MCAT Biology - The Cell

The Cell

Four Tenants of the Cell Theory

All living things are composed of cels, The cell is basic functional unit of life, cells arise only from pre-existing cells, Cells carry genetic information in form of DNA and is passed on from parent to daughter cell

Cytosol

Allows for diffusion of molecules throughout the cell

Nucleus

Contains genetic information for replication of the cell

Nuclear Pores

Allow selective two way exchange of material between cytoplasm and nucleus

Nucleolus

Ribosomal RNA synthesized

Outermembrane of Mitochondria

Serves as barrier between cytosol and inner environments of mitochondria

Inner membrane of Mitochondria

Contains molecules and enzymes of electron transport chain

Intermembrane space

Space between inner and outer membrane

Mitochondrial Matrix

Space inside inner membrane

Lysosomes

Membrane bound structures containing hydrolytic enzymes that are capable of breaking down many different substrates

Endosomes

Transport package and sort cell material traveling to and from the membrane

Cytoplasmic inheritance

transmission of genetic material independent of the nucleus

Apoptosis

Programmed cell death

Endoplasmic Reticulum

Series of interconnected membranes that are contiguous with the nuclear envelope

Smooth ER

Lack ribosomes, utilized for lipid synthesis, detoxification of certain drugs and posions, and transport proteins from teh Rough ER to Golgi

Golgi Apparatus

Modification of cellular products

Peroxisomes

Break down long chain of fatty acid via B oxidation

Rough ER

Interconnected membranous structure with ribosomes studding the outside, site of synthesis of protein destined for insertion into a membrane or secretion

Cytoskeleton

Provides structure to cell and helps maintain its function

Microfilaments

Made of actin, resistnat to compression and fracture providing protection for cell and plays a role in cytokinesis.

Microtubules

Hollow polymers of Tubulin,

Centrioles

Organizing centers for microtubules and are structured as nine triplet of microtubules

Flagella structure

nine pair of mirotubule forming an outer ring with two microtubules in the center

Intermediate filaments

Diverse group of filamentous proteins, involved cell cell adhesion or maintence of overall itegrity of cytoskeleton, help anchor other organelles

Epithelia tissue

Covers body and lines its cavities, providing a means for protection against pathogen invasion and desiccitation.

Parenchyma

Functional parts of the organ

Simple epithelia

One layer of cells

Stratified epithelia

Multiple layers of cells

Pseudostratified epithelia

Appear multiple layer form difference in cell height, but actually ne layer

Cuboidal

Cube shaped

Columnor

Long and thin

Squamous

flat and scale like

Connective tissue

Supports the body and provides a framework for epithelial cells to carry out their unction

Stroma

supportive structure

Light microscopy

Use visible light and lenses to produce a magneified image

Confocal microscopy

Has increased optical resolution through the use of a spatial pinhole that blocks out of focus light to create sharper images

Immunohistochemistry

Antibodies with fluorescent probes are used to label different subcellular components to better visualize the sample allowing better contrast resolution

Scanning electron microscope

Use electron instead of visible light to create an image, resulting in much higher resolution compared to light

Transmission electron microscopy

Pass through the ultrathin sections of specimen to create an image

Flourescence Microscopy

General term that refers to any type of microscopy that uses fluoresecence as means of visulization,

Archea

Single celled organisms visually similar to bacteria but contain genes and several metabolic pathways more similar to eukarya

Extremophiles

Found harsh environments with extremly high temp, high salinity, no light

Mutualistic Symbioles

Both humans and bacteria benefit from relationship

Pathogen/Parasite

No advantage or benefit to host, rather cause disease

Cocci

Spherical Shape

Bacilli

Rod Shaped

Spirilli

Spiral Shape

Obligate aerobes

Require oxygen for metabolism

Anaerobe

cellular metabolism that does not require oxygen

Obligate anaerobe

anaerobes cannot survive in oxygen containing environment

Faculitative anerobe

Switch between metabolic processes using oxygen if present but switching anerobic metabolism if not

Aerotolerant anaerobe

Unable to use oxygen for metabolism but not harmed by its presence

Cell Wall

Forms outer barrier of the cell

Cell Membrane

Composed of phospholipids

Envelope

Cell wall and cell membrane

Gram Positive

Envelope absorbs crystal violet stain (deep purple color)

Gram Negative

Envelope does not absorb crystal violet stain, but absorbs the safranin counterstain (pink red color)

Peptidoglycen in Gram +

Gram + cell walls consist of thick layer of peptidoglycen and also contain lipoteichoic acid

Peptidoglycen in Gram -

Gram - cell walls thin and contain little amounts of peptidoglycen

Periplasmic space

Separates the cell wall and cell membrane

Plasmids

Cary DNA that is not necessary for survival but may confer an advantage such as antibiotic resistance

Flagella

Long whip like structures that can be used for propulsion

Chemotaxis

ability of cell to detect chemical stimuli and move toward or away from it

Filament

hollow helical structure composed of flagellin

basal body

complex structure anchors flagellum to cytoplasmic membrane and motor of flagellum

hook

connects filament and basal body so when basal body rotate it exerts torque on the filament

Binary Fission

Form of asexual reproduction seen in prokaryotes

Virulence factor

trait that incrase pathogenicity

Episomes

A subset of plasmids capable of integrating into the genome of the bacterium

Transformation

Results from the integration of foreign genetic material into the host genome

Competence

State in which extracellular DNA can be taken up

Transformation efficency

effectiveness of transformation

Conjugation

two cells form a conjugation bridge between them that facilitate transfer of genetic material

What is bridge made of

sex pilli found on donor male

Transduction

Bacteriophage infects another bacterium, released trapped DNA into new host

Vector

A virus that carrier genetic material from one bacterium to another

Bacteriophage

Virus that infects bacteria

Hfr (High frequency of recombination)

cells that have undergone this change

Transposons

Genetic elements capable of inserting and removing themselves from the genome

Lag phase

Bacteria first adapt to new conditions

Exponential/log phase

bascteria adapt rate division increases, causing exponential increase in number of bacteria in a colony

Stationary phase

resources redduces, reduction resources slows reproduction

Death Phase

Bacteria exceed ability of environment to support number of bacteria

Capsid

Protein coat of virus

Tail Sheath

Like a syringe, injecting genetic material into bacterium

Tail fibers

Help the bacteriophage recognize and connect to correct host cell

Positive Sense

Implies that the genome may be directly transform to functional proteins by the ribosomes of the host

Negative Sense

RNA viruses are a bit more complicated, the negative sense RNA strand acts as a template for synthesis of complementary strand

Retroviruses

enveloped single stranded RNA viruses in teh family Retrovivdae

Reverse transcriptase

syntehsizes DNA from single stranded RNA

Lytic cycle

The bacteriophage maximizes the use of the cell’s machinery with little regard for survival of host cell. Once host is swollen with new virions the cell lyses, other bacteria can be infected.

Prions

Infectious proteins cause innerfolding

Viroids

small pathogens consisting of a very short circular single strnaded RNA that infect plants.