The cell Flashcards
What are the 4 fundamental tenets of the cell theory
1) All living things are composed of cells
2) The cell is the basic functional unit of life
3) Cells arise from only preexisting cells
4) Cells carry information (DNA) and is passed on from parent to daughter cell
Does the MCAT consider viruses living organisms
No
What is the difference between eukaryotic and prokaryotic cells
prokaryotic cells do not contain any membrane bound organelles
Briefly Describe the phospholipid bilayer of eukaryotic cells
extracellular hydrophilic ends and intracellular hydrophobic ends.
What allows for the diffusion of molecules throughout the cell
cytosol
Whats the importance of nuclear pores
allow selective two-way exchange of material between the cytoplasm and the nucleus
The outer mitochondria membranes purpose
barrier between cytosol and the inner environment of the mitochondria
the inner mitochondria membranes purpose
contains molecules and enzymes that make up the electron transport chain
what is cristae
numerous infoldings of the inner mitochondria
Why are mitochondria “semi-autonomous” (2)
they contain some of their own genes and replicate independently of the nucleus
how do mitochondria replicate?
binary fission independent of the nucleus
lysosomes purpose
break down different substrates
Rough ER purpose
stubbed with ribosomes; permits translation of proteins
Smooth ER purpose
lipid synthesis
Golgi apparatus purpose
modifies cellular products by adding carbs, phosphates, or sulphates
peroxisomes purpose
break down long chain fatty acids, synthesize phospholipids, and contain enzymes in the pentose phosphate pathway
What causes muscle contraction
actin filaments use ATP and react with myosin
Order the 3 cytoskeletal elements in increasing size
microfilaments, microtubules, intermediate filaments
What are microfilaments made of
actin proteins
what are microtubules made of
tublin proteins
What motor proteins use microtubules to carry vessicles
kinesin and dynein
what is the difference between cilia and flagella
cillia dont move the cell, but flagella move the entire cell
how do the cytoskeletal structures of centrioles and flagella differ
centrioles consist of nine triplets of microtubules around a hollow center, while flagella consist of nine doublets on the outside with two microtubules on the inside
what are intermediate filaments made of
keratin, desmin, vimentin, lamins
What are the 4 types of tissue
epithelial tissue, connective tissue, muscle tissue, and nervous tissue.
what are the 3 germs lines
ectoderm, mesoderm, endoderm
What is the purpose of epithelial tissue
1) cover and line the body; protects against pathogen invasion and desiccation
2) in organs; absorption, secretion, and sensation
Why are epithelial cells polarized
bc they usually face an inside and outside (of the body/organ)
importance of archaea
1) ability to use alternative sources of energy
2) used to be consider extromphiles
3) contain genes and metabolic pathways
what is archaea most similar to
Eukaryotes
NOT bacteria
Most Bacteria exist in what 3 shapes
1) cocci - spherical
2) bacilli - rod
3) spirilli - spiral
describe obligate aerobes
require oxygen for metabolism
describe obligate anaerobes
cannot survive in oxygen-containing environments
describe facultative anaerobes
can use oxygen for metabolism but doesn’t require it
describe aerotolerant anaerobes
cant us oxygen for metabolism but is not harmed by it
Bacteria cells are either gram positive or gram negative describe their properties and functions
gram positive: cell walls consist of a thick layer of peptidoglycan which contains lipoteichoic acid (purple)
gram negative: cell walls are thin and contain less peptidoglycan; which is separated from the membrane by the periplasmic space. the outermembranes contain phospholipids and lipopolysaccharides. (pink
what is chemotaxis
ability for a cell to detect a chemical stimuli and move towards or away from it
what is the basal body
the basal body is a complex structure that anchors the flagellum to the cytoplasmic membrane and is also the motor of the flagellum
describe binary fission
a simple form of asexual reproduction seen in prokaryotes, the circular chromosome attaches to the cell wall and replicates while the cell continues to grow in size.
what are plasmids
extrachromosomal material that carry genes
what are virulence factors
traits that increase pathogenicity
what distinguishes episomes
episomes are a subset of plasmids that are capable of integrating into the genome of the bacterium
describe the processes of genetic recombination
Transformation: results from integration of foreign genetic material into the host genome. (gram negative)
Conjugation: two bacteria form a conjugation bridge, genetic material is transferred unidirectionally from donor male (+) to replicant female (-). to form the sex pili bacteria must contain plasmids known as sex factors
Transduction: requires a vector that carries genetic material to another bacteria. (bacteriophages)
describe how the e.coli F factor works
F+ cells replicate the F factor and donates a copy to the F- converting it to a F+ cell. cells that have undergone this change are referred to by the abbreviation Hfr. (high frequency recombination
what are bacteriophages
viruses that infect bacteria
what are transposons
genetic elements capable of inserting and removing themselves from the genome
what are the 4 phases of the bacterial growth curve and there features
Lag phase: get used to environment; little growth
Exponential phase: use available resources to multiply at an exponential rate
Stationary phase: bacterial multiplication slows as resources are used up
Death phase: bacteria die as resources become insufficient to support the colony
Describe viral structure
viruses are composed of genetic material, a protein coat (capsid), and sometimes an envelope containing lipids
what are virions
viral progeny
viral genomes can either be
single or double stranded RNA or DNA
describe positive and negative sense single-stranded RNA viruses
positive: genome can be directly translated to functional proteins by the ribosomes of the host cell, like mRNA
Negative: more complicated; RNA acts as a template for synthesis of a complementary strand which can then be used as a template for protein synthesis
negative sense RNA viruses must carry _ in the virion to ensure the complementary strand is synthesized
RNA replicase
Retrovirus properties
enveloped single stranded RNA viruses; the virion contains two identical RNA molecules. carry reverse transcriptase, which synthesizes DNA from RNA. DNA integrates into the host genome where it is replicated and transcribed. Allows cell to be infected indefinitely.
Describe the Viral life cycle
Infection: virion is inserted into the host cell
Translation and progeny assembly: viral RNA is translated into proteins
Progeny release: cell death, extrusion, and lysing released virions
lytic and lysogenic cycles:
what is extrusion
extrusion is when a virus can leave a cell by fusing with its plasma membrane. keeps host cell alive. a virus in this state is said to be in a productive cycle
be able to describe both the lytic and lysogenic cycle
Draw them out
what are prions
infectious proteins that cause disease by triggering misfolding of other proteins. usually from a a-helical to a B-pleated sheet.
what are viroids
small pathogens consisting of a very short circular s-s RNAs that infect plants. can silence genes in the plant genome
What types of nucleic acid could form the genome of a virus
SS DNA, SS RNA, DS DNA
perioxisome functions
breakdown lipids and carbohydrates
