MCAT biology review ch `1

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. This genetic material is passed on from parent to daughter cell

virus

these are not considered living things because they are acellular, cannot reproduce without the assistance of host cell, and may use RNA as their genetic material

eukaryotes

have membrane bound organelles, a nucleus and may form multi cellular organisms

phospholipids

the cell membrane of organelles contain this which organizes to form hydrophilic interior and exterior surfaces with a hydrophobic core

cytosol

suspends the organelles and allows diffusion of molecules throughout the cell

nucleus

contains DNA organized into chromosomes. it is surrounded by a membrane or envelope.

chromosome

a thread-like structure containing DNA and proteins that carries genetic information in the form of genes, organized within the cell nucleus

nuclear envelope

a double-membrane structure surrounding the nucleus, separating it from the cytoplasm

nuclear pore

a small channel within the nuclear envelope that allows substances to enter and exit the nucleus

genes

a small channel within the nuclear envelope that allows substances to enter and exit the nucleus

nucleolus

subsection of the nucleus where ribosomal rna (rRNA) is synthesized

mitochondria

the "powerhouse of the cell" - membrane-bound organelles responsible for generating the cell's energy through cellular respiration

outer mitochondrial membrane

forms a barrier with the cytosol . a phospholipid bilayer that surrounds the mitochondrion, acting as a barrier between the organelle and the rest of the cell. It's freely permeable to small molecules and contains channels called porins that allow larger molecules to cross. 

inner mitochondrial membrane

highly specialized membrane within a mitochondrion that serves as the primary site for the electron transport chain (ETC) and ATP synthesis.

binary fission

how does the mitochondria divide independently of the nucleus

lysosomes

contain hydrolytic enzymes that can break down substances ingested by endocytosis and cellular waste products. When released these enzymes autolysis of the cell can occur

endoplasmic reticulum (ER)

a series of interconnected membranes that are continuos with the nuclear envelope.

rough ER

studded with ribosomes which permit translation of proteins destined for secretion

smooth ER

used for lipid synthesis and detoxification

golgi apparatus

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

peroxisomes

contain hydrogen peroxide and can break down very long chain fatty acids via B oxidation. They also participate in phospholipid synthesis and the PPP

cytoskeleton

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

microfilaments

composed of actin. they provide structural protection for the cell and can cause muscle contraction through interactions with myosin. They also help form the cleavage furrow during cytokinesis in mitosis

actin

Forms thin filamnet. a key protein involved in muscle contraction and various other cellular movements, particularly in the cytoskeleton. It's a structural protein that, along with myosin, forms contractile filaments in muscle cells. Actin also plays a role in cell shape, division, and migration

myosin

a motor protein, is crucial for muscle contraction. It forms thick filaments and interacts with thin filaments (actin) to generate movement and tension.

cleavage furrow

the indentation of the cell's surface that begins the progression of cleavage,

microtubules

composed of tubulin. Creates pathways for motor proteins like kinesin and dynein to carry vesicles. They also contribute to the structure of cilia and flagella

kinesin

a motor protein that uses ATP to move along microtubules in a cell. It specifically transports cargo from the center of the cell toward the periphery, also known as anterograde transport.

dynein

a motor protein that moves along microtubule filaments in a retrograde direction to transport various cellular cargos.

cilia

short hairlike structures that are used to move entire cells or substances along the outer surface of the cell

flagella

long wavy structures that extend from the plasma membrane and are used to move an entire cell

(9+2) structure

he axoneme, the core structure of cilia and flagella in eukaryotic cells. It's a specific arrangement of microtubules, described as nine pairs (doublets) of microtubules surrounding a central pair of single microtubules. This structure is responsible for the movement of cilia and flagella. 

centrioles

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

centrosome

an organelle near the nucleus of a cell that contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division

mitotic spindle

the apparatus that orchestrates the movement of chromosomes during mitosis.

