial tissues constitute

epithelial tissue classification based on number of layers

simple, stratified, pseudostratified

simple epithelia

epithelia that have one layer of cells

stratified epithelia

epithelia that have multiple layers of cells

pseudostratified epithelia

epithelia that appear to have multiple layers due to difference in cell height but are, in reality, only one layer

epithelial tissue classification based on shape of cells

cuboidal, columnar, squamous

cuboidal

cube-shaped cells

columnar

long and thin cells

squamous

flat and scale-like cells

epithelial, parenchyma, stroma, bone, cartilage, tendons, ligaments, adipose tissue, blood, collagen, elastin, extracellular matrix

connective tissue:

• supports the body and provides a framework for the _____ cells to carry out their functions

• whereas epithelial cells contribute to the _____ of an organ, connective tissues are the main contributors to the _____ or support structure

• examples:

  • _____

  • _____

  • _____

  • _____

  • _____ _____

  • _____

• most cells in connective tissues produce and secrete materials such as _____ and _____ to form the _____ _____

connective tissue

tissue type that supports the body and provides a framework for the epithelial cells to carry out their functions; in organs, are the main contributors to the stroma

stroma

non-functional, structural parts of an organ

extracellular matrix