intermediate filaments

are involved in cell-cell adhesion and maintenance of the integrity of the cytoskeleton; they help anchor organelles. (ex are keratin and desmin)

epithelial tissues

cover the body and line its cavities protecting against pathogen invasion and desiccation. Some absorb or secrete substances or participate in sensation

parenchyma

functional parts of the organ

simple epithelia

one layer

stratified epithelia

many layers

pseudostratified epithelia

appear to have many layers due to differences in cell height, but actually only has one layer

cuboidal cells

cube shaped

columnar cells

long and narrow

squamous cells

flat and scale like

connective tissues

support the body and provide the framework for epithelial cells

stroma

the supporting framework of an organ, gland, or tissue, distinct from the parenchyma (the functional cells). It's primarily composed of connective tissue, blood vessels, and nerves, providing structural support, nutrients, and waste removal. 

connective tissue examples

bone, cartilage, blood, tendons ligaments, adipose tissue

extracellular matrix

a complex network of proteins and other molecules that surrounds and supports cells in tissues

prokaryotes

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

nucleoid region

where DNA in prokaryotic cells is located

archaea bacteria eukarya

3 overarching domains of life

archaea

often extremophiles, living in harsh environments and often use chemical sources of energy rather than light. They have simularities to both eukaryotes and bacteria

bacteria

have many similar structures to eukaryotes and have complex relationships to humans

mutualistic symbiosis

close, long-term interaction between two different species where both species benefit from the relationship.

eukarya

the only non prokaryotic domain

cocci

spherical bacteria

bacillia

rod shaped bacteria

spirilli

spiral shaped bacteria

obligate aerobes

require oxygen for metabolism

obligate anaerobes

cannot survive in oxygen containing environments (can only carry out this type of metabolism)

facultative anaerobes

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

aerotolerant anaerobes

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

envelope

the cell wall and cell membrane of bacteria form this. Together they control the movement of solutes into and out of the cell

gram positive

turns purple, has a thick cell wall composed of peptidoglycan and lipoteichoic acid

gram negative

turns pink red, has a thin cell wall composed of peptoglycan and an outer membrane containing phospholipids and lipopolysaccharides

chemotaxis

moving in response to chemical stimuli

cell membrane

prokaryotes lack mitochondria so they carry out the electron transport chain using —-

prokaryotic ribosome

30s 50s

eukaryotic ribosome

40s 60s

binary fission

how to prokaryotes multiply

binary fission

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

plasmids

a piece of an extragenomic DNA molecule that exists and replicates independently from the chromosomal DNA within a cell. may contain antibiotic resistance genes or virulence factors

virulence factors

traits or structures that enable a pathogen to cause disease. They are essentially the tools a pathogen uses to colonize a host, evade the immune system, and cause damage.

episomes

plasmids that can integrate into the genome

transformation

genetic material from the surroundings is take up by a cell, which can incorperate this material into its genome

conjugation

The transfer of genetic material from one bacterium to another across a conjugation bridge; a plasmid can be transferred from a nF+ cell to an F- cell, or a portion of the genome can be transferred from an Hfr cell to recipient

conjugation bridge

is the physical connection that forms between two bacterial cells during DNA transfer

transduction

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

transposons

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

lag phase

bacteria adapt to new local conditions

exponential (log) phase

bacterial growth increases exponentially

stationary phase

as resources are reduced bacteria growth levels off

death phase

as resources are depleted bacteria undergo death

virus

contain genetic material (RNA), a protein coat and cometimes a lipid containing envelope

virus

obligate intracellular parasites, meaning they cannot survive and replicate outside of a host cell.

virions

individual virus particles

increases

bacterial genetic recombination —- bacterial diversity

Bacteriophages

viruses that target bacteria. they contain a tail sheath and tail fibers

tail sheath

a structure on a bacteriophage that which injects the genetic material into a bacterium

tail fibers

a component of the bacteriophage which allows it to attach to the host cell

viral genomes

may be composed of various nucleic acids. Can be composed of DNA or RNA and may be single or double stranded.

single stranded RNA viruses

can be positive or negative sense

positive sense

can be translated by the host cell

negative sense

required a complementary strand to be synthesized by RNA replicase before translation

retroviruses

contain a single strand RNA genome, from which a complementary DNA strand can then be integrated into the genome

how viruses infect cells

attaching to specific receptors and then entering the cell by fusing with the plasma membrane or by endocytosis, or by entering the cell’s genome

cell death, lysis, extrusion

how can viral progeny be released from the cell”?

lytic cycle

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

virulent

bacteria in the lytic phase

lysogenic cycle

the virus integrates into the hose genome as a provirus of 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